Hematocrit

The hematocrit (Ht or HCT) or packed cell volume (PCV) or erythrocyte volume fraction (EVF) is the percentage of blood volume that is occupied by red blood cells. It is normally about 45% for men and 40% for women. It is considered an integral part of a person's complete blood count results, along with hemoglobin concentration, white blood cell count, and platelet count.

In mammals, hematocrit is independent of body size.

The term "hematocrit" comes from the German/Swedish "haematokrit" coined by Blix at Upsala in 1891 as referenced by SG Hedin in Skandanavia Arch.f Physiolgie 2:134-140,1891 in an article entitled "The Haematokrit: a New Apparatus for the Investigation of Blood." The "Haematokrit" was modeled after the "Lactokrit" which was used in dairy farming. (See also: Scudder & Self in NEJM Oct 30, 1941 225:18 p.679 "Controlled Administration of Fluid in Surgery"