Hematocrit is a measure of how much space (volume) the red blood cells take up in the blood. A hematocrit check is often used to test for anemia, which is a decrease in the amount of oxygen-carrying substance (hemoglobin) found in red blood cells.

The hematocrit value may be given as a percentage of red blood cells in a volume of blood. For example, a hematocrit of 33 means that 33% of the blood's volume is composed of red cells. It may also be measured in millilitres per decilitre (mL/dL) of blood.

Current as of: October 9, 2017

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Brian O'Brien, MD, FRCPC - Internal Medicine & Adam Husney, MD - Family Medicine & Martin J. Gabica, MD - Family Medicine & Joseph F. O'Donnell, MD - Hematology, Oncology