Storage form of iron

Ref Robbins 9/e p650 The normal total body iron mass is about 2.5 g for women and 3.5 g for men. Approximately 80% of func- tional body iron is present in hemoglobin, with the remain- der being found in myoglobin and iron-containing enzymes (e.g., catalase, cytochromes). The iron storage pool, consist- ing of hemosiderin and ferritin-bound iron in the liver, spleen, bone marrow, and skeletal muscle, contains on average 15% to 20% of total body iron. Because serum fer- ritin is largely derived from this storage pool, the serum ferritin level is a good measure of iron stores. Assessment of bone marrow iron is another reliable but more invasive method for estimating iron stores. Iron is transpoed in the plasma bound to the protein transferrin. In normal persons, transferrin is about 33% saturated with iron, yielding serum iron levels that average 120 ug/dL in men and 100 ug/dL in women. Thus, the normal total iron-binding capacity of serum is 300 to 350 ug/dL.