Materiały źródłowe

• #1 Gynecomastia: Etiology, Diagnosis, and Treatment – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK279105/

  Gynecomastia is a relatively common disorder. Its causes range from benign physiological processes to rare neoplasms. To diagnose the etiology of the gynecomastia, the clinician must understand the hormonal factors involved in breast development. […] Since a balance exists between estrogen and androgens in males, any disease state or medication that increases circulating estrogens or decreases circulating androgens, causing an elevation in the estrogen to androgen ratio, can induce gynecomastia. […] Due to the diversity of possible etiologies, including a neoplasm, performing a careful history and physical is imperative. […] Pathologic gynecomastia is due to an increase in the circulating and/or local breast tissue ratio of estrogen to androgen. […] Increased estrogen levels will increase glandular proliferation by several mechanisms.

• #1 Gynecomastia: Practice Essentials, Background, Etiology

  https://emedicine.medscape.com/article/120858-overview

  Gynecomastia results from an altered estrogen-androgen balance, in favor of estrogen, or from increased breast sensitivity to a normal circulating estrogen level. […] The imbalance is between the stimulatory effect of estrogen and the inhibitory effect of androgen. […] Estrogens induce ductal epithelial hyperplasia, ductal elongation and branching, proliferation of the periductal fibroblasts, and an increase in vascularity. […] Estrogen production in males results mainly from the peripheral conversion of androgens (testosterone and androstenedione) to estradiol and estrone, which occurs through the action of the enzyme aromatase (mainly in muscle, skin, and adipose tissue). […] Increased estrogen production and/or action can occur at the testicular level or at the periphery and is characterized as follows: From the testes – Can be due to testicular tumors or to ectopic production of human chorionic gonadotropin (hCG), as is reported with carcinoma of lung, kidney, gastrointestinal (GI) tract, and extragonadal germ cell tumors.

• #1 Gynecomastia: Etiology, Diagnosis, and Treatment – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK279105/

  Decreased testosterone levels can cause an elevation in the estrogen to androgen ratio, thereby producing gynecomastia. […] The gynecomastia of liver disease, particularly cirrhosis, does not have a clear etiology. […] Gynecomastia is associated with spinal cord disorders. […] About 20% of gynecomastia is caused by medications or exogenous chemicals. […] Some drugs may increase estrogen effect by several mechanisms: 1) they possess intrinsic estrogen-like properties, 2) they increase endogenous estrogen production, or 3) they supply an excess of an estrogen precursor (e.g., testosterone or androstenedione) that can be aromatized to estrogen.

• #1 Gynecomastia: What It Is, Causes, Diagnosis & Treatment

  https://my.clevelandclinic.org/health/symptoms/16227-enlarged-male-breast-tissue-gynecomastia

  Gynecomastia most often happens due to an imbalance of testosterone and estrogen. […] Gynecomastia is the enlargement of glandular tissue in your breast(s). Estrogen is responsible for the growth of glandular breast tissue. Estrogen also suppresses the release of testosterone. This is because it suppresses luteinizing hormone (LH), the hormone responsible for the release of testosterone in your testicles. In other words, an increase in estrogen and a decrease in testosterone most often leads to gynecomastia. […] Gynecomastia may be a symptom or result of the following health conditions: Adrenal tumors, Hyperthyroidism (overactive thyroid), Kidney disease or kidney failure, Klinefelter syndrome (an inherited condition), Liver disease and cirrhosis, Male hypogonadism (low testosterone), Pituitary gland tumors (pituitary adenomas), especially prolactinomas, Testicular tumors.

• #1 Gynaecomastia – Zero To Finals

  https://zerotofinals.com/surgery/breast/gynaecomastia/

  Gynaecomastia is generally caused by a hormonal imbalance between oestrogen and androgens (e.g., testosterone), with higher oestrogen and lower androgen levels. […] Raised oestrogen stimulates breast development, whilst androgens have an inhibitory effect on breast development. […] Therefore, raised prolactin (hyperprolactinaemia) can cause gynaecomastia. […] Gynaecomastia can be caused by conditions that increase oestrogen: Obesity (aromatase is an enzyme found in adipose tissue that converts androgens to oestrogen), Testicular cancer (oestrogen secretion from a Leydig cell tumour), Liver cirrhosis and liver failure, Hyperthyroidism, Human chorionic gonadotrophin (hCG) secreting tumour, notably small cell lung cancer. […] Gynaecomastia can be caused by conditions that reduce testosterone: Testosterone deficiency in older age, Hypothalamus or pituitary conditions that reduce LH and FSH levels (e.g., tumours, radiotherapy or surgery), Klinefelter syndrome (XXY sex chromosomes), Orchitis (inflammation of the testicles, e.g., infection with mumps), Testicular damage (e.g., secondary to trauma or torsion).

• #1 Breast enlargement in males: MedlinePlus Medical EncyclopediaLock

  https://medlineplus.gov/ency/article/003165.htm

  When an abnormal amount of breast tissue develops in males, it is called gynecomastia. It is important to find out if the excess growth in the area of the breast is breast tissue and not excess fat tissue (lipomastia). […] Normal hormone changes are the most common cause of breast development in newborns, boys, and men. There are other causes as well. […] Breast enlargement is usually caused by an imbalance of estrogen (female hormone) and testosterone (male hormone). Males have both types of hormones in their body. Changes in the levels of these hormones, or in how the body uses or responds to these hormones, can cause enlarged breasts in males. […] In newborns, breast growth is caused by being exposed to estrogen from the mother. About one half of boy babies are born with enlarged breasts, called breast buds. They usually go away in 2 to 6 months, but can last longer.

• #1 Breast enlargement in males: MedlinePlus Medical EncyclopediaLock

  https://medlineplus.gov/ency/article/003165.htm

  In preteens and teens, breast growth is caused by normal hormone changes that occur during puberty. More than one half of boys develop some breast enlargement during puberty. Breast growth often goes away in 6 months to 2 years. […] In men, hormone changes due to aging can cause breast growth. This may occur more often in overweight or obese men and in men age 50 and older. […] Certain health problems can cause breast growth in adult men, including: Chronic liver disease, Kidney failure and dialysis, Low testosterone level, Obesity (also the most common cause of breast growth due to fat). […] Gynecomastia has also been linked to exposure to endocrine disrupters. These are common chemicals often found in plastics.

