Polycythemia

The presence of too many red blood cells. Polycythemia formally exists when the hemoglobin, red blood cell (RBC) count and total RBC volume are both above normal. For example, the percentage of red blood cells in whole blood (hematocrit) in polycythemia is significantly above 52 percent in men and above 48 percent in females. The normal hematocrit range is from about 42 to 52 percent in males, and 37 to 48 percent in females. The opposite of anemia.

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An increase above the normal in the number of red cells in the blood. SYN: erythrocythemia. [poly- + G. kytos, cell, + haima, blood]

- compensatory p. a secondary p. resulting from anoxia, e.g., in congenital heart disease, pulmonary emphysema, or prolonged residence at a high altitude.

- p. hypertonica p. associated with hypertension, but without splenomegaly. SYN: Gaisböck syndrome.

- relative p. a relative increase in the number of red blood cells as a result of loss of the fluid portion of the blood.

- p. rubra SYN: p. vera.

- p. rubra vera SYN: p. vera.

- p. vera a chronic form of p. of unknown cause; characterized by bone marrow hyperplasia, an increase in blood volume as well as in the number of red cells, redness or cyanosis of the skin, and splenomegaly. SYN: erythremia, Osler disease, Osler-Vaquez disease, p. rubra vera, p. rubra, Vaquez disease.

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poly·cy·the·mia or chiefly Brit poly·cy·thae·mia -(.)sī-'thē-mē-ə n a condition marked by an abnormal increase in the number of circulating red blood cells esp POLYCYTHEMIA VERA compare erythrocytosis

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poly·cy·the·mia (pol″e-si-theґme-ə) [poly- + cyt- + hem- + -ia] an increase in the total red cell mass of the blood, characterized as either absolute p. or relative p. Called also erythrocythemia, hypercythemia, and hypererythrocythemia.