Low erythrocyte distribution width refers to the small average volume of red blood cells, which can be caused by physiological factors or pathological factors. 1. Physiological factors: common in infants and young children, strenuous exercise, etc., is a physiological low red blood cell distribution width, no other uncomfortable symptoms, can be without treatment. After a period of time, it can recover by itself. 2. Pathological factors: common in secondary anemia, iron granulocytic anemia, lead poisoning, carbon monoxide poisoning, iron deficiency anemia and so on. It can also be seen in small cell hypochromic anemia induced by long-term application of anticoagulant drugs. In addition, diseases such as dysglobulinemia, hereditary spherocytosis, and congenital pyruvate kinase deficiency can also lead to low erythrocyte distribution width. There are other causes of low erythrocyte distribution width, and it is recommended that patients seek timely medical treatment to avoid delaying their condition.