Since the corpuscular part of the blood is mostly made up of erythrocytes or red blood cells, the hematocrit can also be defined as the percentage ratio between red blood cells (erythrocytes) and the liquid part of the blood, called plasma.
When a blood sample is taken, it is sufficient to add an anticoagulant substance to the sample to assist in the progressive sedimentation of the corpuscular particles.
Then going to evaluate the ratio, in terms of percentage height, between the illustrated elements and the total volume of the blood, the value of the hematocrit is obtained.
To accelerate the sedimentation process, the test tube can be centrifuged, obtaining, thanks to the sedimenting action of the centrifugal force, a clear separation between the figured elements, which are deposited on the bottom of the test tube, and the straw yellow liquid above them (plasma) .
The number that expresses the percentage of cells massed on the bottom is called hematocrit.
This test is indicated as part of routine tests or when the doctor suspects that the patient has anemia (low hematocrit) or polycythemia (high hematocrit).
In addition, the hematocrit is useful for assessing the state of hydration.