What is the management for a patient with erythrocytosis, characterized by elevated haemoglobin (Hb) and haematocrit (Hct) levels, and a slightly elevated Red Blood Cell (RBC) count?

Management of Erythrocytosis

Phlebotomy is indicated for this patient with erythrocytosis (haemoglobin 163 g/L, haematocrit 0.50 L/L) if symptoms of hyperviscosity are present, but routine phlebotomies should be avoided due to risk of iron depletion and stroke. 1

Diagnostic Approach

Before initiating treatment, it's essential to determine the underlying cause of erythrocytosis:

1. Primary vs. Secondary Erythrocytosis:

   • Primary: Consider Polycythemia Vera (PV)
     • Check serum erythropoietin (EPO) level (low in PV) 1
     • Consider bone marrow examination with JAK2 mutation testing
   • Secondary: Consider causes of tissue hypoxia
     • Cardiopulmonary disease
     • High altitude
     • Smoking
     • Sleep apnea
     • Right-to-left cardiac shunts 1

2. Laboratory Evaluation:

   • Complete blood count with peripheral smear
   • Serum ferritin (to assess iron stores)
   • Renal and liver function tests
   • Arterial blood gas analysis (if hypoxemia suspected)

Treatment Algorithm

1. Symptomatic Patients

If patient has symptoms of hyperviscosity (headache, dizziness, visual disturbances, poor concentration):

• Therapeutic phlebotomy is indicated when:

  • Haemoglobin >20 g/dL OR
  • Haematocrit >65% 1

• Phlebotomy procedure:

  • Remove 1 unit of blood (approximately 450-500 mL)
  • Always replace with equal volume of saline 1
  • Monitor for hemodynamic changes
  • Target hematocrit <45-50%

2. Asymptomatic Patients

For this patient with Hb 163 g/L and Hct 0.50 L/L without symptoms:

• Conservative management is appropriate
• Regular monitoring of CBC every 3-6 months
• Avoid dehydration
• Consider underlying causes and treat accordingly

3. Special Considerations

• Avoid routine repeated phlebotomies as they can lead to:

  • Iron deficiency
  • Decreased oxygen-carrying capacity
  • Increased risk of stroke 1
  • Production of microcytic RBCs with reduced deformability

• Erythrocytapheresis may be considered in selected cases as it:

  • Allows for fewer hemodynamic changes compared to phlebotomy
  • Returns valuable blood components
  • May reduce the number of procedures required 1

Adjunctive Measures

1. Hydration: Maintain adequate hydration to reduce blood viscosity

2. Anticoagulation: Consider in high-risk patients with additional thrombotic risk factors

3. Lifestyle modifications:

   • Smoking cessation
   • Regular physical activity
   • Avoiding prolonged immobility

Monitoring

• Regular CBC monitoring (every 3-6 months)
• Monitor iron status to avoid iron deficiency
• Assess for symptoms of hyperviscosity
• Evaluate for complications (thrombosis, bleeding)

Pitfalls and Caveats

1. Avoid aggressive phlebotomy in asymptomatic patients with only modest elevations in Hb/Hct as seen in this case (Hb 163 g/L, Hct 0.50 L/L) 1

2. Iron deficiency from repeated phlebotomies can lead to microcytic RBCs with reduced deformability, potentially increasing thrombotic risk despite lower Hct 1

3. Dehydration can artificially elevate Hb/Hct values - ensure patient is well-hydrated before diagnostic evaluation

4. Differential diagnosis must include both primary and secondary causes of erythrocytosis, as management differs significantly 1

5. Consider referral to a hematologist if diagnosis is unclear or if patient has severe or symptomatic erythrocytosis

The current patient's values (Hb 163 g/L, Hct 0.50 L/L) are only modestly elevated and would not warrant immediate phlebotomy unless symptomatic. Focus should be on identifying and treating the underlying cause while monitoring for progression or development of symptoms.