Table of ContentsView AllTable of ContentsWhat Is Erythrocytosis?TypesSymptomsCausesDiagnosisComplicationsTreatmentOutlook
Table of ContentsView All
View All
Table of Contents
What Is Erythrocytosis?
Types
Symptoms
Causes
Diagnosis
Complications
Treatment
Outlook
Erythrocytosis, also calledpolycythemia, occurs when people have too many blood cells in the body.It’s a different problem from anemia, which means there are too few red blood cells.
With erythrocytosis, the blood thickens because more cells are packed into the same plasma fluid. This blood has difficulty moving through the blood vessels and can result in strokes, heart attacks,blood clotsor pulmonary embolus (blood clot in the lung).
This article discusses symptoms of erythrocytosis and how the different types are diagnosed. It explains how erythrocytosis is treated as well as complications of the disorder.
What Is Plasma’s Role in the Body?
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Your blood is made up of about 55% fluid, or plasma, and about 90% of that is water.The rest includes different types of cells:
Erythrocytosis causes too many red blood cells in the blood that are out of proportion with the other components. It changes the hematocrit level (percentage of red blood cells in blood) and may alter the hemoglobin level, changing how efficient your body is at moving oxygen and carbon dioxide.
Hematocrit Levels and ErythrocytosisErythrocytosis causes high levels of high levels of hematocrit and/or hemoglobin. As a result, blood is thicker and less able to travel through blood vessels and organs.Normal hematocrit levels for males range from 41% to 50%, with hemoglobin ranges between 13.5 and 17.5 grams per deciliter (g/dL). For females, the normal hematocrit range is 36% to 48% with levels of hemoglobin between 12.0 to 15.5 g/dL.
Hematocrit Levels and Erythrocytosis
Erythrocytosis causes high levels of high levels of hematocrit and/or hemoglobin. As a result, blood is thicker and less able to travel through blood vessels and organs.Normal hematocrit levels for males range from 41% to 50%, with hemoglobin ranges between 13.5 and 17.5 grams per deciliter (g/dL). For females, the normal hematocrit range is 36% to 48% with levels of hemoglobin between 12.0 to 15.5 g/dL.
Erythrocytosis causes high levels of high levels of hematocrit and/or hemoglobin. As a result, blood is thicker and less able to travel through blood vessels and organs.
Normal hematocrit levels for males range from 41% to 50%, with hemoglobin ranges between 13.5 and 17.5 grams per deciliter (g/dL). For females, the normal hematocrit range is 36% to 48% with levels of hemoglobin between 12.0 to 15.5 g/dL.
Hematocrit (HCT) Blood Test
Types of Erythrocytosis
There are two pathways that cause erythrocytosis to occur. Either an increase in red blood cell counts (absolute erythrocytosis) or a decrease in plasma (relative or apparent erythrocytosis) can cause elevated levels of red blood cells.
Absolute types can have either primary or secondary causes.
Primary Erythrocytosis
Red blood cell production itself is high when there is a primary cause of absolute erythrocytosis. This can occur with certain blood -related cancers, likeleukemia, and other disorders that affect the bone marrow calledmyeloproliferative disorders.
Secondary Erythrocytosis
Secondary erythrocytosis occurs when another health condition is forcing the bone marrow to produce more red blood cells. This acceleration can be due to chronichypoxia, in which low oxygen levels occur in tissues.
Causes are many and can include heart and lung disease, an infection, or an underlying anemia.
Hematopoiesis and How Your Body Produces Blood
Symptoms of Erythrocytosis
Some people do not have any symptoms and are diagnosed after routine laboratory work.These symptoms of erythrocytosis can be vague and will depend, in some cases, on the underlying cause. For example, blood clots are common with PV. Other symptoms include:
Other symptoms can include bone pain, an enlarged spleen, and excessive sweating. These can be signs of a blood cancer, butrenal (kidney) cancerand other conditions also may cause symptoms.
Myeloproliferative Neoplasms and Your Enlarged Spleen
Causes of Erythrocytosis
Erythrocytosis and its symptoms can be due to a number of causes, some more common than others. These causes are either primary or secondary in nature.
