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: Newborns: 55-68% One (1) week of age: 47-65% One (1) month of age: 37-49% Three (3) months of age: 30-36% One (1) year of age: 29-41% Ten (10) years of age: 36-40% Adult males: 42-54% Adult women: 38-46% 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.

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1. Percentage of the volume of a blood sample occupied by cells. Cf.:plasmacrit. 2. Obsolete term for a centrifuge or device for separating the cells and other particulate elements of the blood from the plasma. [hemato- + G. krino, to separate]

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he·mat·o·crit or chiefly Brit hae·ma·to·crit hi-'mat-ə-krət, -.krit n

1) an instrument for determining usu. by centrifugation the relative amounts of plasma and corpuscles in blood

2) the percent of the volume of whole blood that is composed of red blood cells as determined by separation of red blood cells from the plasma usu. by centrifugation <a \hematocrit ranging from 42% to 52% in males and 35% to 47% in females is typically considered normal> called also packed cell volume

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he·mat·o·crit (Hct) (he-matґə-krit) [hemato- + Gr. krinein to separate] the proportion of the volume of a blood sample that is red blood cells (packed red blood cells), measured in mL per dL of whole blood or as a per cent.