From the Guidelines
The goal hematocrit target in therapeutic phlebotomy for polycythemia vera should be below 45%, as supported by the randomized phase 3 CYTO-PV trial 1. This target is crucial in reducing the risk of thrombotic complications, which are a major cause of morbidity and mortality in polycythemia vera. Key points to consider in therapeutic phlebotomy for polycythemia vera include:
- Maintaining a hematocrit below 45% to decrease blood viscosity, improve microcirculation, and reduce the risk of both arterial and venous thrombotic events 1.
- Corresponding hemoglobin targets are approximately 14-15 g/dL for men and 12-13 g/dL for women, although these are not directly stated in the provided evidence, they are generally accepted targets.
- Treatment typically involves removing 250-500 mL of blood per session, with frequency determined by individual patient response 1.
- During initial treatment, hematocrit should be checked before each phlebotomy, then less frequently during maintenance.
- Adequate hydration before and after procedures is essential, and iron supplementation should be avoided as iron deficiency helps control erythropoiesis. The CYTO-PV trial demonstrated that maintaining a lower hematocrit target significantly reduces the risk of cardiovascular events and major thrombotic events, with a hazard ratio of 3.91 in the high-hematocrit group compared to the low-hematocrit group 1. Therefore, therapeutic phlebotomy should aim to maintain a hematocrit below 45% to minimize the risk of thrombotic complications and improve patient outcomes.
From the Research
Therapeutic Phlebotomy Targets for Polycythemia Vera
- The goal hematocrit target in therapeutic phlebotomy for polycythemia vera is less than 45% 2, 3, 4.
- Maintaining a hematocrit of less than 45% has been shown to decrease the risk of thrombosis in patients with polycythemia vera 3.
- A study found that patients with a hematocrit target of less than 45% had a significantly lower rate of cardiovascular death and major thrombosis compared to those with a hematocrit target of 45 to 50% 3.
- The target hemoglobin level is not explicitly stated, but it is mentioned that erythrocytosis is defined as a hemoglobin level greater than 16.5 mg/dL in men or greater than 16.0 mg/dL in women 2.
Rationale for Hematocrit Target
- The rationale for maintaining a hematocrit of less than 45% is to reduce the risk of thrombosis, which is a major complication of polycythemia vera 2, 3, 4.
- High hematocrit levels increase blood viscosity, which can lead to thrombosis and other cardiovascular complications 3.
- Maintaining a hematocrit of less than 45% has been shown to improve outcomes in patients with polycythemia vera, including reducing the risk of thrombosis and improving survival 3, 4.