HCT
Hematocrit is a blood test that measures how much of a person's blood is made up of red blood cells as opposed to plasma. This measurement depends on the number of and size of the red blood cells.
A blood sample is needed.
No special preparation is necessary for this test.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
The hematocrit is almost always done as part of a complete blood count (CBC).
Your health care provider may recommend this test if you have signs of or are at risk for anemia. These include having:
Normal results vary, but in general they are:
For babies, normal results are:
The examples above are common measurements for results of these tests. Normal value ranges vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
Low hematocrit may be due to:
High hematocrit may be due to:
Your hematocrit will increase for several weeks when you are in a higher altitude.
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Means RT Jr. Approach to the anemias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 144.
Thom CS, Lambert MP. Blood disorders. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 138.
Vajpayee N, Graham SS, Bem S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 31.
BACK TO TOPReview Date: 3/11/2024
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06/01/2025
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