Materiały źródłowe

• #1 Hypothyroidism – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK519536/

  Hypothyroidism results from low levels of thyroid hormone with varied etiology and manifestations. Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate amounts of thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function. Autoimmune thyroiditis and iodine deficiency are the most common causes of the disease. Central hypothyroidism is rare. […] The most common cause of hypothyroidism is the inability of the thyroid gland to produce a sufficient amount of thyroid hormone; however, less commonly, pituitary and hypothalamus impairment may also result in thyroid dysfunction. The hypothalamus secretes thyrotropin-releasing hormone (TRH) that stimulates the pituitary gland to produce thyroid-stimulating hormone (TSH). Thyroid-stimulating hormones stimulate the thyroid gland to produce and secrete mainly T4, approximately 100 to 125 nmol daily, and smaller quantities of T3. The half-life of T4 is 7 to 10 days, and eventually, T4 is converted to T3 peripherally by 5′-deiodination. Negative feedback on the production of TRH and TSH is exerted primarily by T3 and, to some extent, T4. Alterations in the structure and function of any of these organs or pathways can result in hypothyroidism.

• #2 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone. In the United States and other areas of adequate iodine intake, autoimmune thyroid disease (Hashimoto disease) is the most common cause of hypothyroidism; worldwide, iodine deficiency remains the foremost cause. […] Hypothyroidism can also be secondarythat is, the thyroid gland itself is normal, but it receives insufficient stimulation because of low secretion of thyrotropin (ie, thyroid-stimulating hormone [TSH]) from the pituitary gland. This generally occurs in the presence of other pituitary hormone deficiencies. In tertiary hypothyroidism, inadequate secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus leads to insufficient release of TSH, which in turn causes inadequate thyroid stimulation. However, this is rare.

• #3 Hypothyroidism – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK519536/

  Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate amounts of thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function.

• #4 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone. In the United States and other areas of adequate iodine intake, autoimmune thyroid disease (Hashimoto disease) is the most common cause of hypothyroidism; worldwide, iodine deficiency remains the foremost cause. […] Hypothyroidism can also be secondarythat is, the thyroid gland itself is normal, but it receives insufficient stimulation because of low secretion of thyrotropin (ie, thyroid-stimulating hormone [TSH]) from the pituitary gland. This generally occurs in the presence of other pituitary hormone deficiencies. In tertiary hypothyroidism, inadequate secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus leads to insufficient release of TSH, which in turn causes inadequate thyroid stimulation. However, this is rare.

• #5

  https://step2.medbullets.com/endocrine/120098/hypothyroidism-vs-hyperthyroidism

  Hypothyroidism is a disorder characterized by the under production of thyroid hormone. […] Pathogenesis is primarily due to thyroid disease (primary hypothyroidism) but can be caused by secondary and/or tertiary hypothyroidism. […] Primary hypothyroidism is often due to Hashimoto thyroiditis (chronic autoimmune thyroiditis), which involves cell- and antibody-mediated destruction of thyroid tissue. […] Secondary hypothyroidism is caused by TSH deficiency secondary to any of the causes of hypopituitarism, most commonly due to a pituitary tumor. […] Tertiary hypothyroidism is caused by any disorder that damages the hypothalamus or interferes with hypothalamic-pituitary portal blood flow.

• #6 Hypothyroidism – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK519536/

  Hypothyroidism results from low levels of thyroid hormone with varied etiology and manifestations. Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate amounts of thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function. Autoimmune thyroiditis and iodine deficiency are the most common causes of the disease. Central hypothyroidism is rare. […] The most common cause of hypothyroidism is the inability of the thyroid gland to produce a sufficient amount of thyroid hormone; however, less commonly, pituitary and hypothalamus impairment may also result in thyroid dysfunction. The hypothalamus secretes thyrotropin-releasing hormone (TRH) that stimulates the pituitary gland to produce thyroid-stimulating hormone (TSH). Thyroid-stimulating hormones stimulate the thyroid gland to produce and secrete mainly T4, approximately 100 to 125 nmol daily, and smaller quantities of T3. The half-life of T4 is 7 to 10 days, and eventually, T4 is converted to T3 peripherally by 5′-deiodination. Negative feedback on the production of TRH and TSH is exerted primarily by T3 and, to some extent, T4. Alterations in the structure and function of any of these organs or pathways can result in hypothyroidism.

• #7 Hypothyroidism – Wikipedia

  https://en.wikipedia.org/wiki/Hypothyroidism

  The hypothalamic-pituitary-thyroid axis plays a key role in maintaining thyroid hormone levels within normal limits. Production of TSH by the anterior pituitary gland is stimulated in turn by thyrotropin-releasing hormone (TRH), released from the hypothalamus. Production of TSH and TRH is decreased by thyroxine by a negative feedback process. […] Pregnancy leads to marked changes in thyroid hormone physiology. The gland increases in size by 10%, thyroxine production increases by 50%, and iodine requirements increase.

• #8 Definition, Causes, Pathophysiology, and Management of Hypothyroidism

  https://www.mathewsopenaccess.com/full-text/definition-causes-pathophysiology-and-management-of-hypothyroidism

  TSH, which is created and secreted in the anterior pituitary under activation of thyrotropin-releasing hormone produced in the hypothalamus, directly stimulates thyroid gland hormone synthesis. The thyroid glands metabolism is regulated by a negative feedback regulatory system in people with a healthy hypothalamic-pituitary-thyroid axis. TSH levels are controlled by the pituitary gland in response to feedback from free-thyroxine (FT4) and free-triiodothyronine (FT3) levels, which act as biosensors of thyroid hormone levels. […] The control system has a rather sluggish response time, and it is possible to detect some discrepancy between the levels of TSH and the plasma thyroid hormone concentrations during non-equilibrium periods, which happen at the beginning of hypothyroidism.

• #9 Hypothyroidism – Wikipedia

  https://en.wikipedia.org/wiki/Hypothyroidism

  The hypothalamic-pituitary-thyroid axis plays a key role in maintaining thyroid hormone levels within normal limits. Production of TSH by the anterior pituitary gland is stimulated in turn by thyrotropin-releasing hormone (TRH), released from the hypothalamus. Production of TSH and TRH is decreased by thyroxine by a negative feedback process. […] Pregnancy leads to marked changes in thyroid hormone physiology. The gland increases in size by 10%, thyroxine production increases by 50%, and iodine requirements increase.

• #10 2. Pathophysiology and Diagnosis of Thyroid Disease | Medicare Coverage of Routine Screening for Thyroid Dysfunction | The National Academies Press

  https://nap.nationalacademies.org/read/10682/chapter/4

  Hypothyroidism is a hypometabolic state that results from a deficiency in T4 and T3. Its major clinical manifestations are fatigue, lethargy, cold intolerance, slowed speech and intellectual function, slowed reflexes, hair loss, dry skin, weight gain, and constipation. It is more prevalent in women than men. The most common cause of hypothyroidism is disease of the thyroid itself, primary hypothyroidism. […] The most common cause of primary hypothyroidism is chronic autoimmune thyroiditis (Hashimotos disease), in which the thyroid is destroyed by antibodies or lymphocytes that attack the gland. Other causes are radioactive iodine and surgical therapy for hyperthyroidism or thyroid cancer, thyroid inflammatory disease, iodine deficiency, and several drugs that interfere with the synthesis or availability of thyroid hormone. Hypothyroidism may also occur rarely (1 percent of cases) as a result of deficiency of TRH or impaired TSH secretion due to hypothalamic or pituitary disease, respectively. This is known as secondary or central hypothyroidism because of the negative feedback relationship between serum T4 and T3 levels and TSH secretion. As noted earlier and shown in Figure 2-1, people with primary hypothyroidism have high serum TSH levels. If an individual has a high serum TSH value, serum free T4 should be measured. The concomitant finding of a high serum TSH concentration and a low free T4 level confirms the diagnosis of primary hypothyroidism. People with a high serum TSH concentration and a normal or low-normal serum free T4 level have, by definition, subclinical hypothyroidism. The diagnosis of secondary hypothyroidism is based on the findings of a low serum free T4 level and a serum TSH level that is normal or low. People with secondary hypothyroidism are unlikely to be detected by a screening program based on measurements of serum TSH, but the condition is much less common than primary hypothyroidism.

• #11 2. Pathophysiology and Diagnosis of Thyroid Disease | Medicare Coverage of Routine Screening for Thyroid Dysfunction | The National Academies Press

  https://nap.nationalacademies.org/read/10682/chapter/4

  Hypothyroidism is a hypometabolic state that results from a deficiency in T4 and T3. Its major clinical manifestations are fatigue, lethargy, cold intolerance, slowed speech and intellectual function, slowed reflexes, hair loss, dry skin, weight gain, and constipation. It is more prevalent in women than men. The most common cause of hypothyroidism is disease of the thyroid itself, primary hypothyroidism. […] The most common cause of primary hypothyroidism is chronic autoimmune thyroiditis (Hashimotos disease), in which the thyroid is destroyed by antibodies or lymphocytes that attack the gland. Other causes are radioactive iodine and surgical therapy for hyperthyroidism or thyroid cancer, thyroid inflammatory disease, iodine deficiency, and several drugs that interfere with the synthesis or availability of thyroid hormone. Hypothyroidism may also occur rarely (1 percent of cases) as a result of deficiency of TRH or impaired TSH secretion due to hypothalamic or pituitary disease, respectively. This is known as secondary or central hypothyroidism because of the negative feedback relationship between serum T4 and T3 levels and TSH secretion. As noted earlier and shown in Figure 2-1, people with primary hypothyroidism have high serum TSH levels. If an individual has a high serum TSH value, serum free T4 should be measured. The concomitant finding of a high serum TSH concentration and a low free T4 level confirms the diagnosis of primary hypothyroidism. People with a high serum TSH concentration and a normal or low-normal serum free T4 level have, by definition, subclinical hypothyroidism. The diagnosis of secondary hypothyroidism is based on the findings of a low serum free T4 level and a serum TSH level that is normal or low. People with secondary hypothyroidism are unlikely to be detected by a screening program based on measurements of serum TSH, but the condition is much less common than primary hypothyroidism.

• #12 Hypothyroidism | Nature Reviews Disease Primers

  https://www.nature.com/articles/s41572-022-00357-7

  Hypothyroidism is the common clinical condition of thyroid hormone deficiency and, if left untreated, can lead to serious adverse health effects on multiple organ systems, with the cardiovascular system as the most robustly studied target. Overt primary hypothyroidism is defined as elevated thyroid-stimulating hormone (TSH) concentration in combination with free thyroxine (fT4) concentration below the reference range. Subclinical hypothyroidism, commonly considered an early sign of thyroid failure, is defined by elevated TSH concentrations but fT4 concentrations within the reference range. Hypothyroidism is classified as primary, central or peripheral based on pathology in the thyroid, the pituitary or hypothalamus, or peripheral tissue, respectively. Acquired primary hypothyroidism is the most prevalent form and can be caused by severe iodine deficiency but is more frequently caused by chronic autoimmune thyroiditis in iodine-replete areas.

• #13 Hypothyroidism (Underactive Thyroid): Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/12120-hypothyroidism

  Hypothyroidism (underactive thyroid disease) is a condition that happens when your thyroid gland doesnt make or release enough hormone into your bloodstream. As a result, your metabolism slows down. This can cause unintentional weight gain and make you feel exhausted all the time. […] Hashimotos disease is the most common cause of hypothyroidism. Its an autoimmune disease, so it happens when your immune system attacks your thyroid. […] Without treatment, hypothyroidism can become a serious and life-threatening medical condition.

• #14 Metabolic Characteristics of Hashimoto’s Thyroiditis Patients and the Role of Microelements and Diet in the Disease Management—An Overview

  https://www.mdpi.com/1422-0067/23/12/6580

  Hashimoto’s thyroiditis (HT) is the most common autoimmune disease and the leading cause of hypothyroidism, in which damage to the thyroid gland occurs due to the infiltration of lymphocytes. […] The pathogenesis of HT is related to lymphocytic intrathyroidal infiltration of T and B cells, especially of CD4+ Th1 and the production of antithyroid antibodies. […] The exact mechanisms underlying AIT pathogenesis are not fully understood. Multiple factors from the external environment and the genetic background contribute to the pathogenesis of HT. […] Several genes have been involved in HT pathogenesis, including genes of the immune response (coded in the Human Leukocyte Antigen (HLA) complex) and thyroid function. […] The therapy of hypothyroidism as a result of HT is a daily, oral administration of synthetic thyroid hormone- levothyroxine, at a dosage of 1.6–1.8 micrograms per kilogram of body weight.