• #1 Understanding Gynecomastia and Its Management

  https://www.uspharmacist.com/article/understanding-gynecomastia-and-its-management/preview/uspeditorial?utm_source=TrendMD&utm_medium=cpc&utm_campaign=US_Pharmacist_TrendMD_1

  Gynecomastia in older men may result from decreased serum testosterone concentrations, increased aromatase activity related to increased body fat that leads to increased conversion of androgens to estrogen, and elevated luteinizing hormone (LH) concentrations. […] Notably, gynecomastia is attributable to medications in 80% of cases in older men.

• #1 Enlarged breasts in men (gynecomastia) – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/gynecomastia/symptoms-causes/syc-20351793

  Gynecomastia during puberty. Gynecomastia caused by hormone changes during puberty is somewhat common. […] Gynecomastia in adults. About 24% to 65% of men ages 50 to 80 get gynecomastia. […] Certain health conditions that affect the balance of hormones can either cause or be linked with gynecomastia. […] Conditions that lower the amount of testosterone the body makes can be linked with gynecomastia. […] Hormone changes that happen with aging can cause gynecomastia, especially in people who are overweight. […] Some tumors can make hormones that shift the body’s hormone balance. […] Changes in hormone levels related to liver problems and cirrhosis medicines are linked with gynecomastia. […] When the body doesn’t get enough nutrition, testosterone levels drop. But estrogen levels stay the same. This causes an imbalance in the hormones.

• #1 Gynecomastia – Wikipedia

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

  Gynecomastia may be caused by abnormal hormone changes, any condition that leads to an increase in the ratio of estrogens/androgens such as liver disease, kidney failure, thyroid disease and some non-breast tumors. Alcohol and some drugs can also cause breast enlargement.[4][7] […] Other causes may include Klinefelter syndrome, metabolic dysfunction, or a natural decline in testosterone production.[4][6][8] This may occur even if the levels of estrogens and androgens are both appropriate, but the ratio is altered.[7] […] Gynecomastia is thought to be caused by an altered ratio of estrogens to androgens mediated by an increase in estrogen action, a decrease in androgen action, or a combination of these two factors.[7] Estrogen and androgens have opposing actions on breast tissue: estrogens stimulate proliferation while androgens inhibit proliferation.[7][26] The cause of gynecomastia is unknown in around 25% of cases.[22][27] Known causes can be physiologic (occurring normally) or non-physiologic due to underlying pathologies such as drug use, chronic disease, tumors, or malnutrition.

• #1 Gynecomastia – Wikipedia

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

  About 10-25% of gynecomastia cases are estimated to result from the use of medications or exogenous chemicals.[17][27] Drugs can increase estrogen activity or increase the estrogen to androgen ratio through various mechanisms, such as binding to estrogen receptors, promoting estrogen synthesis, providing precursors that can be aromatized into estrogen, causing damage to the testes, inhibiting testosterone synthesis, inhibiting the action of androgens, or displacing estrogen from SHBG.[29] […] Gynecomastia can be caused by absolute deficiency in androgen production due to primary or secondary hypogonadism. Primary hypogonadism results when there is damage to the testes (due to radiation, chemotherapy, infections, trauma, etc.), leading to impaired androgen production.[7] […] Testicular tumors such as Leydig cell tumors, Sertoli cell tumors and hCG-secreting choriocarcinoma may result in rapid-onset gynecomastia by causing excess production of estrogen.[7] Other tumors such as adrenal tumors, pituitary gland tumors (such as a prolactinoma), or lung cancer, can produce hormones that alter the male-female hormone balance and cause gynecomastia.[22]

• #1 An interesting case of gynaecomastia

  https://www.racgp.org.au/afp/2016/january-february/an-interesting-case-of-gynaecomastia

  Gynaecomastia occurs as a result of an imbalance in the free oestrogen to free testosterone ratio that is secondary to a variety of physiological and non-physiological causes. […] The most frequent non-physiological cause is medications, although there are numerous differentials to consider. […] Keeping these aetiologies of gynaecomastia in mind, take a thorough medication history, and assess for signs of: cirrhosis (jaundice, ascites, pruritus), malnutrition, chronic renal failure (oedema, fatigue), hyperthyroidism (weight loss, palpitations, fine tremor), hypogonadism (erectile dysfunction, decreased muscle mass, testicular atrophy), testicular tumours (testicular mass), adrenal tumours (abdominal mass). […] Testicular malignancies are classified as either germ cell (95%) or sex cord stromal (5%) in origin each causes gynaecomastia via different mechanisms. Germ-cell tumours that have a choriocarcinoma component secrete hCG, resulting in Leydig cell dysfunction and, in turn, increases in both oestradiol and testosterone production. […] Leydig cell tumours (a type of sex cord stromal tumour) are rare, but are more likely to cause gynaecomastia because they directly secrete more oestradiol and convert additional androgen precursors to oestrogens.

• #1 Gynecomastia: Etiology, Diagnosis, and Treatment – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK279105/

  Thus, any cause of estrogen excess from overproduction to peripheral aromatization of androgens can initiate the cascade to breast development. […] Testicular tumors can lead to increased blood estrogen levels by the following mechanisms: estrogen overproduction, androgen overproduction with extragonadal aromatization to estrogens, and secretion of hCG that stimulates normal Leydig cells (via the LH receptor). […] Some neoplasms that overproduce estrogens also possess aromatase overactivity. […] Besides tumors, other conditions have also been associated with excessive aromatization of testosterone and other androgens to estrogen leading to gynecomastia. […] The mechanism is thought to be related to the increased aromatase activity in adipose tissues, but most obese men do not have high estrogen concentrations.

• #1 Gynecomastia: Practice Essentials, Background, Etiology

  https://emedicine.medscape.com/article/120858-overview

  From peripheral conversion – Can be due to increased substrate or increased activity of aromatase, as in chronic liver disease, malnutrition, hyperthyroidism, adrenal tumors, and familial gynecomastia. […] Gynecomastia can be physiologic or pathologic. […] Pathologic gynecomastia can be caused by an increase in the production and/or action of estrogen, by a decrease in the production and/or action of testosterone accompanied by increased aromatization and high estrogen, or by drug use. […] Conditions that result in primary or secondary hypogonadism can lead to gynecomastia in different mechanisms. […] The following are some of the conditions associated with gynecomastia: Klinefelter syndrome, congenital anorchia, testicular trauma, viral orchitis, Kallmann syndrome, pituitary tumors or abnormalities, malignancies that increase the serum level of hCG, renal failure, hyperthyroidism, malnutrition, environmental pollutants, androgen insensitivity syndrome, aromatase excess syndrome.

