There are several ways to classify anemia: 1. Based on cell dosimetry, anemia can be classified as macrocytic anemia, normocytic anemia, and microcytic hypochromic anemia. The average red blood cell volume >100fl is macrocytic anemia, 80-100fl is normocytic anemia, and less than 80fl is microcytic hypochromic anemia. 2. According to the severity classification, anemia can be divided into mild, moderate, severe and very severe anemia, with hemoglobin >90g/L but below normal value as mild anemia, 60-89g/L as moderate anemia, 30-59g/L as severe anemia, and hemoglobin >90g/L but below normal value as mild anemia, 60-89g/L as moderate anemia, and 30-59g/L as severe anemia. L is severe anemia, and hemoglobin below 30g/L is very severe anemia.3. Based on the etiology and pathogenesis, anemia can be divided into three types: decreased erythropoiesis, increased erythrocyte destruction and blood loss.