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Definition
By Mayo Clinic staffHematocrit (he-MAT-uh-krit) is the proportion of your total blood volume that is composed of red blood cells. A hematocrit (Hct) test indicates whether you have too few or too many red blood cells — conditions that can occur as the result of certain diseases. Red blood cells, or erythrocytes (uh-RITH-ro-sites), transport oxygen throughout your body.
A hematocrit test is done using a sample of your blood. A lab technician puts the sample in a device called a centrifuge that spins the blood very quickly in a test tube. This motion separates your blood into three parts: the fluid component (plasma), red blood cells and other blood cells. When the blood is separated, the technician can determine what proportion of the cells are red blood cells. Hematocrit is also called packed-cell volume (PCV).
- Fischbach FT, et al. Blood studies: Hematology and coagulation. In: Fischbach FT, et al. A Manual of Laboratory and Diagnostic Tests. 7th ed. Philadelphia, Pa.: Wolters Kluwer Health Lippincott Williams & Wilkins; 2004. http://ovidsp.ovid.com/ovidweb.cgi?T=JS&NEWS=N&PAGE=booktext&D=books&AN=00140036/7th_Edition/11&XPATH=/OVIDBOOK%5b1%5d/METADATA%5b1%5d/TBY%5b1%5d/EDITORS%5b1%5d. Accessed Dec. 13, 2010.
- Hematocrit. Lab Tests Online. http://www.labtestsonline.org/understanding/analytes/hematocrit/test.html. Accessed Dec. 13, 2010.
- Vajpayee N, et al. Basic examination of blood and bone marrow. In: McPherson RA, et al. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/books/page.do?eid=4-u1.0-B1-4160-0287-1..50033-1--cesec2&isbn=1-4160-0287-1&sid=1095295726&type=bookPage§ionEid=4-u1.0-B1-4160-0287-1..50033-1--cesec23&uniqId=230035913-3#4-u1.0-B1-4160-0287-1..50033-1--cesec23. Accessed Dec. 13, 2010.
- Laboratory reference values. Hematocrit. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2010.
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