Hematocrit: The proportion of the blood that consists of packed red blood cells. The hematocrit is expressed as a percentage by volume. The red cells are packed by centrifugation.
For example, an hematocrit of 25% means that there are 25 milliliters of red blood cells in 100 milliliters of blood. The red cells make up a quarter of the blood.
The normal ranges for the hematocrit are dependant on the age and, after adolescence, the sex of the individual. The normal ranges for the hematocrit are:
These values may vary slightly between laboratories.
The term "hematocrit" was coined in 1903 and comes from the Greek roots hemat-, blood + krites, judge = to judge or gauge the blood. The abbreviation for hematocrit is hct. In medical slang the hematocrit is called the crit.