Management of Elevated Hemoglobin, Hematocrit, and RBC Counts
The primary treatment for elevated hemoglobin, hematocrit, and RBC counts depends on the underlying cause, with phlebotomy being the cornerstone therapy for polycythemia vera and therapeutic phlebotomy to maintain hematocrit below 45% for most secondary polycythemias. 1
Diagnostic Approach
First, determine whether the elevation represents true polycythemia or relative polycythemia:
True polycythemia: Increased red cell mass
- Primary: Polycythemia vera (PV)
- Secondary: Appropriate (hypoxia-driven) or inappropriate (EPO-producing tumors)
Relative polycythemia: Normal red cell mass with decreased plasma volume (dehydration, stress polycythemia)
Key Diagnostic Tests:
- Complete blood count with RBC indices
- JAK2 mutation testing (V617F or exon 12)
- Serum erythropoietin level
- Arterial oxygen saturation
- Abdominal ultrasound (for splenomegaly)
Treatment Algorithm
1. Polycythemia Vera
PV diagnosis requires both major criteria or the first major criterion plus at least two minor criteria 1:
Major criteria:
- Elevated hemoglobin (>16.5 g/dL in men, >16 g/dL in women) or hematocrit (>49% in men, >48% in women)
- Presence of JAK2 mutation
Minor criteria:
- Bone marrow hypercellularity
- Low serum erythropoietin
- Endogenous erythroid colony formation
Treatment:
- Therapeutic phlebotomy: Target hematocrit <45% to reduce thrombotic risk
- Cytoreductive therapy: For high-risk patients (age >60 years or history of thrombosis)
- Hydroxyurea (first-line)
- Interferon alfa-2b (for younger patients or pregnancy)
- Ruxolitinib (for hydroxyurea resistance/intolerance)
- Low-dose aspirin: 81-100 mg daily (unless contraindicated)
2. Secondary Polycythemia
Treatment based on underlying cause:
Hypoxia-driven (COPD, sleep apnea, high altitude, smoking):
- Treat underlying condition
- Phlebotomy if symptomatic or hematocrit >54%
- Oxygen therapy for hypoxemia
EPO-producing tumors (renal cell carcinoma, hepatocellular carcinoma):
- Surgical removal of tumor
- Phlebotomy for symptom management
Congenital disorders (high-oxygen affinity hemoglobinopathies):
- Phlebotomy only if symptomatic
3. Relative Polycythemia
- Rehydration
- Address underlying causes (stress, smoking, diuretics)
- Lifestyle modifications
Special Considerations
Cyanotic Congenital Heart Disease
In patients with cyanotic congenital heart disease, secondary erythrocytosis is a compensatory mechanism 1:
- Do not perform phlebotomy unless symptomatic hyperviscosity is present
- Iron supplementation may be needed if iron-deficient
- Avoid causing microcytic hypochromic red cells, which are less deformable and reduce oxygen delivery
Methemoglobinemia with Polycythemia
For patients who develop polycythemia due to methemoglobinemia 1:
- Phlebotomy is not recommended as higher erythrocyte mass allows normal tissue oxygenation
- Avoid methylene blue and ascorbic acid as they are ineffective in hemoglobin disorders
Monitoring and Follow-up
- Monitor complete blood count every 3-4 months
- For PV patients:
- Check JAK2 allele burden annually
- Monitor for progression to myelofibrosis or leukemia
- Assess for thrombotic complications
Common Pitfalls to Avoid
Missing masked PV: Some patients with JAK2-positive PV may present with normal hemoglobin/hematocrit due to concurrent iron deficiency or blood loss 2
Overdiagnosis: The 2016 WHO criteria lowered hemoglobin thresholds, which overlap with normal values in 6.48% of men and 0.28% of women 3
Aggressive phlebotomy in cyanotic heart disease can worsen tissue hypoxia
Failure to investigate unusual site thrombosis (portal, splenic, hepatic veins) for underlying myeloproliferative disorders, even with normal blood counts
By following this structured approach to elevated hemoglobin and hematocrit, clinicians can effectively diagnose and manage patients while avoiding common pitfalls that could lead to suboptimal outcomes.