• #15 Metabolic Characteristics of Hashimoto’s Thyroiditis Patients and the Role of Microelements and Diet in the Disease Management—An Overview

  https://www.mdpi.com/1422-0067/23/12/6580

  Hashimoto’s thyroiditis (HT) is the most common autoimmune disease and the leading cause of hypothyroidism, in which damage to the thyroid gland occurs due to the infiltration of lymphocytes. […] The pathogenesis of HT is related to lymphocytic intrathyroidal infiltration of T and B cells, especially of CD4+ Th1 and the production of antithyroid antibodies. […] The exact mechanisms underlying AIT pathogenesis are not fully understood. Multiple factors from the external environment and the genetic background contribute to the pathogenesis of HT. […] Several genes have been involved in HT pathogenesis, including genes of the immune response (coded in the Human Leukocyte Antigen (HLA) complex) and thyroid function. […] The therapy of hypothyroidism as a result of HT is a daily, oral administration of synthetic thyroid hormone- levothyroxine, at a dosage of 1.6–1.8 micrograms per kilogram of body weight.

• #16 Hashimoto’s thyroiditis – Wikipedia

  https://en.wikipedia.org/wiki/Hashimoto%27s_thyroiditis

  Hashimoto’s thyroiditis is thought to be due to a combination of genetic and environmental factors. […] The pathophysiology of autoimmune thyroiditis is not well understood. However, once the disease is established, its core processes have been observed: Hashimoto’s thyroiditis is a T-lymphocyte mediated attack on the thyroid gland. […] The three major antibodies are: Thyroid peroxidase Antibodies (TPOAb), Thyroglobulin Antibodies (TgAb), and Thyroid stimulating hormone receptor Antibodies (TRAb), with TPOAb and TgAb being most commonly implicated in Hashimoto’s. […] They are hypothesized to develop as a result of thyroid damage, where T-lymphocytes are sensitized to residual thyroid peroxidase and thyroglobulin, rather than as the initial cause of thyroid damage. […] However, they may exacerbate further thyroid destruction by binding the complement system and triggering apoptosis of thyroid cells. […] Hypothyroidism is caused by replacement of follicular cells with parenchymatous tissue.

• #17 Hashimoto’s thyroiditis – Wikipedia

  https://en.wikipedia.org/wiki/Hashimoto%27s_thyroiditis

  Hashimoto’s thyroiditis is thought to be due to a combination of genetic and environmental factors. […] The pathophysiology of autoimmune thyroiditis is not well understood. However, once the disease is established, its core processes have been observed: Hashimoto’s thyroiditis is a T-lymphocyte mediated attack on the thyroid gland. […] The three major antibodies are: Thyroid peroxidase Antibodies (TPOAb), Thyroglobulin Antibodies (TgAb), and Thyroid stimulating hormone receptor Antibodies (TRAb), with TPOAb and TgAb being most commonly implicated in Hashimoto’s. […] They are hypothesized to develop as a result of thyroid damage, where T-lymphocytes are sensitized to residual thyroid peroxidase and thyroglobulin, rather than as the initial cause of thyroid damage. […] However, they may exacerbate further thyroid destruction by binding the complement system and triggering apoptosis of thyroid cells. […] Hypothyroidism is caused by replacement of follicular cells with parenchymatous tissue.

• #18 Hashimoto’s thyroiditis – Wikipedia

  https://en.wikipedia.org/wiki/Hashimoto%27s_thyroiditis

  Hashimoto’s thyroiditis is thought to be due to a combination of genetic and environmental factors. […] The pathophysiology of autoimmune thyroiditis is not well understood. However, once the disease is established, its core processes have been observed: Hashimoto’s thyroiditis is a T-lymphocyte mediated attack on the thyroid gland. […] The three major antibodies are: Thyroid peroxidase Antibodies (TPOAb), Thyroglobulin Antibodies (TgAb), and Thyroid stimulating hormone receptor Antibodies (TRAb), with TPOAb and TgAb being most commonly implicated in Hashimoto’s. […] They are hypothesized to develop as a result of thyroid damage, where T-lymphocytes are sensitized to residual thyroid peroxidase and thyroglobulin, rather than as the initial cause of thyroid damage. […] However, they may exacerbate further thyroid destruction by binding the complement system and triggering apoptosis of thyroid cells. […] Hypothyroidism is caused by replacement of follicular cells with parenchymatous tissue.

• #19

  https://link.springer.com/article/10.1007/s40618-020-01477-1

  Regulatory T cell (Treg) are now well established as having a critical role in preventing autoimmunity. […] In terms of thyroid cell injury, cytokines derived from the lymphocytic infiltrate play a key role, including their ability to stimulate the thyroid cells themselves to release proinflammatory mediators, thus amplifying and perpetuating the autoimmune response. […] A further proinflammatory cascade has been identified in HT with the finding of increased expression of multiple inflammasome components (NLRP1, NLRP3, NLRC4, AIM2, ASC, and caspase-1) and their associated cytokines (IL-18 and IL-1) in the thyroid of patients, as well as identification of inflammasome component release by thyroid cell stimulated in vitro with the IFN- and tumour necrosis factor-, which may in turn contribute to further cytokine release and cell death through pyroptosis. […] The PD-1/PD ligand-1 axis has also been investigated. This pathway plays a major role in suppressing adaptive immunity in a variety of settings, including the immune response by tumour cells, and as we have seen, blockade can result in autoimmune disease.

• #20

  https://link.springer.com/article/10.1007/s40618-020-01477-1

  Regulatory T cell (Treg) are now well established as having a critical role in preventing autoimmunity. […] In terms of thyroid cell injury, cytokines derived from the lymphocytic infiltrate play a key role, including their ability to stimulate the thyroid cells themselves to release proinflammatory mediators, thus amplifying and perpetuating the autoimmune response. […] A further proinflammatory cascade has been identified in HT with the finding of increased expression of multiple inflammasome components (NLRP1, NLRP3, NLRC4, AIM2, ASC, and caspase-1) and their associated cytokines (IL-18 and IL-1) in the thyroid of patients, as well as identification of inflammasome component release by thyroid cell stimulated in vitro with the IFN- and tumour necrosis factor-, which may in turn contribute to further cytokine release and cell death through pyroptosis. […] The PD-1/PD ligand-1 axis has also been investigated. This pathway plays a major role in suppressing adaptive immunity in a variety of settings, including the immune response by tumour cells, and as we have seen, blockade can result in autoimmune disease.

• #21

  https://link.springer.com/article/10.1007/s40618-020-01477-1

  Regulatory T cell (Treg) are now well established as having a critical role in preventing autoimmunity. […] In terms of thyroid cell injury, cytokines derived from the lymphocytic infiltrate play a key role, including their ability to stimulate the thyroid cells themselves to release proinflammatory mediators, thus amplifying and perpetuating the autoimmune response. […] A further proinflammatory cascade has been identified in HT with the finding of increased expression of multiple inflammasome components (NLRP1, NLRP3, NLRC4, AIM2, ASC, and caspase-1) and their associated cytokines (IL-18 and IL-1) in the thyroid of patients, as well as identification of inflammasome component release by thyroid cell stimulated in vitro with the IFN- and tumour necrosis factor-, which may in turn contribute to further cytokine release and cell death through pyroptosis. […] The PD-1/PD ligand-1 axis has also been investigated. This pathway plays a major role in suppressing adaptive immunity in a variety of settings, including the immune response by tumour cells, and as we have seen, blockade can result in autoimmune disease.

• #22 Hypothyroidism – Endocrine and Metabolic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/thyroid-disorders/hypothyroidism

  Hypothyroidism is thyroid hormone deficiency. […] Primary hypothyroidism is due to decreased secretion of thyroxine (T4) and triiodothyronine (T3) from the thyroid. […] In the United States, the most common cause is autoimmune inflammation. […] The second most common cause is treatment for hyperthyroidism (post-therapeutic hypothyroidism), especially after radioactive iodine therapy or surgery for hyperthyroidism, goiter, or thyroid cancer. […] Iodine deficiency may cause endemic goiter and goitrous hypothyroidism. […] Rare inherited enzymatic defects can alter the synthesis of thyroid hormone and cause goitrous hypothyroidism. […] Hypothyroidism may occur in patients taking lithium, perhaps because lithium inhibits hormone release by the thyroid. […] Hypothyroidism can result from radiation therapy for cancer of the larynx or Hodgkin lymphoma.

• #23 Hypothyroidism (Underactive Thyroid): Symptoms, Causes, Treatment

  https://www.healthline.com/health/hypothyroidism/symptoms-treatments-more

  The most common causes of hypothyroidism are: Hashimotos thyroiditis, radioactive iodine treatment, thyroid surgery, radiation therapy, medications, and iodine deficiency. […] Hashimotos thyroiditis is an autoimmune condition and the most common cause of an underactive thyroid in the United States. This disease attacks your thyroid gland, causing damage that reduces thyroid function. […] If your entire thyroid gland is removed as a result of thyroid problems, youll develop hypothyroidism. […] Radiation used for the treatment of these conditions may slow or halt the production of thyroid hormone, leading to hypothyroidism. […] Several medications may lower thyroid hormone production, resulting in hypothyroidism. […] Iodine deficiency occurs infrequently in the United States, but it is the most common cause of hypothyroidism in other parts of the world.

• #24 Hypothyroidism (underactive thyroid) – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284

  Hypothyroidism happens when the thyroid gland doesn’t make enough hormones. Conditions or problems that can lead to hypothyroidism include: […] The most common cause of hypothyroidism is an autoimmune disease called Hashimoto’s disease. Autoimmune diseases happen when the immune system makes antibodies that attack healthy tissues. Sometimes that process involves the thyroid gland and affects its ability to make hormones. […] Thyroiditis happens when the thyroid gland becomes inflamed. This may be due to an infection. Or it can result from an autoimmune disorder or another medical condition affecting the thyroid. Thyroiditis can trigger the thyroid to release all of its stored thyroid hormone at once. That causes a spike in thyroid activity, a condition called hyperthyroidism. Afterward, the thyroid becomes underactive.

• #25 Thyroiditis: Evaluation and Treatment | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/1200/p609.html

  Thyroiditis is a general term for inflammation of the thyroid gland. Most forms of thyroiditis result in a triphasic disease pattern of thyroid dysfunction. This is followed by hypothyroidism, when the thyroid stores are depleted, and then eventual restoration of normal thyroid function. Some patients may develop permanent hypothyroidism. […] Hashimoto thyroiditis is an autoimmune disorder that presents with or without signs or symptoms of hypothyroidism, often with a painless goiter, and is associated with elevated thyroid peroxidase antibodies. Patients with Hashimoto thyroiditis and overt hypothyroidism are generally treated with lifelong thyroid hormone therapy. […] Most forms of thyroiditis result in a triphasic disease pattern of thyroid dysfunction. Patients have an initial phase of hyperthyroidism (thyrotoxicosis) attributed to the release of preformed thyroid hormone from damaged thyroid follicular cells. This is followed by hypothyroidism, when the thyroid stores are depleted, and then eventual restoration of normal thyroid function. Some patients may develop permanent hypothyroidism requiring thyroid hormone therapy with levothyroxine.

• #26 Thyroiditis: Evaluation and Treatment | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/1200/p609.html

  Thyroiditis is a general term for inflammation of the thyroid gland. Most forms of thyroiditis result in a triphasic disease pattern of thyroid dysfunction. This is followed by hypothyroidism, when the thyroid stores are depleted, and then eventual restoration of normal thyroid function. Some patients may develop permanent hypothyroidism. […] Hashimoto thyroiditis is an autoimmune disorder that presents with or without signs or symptoms of hypothyroidism, often with a painless goiter, and is associated with elevated thyroid peroxidase antibodies. Patients with Hashimoto thyroiditis and overt hypothyroidism are generally treated with lifelong thyroid hormone therapy. […] Most forms of thyroiditis result in a triphasic disease pattern of thyroid dysfunction. Patients have an initial phase of hyperthyroidism (thyrotoxicosis) attributed to the release of preformed thyroid hormone from damaged thyroid follicular cells. This is followed by hypothyroidism, when the thyroid stores are depleted, and then eventual restoration of normal thyroid function. Some patients may develop permanent hypothyroidism requiring thyroid hormone therapy with levothyroxine.

