Low standard deviation of red blood cell distribution width indicates that red blood cell production capacity is reduced, red blood cell volume is more homogeneous, and there may be thalassemia, iron deficiency anemia and other conditions. 1. Thalassemia: Thalassemia is due to genetic defects leading to the synthesis of bead protein peptide chain disorder, the patient will have microcytic hypochromic anemia, due to insufficient synthesis of hemoglobin, the volume of red blood cells are reduced, and show a uniform reduction, which will be the case of low standard deviation of erythrocyte distribution width. For mild thalassemia, no special treatment is needed; for moderate or severe thalassemia, regular blood transfusion treatment or hematopoietic stem cell transplantation is recommended. 2. Iron deficiency anemia: at this time, the volume of red blood cells shrinks and small red blood cells appear, which is manifested as microcytic hypochromic anemia, and the patients may have reduced red blood cells and hemoglobin while the distribution width of red blood cells is low. You can eat some animal offal, spinach and other foods with high iron content; you can also take iron supplements, such as ferrous sulfate oral solution, under the guidance of the doctor. The standard deviation of red blood cell distribution width is low, a single indicator can not diagnose the disease, need to be combined with other test results to make a comprehensive judgment, it is recommended to consult a doctor in a timely manner, and follow the doctor’s instructions for examination and treatment.