Materiały źródłowe

• #1 Erythrocytosis (Polycythaemia): Definition, Causes & Treatment

  https://my.clevelandclinic.org/health/diseases/23468-erythrocytosis

  Erythrocytosis is having a high concentration of red blood cells. Your levels may be high for many reasons. Some causes, like dehydration, are less concerning than others, like polycythemia vera, a serious blood disorder. Erythrocytosis causes you to have high levels of hematocrit and/or hemoglobin. Erythrocytosis is classified based on the blood composition that causes the high concentration of red blood cells. Absolute erythrocytosis causes a high concentration of red blood cells because you have more red blood cells than normal. Relative erythrocytosis causes a high concentration of red blood cells because you don’t have enough plasma in relation to the number of red blood cells. Primary erythrocytosis results from problems in the spongy tissue inside of your bones called bone marrow. Primary erythrocytosis often results from a genetic mutation that affects your bone marrow. Secondary erythrocytosis results from problems outside of your bone marrow. Most secondary erythrocytosis involves your body producing too much of a hormone called erythropoietin (EPO). Conditions that deprive your tissues of oxygen can cause your body to have too little oxygen. In response, EPO levels rise, so more red blood cells are made. Erythrocytosis usually involves high levels of EPO.

• #1 Erythrocytosis (Polycythemia) in Animals – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-polycythemia-in-animals

  Erythrocytosis is a relative or absolute increase in the number of circulating RBCs, resulting in the PCV, hematocrit, RBC count, and hemoglobin concentration increasing above reference intervals. […] Polycythemia is frequently used synonymously with erythrocytosis; however, polycythemia may imply leukocytosis and thrombocytosis, in addition to erythrocytosis. […] Relative erythrocytosis is an increase in RBC numbers without an increase in total RBC mass. Usually, this is caused by loss of plasma water with resultant hemoconcentration, due to dehydration. […] Absolute erythrocytosis, defined as increased RBC numbers because of increased RBC mass, develops from primary or secondary causes. […] Primary erythrocytosis (polycythemia vera) is a myeloproliferative disease resulting from the autonomous clonal expansion of hematopoietic progenitor cells that has been reported in dogs, cats, horses, and ferrets.

• #1 Polycythemia – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526081/

  Causes include severe dehydration due to isolated fluid loss: potentially seen in diarrhea and severe vomiting. […] True Polycythemia is further stratified based on serum erythropoietin (EPO) levels as follows: Low serum EPO levels (Primary polycythemia) includes Polycythemia vera and Primary familial and congenital polycythemia. […] High serum EPO levels (Secondary polycythemia) include high altitude, respiratory disorders, cyanotic heart diseases with right-to-left shunts, renal disorders, elevated carboxyhemoglobin, hemoglobinopathies, EPO-secreting tumors, and iatrogenic causes. […] The increase in hematocrit is a normal compensatory mechanism in infants due to the relative tissue-level hypoxia in the intrauterine environment. […] The primary defect in nearly 95% of cases of polycythemia vera is an acquired mutation in exon 14 of the tyrosine kinase JAK2 (V617F).

• #1 Erythrocytosis

  https://www.nhs.uk/conditions/erythrocytosis/

  Erythrocytosis can be divided into several different types, depending on the underlying cause. In some cases, an underlying cause can’t be identified. […] Apparent erythrocytosis is often caused by being overweight, smoking, drinking too much alcohol or taking certain medicines including diuretics (tablets for high blood pressure that make you pee more). […] „Absolute erythrocytosis” is where your body produces too many red blood cells. There are 2 main types: primary erythrocytosis there’s a problem in the cells produced by the bone marrow that become red blood cells; the most common type is known as polycythaemia vera […] Secondary erythrocytosis is where an underlying condition causes more erythropoietin to be produced. This is a hormone produced by the kidneys that stimulates the bone marrow cells to produce red blood cells.

• #1 Investigation and management of erythrocytosis

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7829024/

  Primary erythrocytosis or autonomous production of excess erythrocytes most commonly occurs due to polycythemia vera (PV), a myeloproliferative neoplastic process that may be asymptomatic or may present with thrombosis, constitutional or vasomotor symptoms, or splenomegaly. […] Secondary erythrocytosis, which is more common than PV, has a broad differential diagnosis that includes hypoxic lung disease, cyanotic congenital heart disease, medications (e.g., testosterone) and erythropoietin-producing malignant disorders. […] Erythrocytosis refers to an erythrocyte count above the sex-specific normal range and can be subclassified into relative erythrocytosis, caused by a reduction in plasma volume (hemoconcentration), or absolute erythrocytosis, caused by increased erythrocyte mass. […] Absolute erythrocytosis can be driven by a clonal bone marrow disease (PV) or be secondary to another disease, including a physiologic response to increased erythropoietin secondary to hypoxia, drugs or erythropoietin-producing solid tumours.

• #1 Investigation and management of erythrocytosis

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7829024/

  Causes of secondary erythrocytosis include generalized tissue hypoxia, local renal hypoxia, drug-associated causes, pathologic erythropoietin production, and miscellaneous causes. […] Polycythemia vera is a myeloproliferative neoplasm characterized by increased erythrocyte mass, thrombosis and vasomotor symptoms. A gain-of-function mutation in Janus kinase 2 (JAK2) underlies 98% of PV cases. […] Treatment should be directed at the underlying cause. There is no definitive evidence that the risk of thromboembolism is increased in patients with secondary erythrocytosis, and, therefore, phlebotomy is not recommended routinely. […] Secondary erythrocytosis can be distinguished from PV in most patients with a focused clinical evaluation and, where available, determination of the erythropoietin level and JAK2 V617F mutation testing.

• #1 Polycythemia – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526081/

  These mutations result in a loss of the auto-inhibitory pseudo-kinase domain of JAK2, resulting in its constitutive activation. […] The pathophysiology would vary, depending on the cause in consideration. […] Cellular hypoxia can occur due to any cause that triggers the release of erythropoietin from the renal peritubular lining capillary cells. […] EPO, in turn, acts on erythroid progenitor cells and stimulates erythropoiesis.

• #1 Erythrocytosis | Radiology Reference Article | Radiopaedia.org

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

  Erythrocytosis (or polycythemia) is the presence of an excessive number of red blood cells in the circulation. It can be primary or arise secondarily to another pathology. […] Following is a list of primary and secondary causes of erythrocytosis. Secondary etiologies are much more common: […] Primary causes include congenital erythropoietin receptor (EPOR) mutations and acquired causes such as polycythemia vera and genetic (LNK) mutations. […] Secondary causes include congenital factors like high oxygen affinity hemoglobins, abnormal 2,3 bisphosphoglycerate mutase, methemoglobinemia, and dysfunctional oxygen-sensing pathway (e.g. VHL mutations). Acquired causes include hypoxia-driven factors such as chronic lung disease, right-to-left cardiopulmonary shunts, carbon monoxide toxicity, smoking-related polycythemia, sleep apnea, and living at high altitude. Local renal hypoxia can be caused by renal artery stenosis, end-stage renal failure, hydronephrosis, polycystic kidney disease, and post-renal transplant erythrocytosis.

