High erythrocyte volume refers to the volume of red blood cells is higher than the normal range. The average volume of normal red blood cells is 80-100fl, and greater than 100fl is high erythrocyte volume. In clinical practice, high erythrocyte volume is commonly found in two conditions: 1. Most commonly in megaloblastic anemia, due to folic acid or vitamin B12 deficiency, the nuclei of erythrocytes are impaired in proliferation and division and cannot proliferate and divide normally, resulting in an increase in nuclei volume, leading to an increase in the entire volume of erythrocytes and the appearance of macrocytic anemia. 2. Commonly in hemolytic diseases, due to hemolytic diseases easily The lack of folic acid in the body can also cause impairment of nucleus proliferation and division, resulting in a large red blood cell volume. Therefore, large erythrocyte volume is common in megaloblastic anemia and hemolytic anemia, and the concentration of folic acid and serum vitamin B12 should be checked.