What is the best course of action for a patient with elevated hematocrit levels and a history of potential comorbidities such as cardiovascular disease or lung disease?

Management of Hemoglobin 16.3 g/dL and Hematocrit 47.6%

These values are within normal range and require no intervention—simply confirm the patient is adequately hydrated and repeat measurements if there are any clinical concerns. 1

Understanding These Values

Your hemoglobin of 16.3 g/dL and hematocrit of 47.6% fall within the normal physiological range for adult males and postmenopausal females (Hb 15.5 ± 2.0 g/dL, Hct 47 ± 6%). 1 These values do not meet criteria for erythrocytosis, which requires hemoglobin >18.5 g/dL in men or >16.5 g/dL in women, and hematocrit >55% in men or >49.5% in women. 1

When to Investigate Further

Diagnostic evaluation is only warranted when hemoglobin exceeds 18.5 g/dL in men (16.5 g/dL in women) or hematocrit exceeds 55% in men (49.5% in women). 1 At those thresholds, you would need to:

• Order complete blood count with red cell indices, reticulocyte count, serum ferritin, transferrin saturation, and C-reactive protein 1
• Test for JAK2 mutations (exon 14 and exon 12) to evaluate for polycythemia vera 1
• Assess for secondary causes including smoking history, sleep apnea, chronic lung disease, testosterone use, or altitude of residence 1

Critical Management Thresholds

Therapeutic phlebotomy is indicated only when hemoglobin exceeds 20 g/dL AND hematocrit exceeds 65%, with associated symptoms of hyperviscosity (headache, visual disturbances, poor concentration), after excluding dehydration. 1, 2 This patient is nowhere near these thresholds.

For confirmed polycythemia vera specifically, the target is stricter: maintain hematocrit strictly below 45% through phlebotomy to reduce thrombotic events from 9.8% to 2.7%. 2 However, this only applies to patients with documented JAK2 mutation and WHO diagnostic criteria for polycythemia vera. 1

Common Pitfalls to Avoid

• Do not perform phlebotomy on patients with normal or borderline elevated hematocrit values, as this causes iron depletion, decreased oxygen-carrying capacity, and paradoxically increases stroke risk. 3, 2
• Do not use standard erythrocytosis thresholds for patients living at high altitude without adjustment—physiologic adaptation can increase hemoglobin by 0.2-4.5 g/dL depending on elevation (1,000-4,500 meters). 1
• Hemoglobin is more reliable than hematocrit for monitoring because hematocrit can falsely increase by 2-4% with prolonged sample storage and is affected by hyperglycemia, while hemoglobin remains stable. 1

Monitoring Recommendations

For this patient with normal values, no specific monitoring is required beyond routine health maintenance. 1 If values were to trend upward on serial measurements over 6 months, then initiate the diagnostic workup described above. 1

In patients with cardiovascular disease or chronic kidney disease, avoid targeting hemoglobin >13 g/dL with erythropoietin therapy, as this increases mortality and cardiovascular events. 2 However, this patient's naturally occurring hemoglobin of 16.3 g/dL represents normal physiology and requires no intervention.