• #1 Gynecomastia: What It Is, Causes, Symptoms, and Treatment | Anadolu Sağlık Merkezi

  https://www.anadolumedicalcenter.com/health-guide/gynecomastia-what-it-is-causes-symptoms-and-treatment

  Testosterone production decreases with aging, which can contribute to the development of gynecomastia. […] In obese men, uncontrolled fat accumulation in the body increases, and fat tissue is an active site where testosterone is converted to estrogen. This reduction in testosterone levels can cause gynecomastia.

• #1 Gynecomastia – Symptoms, Causes, Complications and Prevention PACE Hospitals – Best Hospitals in Hitech City, Hyderabad, India | Near Madhapur, Kukatpally, KPHB, Kondapur, Gachibowli, Jubilee Hills, Banjara HillsPACE Hospitals Contact Num

  https://www.pacehospital.com/gynecomastia-symptoms-causes-complications-and-prevention

  Cirrhosis, or liver disease: Due to the increased production of androstenedione (steroid hormone responsible for the production of oestrogen and testosterone) from the adrenal glands, an increase in the conversion of androstenedione to oestrone and oestrone oestradiol and decreased clearance of adrenal androgens from the liver leads to a decrease in free testosterone. This causes an imbalance between the amount of oestrogen and testosterone in the body, which leads to gynecomastia. […] Male hypogonadism: Primary hypogonadism (production of low amount of sex hormones) can lead to a decrease in testosterone production. […] Hyperthyroidism: In hyperthyroidism, there will be an increase in sex hormone binding globulin (protein), which leads to an increase in oestradiol levels. […] Renal / kidney failure and dialysis: In haemodialysis patients, there will be abnormalities in the function of the Leydig cell (source of testosterone or androgens in males). In case of kidney failure, it leads to hormonal abnormalities, where the testosterone level goes down and oestradiol and luteinizing hormone levels go up.

• #1 Gynecomastia | AAFP

  https://www.aafp.org/pubs/afp/issues/2012/0401/p716.html

  Gynecomastia occurs in 10 to 40 percent of men with hyperthyroidism, although it is rarely the only symptom at presentation. […] Hormonal dysfunction is common in men with renal failure because of overall suppression of testosterone production and direct testicular damage secondary to uremia. […] Conditions that impair absorption, such as ulcerative colitis and cystic fibrosis, may result in gynecomastia. […] Other rare causes of gynecomastia include exposure to phthalates and lead, emotional stress, and repetitive mechanical stress causing unilateral symptoms. […] No cause is found in 25 percent of patients who develop gynecomastia.

• #1 Gynaecomastia: Causes, Symptoms, and Treatment | Doctor

  https://patient.info/doctor/gynaecomastia

  Lack of testosterone: Congenital absence of testes. […] There are absent levels of testosterone with normal estradiol levels and patients experience severe gynaecomastia. […] Klinefelter’s syndrome (XXY syndrome). Associated with gynaecomastia in 80% of cases. […] Increased oestrogen levels: Testicular tumours (for example, Leydig’s cell tumour) which secrete estradiol. […] Liver disease or cirrhosis. In liver disease there is an increased production of androstenedione by the adrenal glands, increased aromatisation of androstenedione to oestrogen, loss of clearance of adrenal androgens by the liver and a rise in SHBG, resulting in gynaecomastia. […] Medication accounts for up to 25% of all cases in adult men. […] Other causes: Long-term type 1 diabetes mellitus. […] Chronic illness. […] Spinal cord injury. […] If no underlying cause is found, it is said to be idiopathic.

• #1 Gynecomastia: Causes, Symptoms, Treatment, Surgery, & Self Care

  https://www.medicinenet.com/gynecomastia/article.htm

  Gynecomastia is an enlargement of the glandular tissue of the male breast. […] Gynecomastia results from an imbalance in hormone levels in which levels of estrogen (female hormones) are increased relative to levels of androgens (male hormones). […] A number of medical conditions may also result in gynecomastia: Malnutrition and re-feeding (recovery from malnutrition) have both been shown to create a hormonal environment that may lead to gynecomastia. Similarly, cirrhosis of the liver alters normal hormone metabolism and may lead to the condition. […] Disorders of the male sex organs (testes) can result in decreased testosterone production and relatively high estrogen levels, leading to gynecomastia. […] Gynecomastia can be a side effect of many medications, for example: Spironolactone, a diuretic that has anti-androgenic activity.

• #1 Azthena logo with the word Azthena

  https://www.news-medical.net/health/Causes-of-Gynecomastia.aspx

  Gynecomastia is a condition characterized by the development of enlarged breasts in males. There are many causes of gynecomastia; physiological, age-related, and drug-induced gynecomastia being just a few. […] When there is an imbalance between the male and female hormones in men, they may develop feminizing characteristics. Notable among these is gynecomastia. […] Gynecomastia may be physiological at three stages of life: in the neonatal period, at puberty, and in aging males. In all three cases it is due to relatively high estrogen levels. […] Some drugs have been known to be linked to gynecomastia, by several mechanisms such as their estrogenic properties, stimulation of estrogen production in the body, or supplying molecules which are easily converted to estrogen. […] Gynecomastia may also be seen in the following situations: Chronic liver disease may increase female hormone production and lead to gynecomastia, End-stage renal disease, due to associated testosterone deficiency, Inadequate levels of testosterone or male hormones, Exposure to female hormones, Anabolic steroids, Certain illicit drugs and alcohol, Radiation therapy and cancer chemotherapy, especially for testicular and prostate cancer, Male hypogonadism, which may have several causes; genetic disorders associated with low testosterone levels in males, such as Klinefelters syndrome (which causes malformation and underdevelopment of the testes accompanied by gynecomastia), acquired testicular diseases causing primary hypogonadism, or enzyme deficiencies, Thyroid disorders, especially associated with hyperthyroidism, Tumors which secrete estrogen, including those of the testes, adrenal glands or pituitary gland, can alter the balance of estrogens and androgens in males, Malnutrition or severe dieting is associated with lowering of the testosterone levels without a corresponding dip in estrogens, causing gynecomastia in some cases, but refeeding after malnutrition is more common, Some herbs like tea tree or lavender have been associated with gynecomastia, purportedly due to their weak estrogenic action. […] In many cases, the cause remains unknown.