Causes of Primary Erythrocytosis
Polycythemia vera is the most common cause of acquired erythrocytosis. Genetic changes, either aJAK2V671F mutation or exon 12 mutations inJAK2, are required as part of a PV diagnosis.Primary causes also can occur with some blood-related cancers.
What Is Genetic Testing?
Causes of Secondary Erythrocytosis
Certain injuries or underlying health conditions can lead to a secondary erythrocytosis. They can include conditions that lead to hypoxia, such as:
In some cases, tumors that secrete erythropoietin can lead to erythrocytosis.This can occur with liver and kidney cancers, and tumors that affect the adrenal glands. Factors that cause the kidneys to produce more erythropoietin also can includecarbon monoxideexposure and steroid use.
Do Lifestyle Factors Play a Role in Erythrocytosis?While certain underlying health conditions can lead to a secondary erythrocytosis, researchers are finding that environmental and lifestyle factors also may play a role. A 2021 review of 20 different studies found cigarette smoking and perhaps obesity are linked to related myeloproliferative disorders but more research is needed. Benzene exposure also may present a risk.
Do Lifestyle Factors Play a Role in Erythrocytosis?
While certain underlying health conditions can lead to a secondary erythrocytosis, researchers are finding that environmental and lifestyle factors also may play a role. A 2021 review of 20 different studies found cigarette smoking and perhaps obesity are linked to related myeloproliferative disorders but more research is needed. Benzene exposure also may present a risk.
Diagnosis of Erythrocytosis
High blood pressure, includingpulmonary hypertensionaffecting the lungs, also can occur.
Does Erythrocytosis Cause Cancer?Erythrocytosis is associated with some cancer types but it is rarely the cause. However, some people develop a complication calledmyelofibrosis,a scarring of the bone marrow. Over time, the changes in blood cell production can lead to acute myeloid leukemia (AML). There are currently no treatments to reduce this risk.
Does Erythrocytosis Cause Cancer?
Erythrocytosis is associated with some cancer types but it is rarely the cause. However, some people develop a complication calledmyelofibrosis,a scarring of the bone marrow. Over time, the changes in blood cell production can lead to acute myeloid leukemia (AML). There are currently no treatments to reduce this risk.
Is Acute Myeloid Leukemia Hereditary?
Treatment for Erythrocytosis
Phlebotomy, a procedure to remove blood from a vein on a regular schedule, is often used to prevent complications with erythrocytosis.The blood is often replaced with normal saline.
Other treatment options can include medications to prevent blood clots. Some options include:
It’s important to note that the use of hydroxyurea, interferon, or ruxolitinib is only for patients with a PV diagnosis. These are not used in patients with erythrocytosis due to other causes.
Lifestyle Changes
Certain lifestyle changes can help to lower cholesterol, improve blood pressure, and limit the risk of complications with erythrocytosis. For example, blood clots already are a risk to people with an erythrocytosis diagnosis, so limiting the additional factors that contribute to blood clots can help.
Talk to your healthcare provider about smoking cessation and weight loss goals that can be managed with diet and exercise.
When a Medical Emergency Needs Immediate CareSome complications of erythrocytosis are serious and can be life-threatening. Seek immediate medical attention if you experience:Heart-related symptoms, includingchest painand shortness of breathStroke symptoms, which can include mental confusion, one-sided weakness, andtrouble speakingSudden, severe shortness of breath that can occur with a pulmonary embolism
When a Medical Emergency Needs Immediate Care
Some complications of erythrocytosis are serious and can be life-threatening. Seek immediate medical attention if you experience:Heart-related symptoms, includingchest painand shortness of breathStroke symptoms, which can include mental confusion, one-sided weakness, andtrouble speakingSudden, severe shortness of breath that can occur with a pulmonary embolism
Some complications of erythrocytosis are serious and can be life-threatening. Seek immediate medical attention if you experience:
How Many People Survive a Heart Attack?
