A hematocrit (he-MAT-uh-krit) test measures the proportion of red blood cells in your blood. Red blood cells carry oxygen throughout your body. Having too few or too many red blood cells can be a sign of certain diseases.
The hematocrit test, also known as a packed-cell volume (PCV) test, is a simple blood test.
Why it's done
A hematocrit test is part of a complete blood count (CBC). Measuring the proportion of red blood cells in your blood can help your doctor make a diagnosis or monitor your response to a treatment.
A lower than normal hematocrit can indicate:
- An insufficient supply of healthy red blood cells (anemia)
- A large number of white blood cells due to long-term illness, infection or a white blood cell disorder such as leukemia or lymphoma
- Vitamin or mineral deficiencies
- Recent or long-term blood loss
A higher than normal hematocrit can indicate:
- A disorder, such as polycythemia vera, that causes your body to produce too many red blood cells
- Lung or heart disease
Results from your hematocrit test are reported as the percentage of blood cells that are red blood cells. Normal ranges vary substantially with race, age and sex. The definition of normal red-blood cell percentage also varies from one medical practice to another.
Generally, a normal range is considered to be:
- For men, 38.8 to 50 percent
- For women, 34.9 to 44.5 percent
For children ages 15 and younger, the normal range varies by age and sex.
Your hematocrit test provides just one piece of information about your health. Talk to your doctor about what your hematocrit test result means in light of the symptoms you're experiencing and the results of other diagnostic tests.