Final answer:
The hematocrit is the percentage of red blood cells in a volume of blood determined by centrifugation. It serves as a key diagnostic tool for assessing RBC mass and can indicate various health conditions.
Step-by-step explanation:
The percentage of red blood cells (RBCs) in a specific volume of blood determined by centrifugation of a microhematocrit tube filled with anticoagulated blood is commonly referred to as the hematocrit. The hematocrit test is used commonly in both human and veterinary medicine as an index of RBC mass. This test measures the volume percentage of erythrocytes in the blood after centrifugation, also known as packed cell volume (PCV). In healthy individuals, normal hematocrit values vary by sex, with females ranging from 37 to 47 and males from 42 to 52.
During the hematocrit test, a blood sample is spun in a centrifuge, which causes separation of the heavier erythrocytes from the lighter plasma. After centrifugation, erythrocytes settle at the bottom of the tube, and a thin layer called the buffy coat, composed of leukocytes and platelets, forms above the red cell layer, constituting less than 1 percent of the volume. The remainder above this is the plasma. Knowing the hematocrit percentage is crucial for diagnosing and monitoring various conditions, including anemia, polycythemia, and hydration status.