What does polycythemia mean?
Polycythemia is an abnormal increase in the number of red blood cells or in the total mass of red cells in the blood. It may be relative, when the proportion of red cells rises because of reduced plasma volume, or absolute, when the body genuinely produces more red cells. Causes include polycythemia vera, a myeloproliferative disorder, as well as secondary effects such as smoking, prolonged exposure to low oxygen, sleep apnea, certain medicines, or dehydration. The condition can increase blood viscosity and make circulation more difficult, so diagnosis generally involves blood counts, examination, and further tests to establish the cause. The word is mainly used in clinical and medical contexts. Polycythemia vera is a specific form of the condition and should not be treated as a synonym for every form of polycythemia.
nounAn abnormal increase in the number of red blood cells in the blood, usually associated with an increased red-cell mass. It may be primary, as in polycythemia vera, or secondary to factors such as prolonged low oxygen exposure, smoking, or certain medications.
- An abnormal increase in the number or mass of red blood cells in the blood.
- The disease polycythemia vera, a myeloproliferative disorder in which the bone marrow produces too many blood cells.
"Her doctor diagnosed relative polycythemia after reviewing her blood test results."
"The patient was evaluated for secondary polycythemia after chronic lung disease was diagnosed."
"A blood smear and genetic tests helped doctors distinguish polycythemia vera from other causes of increased red-cell production."
Plural forms are uncommon because the word is used mainly as a name for a disease or physiological condition.
"The clinic specializes in evaluating rare forms of polycythemias."
Polycythemia makes the blood richer in red cells, but more red cells do not always mean better oxygen delivery.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does polycythemia come from?
Polycythemia combines the Greek combining form poly-, meaning “many,” with elements derived from Greek kythos, “blood,” and haima, “blood.” The term developed in medical usage during the 19th century as a description of an excessive number of red blood cells. Its related medical vocabulary includes anemia, leukemia, and hemophilia, all of which use Greek-derived forms referring to blood or blood-cell conditions.
Related word forms
How polycythemia is actually used
The term is primarily medical. The spelling polycythemia is standard in US medical usage, while polycythaemia is the usual British spelling. When used without qualification, it often refers specifically to polycythemia vera, although the broader sense of any red-cell excess also occurs.
Easily confused with polycythemia
Erythrocytosis is a laboratory finding indicating an increased red-blood-cell count, whereas polycythemia refers more broadly to the clinical condition and can also refer to an increased red-cell mass.