• #1 Erythrocytosis | eClinpath

  https://eclinpath.com/hematology/polycythemia/

  Primary erythrocytosis: This can be a familial disorder or neoplastic. […] Secondary erythrocytosis: This is usually due to increased erythropoietin production. The physiologic stimulus for erythropoietin production is hypoxia, therefore erythropoietin production can be appropriate (in response to hypoxia), albeit excessive, or inappropriate (independent of hypoxia). […] Appropriate secondary erythrocytosis: There is an appropriate stimulus for erythropoietin production, which is principally hypoxia, e.g. cardiovascular or respiratory disease, increased affinity of hemoglobin (carbon monoxide poisoning). […] Inappropriate secondary erythrocytosis: This is due to enhanced erythropoiesis that is independent of a hypoxic stimulus, and is usually mediated via erythropoietin.

• #1 Secondary Erythrocytosis – Blood Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/blood-disorders/myeloproliferative-disorders/secondary-erythrocytosis

  Erythrocytosis is increased production of red blood cells (erythrocytes). […] Erythrocytosis may be […] Primary: Caused by a disorder of the blood-forming cells […] Secondary: Caused by a disorder that triggers increased production by normal blood-forming cells. […] Secondary erythrocytosis develops generally as a result of a disorder that increases erythropoietin secretion. […] Secondary erythrocytosis has many causes. It can be caused by oxygen deprivation, which can result, for example, from […] Smoking […] Severe lung disease, such as COPD (chronic obstructive pulmonary disease) […] Birth defects of the heart […] Carbon monoxide poisoning […] High altitude. […] Other causes of secondary erythrocytosis include […] Treatment with male hormones such as testosterone

• #1 Erythrocytosis: Definition, Causes, Symptoms, and More

  https://resources.healthgrades.com/right-care/blood-conditions/erythrocytosis

  Erythrocytosis causes an increased number of red blood cells. […] Erythrocytosis can be either primary or secondary. Primary erythrocytosis is caused by disorders of the blood-forming cells, such as polycythemia vera. This condition causes the bone marrow to produce too many red blood cells. […] Secondary erythrocytosis is caused by disorders that prompt the increased production of normal blood-forming cells. Secondary erythrocytosis is more common than primary erythrocytosis. […] Erythrocytosis has different causes depending on whether it is primary or secondary. The most common causes of erythrocytosis are: polycythemia vera, oxygen deprivation, smoking, high altitudes, severe lung disease, such as chronic obstructive pulmonary disease (COPD), congenital heart defects, carbon monoxide poisoning, testosterone treatment, kidney problems, tumors of the brain, liver, or adrenal gland, genetic disorders that affect erythropoietin production.

• #1 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  Hemoglobin abnormalities associated with high oxygen affinity and congenital defects can lead to oxidized hemoglobin or methemoglobin. These conditions are usually familial. […] Exposure to carbon monoxide, such as by smoking or working in automobile tunnels, results in an acquired condition. […] Impaired perfusion of the kidneys, which may lead to stimulation of erythropoietin [EPO] production, is usually due to local renal hypoxia in the absence of systemic hypoxia. […] Inappropriate stimulation of EPO production may occur in the following settings: […] Benign renal lesions, such as hydronephrosis and cysts, can stimulate EPO production, possibly due to compromised renal blood flow by compressive or vasoconstrictive mechanisms. […] Malignant and benign tumors that secrete EPO have been observed in patients with renal carcinomas, cerebellar hemangioblastomas, adrenal carcinomas, adrenal adenomas, hepatomas, and uterine leiomyomas.

• #1 Secondary Erythrocytosis – Blood Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/blood-disorders/myeloproliferative-disorders/secondary-erythrocytosis

  Kidney problems, including tumors, cysts, and narrowing of the arteries that go to the kidneys […] Tumors of the liver, brain, or adrenal gland […] Genetic disorders that affect erythropoietin production (congenital erythrocytosis). […] Male hormones such as testosterone stimulate production of erythropoietin. […] Problems that decrease blood flow to the kidneys such as tumors, cysts, and narrowing of the arteries that go to the kidneys increase erythropoietin secretion. […] Tumor-associated erythrocytosis can occur when certain tumors or cysts, such as of the kidneys, liver, brain, or uterus secrete erythropoietin. […] Congenital erythrocytosis is present at birth and is usually caused by an inherited genetic disorder that affects the affinity of hemoglobin for oxygen or the response to hypoxia.

• #1 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  Blood doping is an illegal practice. […] Illicit use of androgenic steroids to build muscles and strength can also increase red blood cell mass by stimulating endogenous serum EPO levels. […] Hemoglobin mutants associated with tight binding to oxygen and a failure to deliver oxygen in the venous blood can cause high EPO levels. […] A von Hippel-Lindau gene mutation results in polycythemia by altering the von Hippel-Lindau protein, which plays an important role in sensing hypoxia and binds to hydroxylated HIF1-alpha to serve as a recognition site of an E3-ubiquitin ligase complex. […] Chuvash polycythemia is caused by an autosomal recessive gene mutation on the von Hippel-Lindau gene, which results in the upregulation of the HIF1-alpha target gene and causes elevations in EPO levels.

• #1 Erythrocytosis (Polycythemia) in Animals – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-polycythemia-in-animals

  Secondary erythrocytosis, in contrast, generally develops from excessive production of EPO. […] If EPO production increases without systemic hypoxia, then the response is physiologically inappropriate. […] Another type of secondary erythrocytosis, called endocrinopathy-associated erythrocytosis, results from hormones other than EPO (eg, cortisol, testosterone, thyroxine, growth hormone) that stimulate erythropoiesis. […] Erythrocytosis can be classified into relative (dehydration, splenic contraction) and absolute (primary or secondary) causes. […] Secondary erythrocytosis results from physiologically appropriate (certain cardiac and pulmonary disorders) and inappropriate (EPO-secreting tumors of the kidneys or other organs, or some non-neoplastic renal conditions) causes. […] Primary erythrocytosis (polycythemia vera) results from the autonomous clonal proliferation of hematopoietic stem cells that require little to no EPO. […] Clinical signs of primary erythrocytosis are attributed to increased blood viscosity and include neurologic disturbances and bleeding tendencies. […] Primary erythrocytosis is usually diagnosed by excluding secondary causes, and it is typically treated by phlebotomy and hydroxyurea.

• #1 Diagnosis and Treatment of Erythrocytosis – touchONCOLOGY

  https://touchoncology.com/haematology/journal-articles/diagnosis-and-treatment-of-erythrocytosis/

  An erythrocytosis arises when the red cell mass is increased. This can be due to a primary intrinsic defect in the erythroid progenitor cells or secondary to erythropoietin production from some source. Primary and secondary causes can be congenital or acquired. […] The main acquired, primary erythrocytosis is polycythaemia vera. […] A number of patients do not have an identifiable cause of erythrocytosis and are therefore described as having idiopathic erythrocytosis. […] An absolute erythrocytosis can be classified depending on its aetiology. Erythrocytoses are classified as primary if there is an intrinsic defect in the erythroid progenitor cells in the bone marrow, or secondary if the increased red cell mass results from factors external to the erythroid progenitor cell (i.e. increased EPO production from any cause, driving red cell production).

