What does it mean to have elevated hemoglobin and hematocrit levels in a CBC (Complete Blood Count) test?

From the Guidelines

Elevated hemoglobin and hematocrit levels in a CBC test indicate a condition called polycythemia, which means you have an increased concentration of red blood cells in your blood, and according to the most recent guidelines, therapeutic phlebotomy is recommended for hemoglobin greater than 20 g per dL and hematocrit greater than 65%, associated with headache, increasing fatigue, or other symptoms of hyperviscosity in the absence of dehydration or anemia 1. Normal hemoglobin ranges are typically 13.5-17.5 g/dL for men and 12.0-15.5 g/dL for women, while normal hematocrit ranges are 41-50% for men and 36-48% for women. Some key points to consider:

• Elevations can be relative (due to dehydration) or absolute (true increase in red cell production)
• Common causes include dehydration, living at high altitude, smoking, certain lung diseases, heart conditions, or blood disorders like polycythemia vera
• If your levels are elevated, it's essential to stay well-hydrated and follow up with your doctor, who may recommend additional testing such as EPO levels or JAK2 mutation testing to determine the underlying cause
• Treatment depends on the cause and may include phlebotomy (blood removal), medication, or addressing underlying conditions
• Elevated levels can increase blood viscosity and potentially lead to blood clots, so proper diagnosis and management are essential, as stated in the guidelines 1. It's also important to note that repetitive phlebotomies can deplete iron stores and may result in production of iron-deficient red blood cells, which is undesirable because of the reduced oxygen-carrying capacity and deformability of red blood cells (microcytes) and increased risk of stroke 1. In the context of your CBC results, with a hemoglobin level of 16.2 g/dL and a hematocrit level of 51.9%, it's crucial to consult with your doctor to determine the best course of action, as these values are above the normal range, and may require further evaluation and management, as suggested by the studies 1.

From the Research

Elevated Hemoglobin and Hematocrit Levels

Elevated hemoglobin and hematocrit levels in a CBC test can be indicative of several conditions, including:

• Polycythemia vera (PV), a myeloproliferative neoplasm characterized by clonal erythrocytosis 2, 3, 4, 5
• Reactive forms of polycythemia, resulting from chronic hypoxemia 6
• Physiologic forms of polycythemia, found in highlanders and athletes training at high altitude 6

Diagnostic Criteria

The World Health Organization's major diagnostic criteria for PV include:

• Elevated hemoglobin or hematocrit level 4, 5
• Abnormal results on bone marrow biopsy 4, 5
• Presence of the Janus kinase 2 genetic mutation, which is present in approximately 98% of cases 4

Clinical Implications

Elevated hemoglobin and hematocrit levels can increase the risk of thrombosis, which is a major complication of PV 3, 4, 5. The goal of therapy is to prevent thrombosis, and treatment options include:

• Periodic phlebotomy to reduce hematocrit levels 4, 5
• Aspirin therapy to reduce the risk of thrombosis 4, 5
• Cytoreductive therapy, such as hydroxyurea, to reduce the risk of thrombosis and progression to myelofibrosis or acute myeloid leukemia 4, 5

Risk Stratification

Patients with PV can be stratified into high-risk and low-risk categories based on factors such as age, leukocytosis, abnormal karyotype, and the presence of adverse mutations 5. High-risk patients require more aggressive treatment to reduce the risk of thrombosis and progression to myelofibrosis or acute myeloid leukemia.