• #27 Thyroiditis: Evaluation and Treatment | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/1200/p609.html

  All patients with HT and hypothyroidism require treatment, even if they are asymptomatic. The goals of treatment include normalizing the TSH level and ameliorating symptoms of hypothyroidism. […] Postpartum thyroiditis is an autoimmune-mediated destructive thyroiditis that results in transient or persistent thyroid dysfunction and occurs within one year of delivery, miscarriage, or medical abortion. […] Subacute thyroiditis results from the inflammatory destruction of thyroid follicles; the condition often occurs after infection of the upper respiratory tract caused by Coxsackie virus, Epstein-Barr virus, adenovirus, influenza viruses, and most recently SARS-CoV-2 virus. […] The goal of treatment is to ameliorate the pain and thyrotoxicosis-related symptoms. Antibiotics have no role in the treatment of subacute thyroiditis. […] Several drug therapies have been associated with the development of thyroiditis, including amiodarone, immune checkpoint inhibitors, interferon-alfa, interleukin-2, lithium, and tyrosine kinase inhibitors.

• #28 Thyroiditis: An Integrated Approach | AAFP

  https://www.aafp.org/pubs/afp/issues/2014/0915/p389.html/1000

  Postpartum thyroiditis is transient or persistent thyroid dysfunction that occurs within one year of parturition, miscarriage, or medical abortion. […] In the case of postpartum thyroiditis, immune-mediated thyroid destruction may result in the release of preformed thyroid hormone into the bloodstream, causing hyperthyroidism. This may be followed by transient or permanent hypothyroidism as a result of depletion of thyroid hormone stores and destruction of thyroid hormone-producing cells. […] Subacute thyroiditis is a transient thyrotoxic state characterized by anterior neck pain, suppressed TSH, and low uptake of iodine 123 on thyroid scanning. […] Many cases of subacute thyroiditis follow an upper respiratory viral illness, which is thought to trigger an inflammatory destruction of thyroid follicles. As in other forms of destructive thyroiditis, preformed thyroid hormone is released into the blood, leading to increased levels of thyroid hormone and suppressed TSH. […] Permanent hypothyroidism is uncommon but is reported to develop in up to 15% of patients with subacute thyroiditis, and can develop more than one year following presentation.

• #29 Central Hypothyroidism – Endocrinology Advisor

  https://www.endocrinologyadvisor.com/ddi/central-hypothyroidism/

  Hypothyroidism may be defined as primary, secondary, or tertiary hypothyroidism. Primary hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone. […] Central hypothyroidism occurs when there is a problem with the pituitary gland (secondary) or hypothalamus (tertiary) rather than with the thyroid gland itself. […] Other causes of CeH include genetic factors, treating primary hypothyroidism with too much thyroid hormone, empty sella syndrome, inflammation, infiltrative causes, head injury, medication-related causes, Sheehan syndrome, thyroid-releasing hormone resistance or deficiency, pituitary macroadenomas, pituitary surgery, past radiation treatment, and head trauma. […] A diagnosis of central hypothyroidism may be made when there is an abnormally low TSH along with below-normal thyroxine (T4) and triiodothyronine (T3).

• #30 Hypothyroidism – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK519536/

  Hypothyroidism results from low levels of thyroid hormone with varied etiology and manifestations. Hypothyroidism is primarily categorized as primary and secondary (ie, central) hypothyroidism. In primary hypothyroidism, the thyroid gland cannot produce adequate amounts of thyroid hormone. The less commonly seen secondary or central hypothyroidism occurs when the thyroid gland functions normally; however, hypothyroidism results from the abnormal pituitary gland or hypothalamus function. Autoimmune thyroiditis and iodine deficiency are the most common causes of the disease. Central hypothyroidism is rare. […] The most common cause of hypothyroidism is the inability of the thyroid gland to produce a sufficient amount of thyroid hormone; however, less commonly, pituitary and hypothalamus impairment may also result in thyroid dysfunction. The hypothalamus secretes thyrotropin-releasing hormone (TRH) that stimulates the pituitary gland to produce thyroid-stimulating hormone (TSH). Thyroid-stimulating hormones stimulate the thyroid gland to produce and secrete mainly T4, approximately 100 to 125 nmol daily, and smaller quantities of T3. The half-life of T4 is 7 to 10 days, and eventually, T4 is converted to T3 peripherally by 5′-deiodination. Negative feedback on the production of TRH and TSH is exerted primarily by T3 and, to some extent, T4. Alterations in the structure and function of any of these organs or pathways can result in hypothyroidism.

• #31 Central Hypothyroidism – Endocrinology Advisor

  https://www.endocrinologyadvisor.com/ddi/central-hypothyroidism/

  Hypothyroidism may be defined as primary, secondary, or tertiary hypothyroidism. Primary hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone. […] Central hypothyroidism occurs when there is a problem with the pituitary gland (secondary) or hypothalamus (tertiary) rather than with the thyroid gland itself. […] Other causes of CeH include genetic factors, treating primary hypothyroidism with too much thyroid hormone, empty sella syndrome, inflammation, infiltrative causes, head injury, medication-related causes, Sheehan syndrome, thyroid-releasing hormone resistance or deficiency, pituitary macroadenomas, pituitary surgery, past radiation treatment, and head trauma. […] A diagnosis of central hypothyroidism may be made when there is an abnormally low TSH along with below-normal thyroxine (T4) and triiodothyronine (T3).

• #32 Disorders that cause hypothyroidism – UpToDate

  https://www.uptodate.com/contents/disorders-that-cause-hypothyroidism

  INTRODUCTION […] Hypothyroidism can result from a defect anywhere in the hypothalamic-pituitary-thyroid axis. In the vast majority of cases, it is caused by thyroid disease (primary hypothyroidism). Much less often it is caused by decreased secretion of thyroid-stimulating hormone (TSH) from the anterior pituitary gland or by decreased secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus (table 1). […] The cause of hypothyroidism should be identified in every patient for the following reasons: […] • Hypothyroidism may be transient and require no or only short-term therapy, as in patients with painless thyroiditis or postpartum thyroiditis. (See „Overview of thyroiditis.”) […] • It may be caused by a drug, such as lithium or an iodine-containing drug, and disappear when the drug is discontinued. […] • It may be the first or only manifestation of hypothalamic or pituitary disease.

• #33 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  Hypothyroidism is a common endocrine disorder resulting from deficiency of thyroid hormone. In the United States and other areas of adequate iodine intake, autoimmune thyroid disease (Hashimoto disease) is the most common cause of hypothyroidism; worldwide, iodine deficiency remains the foremost cause. […] Hypothyroidism can also be secondarythat is, the thyroid gland itself is normal, but it receives insufficient stimulation because of low secretion of thyrotropin (ie, thyroid-stimulating hormone [TSH]) from the pituitary gland. This generally occurs in the presence of other pituitary hormone deficiencies. In tertiary hypothyroidism, inadequate secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus leads to insufficient release of TSH, which in turn causes inadequate thyroid stimulation. However, this is rare.

• #34

  https://step2.medbullets.com/endocrine/120098/hypothyroidism-vs-hyperthyroidism

  Hypothyroidism is a disorder characterized by the under production of thyroid hormone. […] Pathogenesis is primarily due to thyroid disease (primary hypothyroidism) but can be caused by secondary and/or tertiary hypothyroidism. […] Primary hypothyroidism is often due to Hashimoto thyroiditis (chronic autoimmune thyroiditis), which involves cell- and antibody-mediated destruction of thyroid tissue. […] Secondary hypothyroidism is caused by TSH deficiency secondary to any of the causes of hypopituitarism, most commonly due to a pituitary tumor. […] Tertiary hypothyroidism is caused by any disorder that damages the hypothalamus or interferes with hypothalamic-pituitary portal blood flow.

• #35 Congenital hypothyroidism: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/congenital-hypothyroidism/

  Congenital hypothyroidism is a partial or complete loss of function of the thyroid gland (hypothyroidism) that affects infants from birth (congenital). The thyroid gland is a butterfly-shaped tissue in the lower neck. It makes iodine-containing hormones that play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). People with congenital hypothyroidism have lower-than-normal levels of these important hormones. […] Congenital hypothyroidism occurs when the thyroid gland fails to develop or function properly. In 80 to 85 percent of cases, the thyroid gland is absent, severely reduced in size (hypoplastic), or abnormally located. These cases are classified as thyroid dysgenesis. In the remainder of cases, a normal-sized or enlarged thyroid gland (goiter) is present, but production of thyroid hormones is decreased or absent. Most of these cases occur when one of several steps in the hormone synthesis process is impaired; these cases are classified as thyroid dyshormonogenesis. Less commonly, reduction or absence of thyroid hormone production is caused by impaired stimulation of the production process (which is normally done by a structure at the base of the brain called the pituitary gland), even though the process itself is unimpaired. These cases are classified as central (or pituitary) hypothyroidism.

• #36 Congenital hypothyroidism: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/congenital-hypothyroidism/

  Congenital hypothyroidism is a partial or complete loss of function of the thyroid gland (hypothyroidism) that affects infants from birth (congenital). The thyroid gland is a butterfly-shaped tissue in the lower neck. It makes iodine-containing hormones that play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). People with congenital hypothyroidism have lower-than-normal levels of these important hormones. […] Congenital hypothyroidism occurs when the thyroid gland fails to develop or function properly. In 80 to 85 percent of cases, the thyroid gland is absent, severely reduced in size (hypoplastic), or abnormally located. These cases are classified as thyroid dysgenesis. In the remainder of cases, a normal-sized or enlarged thyroid gland (goiter) is present, but production of thyroid hormones is decreased or absent. Most of these cases occur when one of several steps in the hormone synthesis process is impaired; these cases are classified as thyroid dyshormonogenesis. Less commonly, reduction or absence of thyroid hormone production is caused by impaired stimulation of the production process (which is normally done by a structure at the base of the brain called the pituitary gland), even though the process itself is unimpaired. These cases are classified as central (or pituitary) hypothyroidism.

• #37 Congenital hypothyroidism: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/congenital-hypothyroidism/

  Congenital hypothyroidism can also occur as part of syndromes that affect other organs and tissues in the body. These forms of the condition are described as syndromic. Some common forms of syndromic hypothyroidism include Pendred syndrome, Bamforth-Lazarus syndrome, and brain-lung-thyroid syndrome. […] Congenital hypothyroidism can be caused by a variety of factors, only some of which are genetic. The most common cause worldwide is a shortage of iodine in the diet of the mother and the affected infant. Iodine is essential for the production of thyroid hormones. Genetic causes account for about 15 to 20 percent of cases of congenital hypothyroidism. […] The cause of the most common type of congenital hypothyroidism, thyroid dysgenesis, is usually unknown. Studies suggest that 2 to 5 percent of cases are inherited. Two of the genes involved in this form of the condition are PAX8 and TSHR. These genes play roles in the proper growth and development of the thyroid gland. Mutations in these genes prevent or disrupt normal development of the gland. The abnormal or missing gland cannot produce normal amounts of thyroid hormones.

• #38 Congenital hypothyroidism: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/congenital-hypothyroidism/

  Congenital hypothyroidism is a partial or complete loss of function of the thyroid gland (hypothyroidism) that affects infants from birth (congenital). The thyroid gland is a butterfly-shaped tissue in the lower neck. It makes iodine-containing hormones that play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). People with congenital hypothyroidism have lower-than-normal levels of these important hormones. […] Congenital hypothyroidism occurs when the thyroid gland fails to develop or function properly. In 80 to 85 percent of cases, the thyroid gland is absent, severely reduced in size (hypoplastic), or abnormally located. These cases are classified as thyroid dysgenesis. In the remainder of cases, a normal-sized or enlarged thyroid gland (goiter) is present, but production of thyroid hormones is decreased or absent. Most of these cases occur when one of several steps in the hormone synthesis process is impaired; these cases are classified as thyroid dyshormonogenesis. Less commonly, reduction or absence of thyroid hormone production is caused by impaired stimulation of the production process (which is normally done by a structure at the base of the brain called the pituitary gland), even though the process itself is unimpaired. These cases are classified as central (or pituitary) hypothyroidism.

