The erythrocyte distribution width is usually expressed as the coefficient of variation of the erythrocyte distribution width, with normal values ranging from 11% to 15%. Erythrocyte distribution width can be combined with an indicator of mean red blood cell volume to aid in the diagnosis and differential diagnosis of anemia. If the mean erythrocyte volume is normal and the erythrocyte distribution width is normal, it may be caused by acute blood loss anemia or aplastic anemia, leukemia, etc. If the erythrocyte distribution width is elevated, it may be seen in patients with early stage iron deficiency anemia or iron granulocytic anemia. In contrast, in patients with myelodysplastic syndromes, the width of the red blood cell distribution is usually normal, but the mean red blood cell volume is elevated. In macrocytic anemia, such as megaloblastic anemia, the mean red blood cell volume and the width of the red blood cell distribution are both elevated.