What is the diagnosis and management for a patient with Hyperhemoglobinemia and Hyperhematocritemia?

Diagnosis and Management of Elevated Hemoglobin and Hematocrit

The patient's laboratory findings indicate secondary polycythemia (elevated hemoglobin and hematocrit with normal RBC count), which requires evaluation for underlying causes and management based on symptomatology and risk of hyperviscosity complications. 1

Interpretation of Laboratory Values

• Hemoglobin: 16.1 g/dL (High)
• Hematocrit: 48.4% (High)
• RBC count: 4.90 M/uL (Normal)
• Other indices (MCV, MCH, MCHC, RDW): Normal
• WBC and platelets: Normal

This pattern represents a true polycythemia rather than relative polycythemia, as the RBC count is within normal range while hemoglobin and hematocrit are elevated.

Diagnostic Approach

Step 1: Confirm True vs. Relative Polycythemia

• Evaluate for dehydration (the most common cause of relative polycythemia)
• Consider red cell mass measurement if diagnosis is unclear 1

Step 2: Evaluate for Secondary Causes

1. Cardiopulmonary disorders:

   • Check oxygen saturation
   • Screen for sleep apnea
   • Evaluate for congenital heart disease 1

2. Smoking status:

   • "Smoker's polycythemia" from chronic carbon monoxide exposure 1

3. Medication review:

   • Particularly testosterone/androgen therapy 1

4. High altitude exposure:

   • Adjust normal hemoglobin values based on altitude of residence 1

5. Laboratory testing:

   • Erythropoietin level (elevated in secondary polycythemia, low in polycythemia vera)
   • JAK2 mutation testing if primary polycythemia is suspected 1, 2
   • Consider bone marrow examination if myeloproliferative disorder is suspected 3

Management Recommendations

For Secondary Polycythemia:

1. Address underlying cause:

   • Smoking cessation if smoking-related
   • Treat sleep apnea if present
   • Adjust or discontinue testosterone/androgen therapy if medication-induced
   • Treat any underlying cardiopulmonary disease 1

2. Phlebotomy considerations:

   • Phlebotomy is indicated if hematocrit exceeds 54% or if patient is symptomatic with risk of hyperviscosity 1
   • Target hematocrit <45% to reduce risk of thrombotic events 1
   • For patients with hematocrit between 48-54%, phlebotomy should be considered if they have risk factors for vascular occlusion 4

3. Monitoring:

   • Regular follow-up with complete blood counts
   • Monitor for symptoms of hyperviscosity (headache, dizziness, visual disturbances)
   • Assess for thrombotic complications 1

For Polycythemia Vera (if diagnosed):

• Phlebotomy to maintain hematocrit <45%
• Consider cytoreductive therapy in high-risk patients 1
• Low-dose aspirin for thrombosis prevention

Important Considerations and Pitfalls

• Masked polycythemia: Some patients with underlying polycythemia vera may present with normal hemoglobin/hematocrit due to coincidental blood loss or hemodilution 3

• Thrombotic risk: Elevated hematocrit increases blood viscosity and risk of thrombotic events, particularly when >54% 1

• Idiopathic erythrocytosis: If no cause is identified despite thorough evaluation, consider genetic testing for rare mutations (SH2B3, EPOR) 5

• Avoid assuming dehydration: While relative polycythemia from reduced plasma volume is common, true polycythemia requires investigation of underlying causes 4

• Patients with PAH: These patients are particularly sensitive to hemoglobin changes - both anemia and erythrocytosis can be problematic. Consider phlebotomy if hematocrit exceeds 65% and patient is symptomatic 6

The patient's current values (Hb 16.1, Hct 48.4%) warrant investigation for underlying causes but do not require immediate phlebotomy unless the patient is symptomatic with hyperviscosity or has significant risk factors for thrombosis.