Low red blood cells, hemoglobin, and red blood cell pressure are indicative of anemia, because anemia is a lower than normal volume of red blood cells in the peripheral blood, often manifested as a low number of red blood cells, hemoglobin concentration, and red blood cell pressure. There are three clinical causes of anemia: the first is a decrease in red blood cell production, such as a decrease in red blood cell production caused by damage to bone marrow hematopoietic stem cells, such as aplastic anemia, and acute leukemia. In addition, anemia caused by the destruction of the bone marrow hematopoietic environment, such as metastatic cancer of the bone marrow and anemia caused by the lack of hematopoietic materials, the most common ones are iron deficiency anemia, megaloblastic anemia, etc. The second cause of erythrocyte reduction is the destruction of red blood cells, such as autoimmune hemolytic anemia, thalassemia, and sericobacteria. The third cause is the loss of red blood cells. Chronic blood loss caused by various reasons can cause red blood cell loss, resulting in low red blood cell count, hemoglobin concentration and red blood cell pressure.