• #1

  https://link.springer.com/article/10.1007/s10238-023-01283-y

  Polycythemia Vera (PV) is typically caused by V617F or exon 12 JAK2 mutations. Little is known about Polycythemia cases where no JAK2 variants can be detected, and no other causes identified. This condition is defined as idiopathic erythrocytosis (IE). […] We demonstrated that most of our cohort (40/56: 71.4%) showed no evidence of clonal hematopoiesis, suggesting that IE is, in large part, a germline disorder. […] This suggests that a large fraction of IE may be caused by a germline disorder, functionally connected with congenital erythrocytosis but characterized by adult onset and limited penetrance. […] Overall, we identified recurrent germline variants occurring in JAK/STAT, Hypoxia and Iron metabolism pathways in 42 (75%) patients, with a median of 2 variants/patient. […] Taken globally our data suggest that a large fraction of IE cases is represented by germline disorders, characterized by the presence of recurrent germline variants occurring on JAK/STAT, Hypoxia and Iron metabolism pathways, among them: JAK3-V722I and HIF1A-P582S. These findings indicate that the presence of specific variants in the pathway mentioned above could be associated with the emergence of an erythrocytic phenotype. […] The demonstration that a significant fraction of these patients is affected by a genetic disease confirms the need to avoid cytoreductive therapies, unless the presence of a clonal disorder is clearly demonstrated by the presence of somatic variants with high VAF.

• #1 Erythrocytosis: Definition, Causes, Symptoms, and More

  https://resources.healthgrades.com/right-care/blood-conditions/erythrocytosis

  Secondary erythrocytosis is more common than primary, and the most common causes of secondary erythrocytosis are conditions that result in oxygen deprivation. This includes smoking, sleep apnea, and serious lung conditions, such as COPD. The most common cause of primary erythrocytosis is polycythemia vera.

• #1 Polycythemia Vera: Rapid Evidence Review | AAFP

  https://www.aafp.org/pubs/afp/issues/2021/0601/p680.html

  Polycythemia vera is one of three stem-cellderived myeloid malignancies commonly known as myeloproliferative neoplasms. It is characterized by erythrocytosis, often with associated leukocytosis and thrombocytosis. […] The only minor criterion is a subnormal erythropoietin level, which helps differentiate polycythemia vera from common causes of secondary erythrocytosis such as smoking, sleep apnea, and testosterone use. […] The differential diagnosis of PV includes other myeloproliferative neoplasms and secondary erythrocytosis from smoking, sleep apnea, and androgen use and, rarely, erythropoietin-producing tumors. […] Nonmodifiable risk factors for PV include older age, male sex, White race, and European descent. Modifiable risk factors for PV include smoking, obesity, hypertension, diabetes mellitus, and hyperlipidemia.

• #1 Polycythemia – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK526081/

  Polycythemia, also called erythrocytosis, refers to increased red blood cell mass, noted on laboratory evaluation as increased hemoglobin and hematocrit levels. […] The clinical significance of erythrocytosis, due to any cause, is related to the associated risk of thrombotic events due to hyperviscosity of blood. […] Polycythemia vera is a subtype of polycythemia and can be associated with the overproduction of more than just the erythrocytic lineage. […] The clinical significance of erythrocytosis, due to any cause, lies in the associated risk of thrombotic events due to hyperviscosity of blood. Additionally, the potential for progression to leukemia in cases of polycythemia vera also warrants additional management strategies to be implemented. […] This occurs due to volume contraction rather than an increase in true RBC mass.

• #1

  https://haematologica.org/article/view/8839

  In a multivariate analysis of the relationship of peripheral blood cell counts with thrombosis in PV subjects, an increased number of leukocytes was the most significant correlate of increased thrombotic risk. […] Certain disorders with elevated hematocrit, such as PV, CE, primary familial and congenital polycythemia or erythrocytosis (EPOR mutation), and EPAS1 gain-of-function mutations, are associated with thrombotic complications. […] The challenge in these conditions is to elucidate factors for the thrombotic risk other than the elevated hematocrit, and to define what, if any, role that viscosity plays in thrombotic risk.

• #1 Phenotypical differences and thrombosis rates in secondary erythrocytosis versus polycythemia vera | Blood Cancer Journal

  https://www.nature.com/articles/s41408-021-00463-x

  Erythrocytosis is a common condition and an increasingly frequent reason for consultation in hematology. […] Secondary erythrocytosis was defined as sustained elevation in hemoglobin and/or hematocrit above WHO-thresholds for PV with negative JAK2V617F mutation testing and non-subnormal serum Epo levels. […] Etiologies of erythrocytosis in the SE cohort were reported as idiopathic in 50% (n=18), smoking/chronic obstructive pulmonary disease (COPD) in 22.2% (n=8), smoking-related plus additional factors in 8.3% (n=3), sleep apnea and polycystic kidney disease in 5.6% (n=2) each, or combination of the latter two in 2.7% (n=1), sleep apnea plus liver lesion in 2.7% (n=1), and post kidney transplant erythrocytosis in 2.7% (n=1). […] Importantly, rates of thromboembolic events, prior to diagnosis, were comparable in both PV and SE populations, suggesting that from the standpoint of thrombosis, SE may not be as benign as some reports have intimated.

• #1 REVE2 – Overview: Erythrocytosis Evaluation, Blood

  https://www.mayocliniclabs.com/test-catalog/Overview/618830

  Because there are many causes of erythrocytosis, an algorithmic and reflexive testing strategy is useful for evaluating these disorders. Initial JAK2 V617F alteration testing and serum EPO levels are useful. Importantly, a significant subset of HOA hemoglobin variants can be electrophoretically silent on multiple routine screening platforms; however, most, and possibly all, HOA hemoglobin variants can be identified with addition of the intact mass spectrometry method. Our extensive experience with these disorders allows an economical, comprehensive evaluation with high sensitivity.

• #2 Erythrocytosis

  https://www.nhs.uk/conditions/erythrocytosis/

  Erythrocytosis can be divided into several different types, depending on the underlying cause. In some cases, an underlying cause can’t be identified. […] Apparent erythrocytosis is often caused by being overweight, smoking, drinking too much alcohol or taking certain medicines including diuretics (tablets for high blood pressure that make you pee more). […] „Absolute erythrocytosis” is where your body produces too many red blood cells. There are 2 main types: primary erythrocytosis there’s a problem in the cells produced by the bone marrow that become red blood cells; the most common type is known as polycythaemia vera […] Secondary erythrocytosis is where an underlying condition causes more erythropoietin to be produced. This is a hormone produced by the kidneys that stimulates the bone marrow cells to produce red blood cells.