• #1 Causes of Gynecomastia | Stanford Health Care

  https://stanfordhealthcare.org/medical-conditions/mens-health/gynecomastia/causes.html

  In newborns, gynecomastia is caused by estrogen from the mother. […] Gynecomastia can also be caused by an estrogen-producing tumor. […] In adult males, gynecomastia is usually caused by another condition, such as liver or lung cancer, cirrhosis of the liver, overactive thyroid, or by hormone problems, such as cancer of the pituitary gland, adrenal glands, or testicles. […] In older males, gynecomastia can be caused by a change in hormone levels. […] Use of certain medicines may also cause gynecomastia, including:

• #1 Gynecomastia – Symptoms, Causes, Complications and Prevention PACE Hospitals – Best Hospitals in Hitech City, Hyderabad, India | Near Madhapur, Kukatpally, KPHB, Kondapur, Gachibowli, Jubilee Hills, Banjara HillsPACE Hospitals Contact Num

  https://www.pacehospital.com/gynecomastia-symptoms-causes-complications-and-prevention

  Abnormal human chorionic gonadotrophin (hCG) production: Human chorionic gonadotrophin is a hormone produced by the placenta during pregnancy in females. […] True hermaphroditism is characterised by the presence of both ovarian and testicular tissues. […] Overweight/Obese can raise oestrogen levels, causing breast tissue to grow. Overweight people are more likely to have excess fat, which can cause breast tissue to enlarge.

• #1 Gynecomastia in adolescent males: current understanding of its etiology, pathophysiology, diagnosis, and treatment

  https://e-apem.org/journal/view.php?number=1034

  Graves disease (GD) is a contributing factor to hyperthyroidism in adolescents. […] Prolactin-producing pituitary adenomas (prolactinomas) induce GM via their indirect role in change of the androgen/estrogen ratio. […] Testicular trauma, mumps, orchitis, and chemotherapy can all result in primary gonadal failure, which lowers serum testosterone level, increases lutenizing hormone (LH) level, and stimulates Leydig cells to produce estrogens, resulting in GM. […] Testicular feminization syndrome is commonly associated with the development of female breast appearance in males with an XY karyotype as a result of gonadal estrogen production. […] Patients with type 1 diabetes who have had the condition for a long time may develop diabetic mastopathy (DMP), presenting as hard, diffuse enlargements in one or both breasts.

• #1 Drug-induced Gynaecomastia

  https://www.medsafe.govt.nz/profs/PUarticles/September2016/Drug-induced-gynaecomastia.htm

  Medicines cause 10% to 25% of all cases of gynaecomastia. […] Gynaecomastia is a benign proliferation of male breast glandular tissue caused by an imbalance between the actions of oestrogens relative to the actions of androgens on breast tissue. […] Medicines have been estimated to cause 10% to 25% of all cases of gynaecomastia. […] Medicines may cause gynaecomastia through a number of mechanisms including: increased serum oestrogen levels or oestrogen-like activity, decreased testosterone levels, hypogonadism, anti-androgenic effects, increased prolactin levels. […] Other reported non-medicine causes of gynaecomastia include alcohol, amphetamines, heroin, marijuana (cannabis) and phytoestrogens (in some herbal medicines).

• #1 Gynaecomastia: Pathophysiology, Diagnosis, & Treatment

  https://www.theplasticsfella.com/gynaecomastia/

  Gynecomastia is male breast enlargement due to glandular growth and fat, caused by hormonal imbalances. […] Gynaecomastia arises from an imbalance between androgenic and oestrogenic effects on breast tissue. […] Gynaecomastia can be idiopathic, physiological (trimodal distribution) or pathological. […] The aetiology of gynaecomastia can be categorised into three main areas: idiopathic, physiological, and pathological. […] Physiological gynaecomastia has the classic trimodal distribution. […] Pathological causes are less common, but thorough investigations should still be considered. […] Spironolactone causes gynaecomastia by several mechanisms, it blocks testosterone synthesis, blocks androgen action, and displaces oestrogen from SHBG.

• #1 Gynecomastia: What It Is, Causes, Diagnosis & Treatment

  https://my.clevelandclinic.org/health/symptoms/16227-enlarged-male-breast-tissue-gynecomastia

  Gynecomastia may be a side effect of certain medications, including: Cimetidine (for heartburn and acid reflux), Digoxin (for certain heart issues), Finasteride (for enlarged prostate or alopecia), Ketoconazole (for fungal or yeast infections), Spironolactone (for high blood pressure and heart failure), Thiazides (a class of diuretics), Phenothiazines (a class of first-generation antipsychotic medications), Theophylline (for asthma and COPD), Methotrexate (for rheumatoid arthritis and cancer), Imatinib (chemotherapy drug). […] These causes of gynecomastia are natural and to be expected theyre not physically harmful. But gynecomastia can also be a symptom of certain medical conditions that require treatment.

• #1 8 Possible Causes of Gynecomastia: Christopher Brooks, MD: Plastic Surgery

  https://www.brooksplasticsurgery.com/blog/8-possible-causes-of-gynecomastia

  Heavy drinking can trigger gynecomastia. Researchers believe alcohol may induce gynecomastia in several ways: The ethanol in alcohol may disrupt the synthesis of testosterone, while the phytoestrogens in alcohol cause an increase in estrogen. […] Studies have linked several recreational drugs to male breast enlargement. […] Some tumors, like those associated with your testes, adrenal glands, or pituitary gland, can create hormones that negatively affect the delicate male-female hormone balance. […] Liver diseases can cause imbalances in your estrogen-testosterone ratio. […] Kidney failure can trigger hormonal dysfunction in men because of suppressed testosterone production. […] Some herbal products, like tea tree or lavender oils, may also cause gynecomastia. Researchers believe this may be caused by extensive, prolonged use of these products, which have very weak estrogen activity.

