Polycythemia vera (PV) is one of three chronic myeloproliferative disorders, along with essential thrombocythemia and myelofibrosis with myeloid metaplasia. The incidence of PV is 2.3 per 100,000 patients, and the median age at diagnosis is 60 years. Tefferi recommends treatment options for PV.
Polycythemia describes an increase in red blood cell mass. The increase in red blood cell mass may be caused by an actual increase in red blood cell mass (true polycythemia) or a spurious laboratory value (apparent polycythemia). True polycythemia is classified as either primary or secondary. Primary polycythemia is caused by a myeloproliferation and is not mediated by excess erythropoietin. In contrast, secondary polycythemia can be caused by an external source, such as “smoker's polycythemia,” or an internal disorder, such as renal cancer. Erythropoietin levels in secondary polycythemias vary depending on the etiology.
PV can have life-threatening complications, including stroke and evolution into either myelofibrosis with myeloid metaplasia or acute leukemia. Treatment is directed according to patient risk stratification. Frequent phlebotomy and chemotherapy are the cornerstones of treatment. Hematocrit levels should be maintained below 45 percent in white men and 42 percent in women and blacks. Chemotherapy using hydroxyurea, busulfan, or pipobroman is indicated for high-risk patients. (Pipobroman is not available in the United States.) Interferon-alfa is another chemotherapeutic option for reducing red blood cell burden and treating PV-associated pruritus.
Non-life–threatening sequelae include microvascular complications and aquagenic pruritus. Microvascular complications may appear clinically as headache, light-headed-ness, transient neurologic abnormality, transient ocular disturbance, tinnitus, atypical chest pain, paresthesias, and erythromelalgia (a rare but painful burning sensation of the hands or feet). Low-dose aspirin (81 mg or less per day) can be used to treat these disorders. Aquagenic pruritus is a generalized body itching often brought on by a hot bath. Treatment options include either selective serotonin reuptake inhibitors or interferon-alfa.