Polycythemia vera

Alternative names:

hyperglobulinemia; myeloproliferative disorders; polycythemia rubra vera; primary polycythemia; Waldenstrom's disease

Definition:

An abnormal increase in blood cells (primarily red blood cells) resulting from increased production by the bone marrow.

Causes, incidence, and risk factors:

Polycythemia vera is an acquired disorder of the bone marrow, which causes an overproduction of all three blood cell lines: white blood cells, red blood cells, and platelets. It is a rare disorder, occurring more frequently in men, and is rarely seen in those under 40 years old. Its cause is unknown, and the disease is considered a hematologic malignancy. The disease develops slowly, usually after the age of 50 or 60 and may progress to acute myelogenous leukemia. The viscosity of the blood and the increased platelets result in a high potential for clot formation, which can result in stroke or heart attack. In some patients, hemorrhage occurs because, although the platelets responsible for blood clotting are present in high numbers, their clotting ability is impaired. Risk factors are unknown, but the incidence is highest among people of Jewish ancestry.