The prognosis for someone diagnosed with erythrocytosis is not dire, but a shorter life expectancy is common. A 2024 update on PV finds that people live an average of 15 years after their diagnosis, although that rises dramatically to 35 years or more if your diagnosis occurs before age 40.
Keep in mind that prognosis and life expectancy data are based on past experience and new insights and treatment options continue to emerge. Complications such asleukocytosis(high white blood cell counts) or thrombotic clots can affect prognosis, too.
Summary
Erythrocytosis is a condition in which your blood contains too many red blood cells. This can occur due to a primary factor (changes in how the cells are produced in the bone marrow) or a secondary factor (an underlying health issue, injury, medication, or lifestyle exposure that affects production).
When too many red blood cells alter the mix of blood components, it can put you at risk for clots and other complications that can prove life-threatening. Conditions like PV and its complications may increase your symptoms and the need for treatment.
Phlebotomy and aspirin are common therapies for erythrocytosis, and your healthcare provider has other options to treat underlying conditions as well. Lifestyle changes, like weight control, also can help.
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12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Parnes A, Ravi A.Polycythemia and thrombocytosis.Prim Care. 2016;43(4):589-605. doi:10.1016/j.pop.2016.07.011Institute for Quality and Efficiency in Health Care (IQWiG).What does blood do?American Red Cross.Plasma information.American Red Cross.What Does Hematocrit Mean?Wouters HJCM, Mulder R, van Zeventer IA, Schuringa JJ, van der Klauw MM, van der Harst P,et al.Erythrocytosis in the general population: clinical characteristics and association with clonal hematopoiesis.Blood Adv. 2020 Dec 22;4(24):6353-6363. doi:10.1182/bloodadvances.2020003323.MedlinePlus.Polycythemia vera.Mallik N, Das R, Malhotra P, Sharma P.Congenital erythrocytosis.Eur J Haematol. 2021 Jul;107(1):29-37. doi: 10.1111/ejh.13632.Prchal JT.Diagnosing or ruling out polycythemia vera in patients with erythrocytosis.Clin Adv Hematol Oncol. 2019 Jan;17(1):24-27. PMID: 30843892Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management.Am J Hematol.2019;94(1):133-143. doi:10.1002/ajh.25303Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi: 10.1503/cmaj.191587.Allahverdi N, Yassin M, Ibrahim M.Environmental Factors, Lifestyle Risk Factors, and Host Characteristics Associated With Philadelphia Negative Myeloproliferative Neoplasm: A Systematic Review.Cancer Control. 2021;28. doi:10.1177/10732748211046802Tefferi A, Barbui T.Polycythemia vera: 2024 update on diagnosis, risk-stratification, and management.Am J Hematol. 2023 Sep;98(9):1465-1487. doi: 10.1002/ajh.27002.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Parnes A, Ravi A.Polycythemia and thrombocytosis.Prim Care. 2016;43(4):589-605. doi:10.1016/j.pop.2016.07.011Institute for Quality and Efficiency in Health Care (IQWiG).What does blood do?American Red Cross.Plasma information.American Red Cross.What Does Hematocrit Mean?Wouters HJCM, Mulder R, van Zeventer IA, Schuringa JJ, van der Klauw MM, van der Harst P,et al.Erythrocytosis in the general population: clinical characteristics and association with clonal hematopoiesis.Blood Adv. 2020 Dec 22;4(24):6353-6363. doi:10.1182/bloodadvances.2020003323.MedlinePlus.Polycythemia vera.Mallik N, Das R, Malhotra P, Sharma P.Congenital erythrocytosis.Eur J Haematol. 2021 Jul;107(1):29-37. doi: 10.1111/ejh.13632.Prchal JT.Diagnosing or ruling out polycythemia vera in patients with erythrocytosis.Clin Adv Hematol Oncol. 