From the Guidelines
Elevated hematocrit is primarily caused by conditions that either increase red blood cell production or decrease plasma volume, with common causes including polycythemia vera, chronic hypoxic conditions, and certain medications. The causes of elevated hematocrit can be categorized into several groups, including:
- Conditions that increase red blood cell production, such as polycythemia vera, a bone marrow disorder causing excessive red blood cell production, as discussed in 1
- Chronic hypoxic conditions like COPD, sleep apnea, and high-altitude living, where the body produces more red blood cells to compensate for reduced oxygen, as mentioned in 1
- Certain medications, including testosterone and erythropoietin, which can stimulate erythropoiesis, as noted in 1
- Rare genetic mutations affecting oxygen sensing, such as Chuvash polycythemia, as described in 1
- Other causes, including certain kidney diseases, liver conditions like hepatocellular carcinoma, and inappropriate erythropoietin production by tumors, as listed in 1 It is essential to identify and address the underlying cause of elevated hematocrit, as it can increase blood viscosity and raise the risk of clotting, potentially leading to serious complications like stroke or heart attack if left untreated, as warned in 1. Treatment options may include hydration for dehydration, phlebotomy for polycythemia vera, oxygen therapy for hypoxic conditions, or medication adjustments, as suggested in the context of managing elevated hematocrit levels. In clinical practice, it is crucial to consider the potential risks and consequences of elevated hematocrit, particularly in patients with underlying conditions that may be exacerbated by increased blood viscosity, as highlighted in 1.
From the Research
Causes of Elevated Hematocrit
Elevated hematocrit can be caused by several factors, including:
- Polycythemia vera (PV), a myeloproliferative neoplasm characterized by clonal erythrocytosis 2, 3, 4
- Abnormal red blood cell aggregation, which can lead to increased blood viscosity and impaired capillary blood flow 2
- Dehydration, which can cause a relative increase in hematocrit due to decreased plasma volume
- Other conditions that affect red blood cell production or destruction, such as chronic hypoxia or hemolysis
Relationship Between Hematocrit and Thrombosis
A high hematocrit is a major risk factor for thrombosis, as it can lead to increased blood viscosity and impaired blood flow 2, 4. This can result in a range of thrombotic complications, including:
- Arterial thrombosis, such as stroke or myocardial infarction
- Venous thrombosis, such as deep vein thrombosis or pulmonary embolism
- Microcirculatory symptoms, such as erythromelalgia or visual disturbances
Management of Elevated Hematocrit
The management of elevated hematocrit depends on the underlying cause, but may include:
- Phlebotomy, which can help to reduce hematocrit and prevent thrombotic complications 3, 4, 5, 6
- Cytoreductive therapy, such as hydroxyurea or interferon-alpha, which can help to reduce red blood cell production and prevent thrombosis 3, 4, 5, 6
- Aspirin therapy, which can help to prevent thrombotic complications in patients with PV or other myeloproliferative neoplasms 4