Iron Studies (Serum Iron, TIBC, Ferritin): what it measures and how to prepare

What this test measures

Iron studies describe the body's iron stores and its capacity to transport iron. Serum iron is the iron circulating in the blood bound to the protein transferrin. TIBC (total iron-binding capacity) reflects how much transferrin is available, and it rises when iron stores are low. Transferrin saturation is calculated from serum iron and TIBC and shows how much iron is available for use. Ferritin is the main protein that stores iron inside cells, and its level in the blood is used as a marker of total body iron stores.

Commonly ordered for

Doctors commonly order iron studies when a complete blood count shows anaemia, to find out whether iron deficiency is the cause, and to check the response to iron supplements. They are also commonly ordered for women with heavy periods, people who follow a vegetarian or vegan diet, endurance athletes, pregnant women and frequent blood donors, and when iron overload is suspected. A doctor can advise whether this test is appropriate for you and how often to repeat it.