Hematocrit (HCT) represents the percentage of your blood volume made up of red blood cells. Typical reference ranges are about 41–53% for men and 36–46% for women. Low hematocrit usually tracks with anemia, while high hematocrit may reflect dehydration, high-altitude adaptation, chronic hypoxia, or true polycythemia. Because hematocrit is influenced by plasma volume, hydration can shift it meaningfully. For that reason, it is most useful when interpreted together with hemoglobin and RBC count