• #39 Congenital hypothyroidism: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/congenital-hypothyroidism/

  Thyroid dyshormonogenesis results from mutations in one of several genes involved in the production of thyroid hormones. These genes include DUOX2, SLC5A5, TG, and TPO. Mutations in each of these genes disrupt a step in thyroid hormone synthesis, leading to abnormally low levels of these hormones. Mutations in the TSHB gene disrupt the synthesis of thyroid hormones by impairing the stimulation of hormone production. Changes in this gene are the primary cause of central hypothyroidism. The resulting shortage of thyroid hormones disrupts normal growth, brain development, and metabolism, leading to the features of congenital hypothyroidism. […] Mutations in other genes that have not been as well characterized can also cause congenital hypothyroidism. Still other genes are involved in syndromic forms of the disorder.

• #40 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  Although hypothalamic or pituitary disorders can affect thyroid function, localized disease of the thyroid gland that results in decreased thyroid hormone production is the most common cause of hypothyroidism. Under normal circumstances, the thyroid releases 100-125 nmol of T4 daily and small amounts of T3. The ratio of T4:T3 production varies between about 14:1 and 4:1, depending on iodine sufficiency and TSH stimulation. The half-life of T4 is approximately 7-10 days, whereas the half-life of T3 is about 24 hours. T4, a prohormone, is converted via the action of deiodinases to T3, the active form of thyroid hormone. […] Deficiency of thyroid hormone has a wide range of effects. Systemic effects are the result of either derangements in metabolic processes or direct effects by myxedematous infiltration (ie, accumulation of glycosaminoglycans in the tissues).

• #41 Hypothyroidism – Wikipedia

  https://en.wikipedia.org/wiki/Hypothyroidism

  Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as poor ability to tolerate cold, extreme fatigue, muscle aches, constipation, slow heart rate, depression, and weight gain. […] Hashimoto’s thyroiditis, an autoimmune disease where the body’s immune system reacts to the thyroid gland, is the most common cause of hypothyroidism in countries with sufficient dietary iodine. […] The diagnosis of hypothyroidism, when suspected, can be confirmed with blood tests measuring thyroid-stimulating hormone (TSH) and thyroxine (T4) levels. […] Thyroid hormone is required for the normal functioning of numerous tissues in the body. In healthy individuals, the thyroid gland predominantly secretes thyroxine (T4), which is converted into triiodothyronine (T3) in other organs by the selenium-dependent enzyme iodothyronine deiodinase.

• #42 Hypothyroidism – Whole Health Library

  https://www.va.gov/WHOLEHEALTHLIBRARY/tools/hypothyroidism.asp

  Some practitioners feel conventional methods of diagnosis of hypothyroidism are too narrow and miss many cases of hypothyroidism in patients who are clinically symptomatic. An alternative practice is to look at the absolute levels of T3 and T4, not just TSH. If T3 and T4 are low, regardless of TSH, a patient may be diagnosed by these practitioners with hypothyroidism. […] Adequate selenium is also required for proper thyroid function. […] Specifically, selenium facilitates conversion of T4 to the active T3 through selenium dependent deiodinases. […] A 2019 review found that patients with hypothyroidism exhibited lower selenium levels than healthy controls. […] Selenium supplementation may improve thyroid dysfunction in patients who are deficient. […] It is unclear to what extent selenium benefits patients with hypothyroidism in the absence of a selenium deficiency.

• #43 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  Although hypothalamic or pituitary disorders can affect thyroid function, localized disease of the thyroid gland that results in decreased thyroid hormone production is the most common cause of hypothyroidism. Under normal circumstances, the thyroid releases 100-125 nmol of T4 daily and small amounts of T3. The ratio of T4:T3 production varies between about 14:1 and 4:1, depending on iodine sufficiency and TSH stimulation. The half-life of T4 is approximately 7-10 days, whereas the half-life of T3 is about 24 hours. T4, a prohormone, is converted via the action of deiodinases to T3, the active form of thyroid hormone. […] Deficiency of thyroid hormone has a wide range of effects. Systemic effects are the result of either derangements in metabolic processes or direct effects by myxedematous infiltration (ie, accumulation of glycosaminoglycans in the tissues).

• #44 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  The hypothyroid changes in the heart result in decreased contractility, cardiac enlargement, pericardial effusion, decreased pulse, and decreased cardiac output. […] Decreased thyroid hormone effect can cause increased levels of total cholesterol and lowdensity-lipoprotein (LDL) cholesterol and a possible change in highdensity-lipoprotein (HDL) cholesterol because of a change in metabolic clearance. In addition, hypothyroidism may result in an increase in insulin resistance. […] A study by Wopereis et al looked at the increased risk for anemia arising in hypothyroidism, reporting that for overt hypothyroidism, the pooled hazard ratio (HR) for anemia development was 1.38, while for subclinical hypothyroidism, it was 1.18. Although it is not clear how hypothyroidism leads to anemia, there is evidence that reduced thyroid function may interfere with the production of healthy erythrocytes. The possibility exists that T3, T4, and TSH are directly involved in erythropoiesis.

• #45 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  The hypothyroid changes in the heart result in decreased contractility, cardiac enlargement, pericardial effusion, decreased pulse, and decreased cardiac output. […] Decreased thyroid hormone effect can cause increased levels of total cholesterol and lowdensity-lipoprotein (LDL) cholesterol and a possible change in highdensity-lipoprotein (HDL) cholesterol because of a change in metabolic clearance. In addition, hypothyroidism may result in an increase in insulin resistance. […] A study by Wopereis et al looked at the increased risk for anemia arising in hypothyroidism, reporting that for overt hypothyroidism, the pooled hazard ratio (HR) for anemia development was 1.38, while for subclinical hypothyroidism, it was 1.18. Although it is not clear how hypothyroidism leads to anemia, there is evidence that reduced thyroid function may interfere with the production of healthy erythrocytes. The possibility exists that T3, T4, and TSH are directly involved in erythropoiesis.

• #46 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  The hypothyroid changes in the heart result in decreased contractility, cardiac enlargement, pericardial effusion, decreased pulse, and decreased cardiac output. […] Decreased thyroid hormone effect can cause increased levels of total cholesterol and lowdensity-lipoprotein (LDL) cholesterol and a possible change in highdensity-lipoprotein (HDL) cholesterol because of a change in metabolic clearance. In addition, hypothyroidism may result in an increase in insulin resistance. […] A study by Wopereis et al looked at the increased risk for anemia arising in hypothyroidism, reporting that for overt hypothyroidism, the pooled hazard ratio (HR) for anemia development was 1.38, while for subclinical hypothyroidism, it was 1.18. Although it is not clear how hypothyroidism leads to anemia, there is evidence that reduced thyroid function may interfere with the production of healthy erythrocytes. The possibility exists that T3, T4, and TSH are directly involved in erythropoiesis.

• #47 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  The hypothyroid changes in the heart result in decreased contractility, cardiac enlargement, pericardial effusion, decreased pulse, and decreased cardiac output. […] Decreased thyroid hormone effect can cause increased levels of total cholesterol and lowdensity-lipoprotein (LDL) cholesterol and a possible change in highdensity-lipoprotein (HDL) cholesterol because of a change in metabolic clearance. In addition, hypothyroidism may result in an increase in insulin resistance. […] A study by Wopereis et al looked at the increased risk for anemia arising in hypothyroidism, reporting that for overt hypothyroidism, the pooled hazard ratio (HR) for anemia development was 1.38, while for subclinical hypothyroidism, it was 1.18. Although it is not clear how hypothyroidism leads to anemia, there is evidence that reduced thyroid function may interfere with the production of healthy erythrocytes. The possibility exists that T3, T4, and TSH are directly involved in erythropoiesis.

• #48 The Relationship Between Hypothyroidism and Your Reflexes | Paloma Health

  https://www.palomahealth.com/learn/hypothyroidism-reflexes?srsltid=AfmBOopX8IX8NVoll5mVfgjzv7CK3L-6BvKqUaNvIqlgFZd5DR34ELuD

  Thyroid hormones regulate your metabolism, energy levels, and overall growth and development. When youre hypothyroid, your underactive thyroid gland doesnt produce enough thyroid hormones to support all your glands, organs, tissues, cells, and functions. […] One often overlooked symptom of hypothyroidism is its impact on reflexes, those involuntary movements that occur due to a stimulus. Reflexes play a crucial role in maintaining your balance and coordination. […] Reflexes involve the rapid transmission of nerve impulses from sensory receptors to your spinal cord and then back to specific muscles, resulting in a swift response. In hypothyroidism, this process is disrupted, leading to slowed reflexes. […] One of the main reasons for slowed reflexes in hypothyroidism is the reduced metabolic rate caused by the lack of thyroid hormones. Metabolism refers to the bodys ability to convert food into energy and regulate body temperature. Without enough thyroid hormones, the metabolic rate decreases, resulting in a slower overall functioning of bodily processes.

• #49 The Relationship Between Hypothyroidism and Your Reflexes | Paloma Health

  https://www.palomahealth.com/learn/hypothyroidism-reflexes?srsltid=AfmBOopX8IX8NVoll5mVfgjzv7CK3L-6BvKqUaNvIqlgFZd5DR34ELuD

  Thyroid hormones regulate your metabolism, energy levels, and overall growth and development. When youre hypothyroid, your underactive thyroid gland doesnt produce enough thyroid hormones to support all your glands, organs, tissues, cells, and functions. […] One often overlooked symptom of hypothyroidism is its impact on reflexes, those involuntary movements that occur due to a stimulus. Reflexes play a crucial role in maintaining your balance and coordination. […] Reflexes involve the rapid transmission of nerve impulses from sensory receptors to your spinal cord and then back to specific muscles, resulting in a swift response. In hypothyroidism, this process is disrupted, leading to slowed reflexes. […] One of the main reasons for slowed reflexes in hypothyroidism is the reduced metabolic rate caused by the lack of thyroid hormones. Metabolism refers to the bodys ability to convert food into energy and regulate body temperature. Without enough thyroid hormones, the metabolic rate decreases, resulting in a slower overall functioning of bodily processes.

• #50 The Relationship Between Hypothyroidism and Your Reflexes | Paloma Health

  https://www.palomahealth.com/learn/hypothyroidism-reflexes?srsltid=AfmBOopX8IX8NVoll5mVfgjzv7CK3L-6BvKqUaNvIqlgFZd5DR34ELuD

  This decrease in metabolic rate also slows the speed at which nerve cells communicate with each other. Nerve cells rely on an electrical impulse called an action potential to transmit signals throughout the body. However, when the thyroid gland is underactive, and your metabolism is slowed, the generation and propagation of these action potentials are impaired. […] Furthermore, the lack of thyroid hormones affects the myelin sheath, a protective covering around nerve fibers. In hypothyroidism, the myelin sheath may become damaged or deteriorate, impairing the efficiency of nerve signal transmission. This damage can lead to delayed reflexes and a decrease in overall coordination. […] Finally, another factor contributing to slowed reflexes in hypothyroidism is the overall weakness and muscle stiffness often associated with an underactive thyroid. The decrease in thyroid hormones can lead to muscle wasting and decreased muscle tone, making it more challenging for muscles to respond promptly to reflex stimuli.

• #51 The Relationship Between Hypothyroidism and Your Reflexes | Paloma Health

  https://www.palomahealth.com/learn/hypothyroidism-reflexes?srsltid=AfmBOopX8IX8NVoll5mVfgjzv7CK3L-6BvKqUaNvIqlgFZd5DR34ELuD

  In hypothyroidism, deep tendon reflexes are frequently slowed down or even absent. In fact, according to research, the delayed relaxation of deep tendon reflexes, also known as Woltmans sign, is seen in about 75% of patients with hypothyroidism, and the presence of Woltmans sign is considered to be 92% predictive in diagnosing hypothyroidism. […] While hypothyroidism is generally associated with slowed reflexes, there are some cases reported where fast, exaggerated reflexes known as hyperreflexia can occur. In fact, one study found that 38% of patients with hypothyroidism had generalized hyperreflexia. […] The exact mechanism of hyperreflexia in hypothyroidism is not well understood, but it may be related to altered neurotransmitter function or changes in the excitability of the motor neurons.

