Hematocrit Name _______________________ Date _______________Pd_______ A hematocrit is a blood test that measures the ratio of the volume of red blood cells to the total volume of blood. A blood sample is usually collected in a small capillary tube and spun down in a centrifuge so that the more dense erythrocytes settle at the bottom and the liquid plasma rises to the top. The leukocytes and thrombocytes form a whitish layer below the plasma. A hematocrit can also be run from a sample of blood taken from a vein. Then the length of the column is measured and calculations are performed to determine the % of red blood cells. Using what you know about blood composition, draw and label a normal hematocrit result on the test tube image below.