Anemia is a syndrome in which the volume of red blood cells, or hemoglobin, in the blood falls below the lower limit of the normal range. The development of anemia may be related to certain factors that lead to a decrease in erythropoiesis, such as abnormal hematopoietic cell function, abnormal hematopoietic regulation, insufficient hematopoietic raw materials, and certain diseases that lead to excessive destruction of erythrocytes, such as Mediterranean anemia, hereditary spherocytosis, and so on. 1. Anemia caused by decreased erythropoiesis: patients with hematopoietic cell function abnormalities such as aplastic anemia, myelodysplastic syndromes, and multiple myeloma and other hematological disorders will develop anemia during the course of the disease, and such patients usually need to further improve the diagnosis by bone marrow aspiration + biopsy. In addition, patients lacking certain hematopoietic raw materials such as iron, folic acid and vitamin B₁₂ may develop iron deficiency anemia and megaloblastic anemia, and the hemoglobin content of such patients will gradually return to normal after supplementation of the corresponding elements. 2. Anemia caused by excessive destruction of red blood cells: patients with various hemolytic anemias such as thalassemia, hereditary spherocytosis and autoimmune hemolytic anemia will have anemia due to excessive destruction of red blood cells, and such patients may need hormone therapy (prednisone), splenectomy and hematopoietic stem cell transplantation. 3. Trauma, bleeding disease patients due to excessive blood loss will also appear anemia, such patients actively stop bleeding, blood transfusion hemoglobin content will gradually rise to the normal range. Warm reminder: different types of anemia have different treatment options, anemia patients should be clear about the cause of anemia under the guidance of a physician to receive treatment.