• #52 Hashimoto’s disease: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/hashimotos-disease/

  Hashimoto’s disease is a form of chronic inflammation that can damage the thyroid, reducing its ability to produce hormones. […] Hashimoto’s disease is the most common cause of thyroid underactivity (hypothyroidism) in the United States. […] Hashimoto’s disease is classified as an autoimmune disorder, one of a large group of conditions that occur when the immune system attacks the body’s own tissues and organs. In people with Hashimoto’s disease, white blood cells called lymphocytes accumulate abnormally in the thyroid, which can damage it. The lymphocytes make immune system proteins called antibodies that attack and destroy thyroid cells. When too many thyroid cells become damaged or die, the thyroid can no longer make enough hormones to regulate body functions. This shortage of thyroid hormones underlies the signs and symptoms of Hashimoto’s disease. […] People with Hashimoto’s disease have an increased risk of developing other autoimmune disorders, including vitiligo, rheumatoid arthritis, Addison disease, type 1 diabetes, multiple sclerosis, and pernicious anemia.

• #53 Hashimoto’s disease: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/hashimotos-disease/

  Hashimoto’s disease is a form of chronic inflammation that can damage the thyroid, reducing its ability to produce hormones. […] Hashimoto’s disease is the most common cause of thyroid underactivity (hypothyroidism) in the United States. […] Hashimoto’s disease is classified as an autoimmune disorder, one of a large group of conditions that occur when the immune system attacks the body’s own tissues and organs. In people with Hashimoto’s disease, white blood cells called lymphocytes accumulate abnormally in the thyroid, which can damage it. The lymphocytes make immune system proteins called antibodies that attack and destroy thyroid cells. When too many thyroid cells become damaged or die, the thyroid can no longer make enough hormones to regulate body functions. This shortage of thyroid hormones underlies the signs and symptoms of Hashimoto’s disease. […] People with Hashimoto’s disease have an increased risk of developing other autoimmune disorders, including vitiligo, rheumatoid arthritis, Addison disease, type 1 diabetes, multiple sclerosis, and pernicious anemia.

• #54 Immunotherapy-induced thyroid dysfunction: an updated review | The Egyptian Journal of Internal Medicine | Full Text

  https://ejim.springeropen.com/articles/10.1186/s43162-023-00210-7

  Immunotherapy medicines (immune checkpoint inhibitors, ICIs) that work directly on the immune system have shown vastly increased survival for people with cancer in phases 2 and 3 clinical studies during the past few years. An underactive thyroid is among the most frequent endocrine irAE, affecting about 40% of individuals who received ICIs. The incidence of irAEs varies depending on the type of cancer and the treatment regimen. Thyroid dysfunction induced by ICIs depends on the type of immunotherapy administered. In a more recent retrospective investigation by Girimonte et al. (2022), 29.6% (53 out of 179) of metastatic cancer patients taking ICIs developed hypothyroidism, with 44 of those instances experiencing transient thyrotoxicosis followed by hypothyroidism. While treating cancer with anti-PD-1 or anti-PD-L1, the risk of thyroid abnormalities is 510%, with a higher prevalence in combination therapy patients. The exact mechanisms underlying immunotherapy-induced thyroid dysfunction remain unclear. ICIs are typically harmless, but some evidence suggests they may provoke an autoimmune reaction in the thyroid gland by disturbing the delicate balance of immune cells or by producing cross-reactive cancer cell antigens. ICIs may also change thyroid-related gene expression, causing hypothyroidism. Several researchers have investigated possible risk factors for endocrinopathies in patients receiving ICIs to better understand this phenomenon’s origins. The study found that among cancer patients taking PD-1/PD-L1 inhibitors, a history of smoking, hypertension, or opioid use was all associated with adverse events involving the thyroid. Another study found that immunotherapy-related thyroid dysfunction may be linked to a hereditary predisposition to autoimmune thyroid disease. Thyroid dysfunction, which may arise as a side effect of immunotherapy, should be managed cautiously by a multidisciplinary group of oncologists, endocrinologists, and primary care physicians, as highlighted in the article. The initiation of replacement hormonal therapy with levothyroxine after ICI initiation was associated with enhanced overall survival.

• #55 Immunotherapy-induced thyroid dysfunction: an updated review | The Egyptian Journal of Internal Medicine | Full Text

  https://ejim.springeropen.com/articles/10.1186/s43162-023-00210-7

  Immunotherapy medicines (immune checkpoint inhibitors, ICIs) that work directly on the immune system have shown vastly increased survival for people with cancer in phases 2 and 3 clinical studies during the past few years. An underactive thyroid is among the most frequent endocrine irAE, affecting about 40% of individuals who received ICIs. The incidence of irAEs varies depending on the type of cancer and the treatment regimen. Thyroid dysfunction induced by ICIs depends on the type of immunotherapy administered. In a more recent retrospective investigation by Girimonte et al. (2022), 29.6% (53 out of 179) of metastatic cancer patients taking ICIs developed hypothyroidism, with 44 of those instances experiencing transient thyrotoxicosis followed by hypothyroidism. While treating cancer with anti-PD-1 or anti-PD-L1, the risk of thyroid abnormalities is 510%, with a higher prevalence in combination therapy patients. The exact mechanisms underlying immunotherapy-induced thyroid dysfunction remain unclear. ICIs are typically harmless, but some evidence suggests they may provoke an autoimmune reaction in the thyroid gland by disturbing the delicate balance of immune cells or by producing cross-reactive cancer cell antigens. ICIs may also change thyroid-related gene expression, causing hypothyroidism. Several researchers have investigated possible risk factors for endocrinopathies in patients receiving ICIs to better understand this phenomenon’s origins. The study found that among cancer patients taking PD-1/PD-L1 inhibitors, a history of smoking, hypertension, or opioid use was all associated with adverse events involving the thyroid. Another study found that immunotherapy-related thyroid dysfunction may be linked to a hereditary predisposition to autoimmune thyroid disease. Thyroid dysfunction, which may arise as a side effect of immunotherapy, should be managed cautiously by a multidisciplinary group of oncologists, endocrinologists, and primary care physicians, as highlighted in the article. The initiation of replacement hormonal therapy with levothyroxine after ICI initiation was associated with enhanced overall survival.

• #56

  https://link.springer.com/article/10.1007/s12020-024-03718-2

  Thyroid dysfunction is the most common endocrine adverse effect associated with ICI therapy. Most studies report two patterns of ICI-related thyroid dysfunction: thyrotoxicosis followed by hypothyroidism and isolated hypothyroidism. However, the pathophysiological basis that appears to be common is destructive thyroiditis. The underlying pathophysiology is considered to be an immune-mediated acute inflammation followed by destruction of the thyroid gland. ICI therapy induces autoimmune side effects through T cell activation and is characterized by intra-thyroidal predominance of CD8+ and CD4-CD8- T lymphocytes. […] In accordance with the above, recent studies suggest that autoantibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) have been found elevated at baseline in some patients who develop thyroid dysfunction after ICI immunotherapy. TPOAb and TgAb may be present at baseline prior to or may develop after ICI therapy.

• #57

  https://link.springer.com/article/10.1007/s12020-024-03718-2

  The correlation between basal positivity of TPOAb and TgAb and high risk of thyroid dysfunction after the initiation of ICIs therapy is also supported by the study of Zhou et al. Reportedly, the development of positive thyroid autoantibodies after initiation of ICI therapy is associated with higher risk of ICI-induced thyroid dysfunction. […] Individual genetic susceptibility to thyroid dysfunction also plays an important role. More specifically, thyroid dysfunction has been shown to be associated with overexpression of Human Leukocyte Antigen DR-isotype (HLA-DR). Treatment with ICI therapy can change HLA-DR expression, increasing T cell activation and leading to thyroid autoimmune disease. […] Understanding the pathophysiological mechanisms underlying these adverse effects is vital for the development of effective treatment strategies. The management of these thyroid-related side effects necessitates an individualized approach that considers the severity of the condition, the patients clinical state, and the stage of any malignancy involved.

• #58 Update on dyslipidemia in hypothyroidism: the mechanism of dyslipidemia in hypothyroidism in: Endocrine Connections Volume 11 Issue 2 (2022)

  https://ec.bioscientifica.com/view/journals/ec/11/2/EC-21-0002.xml

  Hypothyroidism is often associated with elevated serum levels of total cholesterol, LDL-C and triglycerides. […] Therefore, the mechanism of hypothyroidism-related dyslipidemia is associated with the decrease of TH and the increase of TSH levels. […] The current review focuses on the updated understanding of the mechanism of hypothyroidism-related dyslipidemia. […] The association between thyroid dysfunction and dyslipidemia was first reported in 1930. Since then, it has been gradually recognized that hypothyroidism could cause disorders of lipid metabolism, mainly with increased total cholesterol (TC) and LDL-C in blood. […] These findings suggested that TH and TSH are two important risk factors for lipid metabolic disorders. […] However, the deeper mechanism between hypothyroidism and blood lipid profile is still not fully understood, like the signaling pathway of TSH and other regulatory factors involved in lipid disturbance.

• #59 Update on dyslipidemia in hypothyroidism: the mechanism of dyslipidemia in hypothyroidism in: Endocrine Connections Volume 11 Issue 2 (2022)

  https://ec.bioscientifica.com/view/journals/ec/11/2/EC-21-0002.xml

  Hypothyroidism is often associated with elevated serum levels of total cholesterol, LDL-C and triglycerides. […] Therefore, the mechanism of hypothyroidism-related dyslipidemia is associated with the decrease of TH and the increase of TSH levels. […] The current review focuses on the updated understanding of the mechanism of hypothyroidism-related dyslipidemia. […] The association between thyroid dysfunction and dyslipidemia was first reported in 1930. Since then, it has been gradually recognized that hypothyroidism could cause disorders of lipid metabolism, mainly with increased total cholesterol (TC) and LDL-C in blood. […] These findings suggested that TH and TSH are two important risk factors for lipid metabolic disorders. […] However, the deeper mechanism between hypothyroidism and blood lipid profile is still not fully understood, like the signaling pathway of TSH and other regulatory factors involved in lipid disturbance.

• #60 Update on dyslipidemia in hypothyroidism: the mechanism of dyslipidemia in hypothyroidism in: Endocrine Connections Volume 11 Issue 2 (2022)

  https://ec.bioscientifica.com/view/journals/ec/11/2/EC-21-0002.xml

  The major effect of TH and TSH on lipid metabolism in hypothyroidism has been outlined. […] The total effect of TSH on TC level includes the direct effect and the indirect effect (TH). […] TSH alone also can increase TC levels in CVD patients independent of TH. […] Therefore, current evidence suggests that both TH and TSH affect cholesterol metabolism. […] The decrease of TH and increase of TSH share similar pathogenic mechanisms of LDL-C accumulation in hypothyroidism, both of which could induce the cholesterol production and inhibit clearance. […] The combined impact of TH on cholesterol production and clearance leads to a net accumulation of serum LDL-C in hypothyroidism. […] TSH can also stimulate the expression of SREBP2 to regulate HMGCR. […] The binding of TSH to TSHR of hepatocyte membrane upregulates the expression and activity of HMGCR through the cAMP/PKA/CREB signaling pathway.

• #61 Update on dyslipidemia in hypothyroidism: the mechanism of dyslipidemia in hypothyroidism in: Endocrine Connections Volume 11 Issue 2 (2022)

  https://ec.bioscientifica.com/view/journals/ec/11/2/EC-21-0002.xml

  The decrease of TH causes the declined function that lipoprotein lipase (LPL) hydrolyzes CM and VLDL, and the clearance of LDL and remnant lipoprotein (RLP) by LDL receptor (LDLR) and LDL receptor-related protein 1 (LRP1) decreases too, so TG level increases. […] The HDL clearance and transformation process decrease in hypothyroidism. […] Hypothyroidism could inhibit cholesterol clearance by decreasing scavenger receptor b1. […] The HDL-C level is not constant because regulating factors counteract each other; however, HDL function, a predictor of cardiovascular risk independent of HDL-C levels, is impaired in hypothyroidism.