• #2 Erythrocytosis | eClinpath

  https://eclinpath.com/hematology/polycythemia/

  Primary erythrocytosis: This can be a familial disorder or neoplastic. […] Secondary erythrocytosis: This is usually due to increased erythropoietin production. The physiologic stimulus for erythropoietin production is hypoxia, therefore erythropoietin production can be appropriate (in response to hypoxia), albeit excessive, or inappropriate (independent of hypoxia). […] Appropriate secondary erythrocytosis: There is an appropriate stimulus for erythropoietin production, which is principally hypoxia, e.g. cardiovascular or respiratory disease, increased affinity of hemoglobin (carbon monoxide poisoning). […] Inappropriate secondary erythrocytosis: This is due to enhanced erythropoiesis that is independent of a hypoxic stimulus, and is usually mediated via erythropoietin.

• #2 Erythrocytosis in Horses – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-in-horses

  Relative erythrocytoses are not attributed to an increase in the bodys overall red cell mass. Rather, they are associated with a relative increase in the number of red cells due to a loss of plasma volume or redistribution of red cells. […] Dehydrated animals experience a reduced proportion of plasma due to a loss of water volume. In this manner, dehydration results in a relative erythrocytosis because the increase in red cells is attributed to reduced plasma volume. […] Absolute erythrocytoses are due to a true increase in the bodys red cell mass from increased erythropoiesis, not reduced plasma volume or redistribution of the red cells. This can be due to increased, unregulated, neoplastic, autonomous production of red cells (primary) or increased synthesis or activity of erythropoietin (secondary), the main hormone that stimulates erythropoiesis.

• #2 5 Reasons for Erythrocytosis in Dogs & Cats | Clinician’s Brief

  https://www.cliniciansbrief.com/article/top-5-causes-erythrocytosis-dogs-cats

  Secondary absolute erythrocytosis results from increased concentrations of erythropoietin that stimulate erythroid hyperplasia in bone marrow and increase RBC production and can be appropriate, inappropriate, or endocrinopathy-associated. […] Secondary appropriate absolute erythrocytosis is induced by tissue hypoxia. Secondary inappropriate absolute erythrocytosis is due to uncontrolled erythropoietin secretion, not induced by tissue hypoxia. […] Following are causes of erythrocytosis listed in order of most to least common, according to the authors. […] Dehydration causes hemoconcentration and decreased total intravascular fluid volume without decreased erythrocytes, resulting in an artifactual increase in hematocrit due to hemoconcentration. […] Tissue hypoxia (eg, as a result of adjustment to high altitude, chronic pulmonary disease, cardiac disease, hemoglobin disorders, cardiac shunts, venoarterial shunts) stimulates increased release of erythropoietin, which may lead to secondary appropriate absolute erythrocytosis.

• #2 Erythrocytosis: What Is It, What Causes It, and More

  https://www.webmd.com/a-to-z-guides/what-is-erythrocytosis

  Erythrocytosis is when you have more red blood cells than normal. […] There are two types of erythrocytosis, primary and secondary. While both cause an increase in red blood cells, each type happens for a different reason. […] Primary erythrocytosis can also be caused by a type of blood cancer called polycythemia vera. […] Secondary erythrocytosis can have many causes. These can include: […] Conditions that cause low oxygen. […] Kidney disease. […] Some medicines. […] Tumors. […] Dehydration. […] Relative erythrocytosis can also be caused by diuretics, medicines that cause your kidneys to eliminate salt and water more quickly than normal.

• #2 Erythrocytosis (Polycythemia) in Animals – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-polycythemia-in-animals

  Erythrocytosis is a relative or absolute increase in the number of circulating RBCs, resulting in the PCV, hematocrit, RBC count, and hemoglobin concentration increasing above reference intervals. […] Polycythemia is frequently used synonymously with erythrocytosis; however, polycythemia may imply leukocytosis and thrombocytosis, in addition to erythrocytosis. […] Relative erythrocytosis is an increase in RBC numbers without an increase in total RBC mass. Usually, this is caused by loss of plasma water with resultant hemoconcentration, due to dehydration. […] Absolute erythrocytosis, defined as increased RBC numbers because of increased RBC mass, develops from primary or secondary causes. […] Primary erythrocytosis (polycythemia vera) is a myeloproliferative disease resulting from the autonomous clonal expansion of hematopoietic progenitor cells that has been reported in dogs, cats, horses, and ferrets.

• #2 Investigation and management of erythrocytosis

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7829024/

  Causes of secondary erythrocytosis include generalized tissue hypoxia, local renal hypoxia, drug-associated causes, pathologic erythropoietin production, and miscellaneous causes. […] Polycythemia vera is a myeloproliferative neoplasm characterized by increased erythrocyte mass, thrombosis and vasomotor symptoms. A gain-of-function mutation in Janus kinase 2 (JAK2) underlies 98% of PV cases. […] Treatment should be directed at the underlying cause. There is no definitive evidence that the risk of thromboembolism is increased in patients with secondary erythrocytosis, and, therefore, phlebotomy is not recommended routinely. […] Secondary erythrocytosis can be distinguished from PV in most patients with a focused clinical evaluation and, where available, determination of the erythropoietin level and JAK2 V617F mutation testing.

• #2 Polycythemia Vera – Hematology and Oncology – MSD Manual Professional Edition

  https://www.msdmanuals.com/professional/hematology-and-oncology/myeloproliferative-disorders/polycythemia-vera

  Polycythemia vera involves increased production of red blood cells (RBCs), white blood cells (WBCs), and platelets. […] Increased production confined to the RBC line is termed erythrocytosis; isolated erythrocytosis may occur with polycythemia vera but is more commonly due to other causes (see secondary erythrocytosis). […] Polycythemia vera is caused by a mutation in an hematopoietic stem cell. […] Mutations of the Janus kinase 2 (JAK2) gene are responsible in most cases of polycythemia vera. […] These mutations lead to sustained activation of the JAK2 kinase, which causes excess blood cell production independent of erythropoietin. […] The presence of a known causative mutation in a patient with isolated erythrocytosis is strongly suggestive of polycythemia vera. […] If erythrocytosis is present but secondary causes have not been excluded, serum erythropoietin level should be measured. […] Patients with polycythemia vera typically have low or low-normal serum erythropoietin levels; elevated levels suggest secondary erythrocytosis.

• #2 Familial erythrocytosis: MedlinePlus GeneticsLock

  https://medlineplus.gov/genetics/condition/familial-erythrocytosis/

  Familial erythrocytosis can result from mutations in the EPOR, VHL, EGLN1, or EPAS1 gene. […] The proteins produced from the VHL, EGLN1, and EPAS1 genes are also involved in red blood cell production; they each play a role in regulating erythropoietin. […] Researchers have also described non-familial (acquired) forms of erythrocytosis. Causes of acquired erythrocytosis include long-term exposure to high altitude, chronic lung or heart disease, episodes in which breathing slows or stops for short periods during sleep (sleep apnea), and certain types of tumors. […] In some cases, the cause of erythrocytosis is unknown.