• #1 Gynecomastia: Practice Essentials, Background, Etiology

  https://emedicine.medscape.com/article/120858-overview

  Various drugs are implicated in gynecomastia and can be classified into categories. […] The pathophysiologic mechanism for some drugs, such as estrogens or antiandrogens, is quite clear. […] However, for others such as spironolactone, the mechanism is more complex. […] A study by Den Hond et al on the effects of pollutants on sexual maturation indicated that higher blood levels of lead increased the risk of gynecomastia in the study’s subjects, while higher serum levels of hexachlorobenzene decreased the risk. […] Estimates suggest the following etiologies in males seeking medical attention for gynecomastia: Persistent pubertal gynecomastia – 25%, Drugs – 10-25%, No detectable abnormality – 25%, Cirrhosis or malnutrition – 8%, Primary hypogonadism – 8%, Testicular tumors – 3%, Secondary hypogonadism – 2%, Hyperthyroidism – 1.5%, Chronic renal insufficiency – 1%.

• #1 Gynaecomastia – Symptoms, diagnosis and treatment | BMJ Best Practice

  https://bestpractice.bmj.com/topics/en-gb/869

  Gynaecomastia results from excessive oestrogen action or deficient testosterone action on breast glandular tissue. […] Many drugs, environmental exposures, illnesses, and some genetic conditions increase the risk for gynaecomastia. […] Risk factors include anabolic steroid usage, prostate cancer, hormone therapy for gender dysphoria, drugs that reduce testosterone synthesis, drugs that impair testosterone action, drugs that increase oestrogen levels or stimulate oestrogen receptors, occupational exposure to embalming fluid or oral contraceptives, contact with environmental phyto-oestrogens or phthalates, hyperthyroidism, renal failure, cirrhosis, and drugs with complex or unknown mechanisms.

• #1 Gynecomastia – Genitourinary Disorders – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/genitourinary-disorders/male-reproductive-endocrinology-and-related-disorders/gynecomastia

  Gynecomastia is hypertrophy of breast glandular tissue in men. […] If evaluation reveals no cause for gynecomastia, it is considered idiopathic. The cause may not be found because gynecomastia is physiologic or because there is no longer any evidence of the inciting event. […] In infants and boys, the most common cause is physiologic gynecomastia. In men, the most common causes are persistent pubertal gynecomastia, idiopathic gynecomastia, and medications (particularly spironolactone, anabolic steroids, and antiandrogens). […] Breast cancer, which is uncommon in males, may cause unilateral breast abnormalities but is rarely confused with gynecomastia. […] Gynecomastia is often physiologic or idiopathic. […] A wide variety of medications can cause gynecomastia.

• #1 Patient education: Gynecomastia (breast enlargement in males) (Beyond the Basics) – UpToDate

  https://www.uptodate.com/contents/gynecomastia-breast-enlargement-in-males-beyond-the-basics/print

  Gynecomastia occurs in up to 75 percent of males who take drugs called antiandrogens to treat prostate cancer. […] It is not always clear what causes gynecomastia during mid to late life. Still, as males age, blood testosterone levels tend to decline, and the hormone balance changes to a higher amount of estrogen-to-testosterone ratio. These factors probably conspire to account for most cases of „idiopathic” gynecomastia.

• #1 Gynaecomastia – Differential Diagnosis – Investigations – TeachMeSurgery

  https://teachmesurgery.com/breast/benign-disease/gynaecomastia/

  25% of all cases, either through an increased oestrogen activity or reduced testosterone activity. […] The management ultimately depends on the causative factors and the phase of gynaecomastia. If there is a reversible underlying cause, then treatment or reversal of this should also allow for the resolution of the gynaecomastia as well. […] Pathological gynaecomastia occurs from changes in the oestrogen:androgen activity ratio.

• #2 Enlarged breasts in men (gynecomastia) – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/gynecomastia/symptoms-causes/syc-20351793

  With gynecomastia, tissue inside the breast glands grows. This can cause female-appearing breasts. […] Gynecomastia (guy-nuh-koh-MAS-tee-uh) is an increase in the amount of breast gland tissue in boys or men. An imbalance of the hormones estrogen and testosterone causes it. […] Newborns, boys going through puberty and older men may develop gynecomastia due to natural changes in hormone levels. There are other causes too. […] Gynecomastia can happen when the amount of testosterone in the body drops compared with estrogen. The decrease can be caused by conditions that lower testosterone or block its effects. Or it can be caused by conditions that raise the estrogen level. […] Estrogen levels that are too high or are out of balance with testosterone levels can cause gynecomastia. […] Gynecomastia in infants. More than half of male babies are born with enlarged breasts due to the effects of estrogen during pregnancy.

• #2 Gynecomastia – Wikipedia

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

  Gynecomastia may be caused by abnormal hormone changes, any condition that leads to an increase in the ratio of estrogens/androgens such as liver disease, kidney failure, thyroid disease and some non-breast tumors. Alcohol and some drugs can also cause breast enlargement.[4][7] […] Other causes may include Klinefelter syndrome, metabolic dysfunction, or a natural decline in testosterone production.[4][6][8] This may occur even if the levels of estrogens and androgens are both appropriate, but the ratio is altered.[7] […] Gynecomastia is thought to be caused by an altered ratio of estrogens to androgens mediated by an increase in estrogen action, a decrease in androgen action, or a combination of these two factors.[7] Estrogen and androgens have opposing actions on breast tissue: estrogens stimulate proliferation while androgens inhibit proliferation.[7][26] The cause of gynecomastia is unknown in around 25% of cases.[22][27] Known causes can be physiologic (occurring normally) or non-physiologic due to underlying pathologies such as drug use, chronic disease, tumors, or malnutrition.

• #2 Gynecomastia in adolescent males: current understanding of its etiology, pathophysiology, diagnosis, and treatment

  https://e-apem.org/journal/view.php?number=1034

  The challenge facing endocrinologists lies in their ability to distinguish between physiological and pathologic causes of GM. […] Most cases of pubertal GM are assumed to be caused by an imbalance between the activities of the hormones estrogen and androgen in the breast tissue. […] Pubertal GM is caused by either increased estrogen production, decreased testosterone production, or a combination of both. […] However, some studies have indicated that a significant number of adolescents with pubertal GM had normal estrogen level, and they linked GM to increased susceptibility of the breast tissue to normal level of circulating estrogen. […] Today’s increasing level of obesity is associated with increased breast adipose tissue. […] A study reported that men with a body mass index (BMI) of 25 kg/m2 or higher are far more likely to develop GM or pseudogynecomastia, with a reported prevalence as high as 80%.

