From the Guidelines
Elevated hemoglobin (Hgb), hematocrit (Hct), and red blood cell (RBC) count require immediate medical attention to rule out polycythemia, a condition that can increase the risk of blood clots, stroke, and heart problems. The management of adults with congenital heart disease, as outlined in the acc/aha 2008 guidelines 1, suggests that therapeutic phlebotomy is indicated for hemoglobin greater than 20 g per dL and hematocrit greater than 65%, associated with symptoms of hyperviscosity. Key points to consider include:
- Symptoms such as headache, increasing fatigue, or other signs of hyperviscosity in the absence of dehydration or anemia
- Initial evaluation to determine if the elevated values are due to primary polycythemia (polycythemia vera) or secondary polycythemia caused by factors like dehydration, high altitude, smoking, lung diseases, or sleep apnea
- Importance of proper diagnosis to guide treatment, which may involve phlebotomy, aspirin, and medications like hydroxyurea for polycythemia vera, or addressing the underlying cause in secondary polycythemia
- The need for patients to avoid self-treatment and seek medical care to prevent complications associated with increased blood viscosity.
From the Research
High Hemoglobin, Hematocrit, and Red Blood Cell Count
- Elevated levels of hemoglobin (Hgb), hematocrit (Hct), and red blood cell (RBC) count can be indicative of polycythemia vera (PV), a myeloproliferative neoplasm characterized by an increased red blood cell mass and increased risk of thrombosis 2.
- PV is almost universally associated with a JAK2 gene variant, which helps distinguish it from secondary causes of erythrocytosis, such as tobacco smoking or sleep apnea 2.
- Patients with PV may experience symptoms such as pruritus, erythromelalgia, transient visual changes, and splenomegaly with abdominal discomfort 2.
Diagnosis and Treatment
- 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 2.
- Treatment of PV typically involves therapeutic phlebotomy to maintain a hematocrit of less than 45% and low-dose aspirin to reduce the risk of thrombosis 2, 3.
- Cytoreductive therapy with hydroxyurea or interferon may be recommended for patients at high risk of thrombosis, such as those aged 60 years or older or with a prior thrombosis 2, 3.
Risk of Thrombosis
- The risk of thrombosis is increased in patients with PV, particularly those with a history of thrombosis or aged 60 years or older 2, 3.
- Phlebotomy requirement under hydroxyurea therapy can identify a subset of patients with increased proliferation of PV and higher risk of thrombosis 4.
- Patients with PV who are resistant or intolerant to hydroxyurea may require alternative treatments, such as interferon, ruxolitinib, or busulfan 5, 6.