• #2 Secondary Erythrocytosis – Blood Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/blood-disorders/myeloproliferative-disorders/secondary-erythrocytosis

  Erythrocytosis is increased production of red blood cells (erythrocytes). […] Erythrocytosis may be […] Primary: Caused by a disorder of the blood-forming cells […] Secondary: Caused by a disorder that triggers increased production by normal blood-forming cells. […] Secondary erythrocytosis develops generally as a result of a disorder that increases erythropoietin secretion. […] Secondary erythrocytosis has many causes. It can be caused by oxygen deprivation, which can result, for example, from […] Smoking […] Severe lung disease, such as COPD (chronic obstructive pulmonary disease) […] Birth defects of the heart […] Carbon monoxide poisoning […] High altitude. […] Other causes of secondary erythrocytosis include […] Treatment with male hormones such as testosterone

• #2 Erythrocytosis in Horses – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-in-horses

  Primary absolute erythrocytosis is considered a diagnosis of exclusion reserved for animals with a persistent erythrocytosis without evidence of dehydration, suspected splenic contraction, or identifiable causes for a secondary absolute erythrocytosis. […] An appropriate secondary absolute erythrocytosis occurs when there is increased release of erythropoietin in an attempt to improve the bloods oxygen-carrying capacity. This may occur with cardiac or respiratory disease, high altitudes, or hemoglobin disorders. […] In horses, an appropriate secondary absolute erythrocytosis is most often connected with congenital cardiac defects associated with right to left shunting or lung disease, including chronic pneumonia or pleuropneumonia. […] Inappropriate secondary absolute erythrocytosis is typically a paraneoplastic finding attributed to autonomous synthesis of erythropoietin or prostaglandins enhancing the actions of erythropoietin by a neoplasm or as a response to renal hypoxia.

• #2 Secondary Erythrocytosis – Hematology and Oncology – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/hematology-and-oncology/myeloproliferative-disorders/secondary-erythrocytosis

  In patients who smoke cigarettes, reversible erythrocytosis results mainly from tissue hypoxia due to elevation of blood carboxyhemoglobin concentration, and there is usually plasma volume reduction. […] Patients with chronic hypoxemia (arterial hemoglobin oxygen concentration 92%), typically due to lung disease, right-to-left intracardiac shunts, renal transplantation, prolonged exposure to high altitudes, or hypoventilation syndromes, often develop erythrocytosis. […] Tumor-associated erythrocytosis can occur when renal tumors, cysts, hepatomas, cerebellar hemangioblastomas, or uterine leiomyomas secrete erythropoietin. […] High oxygen-affinity hemoglobinopathies are very rare.

• #2 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  Secondary polycythemia is defined as an absolute increase in red blood cell mass that is caused by enhanced stimulation of red blood cell production. […] Enhanced erythroid stimulation can be a physiologic response to generalized or localized tissue hypoxia, as in the following settings: […] Because of the decreased ambient oxygen concentration at high altitudes, people living in those locales can develop compensatory erythrocytosis as a physiologic response to tissue hypoxia. […] Chronic obstructive pulmonary disease is commonly due to a large amount of ventilation in poor gas exchange units (high ventilation-to-perfusion ratios). […] Alveolar hypoventilation can result from periodic breathing and oxygen desaturation (sleep apnea) or morbid obesity (Pickwickian syndrome). […] Cardiovascular diseases associated with a right-to-left shunt (arteriovenous malformations) can result in venous blood mixing in the arterial system and delivering low oxygen levels to tissues.

• #2 Secondary Erythrocytosis – Hematology and Oncology – Merck Manual Professional Edition

  https://www.merckmanuals.com/professional/hematology-and-oncology/myeloproliferative-disorders/secondary-erythrocytosis

  Secondary erythrocytosis is erythrocytosis that develops secondary to disorders that cause tissue hypoxia, inappropriately increased erythropoietin production, or increased sensitivity to erythropoietin. […] Common causes of secondary erythrocytosis include smoking, chronic arterial hypoxemia, tumors (tumor-associated erythrocytosis), use of androgenic steroids, and surreptitious erythropoietin use. […] Less common causes include certain congenital disorders such as high oxygen-affinity hemoglobinopathies, erythropoietin receptor mutations, Chuvash polycythemia (in which a mutation in the VHL gene affects the hypoxia-sensing pathway and increases in erythropoietin production), right to left arteriovenous shunts in the lungs, and proline hydroxylase 2 and hypoxia-inducible factor 2 alpha (HIF-2) mutations.

• #2 REVE2 – Overview: Erythrocytosis Evaluation, Blood

  https://www.mayocliniclabs.com/test-catalog/Overview/618830

  The most common cause of hereditary erythrocytosis is the presence of a high-oxygen-affinity (HOA) hemoglobin variant. A subset of hemoglobins with increased oxygen (O2) affinity results in clinically evident erythrocytosis caused by decreased O2 unloading at the tissue level. Many are asymptomatic; however, some patients have recurrent headaches, dizziness, fatigue, and restless legs. A subset of patients experience thrombotic episodes. Affected individuals can be plethoric, and many are misclassified as polycythemia vera, particularly prior to more recent genetic testing availability. […] In addition, O2-sensing pathway variants, EPAS1(HIF2A) (OMIM 611783); EGLN1(PHD2) (OMIM 609820), and VHL (OMIM 263400) cause hereditary erythrocytosis and a subset are associated with pheochromocytoma and paragangliomas. All have shown an autosomal dominant pattern of inheritance, except VHL-associated erythrocytosis, which is an autosomal recessive disorder.

• #2 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  Hemoglobin abnormalities associated with high oxygen affinity and congenital defects can lead to oxidized hemoglobin or methemoglobin. These conditions are usually familial. […] Exposure to carbon monoxide, such as by smoking or working in automobile tunnels, results in an acquired condition. […] Impaired perfusion of the kidneys, which may lead to stimulation of erythropoietin [EPO] production, is usually due to local renal hypoxia in the absence of systemic hypoxia. […] Inappropriate stimulation of EPO production may occur in the following settings: […] Benign renal lesions, such as hydronephrosis and cysts, can stimulate EPO production, possibly due to compromised renal blood flow by compressive or vasoconstrictive mechanisms. […] Malignant and benign tumors that secrete EPO have been observed in patients with renal carcinomas, cerebellar hemangioblastomas, adrenal carcinomas, adrenal adenomas, hepatomas, and uterine leiomyomas.

• #2 Secondary Erythrocytosis – Blood Disorders – Merck Manual Consumer Version

  https://www.merckmanuals.com/home/blood-disorders/myeloproliferative-disorders/secondary-erythrocytosis

  Kidney problems, including tumors, cysts, and narrowing of the arteries that go to the kidneys […] Tumors of the liver, brain, or adrenal gland […] Genetic disorders that affect erythropoietin production (congenital erythrocytosis). […] Male hormones such as testosterone stimulate production of erythropoietin. […] Problems that decrease blood flow to the kidneys such as tumors, cysts, and narrowing of the arteries that go to the kidneys increase erythropoietin secretion. […] Tumor-associated erythrocytosis can occur when certain tumors or cysts, such as of the kidneys, liver, brain, or uterus secrete erythropoietin. […] Congenital erythrocytosis is present at birth and is usually caused by an inherited genetic disorder that affects the affinity of hemoglobin for oxygen or the response to hypoxia.

