Iron is an essential raw material for the synthesis of hemoglobin, which is one of the common trace elements in the human body. Hemoglobin is the raw material for the synthesis of hemoglobin and myoglobin, and is also essential for promoting the metabolism of b-vitamins. The iron bound to ferritin in the blood is serum iron. Under normal conditions, divalent iron entering the blood from the small intestine is oxidized to trivalent in the blood, and the trivalent iron is bound to plasma ferritin and transported to the bone marrow and other tissues that require iron to be used. If serum iron is decreased, it is common in patients with iron deficiency anemia and requires iron supplementation. Increased serum serum iron is common in chronic hemolytic anemia, hemochromatosis, etc.