What is the interpretation of erythrocytosis (elevated red blood cell count), elevated hemoglobin (Hb) level of 170 g/L, and hyperhematocrit (elevated hematocrit) of 0.513, according to Canadian laboratory values?

From the Guidelines

The patient's laboratory values (erythrocyte count of 5.65 x 10^12/L, hemoglobin of 170 g/L, and hematocrit of 0.513) indicate polycythemia, but do not meet the criteria for therapeutic phlebotomy as outlined in the acc/aha 2008 guidelines, which require a hemoglobin greater than 20 g/dL and hematocrit greater than 65% with associated symptoms of hyperviscosity 1. The provided laboratory values are elevated above the normal Canadian reference ranges, suggesting polycythemia.

• Erythrocyte count: 5.65 x 10^12/L (normal range: 4.2-5.4 x 10^12/L)
• Hemoglobin: 170 g/L (normal range: 135-165 g/L for men or 120-150 g/L for women)
• Hematocrit: 0.513 (normal range: 0.40-0.50 for men or 0.36-0.46 for women) This condition requires further investigation to determine whether it is primary polycythemia (polycythemia vera) or secondary polycythemia due to causes such as chronic hypoxia, smoking, or dehydration. Immediate management should include adequate hydration and avoidance of factors that could worsen blood viscosity. If these values persist, referral to a hematologist is recommended for additional testing, which may include JAK2 mutation analysis, erythropoietin levels, and bone marrow examination. Treatment will depend on the underlying cause but may include therapeutic phlebotomy to reduce blood viscosity and associated risks of thrombosis, but only if the patient meets the specific criteria outlined in the guidelines 1. It's also important to note that the European guideline on management of major bleeding and coagulopathy following trauma recommends a target haemoglobin of 70–90 g/L for erythrocyte transfusion 1, but this is not directly applicable to the management of polycythemia. The primary concern is to address the underlying cause of the polycythemia and manage the condition to prevent complications such as thrombosis and impaired tissue perfusion, while avoiding unnecessary interventions like repetitive phlebotomies that can lead to iron depletion 1.

From the Research

Interpreting Lab Values

To interpret the given lab values - erythrocyte 5.65, hemoglobin 170, and hematocrit 0.513 - according to Canadian lab values, we need to understand what each of these parameters represents and their normal ranges.

• Erythrocyte (or red blood cell) count is a measure of the number of red blood cells in the blood.
• Hemoglobin is a protein in red blood cells that carries oxygen to different parts of the body.
• Hematocrit is the proportion of blood volume made up by red blood cells.

Normal Ranges and Interpretation

• The normal range for erythrocyte count can vary by age and sex, but generally falls between 4.32 and 5.72 million cells per microliter for adult men and 3.90 to 5.03 million cells per microliter for adult women 2.
• For hemoglobin, normal ranges are approximately 135 to 175 grams per liter for adult men and 120 to 160 grams per liter for adult women 2.
• Hematocrit ranges are about 40.7% to 50.3% for adult men and 36.1% to 48.3% for adult women 2.

Given these values:

• An erythrocyte count of 5.65 million cells per microliter is within the normal range for adult men but slightly above the normal range for adult women.
• A hemoglobin level of 170 grams per liter is within the normal range for adult men but slightly above the normal range for adult women.
• A hematocrit of 0.513 (or 51.3%) is slightly above the normal range for both adult men and women.

Clinical Implications

These lab values could indicate erythrocytosis or polycythemia, conditions characterized by an increased concentration of red blood cells in the blood, which can be associated with various conditions including chronic kidney disease, hypoxia, or primary polycythemia vera 3, 4. It's essential to consider these values in the context of the patient's overall clinical picture, including symptoms, medical history, and other diagnostic findings.

Further Evaluation

Understanding the complete blood count (CBC) and its components is crucial for diagnosing and managing conditions related to blood cell abnormalities 5, 6. Further evaluation might include screening for the JAK2V617F somatic mutation if primary polycythemia vera is suspected, as well as assessing for other causes of erythrocytosis such as chronic kidney disease, lung disease, or the use of certain medications like sodium/glucose cotransporter 2 (SGLT2) inhibitors 3.