Essential mineral. Iron's major function is to combine with protein and copper in making hemoglobin. Prevents anemia: as a constituent of hemoglobin, transports oxygen throughout the body. Virtually all of the oxygen used by cells in the life process are brought to the cells by the hemoglobin of red blood cells. Iron is a small but most vital, component of the hemoglobin in 20,000 billion red blood cells, of which 115 million are formed every minute. Serum iron may be increased in hemolytic, megaloblastic, and aplastic anemias, and in hemochromatosis, acute leukemia, lead poisoning, pyridoxine deficiency, thalassemia, excessive iron therapy, and after repeated transfusions. Drugs causing increased serum iron include chloramphenicol, cisplatin, estrogens (including oral contraceptives), ethanol, iron dextran, and methotrexate. Iron can be decreased in iron deficiency anemia, acute and chronic infections, carcinoma, nephrotic syndrome, hypothyroidism, in protein- calorie malnutrition, and after surgery. The iron assay is one of the less reliable tests on screening panels, so any abnormalities should be followed with other inquiry concerning iron metabolism (history of blood loss, alcohol consumption, lab tests for TIBC, ferritin, etc) before undertaking therapeutic interventions. A deficiency of iron may result in general weakness, paleness of skin, constipation, and/or anemia