What is the diagnosis and treatment for a patient with elevated RBC, HGB, HCT, and BASOS percentages on CBC?

Diagnosis and Management of Elevated Hemoglobin, Hematocrit, and Basophil Percentage

The patient's CBC shows a pattern consistent with polycythemia vera (PV), which requires JAK2 mutation testing and referral to hematology for confirmation and management with therapeutic phlebotomy to maintain hematocrit below 45%. 1

Interpretation of Abnormal CBC Values

The patient presents with multiple abnormal values:

• Elevated RBC (6.20 x10^6/μL)
• Elevated hemoglobin (18.3 g/dL)
• Elevated hematocrit (55.1%)
• Elevated basophil percentage (1.2%)
• Normal WBC, platelets, and other parameters

This constellation of findings strongly suggests a myeloproliferative disorder, most likely polycythemia vera, rather than secondary polycythemia.

Diagnostic Approach

Initial Assessment

1. Confirm true polycythemia: The elevated hemoglobin and hematocrit should be confirmed with repeat testing to ensure they represent true polycythemia rather than relative polycythemia from dehydration 1

2. Essential diagnostic tests:

   • JAK2 V617F mutation testing (positive in >95% of PV cases)
   • Serum erythropoietin level (typically low in PV)
   • Iron studies (ferritin, transferrin saturation)
   • Arterial blood gas analysis to rule out hypoxemia
   • Abdominal ultrasound to assess for splenomegaly

3. Rule out secondary causes:

   • Chronic hypoxic conditions (COPD, sleep apnea)
   • Smoking history
   • High altitude residence
   • Renal or hepatic tumors producing erythropoietin

Differential Diagnosis

1. Polycythemia vera: Most likely given the elevated RBC, hemoglobin, hematocrit, and basophil percentage. The elevated basophil count is particularly suggestive of a myeloproliferative neoplasm. 1, 2

2. Secondary polycythemia: Less likely given normal oxygen saturation (presumed) and elevated basophils, but should be excluded.

3. Relative polycythemia (Gaisböck syndrome): Possible if patient is dehydrated, but the elevated basophil percentage makes a primary myeloproliferative disorder more likely.

Management Recommendations

Immediate Management

1. Therapeutic phlebotomy: If diagnosis of PV is confirmed, initiate phlebotomy to reduce hematocrit to <45% in men and <42% in women to reduce thrombotic risk. 1

2. Hydration: Ensure adequate hydration and recheck CBC after hydration to rule out relative polycythemia.

Risk Stratification

1. Low risk: Age <60 years with no history of thrombosis
2. High risk: Age ≥60 years or history of thrombosis

Long-term Management

1. For all patients:

   • Therapeutic phlebotomy to maintain hematocrit <45%
   • Low-dose aspirin (81-100 mg daily) to reduce thrombotic risk
   • Aggressive management of cardiovascular risk factors

2. For high-risk patients or those requiring frequent phlebotomy (>5/year):

   • Consider cytoreductive therapy:
     • Hydroxyurea (first-line for older patients)
     • Interferon-α (preferred for younger patients and pregnant women)
     • Ruxolitinib (for those intolerant to hydroxyurea)

3. Monitoring:

   • CBC every 3-6 months
   • Assessment for symptoms of hyperviscosity
   • Monitoring for disease progression

Important Considerations

• Thrombotic risk: Elevated hematocrit significantly increases risk of arterial and venous thrombosis, which is the primary cause of morbidity and mortality in PV.

• Avoid iron supplementation: Unless documented iron deficiency is causing symptoms, iron supplementation can worsen polycythemia.

• Disease progression: Monitor for progression to myelofibrosis or acute leukemia, which occurs in a subset of patients with PV.

• Prognosis: With appropriate treatment, life expectancy can extend beyond 10 years, compared to 6-18 months if untreated. 2

Follow-up

• Hematology consultation is strongly recommended for confirmation of diagnosis and management planning.
• Regular monitoring of CBC, symptoms, and complications is essential.
• Patient education regarding symptoms of hyperviscosity and thrombosis is critical.