2019 Jan;17(1):24-27. PMID: 30843892Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management.Am J Hematol.2019;94(1):133-143. doi:10.1002/ajh.25303Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi: 10.1503/cmaj.191587.Allahverdi N, Yassin M, Ibrahim M.Environmental Factors, Lifestyle Risk Factors, and Host Characteristics Associated With Philadelphia Negative Myeloproliferative Neoplasm: A Systematic Review.Cancer Control. 2021;28. doi:10.1177/10732748211046802Tefferi A, Barbui T.Polycythemia vera: 2024 update on diagnosis, risk-stratification, and management.Am J Hematol. 2023 Sep;98(9):1465-1487. doi: 10.1002/ajh.27002.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Parnes A, Ravi A.Polycythemia and thrombocytosis.Prim Care. 2016;43(4):589-605. doi:10.1016/j.pop.2016.07.011Institute for Quality and Efficiency in Health Care (IQWiG).What does blood do?American Red Cross.Plasma information.American Red Cross.What Does Hematocrit Mean?Wouters HJCM, Mulder R, van Zeventer IA, Schuringa JJ, van der Klauw MM, van der Harst P,et al.Erythrocytosis in the general population: clinical characteristics and association with clonal hematopoiesis.Blood Adv. 2020 Dec 22;4(24):6353-6363. doi:10.1182/bloodadvances.2020003323.MedlinePlus.Polycythemia vera.Mallik N, Das R, Malhotra P, Sharma P.Congenital erythrocytosis.Eur J Haematol. 2021 Jul;107(1):29-37. doi: 10.1111/ejh.13632.Prchal JT.Diagnosing or ruling out polycythemia vera in patients with erythrocytosis.Clin Adv Hematol Oncol. 2019 Jan;17(1):24-27. PMID: 30843892Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management.Am J Hematol.2019;94(1):133-143. doi:10.1002/ajh.25303Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi: 10.1503/cmaj.191587.Allahverdi N, Yassin M, Ibrahim M.Environmental Factors, Lifestyle Risk Factors, and Host Characteristics Associated With Philadelphia Negative Myeloproliferative Neoplasm: A Systematic Review.Cancer Control. 2021;28. doi:10.1177/10732748211046802Tefferi A, Barbui T.Polycythemia vera: 2024 update on diagnosis, risk-stratification, and management.Am J Hematol. 2023 Sep;98(9):1465-1487. doi: 10.1002/ajh.27002.
Parnes A, Ravi A.Polycythemia and thrombocytosis.Prim Care. 2016;43(4):589-605. doi:10.1016/j.pop.2016.07.011
Institute for Quality and Efficiency in Health Care (IQWiG).What does blood do?
American Red Cross.Plasma information.
American Red Cross.What Does Hematocrit Mean?
Wouters HJCM, Mulder R, van Zeventer IA, Schuringa JJ, van der Klauw MM, van der Harst P,et al.Erythrocytosis in the general population: clinical characteristics and association with clonal hematopoiesis.Blood Adv. 2020 Dec 22;4(24):6353-6363. doi:10.1182/bloodadvances.2020003323.
MedlinePlus.Polycythemia vera.
Mallik N, Das R, Malhotra P, Sharma P.Congenital erythrocytosis.Eur J Haematol. 2021 Jul;107(1):29-37. doi: 10.1111/ejh.13632.
Prchal JT.Diagnosing or ruling out polycythemia vera in patients with erythrocytosis.Clin Adv Hematol Oncol. 2019 Jan;17(1):24-27. PMID: 30843892
Tefferi A, Barbui T.Polycythemia vera and essential thrombocythemia: 2019 update on diagnosis, risk-stratification and management.Am J Hematol.2019;94(1):133-143. doi:10.1002/ajh.25303
Mithoowani S, Laureano M, Crowther MA, Hillis CM.Investigation and management of erythrocytosis.CMAJ. 2020 Aug 10;192(32):E913-E918. doi: 10.1503/cmaj.191587.
Allahverdi N, Yassin M, Ibrahim M.Environmental Factors, Lifestyle Risk Factors, and Host Characteristics Associated With Philadelphia Negative Myeloproliferative Neoplasm: A Systematic Review.Cancer Control. 2021;28. doi:10.1177/10732748211046802
Tefferi A, Barbui T.Polycythemia vera: 2024 update on diagnosis, risk-stratification, and management.Am J Hematol. 2023 Sep;98(9):1465-1487. doi: 10.1002/ajh.27002.
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