Elevated Hemoglobin in a Patient with History of Chronic Anemia
This patient requires immediate phlebotomy to reduce hemoglobin to safe levels, with a target hemoglobin <15 g/dL in men or <14 g/dL in women, followed by urgent investigation for the underlying cause of this paradoxical elevation. 1
Immediate Management
Perform therapeutic phlebotomy as first-line treatment to reduce viscosity and thrombotic risk, removing 250-500 mL initially. 1 Each 400 mL unit removed will decrease hemoglobin by approximately 1.5 g/dL. 1 This is critical because hemoglobin of 20 g/dL creates significant hyperviscosity and dramatically increases risk of thrombotic complications including stroke, myocardial infarction, and venous thromboembolism.
- Initiate continuous cardiac monitoring during phlebotomy 2
- Target hemoglobin <15 g/dL in men, <14 g/dL in women 1
- Consider low-dose aspirin (81-100 mg daily) to reduce thrombotic risk unless contraindicated 1
Diagnostic Workup
The paradoxical finding of elevated hemoglobin in someone with chronic anemia history demands investigation for:
Primary Polycythemia
- Order JAK2 V617F mutation testing immediately to rule out polycythemia vera, the most concerning cause requiring specific management 1
- Obtain complete blood count with differential to assess other cell lines for myeloproliferative features 1
Secondary Causes of Erythrocytosis
Evaluate systematically for conditions causing compensatory erythrocytosis 1:
- Chronic hypoxemia: Obtain arterial blood gas, pulse oximetry, chest X-ray for COPD, interstitial lung disease 1
- Sleep apnea: Screen with sleep study if clinically indicated 1
- Smoking history: Document pack-years and current status 1
- Renal disease: Check serum creatinine, renal ultrasound for masses or cysts that may produce erythropoietin 1
- Medication review: Immediately discontinue any erythropoiesis-stimulating agents (ESAs) such as epoetin alfa or darbepoetin alfa as these worsen erythrocytosis and are absolutely contraindicated 1
Special Consideration: Methemoglobinemia
If the patient has hereditary methemoglobinemia with compensatory polycythemia, phlebotomy is NOT recommended as the higher erythrocyte mass allows normal tissue oxygenation. 1 However, this would not explain a history of "chronic anemia" unless previous measurements were artifactually low.
Critical Pitfalls to Avoid
Do not assume laboratory error without confirmation. While a hemoglobin of 20 g/dL in someone with documented chronic anemia seems contradictory, repeat the test immediately but proceed with management assuming accuracy until proven otherwise. The thrombotic risk is too high to delay.
Never use ESAs in this setting. If the patient was previously on ESAs for their anemia, these must be stopped immediately as they are contraindicated with elevated hemoglobin and will worsen the condition. 1
Do not overlook secondary causes. Even if polycythemia vera is confirmed, address contributing factors like smoking cessation or CPAP for sleep apnea, as these improve outcomes independently. 1
Monitoring Strategy
- Check hemoglobin daily until stable below target 2
- Monitor for signs of thrombosis (neurologic changes, chest pain, leg swelling) 1
- If polycythemia vera confirmed, maintain hematocrit <45% long-term 1
The key clinical question is whether this represents true polycythemia vera (requiring lifelong management), secondary erythrocytosis (potentially reversible), or measurement/documentation error. The immediate priority is reducing thrombotic risk through phlebotomy while the diagnostic workup proceeds.