Decreased total iron binding capacity 2020-10-12T12:01:40Z A reduction in the total-iron binding capacity, which measures how much serum iron is bound if an excess of radioactive iron is added. The latent (or free) iron binding capacity is the difference between the TIBC and the measured serum iron, corresponding to the transferrin not bound to iron, i.e., free iron binding capacity. Abnormal total iron binding capacity