From the Guidelines
Elevated hemoglobin levels above 20 g/dL with a hematocrit greater than 65% require therapeutic phlebotomy to alleviate symptoms of hyperviscosity, such as headache and fatigue, as recommended by the ACC/AHA 2008 guidelines 1. Elevated hemoglobin, also known as polycythemia, can be caused by various factors, including chronic hypoxemia in patients with cyanotic congenital heart disease. The increase in red blood cell mass is a compensatory response to improve oxygen transport, but it can lead to increased blood viscosity and symptoms such as headache and poor concentration.
- Key considerations for managing elevated hemoglobin include:
- Therapeutic phlebotomy is usually unnecessary unless the hemoglobin is more than 20 g/dL and the hematocrit is greater than 65% with associated symptoms of hyperviscosity and no evidence of dehydration 1.
- Repetitive phlebotomies should be avoided due to the risk of iron depletion, decreased oxygen-carrying capacity, and stroke 1.
- Iron deficiency, even in the face of erythrocytosis, is undesirable and requires careful management, including oral or intravenous iron supplementation, to maintain normal serum ferritin and transferrin saturation levels 1. The goal of treatment is to relieve hyperviscosity symptoms, improve coagulation, and prevent complications such as blood clots, stroke, and heart problems. Therapeutic phlebotomy should be performed with caution, removing 1 unit of blood and replacing it with an equal volume of dextrose or saline, to avoid dehydration and iron depletion 1.
From the Research
Elevated Hemoglobin and Polycythemia Vera
Elevated hemoglobin levels are a key characteristic of polycythemia vera (PV), a myeloproliferative neoplasm that increases the risk of thrombosis and other complications.
- The diagnosis of PV is based on erythrocytosis (hemoglobin >16.5 mg/dL in men or >16.0 mg/dL in women) and the presence of a JAK2 gene variant, which helps distinguish PV from secondary causes of erythrocytosis 2.
- Patients with PV may experience symptoms such as pruritus, erythromelalgia, transient visual changes, and splenomegaly with abdominal discomfort 2.
Treatment of Polycythemia Vera
The treatment of PV aims to reduce the risk of thrombosis and alleviate symptoms.
- Therapeutic phlebotomy is a key component of PV management, with the goal of maintaining a hematocrit level <45% 3, 4, 5, 2.
- Low-dose aspirin is also recommended for all patients with PV, unless contraindicated 2.
- Cytoreductive therapy with hydroxyurea or interferon may be beneficial for patients at high risk of thrombosis or with persistent PV symptoms 3, 4, 5, 2.
- The use of hydroxyurea has been shown to improve survival and reduce the risk of thrombosis in patients with PV, particularly when used in combination with phlebotomy 3, 4.
Risk of Thrombosis
The risk of thrombosis is a major concern in patients with PV.
- Phlebotomy and hydroxyurea have been shown to reduce the risk of thrombosis in patients with PV 3, 4, 5.
- The need for additional phlebotomies during hydroxyurea therapy may identify a subset of patients with increased proliferation of PV and a higher risk of thrombosis 5.
- Patients with PV who are at high risk of thrombosis, such as those aged 60 years or older or with a prior thrombosis, may benefit from cytoreductive therapy with hydroxyurea or interferon 2.