What is the recommended course of action for a patient with fluctuating CBC results, including elevated hemoglobin and hematocrit levels, and variable WBC count, over a long-term monitoring period?

Assessment of CBC Trends

Your CBC results show mildly elevated hemoglobin and hematocrit levels that have been intermittently present over several years, with all other parameters remaining within normal limits—this pattern suggests either relative polycythemia (dehydration, smoking) or early absolute polycythemia that warrants targeted evaluation rather than routine monitoring. 1

Key Findings Analysis

Your CBC demonstrates:

• Hemoglobin: Intermittently elevated (15.6-16.2 g/dL) with most recent value at 15.6 g/dL 1
• Hematocrit: Consistently elevated (45.6-49.7%) over multiple measurements 1
• WBC, platelets, and RBC indices: All within normal ranges with stable trends 1
• No concerning features: No blasts, no significant dysplasia suggested by normal MCV/MCH/MCHC, no cytopenias 1

Recommended Diagnostic Workup

Evaluate for secondary causes of polycythemia before assuming this is benign:

• Obtain erythropoietin (EPO) level to distinguish between primary and secondary polycythemia 2
• Assess for hypoxic conditions: pulse oximetry, consider sleep apnea screening if clinically indicated 2
• Review medication history that may affect CBC parameters, as this is a commonly overlooked cause of abnormalities 1
• Evaluate hydration status and smoking history, as these are the most common causes of relative polycythemia 3, 2

Follow-Up Monitoring Strategy

For stable, mildly abnormal results without concerning features, repeat CBC in 3 months to establish trend stability: 1, 4

• If values remain stable and secondary causes are excluded, extend monitoring intervals to every 6-12 months 4, 5
• If hemoglobin/hematocrit continues to rise or new cytopenias develop, repeat CBC within 2-4 weeks 4
• Do not continue frequent monitoring indefinitely—lengthen intervals once stability is established 4

When to Refer to Hematology

Hematology referral is indicated if: 1

• Hemoglobin rises above 18 g/dL (men) or 16 g/dL (women) 2
• Development of new cytopenias affecting any cell line 1
• Multiple cell line abnormalities suggesting bone marrow pathology 1
• Persistent unexplained elevations despite evaluation for secondary causes 1

Critical Pitfalls to Avoid

• Do not dismiss mildly elevated hemoglobin/hematocrit as "normal variation" without evaluating for treatable secondary causes like sleep apnea or smoking 1, 2
• Avoid ordering CBC too frequently once stability is documented—this is not cost-effective and does not improve outcomes 4, 6
• Remember that single abnormal values may represent laboratory variation or pre-analytical factors (sample handling, temperature effects)—trends over time are more meaningful than isolated values 7, 8
• If CBC worsens or remains abnormal over two or more measurements, proceed to bone marrow evaluation rather than continued CBC monitoring alone 4