Hematocrit (EVF) – Red Blood Cell Volume Test
Hematocrit, also called erythrocyte volume fraction (EVF), tells you what proportion of your blood consists of red blood cells. It is a fast and reliable way to check for anemia or polycythemia and is always included in a complete blood count. Changes in hematocrit can reflect dehydration, blood loss, or bone marrow disorders.
Why Test Hematocrit?
Testing hematocrit helps detect anemia, polycythemia, and dehydration. It is routinely ordered alongside hemoglobin and red blood cell counts to give a complete picture of blood health. It is especially useful before surgery, during pregnancy, or when investigating unexplained fatigue.
What Do High Hematocrit Levels Mean?
High hematocrit may result from dehydration, smoking, lung disease, living at high altitude, or polycythemia vera. Thicker blood increases the risk of blood clots, strokes, and cardiovascular complications.
What Do Low Hematocrit Levels Mean?
Low hematocrit combined with low hemoglobin and red blood cells indicates anemia. Common causes include iron deficiency, B12 or folate deficiency, chronic disease, blood loss, and bone marrow disorders.
Symptoms to Watch For
- Fatigue and weakness
- Pale or yellowish skin
- Shortness of breath
- Dizziness or lightheadedness
- Cold extremities
- Chest pain or irregular heartbeat
Who Should Get Tested?
- Anyone with symptoms of anemia or polycythemia
- Patients undergoing pre-surgical evaluation
- Pregnant women
- People with chronic lung or heart disease
- Those experiencing unexplained dehydration symptoms
How to Prepare for Your Test
No special preparation is needed. Bring valid ID.
Frequently Asked Questions
What is a normal hematocrit level?
Can dehydration affect hematocrit?
Is hematocrit the same as hemoglobin?
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Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
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The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.