From the Guidelines
Your elevated red blood cell count, hemoglobin, and hematocrit levels do not necessitate therapeutic phlebotomy at this time, as they are below the threshold of hemoglobin greater than 20 g/dL and hematocrit greater than 65% recommended by the ACC/AHA guidelines 1. Your blood test results show that your white blood cell count is normal at 9.0 thousand/uL (reference range 3.8-10.8), indicating your immune system is functioning appropriately. However, your red blood cell count (5.46 million/uL), hemoglobin (16.2 g/dL), and hematocrit (48.5%) are all elevated above the normal ranges. These elevated values suggest a condition called erythrocytosis or polycythemia, which means you have an increased concentration of red blood cells in your blood. Some key points to consider:
- Your red blood cell indices (MCV, MCH, MCHC) are normal, indicating the red blood cells themselves are of normal size and contain normal amounts of hemoglobin.
- Elevated red blood cell parameters can sometimes indicate dehydration, living at high altitude, smoking, certain lung diseases, or potentially polycythemia vera (a bone marrow disorder) 1.
- The ACC/AHA guidelines recommend therapeutic phlebotomy only when hemoglobin is greater than 20 g/dL and hematocrit is greater than 65% with associated symptoms of hyperviscosity and no evidence of dehydration 1. You should consult with your healthcare provider about these results, as they may recommend additional tests such as arterial oxygen saturation, serum erythropoietin level, or possibly bone marrow examination to determine the underlying cause. Staying well-hydrated before future blood tests may help if dehydration is contributing to these results.
From the Research
Blood Test Results
- White blood cell count: 9.0 thousand/uL (normal range: 3.8-10.8 thousand/uL)
- Red blood cell count: 5.46 million/uL (high, normal range: 3.80-5.10 million/uL)
- Hemoglobin: 16.2 g/dL (high, normal range: 11.7-15.5 g/dL)
- Hematocrit: 48.5 % (high, normal range: 35.0-45.0 %)
- MCV: 88.8 fL (normal range: 80.0-100.0 fL)
- MCH: 29.7 pg (normal range: 27.0-33.0 pg)
- MCHC: 33.4
Possible Causes of High Red Blood Cell Count
- Polycythemia vera (PV), a myeloproliferative neoplasm that is associated with an elevated risk of thrombosis 2, 3
- Secondary polycythemias, caused by conditions resulting in increased EPO production 3
- Chronic hypoxia, which can develop a physiologically appropriate "secondary" polycythemia that improves oxygen carrying capacity 4
- Other non-hematological pathology, such as cardiopulmonary processes, drug-induced, or secondary to smoking 5
Diagnosis and Investigation
- Measurement of the erythropoietin level is a first step to explore for a cause of erythrocytosis 6
- A low erythropoietin level indicates a primary cause, and a normal or elevated level indicates a secondary etiology 6
- Further investigation is then dictated by initial findings and includes mutational testing with PCR and NGS for those in whom a congenital cause is suspected 6
- A systematic approach to the clinical and laboratory evaluation of each patient is indicated to consider diverse differential diagnosis possibilities and to identify the underlying etiology of erythrocytosis 5