[Clinical significance of red cell distribution width in polycythemia vera]

We evaluated changes in red cell distribution width-standard deviation (RDW-SD) measured using a multiple parameter automated hematology analyzer E 4000 in patients with polycythemia vera (PV). Patients with iron deficiency anemia, those with chronic myelogenous leukemia, those with primary thrombocythemia, and normal subjects were examined as controls. In the patients with PV, as in those with the other 3 diseases, RDW-SD tended to be higher than in the normal controls when red blood cell counts were high. The RDW-SD in patients with PV transiently increased following administration of a myelosuppressive, which corresponded to the transition period from microcytes to normal blood cells. It was even higher during the polycythemic period than during the myelofibrotic period. This may be associated with hematopoietic abnormality due to extramedullary hematopoiesis. RDW-SD seems to well reflect the pathologic status of PV.