Hematocrit
Disclaimer: Information on this page is for educational purposes. Consult a physician to interpret your test results. Lissa Health helps track biomarker trends but does not replace medical advice.
What This Test Measures
Hematocrit (Hct) measures the proportion of blood volume occupied by red blood cells, expressed as a percentage. It closely correlates with hemoglobin and RBC count.
This marker helps diagnose anemia, assess dehydration severity, and detect polycythemia. At equal hemoglobin levels, hematocrit may differ with micro- or macrocytosis.
Hematocrit is used to monitor RBC transfusions and hydration status in hospitalized patients.
Normal Ranges
| Group | Reference Range |
|---|---|
| Men | 40–50% |
| Women | 36–44% |
| Children | 32–44% (age-dependent) |
Reference ranges may vary by laboratory and assay method.
Causes of High Levels
- Dehydration
- Polycythemia vera
- Chronic hypoxia
- Diuretics and erythropoiesis stimulants
Causes of Low Levels
- All types of anemia
- Overhydration (excessive fluid administration)
- Pregnancy (physiologic hemodilution)
- Blood loss
Test Preparation
- Standard CBC preparation
- Maintain normal fluid intake
- Report pregnancy and recent blood transfusions
Related Biomarkers
| Biomarker | Relationship |
|---|---|
| Hemoglobin | Oxygen-carrying protein amount |
| Red Blood Cells | Red blood cell count |
| Mean Corpuscular Volume (MCV) | Red cell size affects hematocrit |
FAQ
How often should I take this test?
With CBC — annually or more often with chronic conditions.
What should I do if my result is abnormal?
Compare with hemoglobin and MCV. Sudden drops — rule out blood loss; elevation — assess hydration.
Last updated: June 2026