Which test is used to monitor polycythemia vera?

• A. Measure cholesterol levels
• B. Test blood samples for hematocrit
• C. Perform urine culture
• D. Assess blood pressure

Answer: (B)

Polycythemia vera is driven by an increased red blood cell mass, so the most informative way to track the disease is to measure how much of the blood is made up of red cells. This is hematocrit, the percentage of blood volume occupied by red blood cells. Regular hematocrit testing from a blood sample shows whether the red cell mass is within the target range, guiding treatments like phlebotomy to reduce blood viscosity and lower the risk of clotting. The other options don’t reflect the main abnormality in PV: cholesterol levels, urine cultures, and blood pressure do not directly indicate red cell mass or disease activity.