A hematocrit (he-mat-uh-krit) test measures the proportion of red blood cells in the blood. red blood cells carry oxygen throughout the body. having too few or too many red blood cells can be a sign of certain diseases.
The hematocrit test, also known as the packed cell volume (PCV) test, is a simple blood test.
why is it 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 treatment.
A lower than normal hematocrit may 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 prolonged blood loss
- a disorder, such as polycythemia vera, that causes your body to make too many red blood cells
- lung or heart disease
- for men, 38.3 to 48.6 percent
- for women, 35.5 to 44.9 percent
- living at high altitudes
- significant recent blood loss
- recent blood transfusion
- severe dehydration
A higher than normal hematocrit may indicate:
how do you prepare
hematocrit is a simple blood test. You won’t need to fast before the test or make any other preparations.
what you can expect
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The blood sample is usually drawn with a needle from a vein in the arm. You may feel some tenderness at the site, but you will be able to resume normal activities afterward.
Your hematocrit test results are reported as the percentage of your blood volume made up of red blood cells. normal ranges vary substantially with race, age, and sex. the definition of normal percentage of red blood cells also varies from one medical practice to another.
A normal range is generally considered to be:
For children under 17, the normal range varies by age and gender.
Your hematocrit test provides only part of the information about your health. Talk to your doctor about what your hematocrit test result means in light of the symptoms you are experiencing and the results of other diagnostic tests.
accuracy of test results
A number of factors can affect the result of a hematocrit test and produce inaccurate or misleading results, including:
Your doctor will take into account possible complicating factors when interpreting the results of your hematocrit test. Your doctor may want to repeat the hematocrit test and perform other blood tests if the results give conflicting or unexpected information.