From the Guidelines
A workup for high hemoglobin should begin with confirming the elevation with repeat testing and determining whether it's primary or secondary, considering factors such as altitude, age, race, and smoking history, as these can influence the interpretation of normal hemoglobin ranges 1. The initial evaluation should include a complete blood count with differential, comprehensive metabolic panel, erythropoietin level, and arterial blood gas analysis.
- For suspected polycythemia vera (primary erythrocytosis), JAK2 mutation testing should be performed.
- Secondary causes to investigate include:
- Hypoxemia (check oxygen saturation, pulmonary function tests)
- Sleep apnea (consider sleep study)
- Smoking history
- High altitude exposure
- Certain medications or hormonal disorders Abdominal ultrasound may be indicated to evaluate for renal or hepatic pathology.
- Bone marrow biopsy might be necessary if primary bone marrow disorder is suspected. Treatment depends on the underlying cause - addressing secondary factors when identified, while primary polycythemia vera typically requires phlebotomy to maintain hematocrit below 45%, possibly with cytoreductive therapy like hydroxyurea in high-risk patients 1. This comprehensive approach is important because elevated hemoglobin can increase blood viscosity and thrombotic risk, potentially leading to serious cardiovascular complications if left untreated. It's also crucial to consider the patient's quality of life and morbidity when managing high hemoglobin levels, as partial correction of anemia has been shown to improve quality of life and reduce the risk of left ventricular hypertrophy and mortality 1.
From the Research
Work-up for High Hemoglobin
- High hemoglobin levels can be indicative of polycythemia vera (PV), a myeloproliferative neoplasm characterized by erythrocytosis 2
- The current treatment of PV is directed towards reducing the risk of additional thrombotic events, with a focus on reducing hemoglobin levels through phlebotomy and cytoreductive therapy 3
- The goal of therapy is to prevent thrombosis, with periodic phlebotomy and aspirin therapy being the cornerstone of treatment in all patients, regardless of risk category 2
Diagnostic Criteria
- A working diagnosis of PV is considered in the presence of a JAK2 mutation associated with hemoglobin/hematocrit levels of >16.5 g/dL/49% in men or 16 g/dL/48% in women 2
- Morphologic confirmation by bone marrow examination is advised but not mandated 2
Treatment Options
- Phlebotomy is a key component of treatment, with a hematocrit target of <45% 2, 4
- Cytoreductive therapy is reserved for high-risk disease, with first-line drugs of choice being hydroxyurea and pegylated interferon-α, and second-line busulfan and ruxolitinib 2
- The need for additional phlebotomies during hydroxyurea therapy can identify a subset of patients with increased proliferation of PV and higher risk of thrombosis 5