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polycythemia

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Also known as erythrocythemia

Polycythemia (also spelt polycythaemia) is a laboratory finding that the hematocrit (the volume percentage of red blood cells in the blood) and/or hemoglobin concentration are increased in the blood. Polycythemia is sometimes called erythrocytosis, and there is significant overlap in the two findings, but the terms are not the same: polycythemia describes any increase in hematocrit and/or hemoglobin, while erythrocytosis describes an increase specifically in the number of red blood cells in the blood.

Key facts

Medical condition (new).name
Polycythemia
Medical condition (new).image
1901 Composition of Blood.jpg
Medical condition (new).caption
Diagram illustrating normal composition of blood compared to anemia and polycythemia
Medical condition (new).field
Hematology
Medical condition (new).synonyms
Erythrocytosis, Hypercythemia, Hypererythrocythemia

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Research

17,403 papers

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Wikidata facts

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NCI Thesaurus ID
C26863
Commons category
Polycythemias
Sources (2)

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~17 min read

Article

21 sections
Contents
  • Definition
  • Differential diagnoses
  • Polycythemia in adults
  • Polycythemia in neonates
  • Pathophysiology
  • Evaluation
  • History and physical exam
  • Laboratory evaluation
  • Additional testing
  • Polycythemia types
  • Primary polycythemia
  • Secondary polycythemia
  • Testosterone replacement therapy (TRT) and secondary polycythemia
  • Altered oxygen sensing
  • Symptoms
  • Epidemiology
  • Management
  • Relation to athletic performance
  • See also
  • References
  • External links

Polycythemia (also spelt polycythaemia) is a laboratory finding that the hematocrit (the volume percentage of red blood cells in the blood) and/or hemoglobin concentration are increased in the blood. Polycythemia is sometimes called erythrocytosis, and there is significant overlap in the two findings, but the terms are not the same: polycythemia describes any increase in hematocrit and/or hemoglobin, while erythrocytosis describes an increase specifically in the number of red blood cells in the blood.

Polycythemia has many causes. It can describe an increase in the number of red blood cells ("absolute polycythemia") or a decrease in the volume of plasma ("relative polycythemia"). Absolute polycythemia can be due to genetic mutations in the bone marrow ("primary polycythemia"), physiological adaptations to one's environment, medications, and/or other health conditions. Laboratory studies such as serum erythropoeitin levels and genetic testing might be helpful to clarify the cause of polycythemia if the physical exam and patient history do not reveal a likely cause.

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