From the Guidelines
Phlebotomy is indicated in polycythemia when the hematocrit exceeds 45% to reduce the risk of thrombotic events, as evidenced by the CYTO-PV trial 1. The goal of phlebotomy in polycythemia vera is to maintain the hematocrit below 45% to minimize the risk of thrombosis. Key points to consider in the management of polycythemia vera include:
- The standard approach involves removing 300-500 mL of blood per session, typically 1-2 times weekly until the target hematocrit is achieved 1.
- Phlebotomy should be performed more cautiously in elderly patients or those with cardiovascular disease, removing smaller volumes (200-300 mL) per session 1.
- During the procedure, patients should be well-hydrated and monitored for hypotension or symptoms of hypovolemia, with replacement with normal saline as necessary in hemodynamically unstable patients.
- Long-term management often requires maintenance phlebotomies every 2-3 months based on hematocrit levels, with the aim of keeping the hematocrit below 45% to reduce the risk of thrombotic events, as supported by the European LeukemiaNet recommendations 1.
- Iron deficiency may develop with repeated phlebotomies, but supplementation is generally avoided as it can stimulate further erythropoiesis, unless there are symptoms of severe iron deficiency 1. The most recent and highest quality evidence from the CYTO-PV trial 1 and the European LeukemiaNet recommendations 1 supports the use of phlebotomy to maintain a hematocrit below 45% in patients with polycythemia vera to reduce the risk of thrombotic events.
From the Research
Indications for Phlebotomy in Polycythemia
- Phlebotomy is a therapeutic procedure used to reduce the risk of thrombosis in patients with polycythemia vera (PV) by lowering the hematocrit level to less than 45% 2, 3, 4, 5, 6.
- The goal of phlebotomy is to decrease blood viscosity and reduce the risk of thrombotic events, which are a major cause of morbidity and mortality in patients with PV 2, 3, 4.
- Phlebotomy is recommended for all patients with PV, regardless of their risk category, as it has been shown to improve overall survival and reduce the risk of thrombosis 4, 5, 6.
- The frequency of phlebotomy may vary depending on the individual patient's needs, with some patients requiring more frequent phlebotomies to maintain a hematocrit level below 45% 3.
- Phlebotomy is often used in combination with other therapies, such as low-dose aspirin and cytoreductive therapy, to manage PV and reduce the risk of thrombotic events 2, 5, 6.
Patient Selection for Phlebotomy
- Patients with PV who are at high risk of thrombosis, such as those aged 60 years or older or with a history of thrombosis, may benefit from more frequent phlebotomies and cytoreductive therapy 2, 5, 6.
- Patients with extreme thrombocytosis (platelet count >1000 × 10^9/L) may be at risk of acquired von Willebrand syndrome and bleeding, and should be screened for this condition before undergoing phlebotomy or receiving aspirin therapy 5, 6.
- Patients who are intolerant of or resistant to hydroxyurea may benefit from alternative cytoreductive therapies, such as interferon-α or busulfan, in addition to phlebotomy 5, 6.