Hematocrit is medically known as hematocrit. High hematocrit may be caused by factors such as body physiological reactions, ischemic diseases and blood system diseases. 1. Body compensation: Commonly, long-term chronic hypoxia increases the concentration of hemopoietin in the body, and blood cells will increase compensatorily, which will result in high hematocrit. In addition, hypoxia in highland areas can also cause elevated hematocrit. 2. Loss of body fluids: When there is loss of body fluids such as diarrhea, extensive burns, and profuse sweating, the number of blood cells will relatively increase, which may lead to high hematocrit. 3. Blood system diseases: such as true erythrocytosis, there may be an abnormal increase in red blood cells, resulting in a high hematocrit. When a high hematocrit occurs, it is necessary to go to the hematology department of the hospital in time and be treated under the guidance of the doctor.