• #62 Hypothyroidism/subclinical hypothyroidism and metabolic dysfunction-associated steatotic liver disease: advances in mechanism and treatment | Lipids in Health and Disease | Full Text

  https://lipidworld.biomedcentral.com/articles/10.1186/s12944-025-02474-0

  Hypothyroidism is a risk factor for metabolic dysfunction-associated steatotic liver disease (MASLD) but it is not clear whether subclinical hypothyroidism (SCH) increases the risk of MASLD and whether SCH patients with MASLD require treatment. […] According to recent studies, growing evidence supports the hypothesis that hypothyroidism significantly increases the likelihood of MASLD. However, further investigation is required to establish a definitive link between SCH and MASLD. Furthermore, the impacts of thyroid hormones (THs) on the progression of MASLD require elucidation. […] Hypothyroidism is recognized as a risk factor for MASLD and the possible mechanism involves hypothyroidism-associated dyslipidemia leading to hepatic fat accumulation, which then contributes to insulin resistance and the development of MASLD.

• #63 Hypothyroidism/subclinical hypothyroidism and metabolic dysfunction-associated steatotic liver disease: advances in mechanism and treatment | Lipids in Health and Disease | Full Text

  https://lipidworld.biomedcentral.com/articles/10.1186/s12944-025-02474-0

  Hypothyroidism is a risk factor for metabolic dysfunction-associated steatotic liver disease (MASLD) but it is not clear whether subclinical hypothyroidism (SCH) increases the risk of MASLD and whether SCH patients with MASLD require treatment. […] According to recent studies, growing evidence supports the hypothesis that hypothyroidism significantly increases the likelihood of MASLD. However, further investigation is required to establish a definitive link between SCH and MASLD. Furthermore, the impacts of thyroid hormones (THs) on the progression of MASLD require elucidation. […] Hypothyroidism is recognized as a risk factor for MASLD and the possible mechanism involves hypothyroidism-associated dyslipidemia leading to hepatic fat accumulation, which then contributes to insulin resistance and the development of MASLD.

• #64 Hypothyroidism/subclinical hypothyroidism and metabolic dysfunction-associated steatotic liver disease: advances in mechanism and treatment | Lipids in Health and Disease | Full Text

  https://lipidworld.biomedcentral.com/articles/10.1186/s12944-025-02474-0

  Hypothyroidism is a risk factor for metabolic dysfunction-associated steatotic liver disease (MASLD) but it is not clear whether subclinical hypothyroidism (SCH) increases the risk of MASLD and whether SCH patients with MASLD require treatment. […] According to recent studies, growing evidence supports the hypothesis that hypothyroidism significantly increases the likelihood of MASLD. However, further investigation is required to establish a definitive link between SCH and MASLD. Furthermore, the impacts of thyroid hormones (THs) on the progression of MASLD require elucidation. […] Hypothyroidism is recognized as a risk factor for MASLD and the possible mechanism involves hypothyroidism-associated dyslipidemia leading to hepatic fat accumulation, which then contributes to insulin resistance and the development of MASLD.

• #65 Relationship between Vitamin D Deficiency and Hypothyroidism-A Review – Journal of Young Pharmacists

  https://jyoungpharm.org/7994/

  Vitamin D has a crucial role in maintaining thyroid and immune function. In hypothyroidism, the gland is underactive and Vitamin D impacts this condition. Vitamin D regulates gene expression in thyroid hormone synthesis and influences the immune system, affecting overall thyroid health. From the literatures, it is evident that hypothyroidism is correlated with hypovitaminosis D. The immune-mediated properties of Vitamin D reduce the symptoms of hypothyroidism caused by autoimmune conditions. Understanding the correlation of Vitamin D with hypothyroidism is crucial as it holds potential therapeutic implications. Maintaining adequate Vitamin D improves gland function and prevents disease-related complications. […] The primary cause of the disease worldwide is commonly attributed to iodine deficiency. In places where there’s enough iodine, hypothyroidism can be caused by factors like autoimmune issues (such as Hashimoto’s thyroiditis) or iatrogenic reasons.

• #66 Relationship between Vitamin D Deficiency and Hypothyroidism-A Review – Journal of Young Pharmacists

  https://jyoungpharm.org/7994/

  Vitamin D has a crucial role in maintaining thyroid and immune function. In hypothyroidism, the gland is underactive and Vitamin D impacts this condition. Vitamin D regulates gene expression in thyroid hormone synthesis and influences the immune system, affecting overall thyroid health. From the literatures, it is evident that hypothyroidism is correlated with hypovitaminosis D. The immune-mediated properties of Vitamin D reduce the symptoms of hypothyroidism caused by autoimmune conditions. Understanding the correlation of Vitamin D with hypothyroidism is crucial as it holds potential therapeutic implications. Maintaining adequate Vitamin D improves gland function and prevents disease-related complications. […] The primary cause of the disease worldwide is commonly attributed to iodine deficiency. In places where there’s enough iodine, hypothyroidism can be caused by factors like autoimmune issues (such as Hashimoto’s thyroiditis) or iatrogenic reasons.

• #67 Relationship between Vitamin D Deficiency and Hypothyroidism-A Review – Journal of Young Pharmacists

  https://jyoungpharm.org/7994/

  Research suggests that hypovitaminosis D in patients with hypothyroidism and Graves disease may play an important role in musculoskeletal complications. […] The decrease in serum Vitamin D among hypothyroid patients can be described by two potential explanations. Firstly, it may result from insufficient absorption in the intestine. Furthermore, these patients might have difficulties in properly activating Vitamin D within their bodies. Vitamin D performs its biological functions by binding to the Vitamin D Receptor (VDR). Consequently, the activation of genes, found in specific target tissues, responsive to VDR is initiated. […] Recent research highlights the connection between a lack of Vitamin D and autoimmune issues related to the thyroid. This link seems to be present consistently across different age groups and it has been observed that supplements containing cholecalciferol effectively reduce levels of Thyroid Peroxidase Antibody (TPO-Ab) in individuals with Hashimoto’s Thyroiditis (HT) who have a Vitamin D deficiency.

• #68 Relationship between Vitamin D Deficiency and Hypothyroidism-A Review – Journal of Young Pharmacists

  https://jyoungpharm.org/7994/

  Research suggests that hypovitaminosis D in patients with hypothyroidism and Graves disease may play an important role in musculoskeletal complications. […] The decrease in serum Vitamin D among hypothyroid patients can be described by two potential explanations. Firstly, it may result from insufficient absorption in the intestine. Furthermore, these patients might have difficulties in properly activating Vitamin D within their bodies. Vitamin D performs its biological functions by binding to the Vitamin D Receptor (VDR). Consequently, the activation of genes, found in specific target tissues, responsive to VDR is initiated. […] Recent research highlights the connection between a lack of Vitamin D and autoimmune issues related to the thyroid. This link seems to be present consistently across different age groups and it has been observed that supplements containing cholecalciferol effectively reduce levels of Thyroid Peroxidase Antibody (TPO-Ab) in individuals with Hashimoto’s Thyroiditis (HT) who have a Vitamin D deficiency.

• #69

  https://journals.lww.com/indjem/fulltext/2012/16020/interactions_between_thyroid_disorders_and_kidney.10.aspx

  Hypothyroidism is associated with reduced GFR and hyperthyroidism results in increased GFR as well as increased renin angiotensin aldosterone activation. […] The GFR is reversibly reduced (by about 40%) in more than 55% of adults with hypothyroidism due to several reasons. There is decreased sensitivity to -adrenergic stimulus and decreased renin release along with decreased angiotensin II and impaired RAAS activity, resulting in loss of GFR. […] Hypothyroidism results in low cardiac output which triggers the carotid baroreceptors and consequently increases the non-osmotic ADH secretion. […] Hypothyroidism also results in increased glomerular capillary permeability to proteins. The consequent proteinuria often precedes the reduction in GFR in hypothyroidism.

• #70 Hypothyroidism and Joint Pain – Rheumatology Advisor

  https://www.rheumatologyadvisor.com/ddi/hypothyroidism-and-joint-pain/

  Hypothyroidism occurs when this hormone is in short supply, which causes body processes to slow down, resulting in a constellation of symptoms, including joint pain. […] This joint pain may stem from how the thyroid hormone affects the proliferation and differentiation of bone and cartilage at the cellular level. As such, hypothyroidism may lead to musculoskeletal conditions, including:1 Epiphyseal dysgenesis, Septic necrosis, Arthritis, crystal-induced arthritis, and erosive osteoarthritis, Arthralgias, Muscle weakness, Myalgias (with or without elevations in creatinine phosphokinase), Carpal tunnel syndrome, Highly viscous, noninflammatory joint effusions in the knees, wrists, and hands. […] Hypothyroid arthropathy, a joint disease that includes arthritis, most commonly strikes the knees and hands in adults and the hip and the epiphysis of the femoral head in children.

• #71 Hypothyroidism and Joint Pain – Rheumatology Advisor

  https://www.rheumatologyadvisor.com/ddi/hypothyroidism-and-joint-pain/

  Hypothyroidism occurs when this hormone is in short supply, which causes body processes to slow down, resulting in a constellation of symptoms, including joint pain. […] This joint pain may stem from how the thyroid hormone affects the proliferation and differentiation of bone and cartilage at the cellular level. As such, hypothyroidism may lead to musculoskeletal conditions, including:1 Epiphyseal dysgenesis, Septic necrosis, Arthritis, crystal-induced arthritis, and erosive osteoarthritis, Arthralgias, Muscle weakness, Myalgias (with or without elevations in creatinine phosphokinase), Carpal tunnel syndrome, Highly viscous, noninflammatory joint effusions in the knees, wrists, and hands. […] Hypothyroid arthropathy, a joint disease that includes arthritis, most commonly strikes the knees and hands in adults and the hip and the epiphysis of the femoral head in children.

• #72 Hypothyroidism and Joint Pain – Rheumatology Advisor

  https://www.rheumatologyadvisor.com/ddi/hypothyroidism-and-joint-pain/

  Hypothyroidism occurs when this hormone is in short supply, which causes body processes to slow down, resulting in a constellation of symptoms, including joint pain. […] This joint pain may stem from how the thyroid hormone affects the proliferation and differentiation of bone and cartilage at the cellular level. As such, hypothyroidism may lead to musculoskeletal conditions, including:1 Epiphyseal dysgenesis, Septic necrosis, Arthritis, crystal-induced arthritis, and erosive osteoarthritis, Arthralgias, Muscle weakness, Myalgias (with or without elevations in creatinine phosphokinase), Carpal tunnel syndrome, Highly viscous, noninflammatory joint effusions in the knees, wrists, and hands. […] Hypothyroid arthropathy, a joint disease that includes arthritis, most commonly strikes the knees and hands in adults and the hip and the epiphysis of the femoral head in children.

• #73 Hypothyroidism and Joint Pain – Rheumatology Advisor

  https://www.rheumatologyadvisor.com/ddi/hypothyroidism-and-joint-pain/

  The link between hypothyroidism and joint pain appears to be bi-directional. For example, people with rheumatoid arthritis (RA) are more likely to develop a thyroid condition such as hypothyroidism, and people with hypothyroidism are also at risk for joint pain and joint-related diseases. […] Specifically, people with autoimmune hypothyroid disease are at risk for:2 Chronic, widespread pain, Fibromyalgia, Degenerative joint disease, Osteoarthritis, Seronegative inflammatory arthritis. […] Hypothyroidism is typically treated with levothyroxine, a thyroid hormone. Most patients receive 1.6 mcg/kg per day, while elderly and atrial fibrillation patients may require lower doses. […] Effective treatment should help improve all hypothyroidism symptoms. If a patients labs are normal while on thyroid replacement, but joint symptoms do not resolve, they likely are not due to hypothyroidism.

