Low red blood cell and hemoglobin concentrations refer to red blood cell counts and hemoglobin concentrations below normal reference values, and this condition can be diagnosed as anemia. There are various clinical causes that can cause anemia, and the common causes are mainly as follows: 1. decreased erythropoiesis, commonly seen in malnutrition anemia, such as iron deficiency anemia, megaloblastic anemia, aplastic anemia; 2. anemia caused by increased destruction of red blood cells, commonly seen in autoimmune hemolytic anemia, thalassemia, sericosis, paroxysmal sleep hemoglobinuria; 3. anemia caused by blood loss It is common in acute blood loss caused by trauma and hemorrhage, and chronic blood loss caused by long-term blood in stool from hemorrhoids or excessive menstrual flow can also cause anemia. For the above causes and types of anemia, different drugs can be used to correct the anemia.