• #2 Polycythemia – Wikipedia

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

  Rare inherited mutations in three genes which all result in increased stability of hypoxia-inducible factors, leading to increased erythropoietin production, have been shown to cause secondary polycythemia: Chuvash erythrocytosis or Chuvash polycythemia is an autosomal recessive form of erythrocytosis endemic in patients from the Chuvash Republic in Russia. […] Patients with Chuvash erythrocytosis experience a significantly elevated risk of events.

• #2 5 Reasons for Erythrocytosis in Dogs & Cats | Clinician’s Brief

  https://www.cliniciansbrief.com/article/top-5-causes-erythrocytosis-dogs-cats

  Secondary inappropriate absolute erythrocytosis can occur due to increased production of erythrocytes induced by an erythropoietin-secreting neoplasm; this is an inappropriate response because erythropoietin production is increased in the absence of systemic hypoxia. […] Hormones (eg, cortisol in dogs, thyroxine and growth hormone in cats) can directly or indirectly stimulate erythropoiesis. […] Polycythemia vera, the cause of primary absolute erythrocytosis, is a chronic myeloproliferative disease characterized by an increase in hematocrit or packed cell volume 65%, no increase in erythropoietin concentration, normal blood volume, and normal arterial partial pressure of oxygen.

• #2 The diagnosis and management of erythrocytosis | The BMJ

  https://www.bmj.com/content/347/bmj.f6667

  Erythrocytosis is a common reason for referral to haematology services and is usually secondary in origin. […] The cause can often be elucidated from a detailed medical and drug history. […] Common secondary causes include smoking, hypoxia, and diuretics. […] The prevalence of secondary erythrocytosis is considerably higher but is difficult to quantify owing to the diversity of causes and paucity of data.

• #2 Erythrocytosis – Causes, Symptoms, Diagnosis, and Treatment

  https://www.apollohospitals.com/diseases-and-conditions/erythrocytosis

  Several risk factors can increase the likelihood of developing erythrocytosis, including: Age: The risk of erythrocytosis increases with age, particularly in individuals over 60. Gender: Males are more likely to develop erythrocytosis than females. Geographic Location: Individuals living at high altitudes are at a higher risk due to lower oxygen levels. Underlying Conditions: Chronic lung diseases, heart diseases, and certain tumors can stimulate red blood cell production. […] If left untreated or poorly managed, erythrocytosis can lead to several complications: Thrombosis: Increased blood viscosity raises the risk of blood clots, which can lead to strokes or heart attacks. Hypertension: Elevated blood pressure may occur due to increased blood volume and viscosity. Organ Damage: Chronic erythrocytosis can lead to damage in organs such as the heart, kidneys, and brain due to reduced blood flow.

• #2

  https://haematologica.org/article/view/8839

  Here we critically evaluate the role of elevated hematocrit as the principal determinant of thrombotic risk in polycythemia and erythrocytosis, defined by an expansion of red cell mass. […] Although the increased thrombotic risk is assumed to be due to the elevated hematocrit and an associated increase in blood viscosity, thrombosis does not accompany most types of erythrocytosis. […] Inherited and environmental causes that lead to polycythemia and erythrocytosis are accompanied by diverse cellular changes that could directly affect thrombotic risk, irrespective of the elevated hematocrit. […] The pressing issue in these disorders is to define factors other than elevated hematocrit that determine thrombotic risk. […] The propensity to thrombosis is even higher in CE than in PV. […] The high rate of thrombosis in CE begins in childhood and increases with age.

• #2 Phenotypical differences and thrombosis rates in secondary erythrocytosis versus polycythemia vera | Blood Cancer Journal

  https://www.nature.com/articles/s41408-021-00463-x

  While post-diagnosis thrombotic rates appeared lower in SE patients, limited follow-up in this cohort precludes accurate interpretation. […] Furthermore, regardless of erythrocytosis etiology, classic cardiovascular risk factors (age, hypertension, obesity, etc.) significantly clustered with thrombosis risk, emphasizing the importance of controlling these risk factors in PV (in addition to Hct targets) as well as SE patients. […] Finally, while further studies are needed to more comprehensively address the unmet needs relevant to SE, the current observations call for a reappraisal of workup and management practices, and raise concerns for potentially increased thrombotic complications in this understudied population.

• #2 Why Do I Have Too Many Red Blood Cells? Causes of Erythrocytosis Explained – Doctronic, Your Trusted AI Doctor

  https://www.doctronic.ai/conditions-diseases/why-do-i-have-too-many-red-blood-cells-causes-of-erythrocytosis-explained-Np4wAr

  In rare cases, certain tumors can cause erythrocytosis by producing too much erythropoietin (EPO), the hormone that stimulates red blood cell production. Kidney cancers, liver tumors, and some brain tumors are known to sometimes cause this. […] Some medications can cause erythrocytosis as a side effect. For example, testosterone replacement therapy and anabolic steroids can boost red blood cell production. Certain kidney diseases and post-kidney transplant conditions can also lead to erythrocytosis. In some cases, the cause might be a combination of factors or remain unknown, which doctors call idiopathic erythrocytosis. […] Chronic stress may contribute, but it’s rarely the sole cause. […] Not always, but it can lead to complications if left untreated. […] Yes, a diet very high in iron could potentially contribute to erythrocytosis. […] Severe dehydration can cause a temporary increase in red blood cell concentration. […] Identifying the cause of erythrocytosis is crucial for effective treatment and management of your health.

• #3 Erythrocytosis: What Is It, What Causes It, and More

  https://www.webmd.com/a-to-z-guides/what-is-erythrocytosis

  Erythrocytosis is when you have more red blood cells than normal. […] There are two types of erythrocytosis, primary and secondary. While both cause an increase in red blood cells, each type happens for a different reason. […] Primary erythrocytosis can also be caused by a type of blood cancer called polycythemia vera. […] Secondary erythrocytosis can have many causes. These can include: […] Conditions that cause low oxygen. […] Kidney disease. […] Some medicines. […] Tumors. […] Dehydration. […] Relative erythrocytosis can also be caused by diuretics, medicines that cause your kidneys to eliminate salt and water more quickly than normal.

• #3 Overproduction of Red Blood Cells in Dogs – Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

  https://wagwalking.com/condition/erythrocytosis

  Erythrocytosis also referred to as polycythemia, is a disease that causes an excess of red blood cells to be produced. There are four types of erythrocytosis: relative, primary, secondary, and endocrinopathy-associated. […] Erythrocytosis, regularly used synonymously with polycythemia, is a disease in which the bone marrow produces too many red blood cells. […] Relative erythrocytosis is primarily caused by severe dehydration. This dehydration can be caused by lack of water intake, vomiting, and diarrhea. Separately, relative erythrocytosis can be caused by increased fear, excitement, or other states of arousal occur, releasing red blood cells into circulation. […] Primary erythrocytosis, or polycythemia vera, can be linked to congenital heart disease, kidney tumors, and some types of bone marrow cancer. The specific cause of this form of erythrocytosis is unknown. […] Secondary erythrocytosis is caused by decreases in the amount of oxygen reaching the tissues in the body, called hypoxia. […] Endocrinopathy-associated erythrocytosis is caused by hormones other than serum erythropoietin mimicking the effects of secondary erythrocytosis.

