Screening for chronic iron overload diseases, particularly hereditary hemochromatosis. Serum iron, TIBC, and percent saturation are widely used for the diagnosis of iron deficiency. However, serum ferritin is a much more sensitive and reliable test for demonstration of iron deficiency.Total iron-binding capacity (TIBC) is most frequently used along with a serum iron test to evaluate people suspected of having either iron deficiency or iron overload. These two tests are used to calculate the transferrin saturation, a more useful indicator of iron status than just iron or TIBC alone. In healthy people, about 20-40% of available transferrin sites are used to transport iron.