• #2 Gynaecomastia: Causes, Symptoms, and Treatment | Doctor

  https://patient.info/doctor/gynaecomastia

  Gynaecomastia is a benign proliferation of the glandular tissue of the breast in men. […] It may occur at any time and there are a number of causes, some physiological and others pathological. Pathological causes involve an imbalance between the activity of androgens and oestrogens – the former is decreased compared with the latter. […] Gynaecomastia may therefore be caused by conditions which cause raised oestrogen levels. […] Conditions which cause low testosterone levels. […] Conditions which affect levels of sex hormone-binding globulin (SHBG), as it affects the free testosterone:oestrogen balance. […] Conditions which cause androgen resistance. […] Conditions which cause an increased conversion of androgens to oestrogens. […] Increased levels of oestrogen suppress luteinising hormone, which causes further suppression of testicular production of oestrogen.

• #2 Epidemiology, pathophysiology, and causes of gynecomastia – UpToDate

  https://www.uptodate.com/contents/epidemiology-pathophysiology-and-causes-of-gynecomastia

  Gynecomastia, a benign proliferation of the glandular tissue of the male breast, is common in infancy, adolescence, and in middle-aged to older males. […] Gynecomastia is common in infancy, puberty, and in middle-aged to older males. One estimate is that between 60 to 90 percent of infants have transient gynecomastia due to the high estrogenic milieu of pregnancy. […] The causes, evaluation, and management are discussed separately. […] The causes of gynecomastia include common etiologies such as physiologic factors, drugs, idiopathic causes, cirrhosis, starvation and refeeding, male hypogonadism, testicular neoplasms, hyperthyroidism, chronic kidney disease, and other rare causes.

• #2 What Causes Gynecomastia? | Aspira Plastic Surgery

  https://aspiraplasticsurgery.com/blog/gynecomastia-causes/

  Gynecomastia the enlargement of male breast tissue is a condition that can affect men of all ages. Understanding the causes of gynecomastia is essential for identifying potential treatments and managing the condition. This blog post will explore the common factors contributing to the development of gynecomastia, ranging from hormonal imbalances to lifestyle choices and underlying health conditions. […] Men can develop gynecomastia when there is an imbalance between estrogen and testosterone levels in the body. Hormonal changes naturally occur during certain life stages, such as infancy, puberty, and older age. Pubertal gynecomastia affects approximately 50-60% of adolescent boys, typically developing between ages 10-14, when glandular breast tissue forms due to temporary hormonal imbalances.

• #2 What Causes Gynecomastia? | Aspira Plastic Surgery

  https://aspiraplasticsurgery.com/blog/gynecomastia-causes/

  Similarly, up to 70% of males over 50 may experience some degree of gynecomastia, as testosterone levels naturally decline with age. […] Excess body fat contributes significantly to male breast enlargement, though this condition differs from true gynecomastia and is sometimes called pseudogynecomastia. […] Hypogonadism refers to conditions where the testes (male reproductive organs) produce insufficient testosterone, disrupting the bodys estrogen-to-testosterone ratio. […] Certain tumors can produce hormones that trigger breast enlargement in men. Testicular tumors may lead to excess estrogen, directly affecting breast tissue growth. […] Overactive thyroid function (hyperthyroidism) increases the production of thyroid hormones, which can disrupt the bodys estrogen-testosterone balance.

• #2 Gynecomastia: Practice Essentials, Background, Etiology

  https://emedicine.medscape.com/article/120858-overview

  From peripheral conversion – Can be due to increased substrate or increased activity of aromatase, as in chronic liver disease, malnutrition, hyperthyroidism, adrenal tumors, and familial gynecomastia. […] Gynecomastia can be physiologic or pathologic. […] Pathologic gynecomastia can be caused by an increase in the production and/or action of estrogen, by a decrease in the production and/or action of testosterone accompanied by increased aromatization and high estrogen, or by drug use. […] Conditions that result in primary or secondary hypogonadism can lead to gynecomastia in different mechanisms. […] The following are some of the conditions associated with gynecomastia: Klinefelter syndrome, congenital anorchia, testicular trauma, viral orchitis, Kallmann syndrome, pituitary tumors or abnormalities, malignancies that increase the serum level of hCG, renal failure, hyperthyroidism, malnutrition, environmental pollutants, androgen insensitivity syndrome, aromatase excess syndrome.

• #2 An interesting case of gynaecomastia

  https://www.racgp.org.au/afp/2016/january-february/an-interesting-case-of-gynaecomastia

  Gynaecomastia occurs as a result of an imbalance in the free oestrogen to free testosterone ratio that is secondary to a variety of physiological and non-physiological causes. […] The most frequent non-physiological cause is medications, although there are numerous differentials to consider. […] Keeping these aetiologies of gynaecomastia in mind, take a thorough medication history, and assess for signs of: cirrhosis (jaundice, ascites, pruritus), malnutrition, chronic renal failure (oedema, fatigue), hyperthyroidism (weight loss, palpitations, fine tremor), hypogonadism (erectile dysfunction, decreased muscle mass, testicular atrophy), testicular tumours (testicular mass), adrenal tumours (abdominal mass). […] Testicular malignancies are classified as either germ cell (95%) or sex cord stromal (5%) in origin each causes gynaecomastia via different mechanisms. Germ-cell tumours that have a choriocarcinoma component secrete hCG, resulting in Leydig cell dysfunction and, in turn, increases in both oestradiol and testosterone production. […] Leydig cell tumours (a type of sex cord stromal tumour) are rare, but are more likely to cause gynaecomastia because they directly secrete more oestradiol and convert additional androgen precursors to oestrogens.

• #2 Gynecomastia: Etiology, Diagnosis, and Treatment – Endotext – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK279105/

  Thus, any cause of estrogen excess from overproduction to peripheral aromatization of androgens can initiate the cascade to breast development. […] Testicular tumors can lead to increased blood estrogen levels by the following mechanisms: estrogen overproduction, androgen overproduction with extragonadal aromatization to estrogens, and secretion of hCG that stimulates normal Leydig cells (via the LH receptor). […] Some neoplasms that overproduce estrogens also possess aromatase overactivity. […] Besides tumors, other conditions have also been associated with excessive aromatization of testosterone and other androgens to estrogen leading to gynecomastia. […] The mechanism is thought to be related to the increased aromatase activity in adipose tissues, but most obese men do not have high estrogen concentrations.

