Iron is measured in several different ways in the blood. First, a serum iron assay measures how much actual circulating iron is in the bloodstream, and this form of iron is bound to a protein called transferrin. Usually, the range of normal is from 37-158 ug/dl. A second assay measures how much ferritin is in the blood; ferritin is the major protein complex that cells use to store iron. A normal ferritin range is usually 20-400 ug/L. A third way to test for iron deficiency is by calculating the total-iron binding capacity (TIBC); this test looks at the blood's ability to use the transferrin protein to bind up circulating iron. A high TIBC signifies a low-iron state, whereas a low TIBC argues against iron deficiency.
Typically a person has low iron levels either because dietary intake of iron is low, or if iron is lost by the body (in other words, by blood loss). Menstruating women are at risk of iron-deficiency anemia
if they have particularly heavy or prolonged menstrual cycles. The other major form of blood loss is through the gastrointestinal tract. Gastrointestinal bleeding
from such sources as stomach ulcers or colon cancer can present with subtle bleeding and cause iron-deficiency anemia, which is why it is very important to make sure you are evaluated by your physician and that your cancer screening
is up-to-date. Once the cause of your iron-deficiency is established, you can start oral supplementation with iron pills to bring up your levels.