Diagnostic Approach to Elevated Hemoglobin

Initial Evaluation

For males at sea level, hemoglobin levels greater than 16.5 g/dL warrant investigation, according to the American College of Physicians 1
For females at sea level, hemoglobin levels greater than 16.0 g/dL (using adjusted thresholds) require evaluation, as recommended by the American College of Physicians 2
Altitude adjustment is critical, as hemoglobin increases approximately 0.9 g/dL per 1000 meters above sea level, and failure to adjust leads to overdiagnosis of polycythemia, as noted by the American College of Physicians 2

A repeat complete blood count (CBC) using an automated cell counter is necessary to confirm elevation, as suggested by the National Kidney Foundation 3, 4
Hemoglobin is preferred over hematocrit as it remains stable at room temperature, whereas hematocrit can increase 2-4% with prolonged storage, according to the American College of Physicians 2
A full CBC with differential should be performed to evaluate all cell lines and look for isolated erythrocytosis versus pancytosis, which suggests polycythemia vera, as recommended by the American Society of Clinical Oncology 5

Serum erythropoietin level should be measured, as low or inappropriately normal levels suggest polycythemia vera, while elevated levels suggest secondary polycythemia, according to the American Society of Clinical Oncology 5
JAK2 V617F mutation testing should be performed, as the mutation is present in over 95% of polycythemia vera cases, as noted by the American Society of Clinical Oncology 5
Iron studies (ferritin, transferrin saturation) should be conducted, as iron deficiency must be corrected before accurate interpretation, as recommended by the American College of Physicians 2

The World Health Organization (WHO) diagnostic criteria for polycythemia vera include hemoglobin levels greater than the 99th percentile for age, sex, and altitude, and the presence of JAK2 mutation or other clonal marker, as defined by the WHO 5
Bone marrow biopsy may be needed if diagnosis remains unclear, as suggested by the American Society of Clinical Oncology 5

In patients with chronic kidney disease, elevated hemoglobin is unusual and requires investigation for polycystic kidney disease, as recommended by the National Kidney Foundation 6, 3
Patients on erythropoietin therapy should be monitored for blood pressure and target hemoglobin levels, as recommended by the National Kidney Foundation 6, 3