From the Guidelines
Therapeutic phlebotomy should be performed to maintain the hematocrit below 45% in patients with polycythemia vera, with an initial regimen of 300 to 450 ml of blood withdrawn weekly or twice weekly until the target is reached. This approach is based on the revised management recommendations from the European LeukemiaNet 1. The maintenance phase should involve the same amount of blood volume removed per phlebotomy as in the induction phase, with intervals determined by hematocrit levels.
Key considerations for therapeutic phlebotomy in polycythemia vera include:
- Initial phlebotomy regimen: 300 to 450 ml of blood withdrawn weekly or twice weekly until the hematocrit target is reached
- Maintenance phase: same amount of blood volume removed per phlebotomy as in the induction phase, with intervals determined by hematocrit levels
- Cytoreduction is recommended in high-risk cases, such as patients older than 60 years or those with a previous thrombotic event
- Iron supplementation is indicated in cases of documented severe tissue iron deficiency associated with detrimental symptoms
The goal of therapeutic phlebotomy is to reduce blood viscosity and the risk of thrombotic complications by decreasing red blood cell mass, as recommended by the European LeukemiaNet 1. Patients should be educated about maintaining adequate hydration, avoiding activities that could increase hematocrit, and recognizing symptoms that might indicate the need for additional phlebotomy. Concurrent cytoreductive therapy, such as hydroxyurea, may be necessary for high-risk patients or those requiring frequent phlebotomies, as suggested by the European LeukemiaNet guidelines 1.
From the Research
Therapeutic Phlebotomy Guidelines for Polycythemia Vera
Therapeutic phlebotomy is a crucial treatment for patients with polycythemia vera (PV), aiming to reduce the risk of thrombotic events by maintaining a hematocrit level below 45% 2. The following guidelines are based on available evidence:
- Hematocrit target: The goal hematocrit level is less than 45% 2, 3.
- Phlebotomy frequency: The frequency of phlebotomy varies among patients, with some requiring more than 5 phlebotomies per year in the maintenance phase 4.
- Indications for cytoreduction: Cytoreductive therapy may be considered for patients with worsening thrombocytosis, age > 60 years, or microvascular symptoms 4.
- Thrombosis risk: Patients with PV are at increased risk of thrombosis, with an incidence rate of 0.8% per year and an estimated probability of thrombosis at 10 years of 8.5% 4.
- Bleeding risk: Patients with PV may also be at risk of bleeding, especially those with acquired von Willebrand disease or extreme thrombocytosis 2.
Patient Management
Patient management involves a balance between preventing thrombotic complications and minimizing the risk of drug side effects and toxicity 5. The following considerations are important:
- Aspirin therapy: Low-dose aspirin is recommended for all patients with PV, unless contraindicated 2, 5.
- Cytoreductive therapy: Cytoreductive therapy, such as hydroxyurea or interferon, may be considered for patients at high risk of thrombosis or with persistent PV symptoms 2, 5.
- Phlebotomy burden: Therapeutic phlebotomies can be burdensome for patients, and reducing the need for frequent phlebotomies is an important consideration in PV management 6.
Ongoing Challenges
Despite advances in PV management, several challenges remain, including:
- Inflammatory symptoms: PV is often accompanied by inflammatory symptoms that negatively impact quality of life 6.
- Phlebotomy needs: Patients may require recurrent therapeutic phlebotomies, limiting their autonomy and contributing to quality-of-life decline 6.
- Cytoreductive therapy limitations: Standard first-line cytoreductive options have not been shown to significantly improve symptom burden, highlighting the need for newer therapies 6.