Causes and Treatment of Elevated Hemoglobin
The most important first step is to distinguish true polycythemia (elevated red blood cell mass) from pseudopolycythemia (hemoconcentration from dehydration), as the causes and treatments differ fundamentally—true polycythemia requires investigation for primary bone marrow disorders or secondary causes like hypoxia, while pseudopolycythemia resolves with rehydration.
Understanding the Distinction
The provided evidence focuses primarily on methemoglobinemia (a qualitative hemoglobin disorder) rather than elevated hemoglobin concentration. However, I can address your question using general medical knowledge combined with relevant insights from the evidence:
Causes of Elevated Hemoglobin
Primary Causes (Bone Marrow Disorders):
- Polycythemia vera—a myeloproliferative disorder causing autonomous red blood cell production
- Other myeloproliferative neoplasms
Secondary Causes (Appropriate Response):
- Chronic hypoxia: Chronic obstructive pulmonary disease, sleep apnea, high altitude exposure 1
- Renal disorders: Renal cell carcinoma or renal artery stenosis causing inappropriate erythropoietin production
- Cardiac disease: Cyanotic heart disease with right-to-left shunting
- High altitude adaptation: Prolonged exposure stimulates erythropoietin and increases hemoglobin mass by up to 13% 1
Relative Polycythemia (Pseudopolycythemia):
- Dehydration/hemoconcentration: The most common cause of transiently elevated hemoglobin 1
- Volume depletion from any cause (diuretics, poor fluid intake, vomiting, diarrhea)
- At high altitude, initial hemoconcentration from dehydration can cause hemoglobin to reach 131% of baseline before true erythropoiesis occurs 1
Treatment Approach
Step 1: Determine if True or Relative Polycythemia
For suspected hemoconcentration:
- Rehydrate with intravenous or oral fluids
- Recheck hemoglobin after adequate hydration—if it normalizes, no further workup needed 1
For confirmed true polycythemia:
- Measure erythropoietin levels to distinguish primary from secondary causes
- Low/normal erythropoietin suggests polycythemia vera
- Elevated erythropoietin suggests secondary polycythemia
Step 2: Address Underlying Cause
For secondary polycythemia:
- Treat hypoxia: Optimize lung disease management, initiate CPAP for sleep apnea, provide supplemental oxygen
- Address renal causes: Imaging for renal masses, evaluate for renovascular disease
- Manage cardiac disease: Cardiology referral for structural heart disease
For polycythemia vera:
- Phlebotomy to maintain hematocrit <45% in men, <42% in women
- Low-dose aspirin for thrombosis prevention
- Cytoreductive therapy (hydroxyurea) for high-risk patients
- Hematology referral for definitive management
Step 3: Monitor for Complications
Key complications to prevent:
- Thrombosis risk: Elevated hemoglobin increases blood viscosity and thrombotic events
- Hyperviscosity symptoms: Headache, dizziness, visual disturbances, pruritus after bathing
- Cardiovascular events: Stroke, myocardial infarction, deep vein thrombosis
Critical Pitfalls to Avoid
- Don't assume dehydration without confirming: Always recheck after hydration before extensive workup
- Don't overlook sleep apnea: A common and treatable cause of secondary polycythemia
- Don't delay phlebotomy in symptomatic patients: Hyperviscosity can cause acute thrombotic events
- Don't confuse with methemoglobinemia: Methemoglobinemia causes functional anemia despite normal hemoglobin concentration and presents with cyanosis unresponsive to oxygen 2
The evidence regarding hemoglobin M variants and hereditary methemoglobinemia 3 describes conditions where abnormal hemoglobin structure exists but does not typically cause elevated hemoglobin concentration—rather, these cause cyanosis with normal or low hemoglobin levels. In methemoglobinemia associated with hemoglobin disorders, phlebotomy is specifically not recommended as higher erythrocyte mass allows provision of normal tissue oxygenation 3.