What is the management for elevated hemoglobin (Hb) and hematocrit (Hct) levels?

Management of Elevated Hemoglobin and Hematocrit

Therapeutic phlebotomy is the first-line treatment for patients with elevated hemoglobin (Hb) and hematocrit (Hct) levels, with the goal of maintaining hematocrit below 45% to reduce thrombotic risk. 1

Diagnostic Approach

• Elevated Hb/Hct should be confirmed with repeated measurements, as a single value may not accurately reflect the patient's true status 2
• Evaluate for potential causes:
  • Primary polycythemia (polycythemia vera)
  • Secondary polycythemia (hypoxic conditions, high altitude, smoking, sleep apnea)
  • Relative polycythemia (dehydration, stress polycythemia) 3
• Assess for symptoms of hyperviscosity:
  • Headache, dizziness, visual disturbances
  • Fatigue, pruritus (especially after warm baths)
  • Erythromelalgia (burning pain in extremities) 1

Initial Management

• For asymptomatic patients with mildly elevated Hb/Hct, identify and address underlying causes:
  • Smoking cessation
  • Treatment of sleep apnea
  • Adequate hydration 3
• For symptomatic patients or those with significantly elevated values (Hct >50-55%):
  • Therapeutic phlebotomy to maintain Hct <45% 1
  • Low-dose aspirin (100 mg daily) unless contraindicated to reduce thrombotic risk 1

Phlebotomy Protocol

• Remove 250-500 mL of blood per session
• Initial frequency depends on severity:
  • For Hct >55%: Twice weekly until target achieved
  • For Hct 50-55%: Weekly until target achieved 1
• Monitor Hb/Hct levels every 1-2 weeks during initial treatment 2
• Once target is achieved, adjust frequency to maintain Hct <45% (typically every 2-3 months) 1

Risk Stratification

• High-risk patients requiring more aggressive management:
  • Age ≥60 years
  • History of prior thrombosis
  • Poor tolerance of phlebotomy
  • Symptomatic or progressive splenomegaly
  • Severe disease-related symptoms
  • Platelet count >1,500 × 10^9/L
  • Progressive leukocytosis 1

Cytoreductive Therapy

• Consider cytoreductive therapy for high-risk patients or those requiring frequent phlebotomy
• First-line options include:
  • Hydroxyurea (starting at 15-20 mg/kg/day)
  • Interferon alfa
  • Pegylated interferon 1, 4
• Hydroxyurea should be used with caution in younger patients (<40 years) due to potential long-term risks 1

Special Considerations

Iron Deficiency

• Repeated phlebotomy can lead to iron deficiency
• Cautious iron supplementation may be considered in symptomatic iron-deficient patients, but requires close monitoring as it may increase red cell production 1
• Monitor for symptoms of iron deficiency (fatigue, restless legs, pica)

Methemoglobinemia

• In patients with elevated Hb/Hct due to methemoglobinemia:
  • Identify and remove precipitating factors 2
  • For symptomatic patients, methylene blue (1-2 mg/kg) is first-line treatment 2
  • Ascorbic acid can be added as adjunctive therapy 2

Eisenmenger Syndrome

• For patients with Eisenmenger physiology and elevated Hb/Hct:
  • Therapeutic phlebotomy has very limited role and should only be performed if Hb >20 g/dL and Hct >65% with associated symptoms of hyperviscosity 2
  • Avoid iron deficiency anemia as iron-deficient red blood cells have less oxygen-carrying capacity 2

Monitoring Response

• Complete response is defined as:
  • Hct <45% without phlebotomy
  • Platelet count <400 × 10^9/L
  • WBC count <10 × 10^9/L
  • Resolution of disease-related symptoms 1
• Monitor Hb/Hct every 1-2 weeks after initiation of treatment or dose adjustment 2
• Once stable, monitoring can be extended to every 1-3 months 2

Complications and Cautions

• Avoid dehydration which can worsen hyperviscosity 3
• Monitor for thrombotic events (both arterial and venous)
• In patients receiving hydroxyurea, monitor for myelosuppression with regular complete blood counts 4
• For patients with testosterone deficiency receiving testosterone therapy, monitor Hb/Hct closely as testosterone can increase red cell production 2