• #74 Precocious Puberty: An Unusual Presentation of Hypothyroidism

  https://jpp.mums.ac.ir/article_2165.html

  Hypothyroidism is usually associated with delayed pubertal development but in rare occasions precocious puberty may ensue which is seen in cases of prolonged and untreated hypothyroidism. This is also called the Van Wyk Grumbach syndrome. […] Delayed puberty is a common manifest- tation in hypothyroid patients but rarely can it present as precocious puberty. The onset is usually with breast enlargement and vaginal bleeding in girls and testicular enlargement without virilization in boys. This presentation is also called as Van Wyk Grumbach syndrome. Recognition of this syndrome is very important because symptoms regress with thyroid hormone replacement and patients can enter into true puberty at its appropriate time. […] Hypothyroidism associated precocious puberty is also called Van Wyk Grumbach syndrome. It was first described in 1960 by Van Wyk and Grumbach. In girls the onset of symptoms is with thelarche followed by menarche and charactaristicly there is no development of pubic or axillary hair and opposite the patients with true precocious puberty these patients have a decreased linear growth.

• #75 Precocious Puberty: An Unusual Presentation of Hypothyroidism

  https://jpp.mums.ac.ir/article_2165.html

  Hypothyroidism is usually associated with delayed pubertal development but in rare occasions precocious puberty may ensue which is seen in cases of prolonged and untreated hypothyroidism. This is also called the Van Wyk Grumbach syndrome. […] Delayed puberty is a common manifest- tation in hypothyroid patients but rarely can it present as precocious puberty. The onset is usually with breast enlargement and vaginal bleeding in girls and testicular enlargement without virilization in boys. This presentation is also called as Van Wyk Grumbach syndrome. Recognition of this syndrome is very important because symptoms regress with thyroid hormone replacement and patients can enter into true puberty at its appropriate time. […] Hypothyroidism associated precocious puberty is also called Van Wyk Grumbach syndrome. It was first described in 1960 by Van Wyk and Grumbach. In girls the onset of symptoms is with thelarche followed by menarche and charactaristicly there is no development of pubic or axillary hair and opposite the patients with true precocious puberty these patients have a decreased linear growth.

• #76 Precocious Puberty: An Unusual Presentation of Hypothyroidism

  https://jpp.mums.ac.ir/article_2165.html

  The exact hormonal mechanism of hypothyroidism associated precocious puberty is not understood. Wyk and Grumbach explained that in response to thyroid hormone deficiency overproduction of gonadotropins as well as thyrotropin (which both share common subunit) occurs. But these elevated gonadotropins have been shown to be bioinactive in earlier studies and also absence of characteristics of gonadotropin excess such as advanced bone age in these cases makes the gonadotropin excess as the underlying mechanism unlikely. […] Another theory is that interaction of TSH with human FSH receptor is the possible mechanism of this syndrome. Elevated levels of TSH produce FSH like effects on the gonads in the absence of LH effects. This seems to be the most likely mechanism of this syndrome. All symptoms of this syndrome resolve with thyroxine replacement therapy, the endocrine abnormalities subside, the ovarian cysts decrease in size or disappear, as seen in our patients during their follow up.

• #77 Precocious Puberty: An Unusual Presentation of Hypothyroidism

  https://jpp.mums.ac.ir/article_2165.html

  The exact hormonal mechanism of hypothyroidism associated precocious puberty is not understood. Wyk and Grumbach explained that in response to thyroid hormone deficiency overproduction of gonadotropins as well as thyrotropin (which both share common subunit) occurs. But these elevated gonadotropins have been shown to be bioinactive in earlier studies and also absence of characteristics of gonadotropin excess such as advanced bone age in these cases makes the gonadotropin excess as the underlying mechanism unlikely. […] Another theory is that interaction of TSH with human FSH receptor is the possible mechanism of this syndrome. Elevated levels of TSH produce FSH like effects on the gonads in the absence of LH effects. This seems to be the most likely mechanism of this syndrome. All symptoms of this syndrome resolve with thyroxine replacement therapy, the endocrine abnormalities subside, the ovarian cysts decrease in size or disappear, as seen in our patients during their follow up.

• #78 Precocious Puberty: An Unusual Presentation of Hypothyroidism

  https://jpp.mums.ac.ir/article_2165.html

  The exact hormonal mechanism of hypothyroidism associated precocious puberty is not understood. Wyk and Grumbach explained that in response to thyroid hormone deficiency overproduction of gonadotropins as well as thyrotropin (which both share common subunit) occurs. But these elevated gonadotropins have been shown to be bioinactive in earlier studies and also absence of characteristics of gonadotropin excess such as advanced bone age in these cases makes the gonadotropin excess as the underlying mechanism unlikely. […] Another theory is that interaction of TSH with human FSH receptor is the possible mechanism of this syndrome. Elevated levels of TSH produce FSH like effects on the gonads in the absence of LH effects. This seems to be the most likely mechanism of this syndrome. All symptoms of this syndrome resolve with thyroxine replacement therapy, the endocrine abnormalities subside, the ovarian cysts decrease in size or disappear, as seen in our patients during their follow up.

• #79 Hypothyroidism conversion to hyperthyroidism: it’s never too late in: Endocrinology, Diabetes & Metabolism Case Reports Volume 2018 Issue 1 (2018)

  https://edm.bioscientifica.com/view/journals/edm/2018/1/EDM18-0047.xml

  Primary hypothyroidism is a common endocrine condition, most commonly caused by autoimmune thyroiditis (Hashimotos disease) while Graves disease is the most common cause of hyperthyroidism. […] Transformation from Hashimotos disease to Graves disease is considered rare but recently been increasingly recognised. […] This case highlights that there should be a high index of suspicion for a possible conversion of hypothyroidism to hyperthyroidism, even many years after the initial diagnosis of hypothyroidism. […] The underlying aetiology for the conversion is not exactly known but probably involves autoimmune switch by an external stimulus in genetically susceptible individuals. […] Although cases of conversion from hyperthyroidism to hypothyroidism are often encountered in clinical practice, it is rare to see conversion of primary hypothyroidism due to Hashimotos disease to hyperthyroidism due to Graves disease.

• #80 Hypothyroidism conversion to hyperthyroidism: it’s never too late in: Endocrinology, Diabetes & Metabolism Case Reports Volume 2018 Issue 1 (2018)

  https://edm.bioscientifica.com/view/journals/edm/2018/1/EDM18-0047.xml

  Primary hypothyroidism is a common endocrine condition, most commonly caused by autoimmune thyroiditis (Hashimotos disease) while Graves disease is the most common cause of hyperthyroidism. […] Transformation from Hashimotos disease to Graves disease is considered rare but recently been increasingly recognised. […] This case highlights that there should be a high index of suspicion for a possible conversion of hypothyroidism to hyperthyroidism, even many years after the initial diagnosis of hypothyroidism. […] The underlying aetiology for the conversion is not exactly known but probably involves autoimmune switch by an external stimulus in genetically susceptible individuals. […] Although cases of conversion from hyperthyroidism to hypothyroidism are often encountered in clinical practice, it is rare to see conversion of primary hypothyroidism due to Hashimotos disease to hyperthyroidism due to Graves disease.

• #81 Hypothyroidism conversion to hyperthyroidism: it’s never too late in: Endocrinology, Diabetes & Metabolism Case Reports Volume 2018 Issue 1 (2018)

  https://edm.bioscientifica.com/view/journals/edm/2018/1/EDM18-0047.xml

  Primary hypothyroidism is a common endocrine condition, most commonly caused by autoimmune thyroiditis (Hashimotos disease) while Graves disease is the most common cause of hyperthyroidism. […] Transformation from Hashimotos disease to Graves disease is considered rare but recently been increasingly recognised. […] This case highlights that there should be a high index of suspicion for a possible conversion of hypothyroidism to hyperthyroidism, even many years after the initial diagnosis of hypothyroidism. […] The underlying aetiology for the conversion is not exactly known but probably involves autoimmune switch by an external stimulus in genetically susceptible individuals. […] Although cases of conversion from hyperthyroidism to hypothyroidism are often encountered in clinical practice, it is rare to see conversion of primary hypothyroidism due to Hashimotos disease to hyperthyroidism due to Graves disease.

• #82 Hypothyroidism conversion to hyperthyroidism: it’s never too late in: Endocrinology, Diabetes & Metabolism Case Reports Volume 2018 Issue 1 (2018)

  https://edm.bioscientifica.com/view/journals/edm/2018/1/EDM18-0047.xml

  What causes this conversion is not well understood, but there are different theories postulated. […] We believe that genetically susceptible individuals may require an external trigger to switch from autoimmune hypothyroidism to Graves disease, such as an infection or neck irradiation, which would cause the balance to shift from TSH receptor-blocking antibodies to TSH receptor-stimulating antibodies. […] Further research, however, is needed to establish the exact pathogenesis of this phenomenon.

• #83 Hypothyroidism conversion to hyperthyroidism: it’s never too late in: Endocrinology, Diabetes & Metabolism Case Reports Volume 2018 Issue 1 (2018)

  https://edm.bioscientifica.com/view/journals/edm/2018/1/EDM18-0047.xml

  What causes this conversion is not well understood, but there are different theories postulated. […] We believe that genetically susceptible individuals may require an external trigger to switch from autoimmune hypothyroidism to Graves disease, such as an infection or neck irradiation, which would cause the balance to shift from TSH receptor-blocking antibodies to TSH receptor-stimulating antibodies. […] Further research, however, is needed to establish the exact pathogenesis of this phenomenon.

• #84 Pathophysiology and Diagnosis of Thyroid Disease – Medicare Coverage of Routine Screening for Thyroid Dysfunction – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK221541/

  Hypothyroidism is a hypometabolic state that results from a deficiency in T4 and T3. Its major clinical manifestations are fatigue, lethargy, cold intolerance, slowed speech and intellectual function, slowed reflexes, hair loss, dry skin, weight gain, and constipation. It is more prevalent in women than men. The most common cause of hypothyroidism is disease of the thyroid itself, primary hypothyroidism. […] The most common cause of primary hypothyroidism is chronic autoimmune thyroiditis (Hashimoto’s disease), in which the thyroid is destroyed by antibodies or lymphocytes that attack the gland. Other causes are radioactive iodine and surgical therapy for hyperthyroidism or thyroid cancer, thyroid inflammatory disease, iodine deficiency, and several drugs that interfere with the synthesis or availability of thyroid hormone. Hypothyroidism may also occur rarely (1 percent of cases) as a result of deficiency of TRH or impaired TSH secretion due to hypothalamic or pituitary disease, respectively. This is known as secondary or central hypothyroidism because of the negative feedback relationship between serum T4 and T3 levels and TSH secretion. As noted earlier and shown in Figure 2-1, people with primary hypothyroidism have high serum TSH levels. If an individual has a high serum TSH value, serum free T4 should be measured. The concomitant finding of a high serum TSH concentration and a low free T4 level confirms the diagnosis of primary hypothyroidism. People with a high serum TSH concentration and a normal or low-normal serum free T4 level have, by definition, subclinical hypothyroidism. The diagnosis of secondary hypothyroidism is based on the findings of a low serum free T4 level and a serum TSH level that is normal or low. People with secondary hypothyroidism are unlikely to be detected by a screening program based on measurements of serum TSH, but the condition is much less common than primary hypothyroidism.

• #85 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  There are two types of thyroid disease, hyperthyroidism (an overactive thyroid) and hypothyroidism (an underactive thyroid). […] Patients with an underactive thyroid produce too little thyroid hormone, causing their metabolism to slow significantly. This manifests as symptoms such as lethargy and weight gain. Hypothyroidism is more common than hyperthyroidism, with about 1 in 20 Americans suffering from the condition. […] One of the key signs that a patient is developing hypothyroidism is fatigue; however, the fatigue associated with hypothyroidism is different from the fatigue experienced on an everyday basis. […] With too little thyroid hormone circulating in the body, the metabolism slows, and the body converts food to energy at a slower rate. Consequently, patients with hypothyroidism often gain weight rapidly without altering their diet.

• #86 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  There are two types of thyroid disease, hyperthyroidism (an overactive thyroid) and hypothyroidism (an underactive thyroid). […] Patients with an underactive thyroid produce too little thyroid hormone, causing their metabolism to slow significantly. This manifests as symptoms such as lethargy and weight gain. Hypothyroidism is more common than hyperthyroidism, with about 1 in 20 Americans suffering from the condition. […] One of the key signs that a patient is developing hypothyroidism is fatigue; however, the fatigue associated with hypothyroidism is different from the fatigue experienced on an everyday basis. […] With too little thyroid hormone circulating in the body, the metabolism slows, and the body converts food to energy at a slower rate. Consequently, patients with hypothyroidism often gain weight rapidly without altering their diet.

