In which disorder would an increased percent saturation of transferrin be expected?

• A. Hemochromatosis
• B. Iron-deficiency anemia
• C. Myocardial infarction
• D. Malignancy

Answer: (A)

Transferrin saturation reflects what fraction of transferrin’s iron-binding sites are occupied by iron. It’s calculated as serum iron divided by TIBC, multiplied by 100. When iron overload occurs, as in hereditary hemochromatosis, serum iron rises while TIBC may stay the same or drop modestly, so a larger share of transferrin is saturated with iron. This pushes transferrin saturation high, often well above the normal range. In iron-deficiency anemia, serum iron is low, so transferrin saturation is reduced. In myocardial infarction or malignancy, iron studies aren’t characterized by a consistently high transferrin saturation; inflammation can even lower serum iron and thus lower saturation. So the disorder that shows increased transferrin saturation is hemochromatosis.