• #2 Gynaecomastia Causes & Risk Factors: What You Need to Know | Medanta

  https://www.medanta.org/patient-education-blog/is-gynaecomastia-genetic-exploring-the-causes-and-risks

  Certain health conditions disturb the production of hormones, thus increasing the chance of developing Gynaecomastia. These include: Liver Disease and Cirrhosis, Kidney Failure, Hyperthyroidism, Tumours, Obesity. […] Any condition or imbalance that disturbs the harmony of testosterone and oestrogen can also raise the likelihood of Gynaecomastia. […] Fat encourages oestrogen production, which in turn, leads to the stimulation of breast tissue. […] Gynaecomastia is a known side effect in most prescription and some over-the-counter medications, especially: Anti-androgen drugs, Anabolic steroids, Digoxin and spironolactone, Anti-anxiety drugs, and antidepressants, Chemotherapy agents, Medicines in treating ulcers and acid reflux disease. […] The presence of chronic disease or health conditions that could increase your chance of suffering from Gynaecomastia are: Liver disease, Kidney disease, Hyperthyroidism, Tumours.

• #2 Gynaecomastia – Zero To Finals

  https://zerotofinals.com/surgery/breast/gynaecomastia/

  Gynaecomastia is generally caused by a hormonal imbalance between oestrogen and androgens (e.g., testosterone), with higher oestrogen and lower androgen levels. […] Raised oestrogen stimulates breast development, whilst androgens have an inhibitory effect on breast development. […] Therefore, raised prolactin (hyperprolactinaemia) can cause gynaecomastia. […] Gynaecomastia can be caused by conditions that increase oestrogen: Obesity (aromatase is an enzyme found in adipose tissue that converts androgens to oestrogen), Testicular cancer (oestrogen secretion from a Leydig cell tumour), Liver cirrhosis and liver failure, Hyperthyroidism, Human chorionic gonadotrophin (hCG) secreting tumour, notably small cell lung cancer. […] Gynaecomastia can be caused by conditions that reduce testosterone: Testosterone deficiency in older age, Hypothalamus or pituitary conditions that reduce LH and FSH levels (e.g., tumours, radiotherapy or surgery), Klinefelter syndrome (XXY sex chromosomes), Orchitis (inflammation of the testicles, e.g., infection with mumps), Testicular damage (e.g., secondary to trauma or torsion).

• #2 Gynaecomastia: Causes, Symptoms, and Treatment | Doctor

  https://patient.info/doctor/gynaecomastia

  Lack of testosterone: Congenital absence of testes. […] There are absent levels of testosterone with normal estradiol levels and patients experience severe gynaecomastia. […] Klinefelter’s syndrome (XXY syndrome). Associated with gynaecomastia in 80% of cases. […] Increased oestrogen levels: Testicular tumours (for example, Leydig’s cell tumour) which secrete estradiol. […] Liver disease or cirrhosis. In liver disease there is an increased production of androstenedione by the adrenal glands, increased aromatisation of androstenedione to oestrogen, loss of clearance of adrenal androgens by the liver and a rise in SHBG, resulting in gynaecomastia. […] Medication accounts for up to 25% of all cases in adult men. […] Other causes: Long-term type 1 diabetes mellitus. […] Chronic illness. […] Spinal cord injury. […] If no underlying cause is found, it is said to be idiopathic.

• #2 Gynecomastia – Symptoms, Causes, Complications and Prevention PACE Hospitals – Best Hospitals in Hitech City, Hyderabad, India | Near Madhapur, Kukatpally, KPHB, Kondapur, Gachibowli, Jubilee Hills, Banjara HillsPACE Hospitals Contact Num

  https://www.pacehospital.com/gynecomastia-symptoms-causes-complications-and-prevention

  Cirrhosis, or liver disease: Due to the increased production of androstenedione (steroid hormone responsible for the production of oestrogen and testosterone) from the adrenal glands, an increase in the conversion of androstenedione to oestrone and oestrone oestradiol and decreased clearance of adrenal androgens from the liver leads to a decrease in free testosterone. This causes an imbalance between the amount of oestrogen and testosterone in the body, which leads to gynecomastia. […] Male hypogonadism: Primary hypogonadism (production of low amount of sex hormones) can lead to a decrease in testosterone production. […] Hyperthyroidism: In hyperthyroidism, there will be an increase in sex hormone binding globulin (protein), which leads to an increase in oestradiol levels. […] Renal / kidney failure and dialysis: In haemodialysis patients, there will be abnormalities in the function of the Leydig cell (source of testosterone or androgens in males). In case of kidney failure, it leads to hormonal abnormalities, where the testosterone level goes down and oestradiol and luteinizing hormone levels go up.

• #2 Gynecomastia in boys – Children’s Health Plastic Surgery

  https://www.childrens.com/specialties-services/conditions/gynecomastia

  Gynecomastia is the development of this breast tissue in males and is common. […] It may be caused by a problem with the production or regulation of hormones, or even a type of tumor, in which case it is likely to need treatment. […] Despite these known causes, in about a quarter of all cases the reason for developing gynecomastia is unknown. […] Hyperthyroidism – gland that regulates the metabolism can alter hormones. […] Hypogonadism – any condition that increases testosterone (like pituitary insufficiency or Klinefelter’s syndrome). […] Hormonal imbalance. […] Liver failure. […] Kidney failure – hormonal changes in response to medicines and dialysis. […] Malnutrition or starvation – poor nutrition causes testosterone to drop, but estrogen remains constant. […] Medications – steroids, antibiotics, chemotherapy or heart medications.