• #87 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  There are two types of thyroid disease, hyperthyroidism (an overactive thyroid) and hypothyroidism (an underactive thyroid). […] Patients with an underactive thyroid produce too little thyroid hormone, causing their metabolism to slow significantly. This manifests as symptoms such as lethargy and weight gain. Hypothyroidism is more common than hyperthyroidism, with about 1 in 20 Americans suffering from the condition. […] One of the key signs that a patient is developing hypothyroidism is fatigue; however, the fatigue associated with hypothyroidism is different from the fatigue experienced on an everyday basis. […] With too little thyroid hormone circulating in the body, the metabolism slows, and the body converts food to energy at a slower rate. Consequently, patients with hypothyroidism often gain weight rapidly without altering their diet.

• #88 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  There are two types of thyroid disease, hyperthyroidism (an overactive thyroid) and hypothyroidism (an underactive thyroid). […] Patients with an underactive thyroid produce too little thyroid hormone, causing their metabolism to slow significantly. This manifests as symptoms such as lethargy and weight gain. Hypothyroidism is more common than hyperthyroidism, with about 1 in 20 Americans suffering from the condition. […] One of the key signs that a patient is developing hypothyroidism is fatigue; however, the fatigue associated with hypothyroidism is different from the fatigue experienced on an everyday basis. […] With too little thyroid hormone circulating in the body, the metabolism slows, and the body converts food to energy at a slower rate. Consequently, patients with hypothyroidism often gain weight rapidly without altering their diet.

• #89 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  Often, patients with hypothyroidism report stomach and digestive issues in conjunction with other symptoms. With too little thyroid hormone, patients with an underactive thyroid are at risk of an overgrowth or imbalance of the bacteria in the digestive system. […] In patients with hypothyroidism, the lower levels of thyroid hormones can lead to an unusual perception of cold. […] In patients with hypothyroidism, this most commonly manifests as dry skin: a study published in the Journal of General Internal Medicine found that 74% of participants with an underactive thyroid also had dry skin. […] Thyroid hormones play a role in the growth of new hair; with low levels of thyroid hormones, the body’s growth of new hair is impaired. […] While hypothyroidism is commonly associated with lethargy and a desire for sleep, studies have linked an underactive thyroid to poor sleep quality, shorter sleep duration, and longer sleep onset.

• #90 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  Often, patients with hypothyroidism report stomach and digestive issues in conjunction with other symptoms. With too little thyroid hormone, patients with an underactive thyroid are at risk of an overgrowth or imbalance of the bacteria in the digestive system. […] In patients with hypothyroidism, the lower levels of thyroid hormones can lead to an unusual perception of cold. […] In patients with hypothyroidism, this most commonly manifests as dry skin: a study published in the Journal of General Internal Medicine found that 74% of participants with an underactive thyroid also had dry skin. […] Thyroid hormones play a role in the growth of new hair; with low levels of thyroid hormones, the body’s growth of new hair is impaired. […] While hypothyroidism is commonly associated with lethargy and a desire for sleep, studies have linked an underactive thyroid to poor sleep quality, shorter sleep duration, and longer sleep onset.

• #91 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  Often, patients with hypothyroidism report stomach and digestive issues in conjunction with other symptoms. With too little thyroid hormone, patients with an underactive thyroid are at risk of an overgrowth or imbalance of the bacteria in the digestive system. […] In patients with hypothyroidism, the lower levels of thyroid hormones can lead to an unusual perception of cold. […] In patients with hypothyroidism, this most commonly manifests as dry skin: a study published in the Journal of General Internal Medicine found that 74% of participants with an underactive thyroid also had dry skin. […] Thyroid hormones play a role in the growth of new hair; with low levels of thyroid hormones, the body’s growth of new hair is impaired. […] While hypothyroidism is commonly associated with lethargy and a desire for sleep, studies have linked an underactive thyroid to poor sleep quality, shorter sleep duration, and longer sleep onset.

• #92 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  Often, patients with hypothyroidism report stomach and digestive issues in conjunction with other symptoms. With too little thyroid hormone, patients with an underactive thyroid are at risk of an overgrowth or imbalance of the bacteria in the digestive system. […] In patients with hypothyroidism, the lower levels of thyroid hormones can lead to an unusual perception of cold. […] In patients with hypothyroidism, this most commonly manifests as dry skin: a study published in the Journal of General Internal Medicine found that 74% of participants with an underactive thyroid also had dry skin. […] Thyroid hormones play a role in the growth of new hair; with low levels of thyroid hormones, the body’s growth of new hair is impaired. […] While hypothyroidism is commonly associated with lethargy and a desire for sleep, studies have linked an underactive thyroid to poor sleep quality, shorter sleep duration, and longer sleep onset.

• #93 7 Early Warning Signs of Thyroid Issues – Associated Endocrinologist, P.C.

  https://www.endocrinemds.com/blogs/7-early-warning-signs-of-thyroid-issues/

  Often, patients with hypothyroidism report stomach and digestive issues in conjunction with other symptoms. With too little thyroid hormone, patients with an underactive thyroid are at risk of an overgrowth or imbalance of the bacteria in the digestive system. […] In patients with hypothyroidism, the lower levels of thyroid hormones can lead to an unusual perception of cold. […] In patients with hypothyroidism, this most commonly manifests as dry skin: a study published in the Journal of General Internal Medicine found that 74% of participants with an underactive thyroid also had dry skin. […] Thyroid hormones play a role in the growth of new hair; with low levels of thyroid hormones, the body’s growth of new hair is impaired. […] While hypothyroidism is commonly associated with lethargy and a desire for sleep, studies have linked an underactive thyroid to poor sleep quality, shorter sleep duration, and longer sleep onset.

• #94 Hypothyroidism (underactive thyroid) – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284

  Hypothyroidism that isn’t treated can lead to other health problems, including: […] Hypothyroidism may cause the thyroid gland to become larger. This condition is called a goiter. A large goiter may cause problems with swallowing or breathing. […] Hypothyroidism can lead to a higher risk of heart disease and heart failure. That’s mainly because people with an underactive thyroid tend to develop high levels of low-density lipoprotein (LDL) cholesterol the „bad” cholesterol. […] Hypothyroidism that goes without treatment for a long time can damage the peripheral nerves. These are the nerves that carry information from the brain and spinal cord to the rest of the body. Peripheral neuropathy may cause pain, numbness and tingling in the arms and legs. […] Low levels of thyroid hormone can interfere with ovulation, which can limit fertility. Some of the causes of hypothyroidism, such as autoimmune disorders, also can harm fertility.

• #95 Hypothyroidism (underactive thyroid) – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284

  Babies born to people with untreated thyroid disease may have a higher risk of birth defects compared with babies born to mothers who do not have thyroid disease. […] This rare, life-threatening condition can happen when hypothyroidism goes without treatment for a long time. A myxedema coma may be triggered by sedatives, infection or other stress on the body. Its symptoms include intense cold intolerance and drowsiness, followed by an extreme lack of energy and then unconsciousness. Myxedema coma requires emergency medical treatment.

• #96 Hypothyroidism – Endocrine and Metabolic Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/thyroid-disorders/hypothyroidism

  Hypothyroidism is thyroid hormone deficiency. […] Primary hypothyroidism is due to decreased secretion of thyroxine (T4) and triiodothyronine (T3) from the thyroid. […] In the United States, the most common cause is autoimmune inflammation. […] The second most common cause is treatment for hyperthyroidism (post-therapeutic hypothyroidism), especially after radioactive iodine therapy or surgery for hyperthyroidism, goiter, or thyroid cancer. […] Iodine deficiency may cause endemic goiter and goitrous hypothyroidism. […] Rare inherited enzymatic defects can alter the synthesis of thyroid hormone and cause goitrous hypothyroidism. […] Hypothyroidism may occur in patients taking lithium, perhaps because lithium inhibits hormone release by the thyroid. […] Hypothyroidism can result from radiation therapy for cancer of the larynx or Hodgkin lymphoma.

• #97 2. Pathophysiology and Diagnosis of Thyroid Disease | Medicare Coverage of Routine Screening for Thyroid Dysfunction | The National Academies Press

  https://nap.nationalacademies.org/read/10682/chapter/4

  Hypothyroidism is a hypometabolic state that results from a deficiency in T4 and T3. Its major clinical manifestations are fatigue, lethargy, cold intolerance, slowed speech and intellectual function, slowed reflexes, hair loss, dry skin, weight gain, and constipation. It is more prevalent in women than men. The most common cause of hypothyroidism is disease of the thyroid itself, primary hypothyroidism. […] The most common cause of primary hypothyroidism is chronic autoimmune thyroiditis (Hashimotos disease), in which the thyroid is destroyed by antibodies or lymphocytes that attack the gland. Other causes are radioactive iodine and surgical therapy for hyperthyroidism or thyroid cancer, thyroid inflammatory disease, iodine deficiency, and several drugs that interfere with the synthesis or availability of thyroid hormone. Hypothyroidism may also occur rarely (1 percent of cases) as a result of deficiency of TRH or impaired TSH secretion due to hypothalamic or pituitary disease, respectively. This is known as secondary or central hypothyroidism because of the negative feedback relationship between serum T4 and T3 levels and TSH secretion. As noted earlier and shown in Figure 2-1, people with primary hypothyroidism have high serum TSH levels. If an individual has a high serum TSH value, serum free T4 should be measured. The concomitant finding of a high serum TSH concentration and a low free T4 level confirms the diagnosis of primary hypothyroidism. People with a high serum TSH concentration and a normal or low-normal serum free T4 level have, by definition, subclinical hypothyroidism. The diagnosis of secondary hypothyroidism is based on the findings of a low serum free T4 level and a serum TSH level that is normal or low. People with secondary hypothyroidism are unlikely to be detected by a screening program based on measurements of serum TSH, but the condition is much less common than primary hypothyroidism.

• #98

  https://step2.medbullets.com/endocrine/120098/hypothyroidism-vs-hyperthyroidism

  Hypothyroidism is a disorder characterized by the under production of thyroid hormone. […] Pathogenesis is primarily due to thyroid disease (primary hypothyroidism) but can be caused by secondary and/or tertiary hypothyroidism. […] Primary hypothyroidism is often due to Hashimoto thyroiditis (chronic autoimmune thyroiditis), which involves cell- and antibody-mediated destruction of thyroid tissue. […] Secondary hypothyroidism is caused by TSH deficiency secondary to any of the causes of hypopituitarism, most commonly due to a pituitary tumor. […] Tertiary hypothyroidism is caused by any disorder that damages the hypothalamus or interferes with hypothalamic-pituitary portal blood flow.

• #99 Hypothyroidism: Practice Essentials, Background, Pathophysiology

  https://emedicine.medscape.com/article/122393-overview

  Although hypothalamic or pituitary disorders can affect thyroid function, localized disease of the thyroid gland that results in decreased thyroid hormone production is the most common cause of hypothyroidism. Under normal circumstances, the thyroid releases 100-125 nmol of T4 daily and small amounts of T3. The ratio of T4:T3 production varies between about 14:1 and 4:1, depending on iodine sufficiency and TSH stimulation. The half-life of T4 is approximately 7-10 days, whereas the half-life of T3 is about 24 hours. T4, a prohormone, is converted via the action of deiodinases to T3, the active form of thyroid hormone. […] Deficiency of thyroid hormone has a wide range of effects. Systemic effects are the result of either derangements in metabolic processes or direct effects by myxedematous infiltration (ie, accumulation of glycosaminoglycans in the tissues).

• #100

  https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/

  An underactive thyroid gland (hypothyroidism) is where your thyroid gland does not produce enough hormones. […] Most cases are caused either by the immune system attacking the thyroid gland and damaging it, or by damage to the thyroid that occurs during some treatments for an overactive thyroid or thyroid cancer. […] Treatment for an underactive thyroid involves taking daily hormone replacement tablets, called levothyroxine, to raise your thyroxine levels. […] Many of the body’s functions slow down when the thyroid does not produce enough of these hormones.

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