Polycythemia rubra vera

PV represents a clonal disorder characterized by excessive erythropoiesis accompanied by low serum EPO levels. Two populations of erythroid progenitors have been identified in the BM of patients with PV. One population responds normally to EPO and the other, the malignant clone, is exquisitely sensitive to EPO. The latter phenomenon is regarded as the most readily accepted explanation for the pathophysiology of this disease, although other mechanisms have been proposed. Thrombohemorrhagiccomplications, which usually correlate with the hematocrit level, are the most important because of their frequency and severity. Preventing such complications represents one of the most important therapeutic goals. Diagnostic criteria have been established enabling an accurate diagnosis of PV, in which the majority of patients live an excess of 10 years. Some will develop a falling hematocrit secondary to PPMM, also termed the spent phase. Patients may also develop acute leukemia, which is increased in incidence if myelosuppressive therapy is used, compared with phlebotomies alone. The initial treatment is phlebotomy to an hematocrit of 45% or less. The studies of the PVSG have shown that chlorambucil produces excessive mortality from malignancy, and 32P and phlebotomy are associated with superior survivals which are equivalent. Because of the substantial risk of thrombotic complications, elderly patients, ie, those older than 70 years, should be treated initially with phlebotomy and myelosuppressive therapy, usually 32P. Hydroxyurea appears less leukemogenic than 32P or alkylating agents; however, recent reports have questioned this. IFN is a promising new agent which may become a standard form of therapy in the future.