In polycythemia vera, which treatment is used for high-risk patients to reduce thrombotic risk?

• A. Erythropoietin
• B. Hydroxyurea
• C. Vitamin D
• D. Insulin

Answer: (B)

Reducing thrombotic risk in high-risk polycythemia vera relies on methods that lower the red cell mass and platelet counts, thereby decreasing blood viscosity and clot formation. In patients over 60 or with a history of thrombosis, cytoreductive therapy is added to phlebotomy and low-dose aspirin to suppress marrow production. Hydroxyurea works by inhibiting DNA synthesis in rapidly dividing cells, which reduces production of red blood cells and platelets. This helps bring hematocrit and platelet counts down, lowering the chance of clotting events. While phlebotomy and aspirin address viscosity and platelet activity, hydroxyurea provides ongoing control of cell production in the marrow. Erythropoietin would raise red cell production, worsening viscosity; vitamin D and insulin do not address PV pathophysiology or thrombosis risk.