Hematocrit, the volume of blood cells in the peripheral blood as a percentage of blood volume, is 40%-50% for normal adult males and 37%-48% for adult females. Below the normal range, the hematocrit is low. In clinical practice, the most common cause of low hematocrit is a decrease in the number of red blood cells. The decrease in the number of red blood cells is common in all kinds of anemia, because in anemia, the decrease in the number of red blood cells and the decrease in the volume of red blood cells will result in a low erythropoietic pressure, most commonly in patients with iron deficiency anemia, due to iron deficiency, the red blood cells cannot adequately synthesize hemoglobin, resulting in a smaller red blood cell volume and a decrease in the average amount of hemoglobin in the red blood cells, which will result in a significantly low erythropoietic pressure. The situation. In addition, in patients with aplastic anemia, the number of red blood cells is significantly reduced due to the damage of bone marrow hematopoietic stem cells, which cannot proliferate and divide normally, which also causes a decrease in blood cell pressure.