• #3 Erythrocytosis in Horses – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-in-horses

  Relative erythrocytoses are not attributed to an increase in the bodys overall red cell mass. Rather, they are associated with a relative increase in the number of red cells due to a loss of plasma volume or redistribution of red cells. […] Dehydrated animals experience a reduced proportion of plasma due to a loss of water volume. In this manner, dehydration results in a relative erythrocytosis because the increase in red cells is attributed to reduced plasma volume. […] Absolute erythrocytoses are due to a true increase in the bodys red cell mass from increased erythropoiesis, not reduced plasma volume or redistribution of the red cells. This can be due to increased, unregulated, neoplastic, autonomous production of red cells (primary) or increased synthesis or activity of erythropoietin (secondary), the main hormone that stimulates erythropoiesis.

• #3 Diagnosis and Treatment of Erythrocytosis – touchONCOLOGY

  https://touchoncology.com/haematology/journal-articles/diagnosis-and-treatment-of-erythrocytosis/

  Primary erythrocytoses will have an EPO level below normal, as the intrinsic defect in the progenitor is responsible for the red cell production, and the physiological response to this is depression of EPO levels. In secondary erythrocytoses, EPO levels will be normal (inappropriate for a raised Hb) or elevated as the EPO is driving the erythrocytosis. […] A congenital erythrocytosis can arise due to mutations of the EPO receptor. […] The main acquired primary erythrocytosis is polycythaemia vera (PV). […] Anything leading to the increased production of EPO can produce an erythrocytosis. […] There remains a small group of patients who do not have an identified cause for their erythrocytosis and are consequently diagnosed with idiopathic erythrocytosis. […] An erythrocytosis can arise from primary and secondary causes. Investigation should be directed by the EPO level, and may then explore EPO signalling in those with low EPO levels or investigation of oxygen sensing in those with normal or elevated levels.

• #3 Polycythemia vera – Symptoms & causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/polycythemia-vera/symptoms-causes/syc-20355850

  Polycythemia vera happens when a change in a gene causes a problem with making blood cells. The body typically controls the number of each of the three types of blood cells. These are red blood cells, white blood cells and platelets. But in polycythemia vera, the bone marrow makes too many of some of these blood cells. […] The cause of the gene change in polycythemia vera is unknown. But it’s not passed through families.

• #3 What is polycythameia vera? | Cancer Research UK

  https://www.cancerresearchuk.org/about-cancer/polycythaemia-vera/what-is-pv

  We know from research that more than 95 out of 100 people (more than 95%) who have polycythaemia vera have a change in the JAK2 gene. A fault in the JACK2 gene occurs in myeloproliferative neoplasms (MPNs). […] The JAK2 gene makes a protein that controls how many blood cells the stem cells make. The fault with your JAK2 gene means the stem cells can start producing red blood cells when they’re not meant to. This results in too many red cells being produced. […] In rarer cases, you might have a history of myeloproliferative neoplasms in your family. This might mean there is a faulty gene in your family that increases your risk of developing MPNs.

• #3 Erythrocytosis: genes and pathways involved in disease development | Blood Transfusion

  https://www.bloodtransfusion.it/bt/article/view/56

  Erythrocytosis is a blood disorder characterised by an increased red blood cell mass. The most common causes of erythrocytosis are acquired and caused by diseases and conditions that are accompanied by hypoxaemia or overproduction of erythropoietin. More rarely, erythrocytosis has a known genetic background, such as for polycythaemia vera and familial erythrocytosis. The majority of cases of polycythaemia vera are associated with acquired variants in JAK2, while familial erythrocytosis is a group of congenital disorders. Familial erythrocytosis type 1 is associated with hypersensitivity to erythropoietin (variants in EPOR), types 2-5 with defects in oxygen-sensing pathways (variants in VHL, EGLN1, EPAS1, EPO), and types 6-8 with an increased affinity of haemoglobin for oxygen (variants in HBB, HBA1, HBA2, BPGM). Due to a heterogenic genetic background, the causes of disease are not fully discovered and in more than 70% of patients the condition remains labelled idiopathic.

• #3 Erythrocytosis: Definition, Causes, Symptoms, and More

  https://resources.healthgrades.com/right-care/blood-conditions/erythrocytosis

  Erythrocytosis causes an increased number of red blood cells. […] Erythrocytosis can be either primary or secondary. Primary erythrocytosis is caused by disorders of the blood-forming cells, such as polycythemia vera. This condition causes the bone marrow to produce too many red blood cells. […] Secondary erythrocytosis is caused by disorders that prompt the increased production of normal blood-forming cells. Secondary erythrocytosis is more common than primary erythrocytosis. […] Erythrocytosis has different causes depending on whether it is primary or secondary. The most common causes of erythrocytosis are: polycythemia vera, oxygen deprivation, smoking, high altitudes, severe lung disease, such as chronic obstructive pulmonary disease (COPD), congenital heart defects, carbon monoxide poisoning, testosterone treatment, kidney problems, tumors of the brain, liver, or adrenal gland, genetic disorders that affect erythropoietin production.

• #3 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  Secondary polycythemia is defined as an absolute increase in red blood cell mass that is caused by enhanced stimulation of red blood cell production. […] Enhanced erythroid stimulation can be a physiologic response to generalized or localized tissue hypoxia, as in the following settings: […] Because of the decreased ambient oxygen concentration at high altitudes, people living in those locales can develop compensatory erythrocytosis as a physiologic response to tissue hypoxia. […] Chronic obstructive pulmonary disease is commonly due to a large amount of ventilation in poor gas exchange units (high ventilation-to-perfusion ratios). […] Alveolar hypoventilation can result from periodic breathing and oxygen desaturation (sleep apnea) or morbid obesity (Pickwickian syndrome). […] Cardiovascular diseases associated with a right-to-left shunt (arteriovenous malformations) can result in venous blood mixing in the arterial system and delivering low oxygen levels to tissues.

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

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

  Erythrocytosis (or polycythemia) is the presence of an excessive number of red blood cells in the circulation. It can be primary or arise secondarily to another pathology. […] Following is a list of primary and secondary causes of erythrocytosis. Secondary etiologies are much more common: […] Primary causes include congenital erythropoietin receptor (EPOR) mutations and acquired causes such as polycythemia vera and genetic (LNK) mutations. […] Secondary causes include congenital factors like high oxygen affinity hemoglobins, abnormal 2,3 bisphosphoglycerate mutase, methemoglobinemia, and dysfunctional oxygen-sensing pathway (e.g. VHL mutations). Acquired causes include hypoxia-driven factors such as chronic lung disease, right-to-left cardiopulmonary shunts, carbon monoxide toxicity, smoking-related polycythemia, sleep apnea, and living at high altitude. Local renal hypoxia can be caused by renal artery stenosis, end-stage renal failure, hydronephrosis, polycystic kidney disease, and post-renal transplant erythrocytosis.

