Low mean red blood cell volume may be caused by chronic liver and kidney diseases, iron deficiency anemia, thalassemia and other diseases. 1. Chronic Liver and Kidney Diseases: Chronic kidney disease may also cause low mean red blood cell volume. The main reason is that various toxins affect the bone marrow hematopoietic system, and generally chronic kidney disease will be combined with malnutrition, resulting in anemia caused by decreased hematopoietic function, which leads to low red blood cell volume. 2. Iron deficiency anemia: Iron absorption and excretion imbalance in the body, leading to a decrease in the body’s iron content, resulting in iron deficiency anemia. Patients can generally show symptoms such as pale skin, dizziness and shortness of breath. 3. Thalassemia: Thalassemia, i.e. anemia with impaired production of beads, is generally due to the absence of the gene for the bead protein chain of hemoglobin, which leads to the low average volume of red blood cells. It is recommended that the patient undergo further examination to analyze the specific reasons for the low average volume of red blood cells, and definitively treat the disease under the guidance of the doctor.