erythrocytosis

(medicine) An increase in the number of circulating erythrocytes of more than two standard deviations above the mean normal, usually occurring secondary to hypoxia. Also known as erythremia; polycythemia.

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An abnormal increase in the number of circulating red blood cells.

Increase in the total red cell mass secondary to any of a number of nonhematogenic systemic disorders in response to a known stimulus (secondary polycythemia), in contrast to primary polycythemia (polycythemia vera).

• e. stimulating factor — a lipid isolated from the plasma of anemic animals; distinct from erythropoietin, causes production of microcytes without increasing hemoglobin. Its role in disease is unknown.
• stress e. — an apparent polycythemia resulting from diminished plasma volume.

(secondary polycythemia) an increased circulating red blood cell mass resulting from compensatory effort to meet reduced oxygen content. May be seen in persons living at high altitudes, as well as in persons with emphysema, pulmonary insufficiency, and heart failure.