Normal serum iron and elevated total iron-binding capacity in iron-deficiency states.

Five nonanemic patients with normal erythrocytic indexes were found to have normal serum iron, elevated total iron-binding capacity, normal percentage of saturation of transferrin, and depleted bone marrow iron stores. These findings suggest that during the development of iron deficiency, an elevation of total iron-binding capacity occurs before the decrease of the serum iron. This may represent a compensatory mechanism to mobilize all traces of tissue iron to maintain normal erythropoiesis.