• #3 Erythrocytosis in Horses – Circulatory System – Merck Veterinary Manual

  https://www.merckvetmanual.com/circulatory-system/erythrocytosis-polycythemia/erythrocytosis-in-horses

  Primary absolute erythrocytosis is considered a diagnosis of exclusion reserved for animals with a persistent erythrocytosis without evidence of dehydration, suspected splenic contraction, or identifiable causes for a secondary absolute erythrocytosis. […] An appropriate secondary absolute erythrocytosis occurs when there is increased release of erythropoietin in an attempt to improve the bloods oxygen-carrying capacity. This may occur with cardiac or respiratory disease, high altitudes, or hemoglobin disorders. […] In horses, an appropriate secondary absolute erythrocytosis is most often connected with congenital cardiac defects associated with right to left shunting or lung disease, including chronic pneumonia or pleuropneumonia. […] Inappropriate secondary absolute erythrocytosis is typically a paraneoplastic finding attributed to autonomous synthesis of erythropoietin or prostaglandins enhancing the actions of erythropoietin by a neoplasm or as a response to renal hypoxia.

• #3 Primary Erythrocytosis in a Dog | Today’s Veterinary Practice

  https://todaysveterinarypractice.com/hematology/primary-erythrocytosis-in-a-dog/

  Causes of secondary erythrocytosis include conditions that cause whole-body hypoxemia or secretion of erythropoietin out of control of the normal feedback loop. The best-understood hypoxemic cause is cardiac disease causing right-to-left shunting. […] Hereditary methemoglobinemia can cause erythrocytosis through decreased oxygen saturation of hemoglobin despite normal oxygen partial pressure. […] Secretion of erythropoietin out of control of the normal feedback loop can result from paraneoplastic erythropoietin secretion or hormonal stimulation of erythropoietin secretion by thyroid and other hormones. […] Primary absolute erythrocytosis is the result of RBC production in the bone marrow, independent of stimulation by the normal hypoxemia–erythropoietin feedback loop.

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

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

  Pathological erythropoietin secretion can occur due to neoplasms such as cerebellar hemangioblastoma, meningioma, parathyroid adenoma/carcinoma, hepatocellular carcinoma, renal cell carcinoma, and pheochromocytoma. […] Exogenous erythropoietin can result from drug administration, either physician-directed or illicit, including erythropoietin (EPO) and androgens.

• #3 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  Blood doping is an illegal practice. […] Illicit use of androgenic steroids to build muscles and strength can also increase red blood cell mass by stimulating endogenous serum EPO levels. […] Hemoglobin mutants associated with tight binding to oxygen and a failure to deliver oxygen in the venous blood can cause high EPO levels. […] A von Hippel-Lindau gene mutation results in polycythemia by altering the von Hippel-Lindau protein, which plays an important role in sensing hypoxia and binds to hydroxylated HIF1-alpha to serve as a recognition site of an E3-ubiquitin ligase complex. […] Chuvash polycythemia is caused by an autosomal recessive gene mutation on the von Hippel-Lindau gene, which results in the upregulation of the HIF1-alpha target gene and causes elevations in EPO levels.

• #3 REVE2 – Overview: Erythrocytosis Evaluation, Blood

  https://www.mayocliniclabs.com/test-catalog/Overview/618830

  The most common cause of hereditary erythrocytosis is the presence of a high-oxygen-affinity (HOA) hemoglobin variant. A subset of hemoglobins with increased oxygen (O2) affinity results in clinically evident erythrocytosis caused by decreased O2 unloading at the tissue level. Many are asymptomatic; however, some patients have recurrent headaches, dizziness, fatigue, and restless legs. A subset of patients experience thrombotic episodes. Affected individuals can be plethoric, and many are misclassified as polycythemia vera, particularly prior to more recent genetic testing availability. […] In addition, O2-sensing pathway variants, EPAS1(HIF2A) (OMIM 611783); EGLN1(PHD2) (OMIM 609820), and VHL (OMIM 263400) cause hereditary erythrocytosis and a subset are associated with pheochromocytoma and paragangliomas. All have shown an autosomal dominant pattern of inheritance, except VHL-associated erythrocytosis, which is an autosomal recessive disorder.

• #3 What Is Erythrocytosis?

  https://www.icliniq.com/articles/blood-health/erythrocytosis

  The cause of secondary erythrocytosis is not always known. […] The body can experience an oxygen deficit due to a variety of conditions. More red blood cells are produced as a result of an increase in EPO (erythropoietin) levels. Heart disease, lung disease, and sleep apnea are among the illnesses. Secondary erythrocytosis can also be brought on by a group of diseases known as hemoglobinopathy. Hemoglobin, a crucial protein that makes up red blood cells, is affected by these conditions.

• #3

  https://haematologica.org/article/view/8839

  However, higher hematocrit is not an independent predictor of thrombotic risk in either children or adults. […] Thus, the thrombotic risk in CE appears to be independent of viscosity, but rather to be related to changes in the upregulated hypoxic responses associated with the homozygous VHL mutation. […] The rationale for phlebotomy in PV was provided by a retrospective analysis of 69 patients in whom elevated hematocrit was controlled by phlebotomy and thrombocytosis by busulfan or other forms of chemotherapy. […] Overall, therapeutic phlebotomy was independently and significantly associated with an increased risk of thrombosis compared to chemotherapy, but hematocrit level was not independently associated with thrombotic risk. […] The increased risk of thrombosis with phlebotomy compared to chemotherapy observed in the PVSG 01 study was followed up in the PVSG 05 study.

• #4 Investigation and management of erythrocytosis

  https://pmc.ncbi.nlm.nih.gov/articles/PMC7829024/

  Primary erythrocytosis or autonomous production of excess erythrocytes most commonly occurs due to polycythemia vera (PV), a myeloproliferative neoplastic process that may be asymptomatic or may present with thrombosis, constitutional or vasomotor symptoms, or splenomegaly. […] Secondary erythrocytosis, which is more common than PV, has a broad differential diagnosis that includes hypoxic lung disease, cyanotic congenital heart disease, medications (e.g., testosterone) and erythropoietin-producing malignant disorders. […] Erythrocytosis refers to an erythrocyte count above the sex-specific normal range and can be subclassified into relative erythrocytosis, caused by a reduction in plasma volume (hemoconcentration), or absolute erythrocytosis, caused by increased erythrocyte mass. […] Absolute erythrocytosis can be driven by a clonal bone marrow disease (PV) or be secondary to another disease, including a physiologic response to increased erythropoietin secondary to hypoxia, drugs or erythropoietin-producing solid tumours.

• #4 Secondary Polycythemia: Practice Essentials, Pathophysiology, Etiology

  https://emedicine.medscape.com/article/205039-overview

  The administration of androgen esters to hypogonadal men can lead to polycythemia. […] The incidence of testosterone-associated polycythemia may be lower in men receiving pharmacokinetically steady-state delivery of testosterone formulations, as occurs following the subcutaneous implantation of testosterone pellets, than it is in men receiving intramuscular injections of shorter-acting androgen esters. […] Secondary polycythemia has been reported as a paraneoplastic phenomenon in patients with testicular cancer.

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