• #2 Gynecomastia – Wikipedia

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

  About 10-25% of gynecomastia cases are estimated to result from the use of medications or exogenous chemicals.[17][27] Drugs can increase estrogen activity or increase the estrogen to androgen ratio through various mechanisms, such as binding to estrogen receptors, promoting estrogen synthesis, providing precursors that can be aromatized into estrogen, causing damage to the testes, inhibiting testosterone synthesis, inhibiting the action of androgens, or displacing estrogen from SHBG.[29] […] Gynecomastia can be caused by absolute deficiency in androgen production due to primary or secondary hypogonadism. Primary hypogonadism results when there is damage to the testes (due to radiation, chemotherapy, infections, trauma, etc.), leading to impaired androgen production.[7] […] Testicular tumors such as Leydig cell tumors, Sertoli cell tumors and hCG-secreting choriocarcinoma may result in rapid-onset gynecomastia by causing excess production of estrogen.[7] Other tumors such as adrenal tumors, pituitary gland tumors (such as a prolactinoma), or lung cancer, can produce hormones that alter the male-female hormone balance and cause gynecomastia.[22]

• #2 Gynecomastia | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/gynecomastia-1?lang=us

  Gynecomastia refers to a benign excess of the male breast tissue, that is usually reversible. It is not a risk factor per se for developing male breast cancer. […] The imbalance between estrogen action relative to androgen action at the breast tissue level appears to be a key etiological factor in gynecomastia. […] The causes of gynecomastia are many and include: […] hormonal […] neonatal: maternal estrogens […] pubertal: high estradiol levels […] elderly: decline in testosterone levels […] hypogonadism/androgen deficiency states: […] Klinefelter syndrome […] anorchism […] testicular failure, e.g. testicular cancer […] drugs […] diethylstilbestrol […] spironolactone […] thiazide diuretics […] digoxin […] anabolic steroids […] estrogen treatment […] flutamide

• #2 Gynecomastia (for Teens) | Nemours KidsHealth

  https://kidshealth.org/en/teens/boybrst.html

  Gynecomastia causes breast enlargement. […] Puberty is the main cause of gynecomastia in adolescent boys. Hormones are chemical messengers. The ones involved in puberty can get out of balance and lead to gynecomastia. […] Some medicines, drugs (including alcohol, marijuana, amphetamines, and heroin), anabolic steroids (taken to build muscle and improve strength), and other medicines also can cause gynecomastia. The herbal supplements tea tree oil and lavender oil may also lead to gynecomastia. Rarely, gynecomastia can be a sign of other medical conditions.

• #2 What are the Causes of Gynecomastia?

  https://drrajatgupta.com/what-are-the-causes-of-gynecomastia/

  Gynecomastia is a condition in males caused by the swelling of their breast tissue, which is usually flat. […] This happens because of an imbalance in testosterone and estrogen levels when estrogen levels in males increase due to certain reasons. […] When testosterone levels are low in men in comparison to estrogen levels, they can experience gynecomastia. […] Intake of certain medications without a doctors prescription can also cause gynecomastia, like: Anabolic steroids, AIDS and HIV medicines, ADHD medicines, Anti-anxiety pills, Heart medicines and some antibiotics. […] Substances like excessive alcohol, marijuana, methadone, etc., also cause male breast enlargement. […] The following health conditions can be linked with gynecomastia: Aging, Hypogonadism, Tumors, Kidney Failure, Malnutrition. […] Certain herbal products used in shampoos, soaps, and lotions, such as tea tree and lavender oil, are associated with gynecomastia because they contain compounds that mimic estrogen and affect testosterone levels.

• #2 Gynecomastia: Practice Essentials, Background, Etiology

  https://emedicine.medscape.com/article/120858-overview

  Various drugs are implicated in gynecomastia and can be classified into categories. […] The pathophysiologic mechanism for some drugs, such as estrogens or antiandrogens, is quite clear. […] However, for others such as spironolactone, the mechanism is more complex. […] A study by Den Hond et al on the effects of pollutants on sexual maturation indicated that higher blood levels of lead increased the risk of gynecomastia in the study’s subjects, while higher serum levels of hexachlorobenzene decreased the risk. […] Estimates suggest the following etiologies in males seeking medical attention for gynecomastia: Persistent pubertal gynecomastia – 25%, Drugs – 10-25%, No detectable abnormality – 25%, Cirrhosis or malnutrition – 8%, Primary hypogonadism – 8%, Testicular tumors – 3%, Secondary hypogonadism – 2%, Hyperthyroidism – 1.5%, Chronic renal insufficiency – 1%.

• #3 Gynecomastia | Radiology Reference Article | Radiopaedia.org

  https://radiopaedia.org/articles/gynecomastia-1?lang=us

  finasteride […] isoniazid […] ergotamine […] narcotics: […] marijuana […] heroin […] cimetidine […] nifedipine […] reserpine […] efavirenz […] methyldopa […] theophylline […] valproic acid […] systemic disorders […] advanced alcoholic cirrhosis […] chronic pulmonary disease, e.g. emphysema, tuberculosis […] hemodialysis in chronic renal failure […] hyperthyroidism […] malnutrition […] tumors: particularly oestrogenic tumors […] adrenal carcinoma […] hepatoma […] lung cancer […] pituitary adenoma […] testicular cancer: including sex-cord stromal, and germ cell tumors […] idiopathic.

• #3 Drug-induced Gynaecomastia

  https://www.medsafe.govt.nz/profs/PUarticles/September2016/Drug-induced-gynaecomastia.htm

  Medicines cause 10% to 25% of all cases of gynaecomastia. […] Gynaecomastia is a benign proliferation of male breast glandular tissue caused by an imbalance between the actions of oestrogens relative to the actions of androgens on breast tissue. […] Medicines have been estimated to cause 10% to 25% of all cases of gynaecomastia. […] Medicines may cause gynaecomastia through a number of mechanisms including: increased serum oestrogen levels or oestrogen-like activity, decreased testosterone levels, hypogonadism, anti-androgenic effects, increased prolactin levels. […] Other reported non-medicine causes of gynaecomastia include alcohol, amphetamines, heroin, marijuana (cannabis) and phytoestrogens (in some herbal medicines).

• #3 Gynaecomastia – treatment and surgery | healthdirect

  https://www.healthdirect.gov.au/gynaecomastia

  Gynaecomastia is an increase in breast tissue in males. […] It is caused by a hormone imbalance, medicines, or an underlying illness. […] Gynaecomastia is caused by an imbalance between the hormones oestrogen and testosterone. […] This imbalance often occurs naturally in infants aged 0 to 3 weeks, puberty aged 10 to 17 years, and older men it becomes more common after 50 years. […] Gynaecomastia can also be caused by medicines that affect your hormones, some genetic conditions such as Klinefelter syndrome, some dietary supplements and complementary or alternative medicines, obesity or poor nutrition, alcohol overuse, kidney or liver disease, hyperthyroidism, and tumours in your testicles or adrenal glands. […] In about 1 in 4 people the cause of gynaecomastia is not known.

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