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HCT Hematocrit, Ht


Hematocrit is a measure of the portion of blood occupied by cells (red blood cells, white blood cells and platelets). A hematocrit of 0.40 L/L (litre of cells per litre of blood) indicates that 40% of the blood volume is composed of cells, with plasma making up the other 60%.

Since red blood cells normally make up about 98% of blood cells, a measurement of hematocrit, which is included in a complete blood count, provides essentially the same information as a red blood cell count (see that section) or hemoglobin levels when testing for anemia or polyglobulia (abnormally high red blood cell count). Hematocrit is also a function of the size of the red blood cells (see section on MCV). If red blood cell size decreases, hematocrit decreases and vice versa.

Term of the Week

Predictive medicine

Medicine that links medical knowledge with data to predict a patient’s potential health problems. Examples include artificial intelligence and genetics.