The presence of low ferritin reflects the lowering of iron reserves in the body, considering the existence of iron deficiency anemia or nutritional anemia, chronic blood loss or long-term diarrhea caused by iron absorption disorders, and the possibility of chronic liver disease. Ferritin is one of the main forms of iron stored in the body, with the ability to bind iron and reserve iron. Serum ferritin test is to check the level of ferritin in the blood, with a normal range of 12~150ug/L for women and 15~200ug/L for men. Insufficient iron intake or long-term drinking strong tea, chronic diarrhea caused by iron absorption obstacles can cause the body’s iron content can be reduced, manifested as a decline in serum ferritin, iron is one of the elements of the synthesis of hemoglobin, iron deficiency can be iron-deficiency anemia, nutritional anemia; in the presence of severe liver disease, ferritin production capacity decreases, ferritin can also be reduced. In the presence of severe liver disease, the ability to produce ferritin decreases, and ferritin can also be reduced. Long-term low ferritin needs to go to the hospital to further identify the cause of the cause of treatment.