Differentiation of iron deficiency and the anemia of chronic disease.

The predictive value positive of serum iron studies and erythrocyte indices in differentiating between iron deficiency anemia and the anemia of chronic disease (ACD) were determined in 82 hospitalized patients with an iron-binding saturation of 15 percent or less. Iron deficiency, determined by serum ferritin of 20 ng/mL or less, was present in only 31 percent of patients with a serum iron level of 10 micrograms/dL or less; 39 percent of patients with a transferrin saturation of 5 percent or less, and 54 percent of patients with a total iron-binding capacity (TIBC) of 350 micrograms/dL or greater; conversely, iron deficiency was present in only 3 percent of patients with a TIBC of 250 micrograms/dL or less. Iron deficiency was present in 83 percent of patients with a mean corpuscular volume (MCV) of 75 microns3 or less, but only 2 percent of patients with an MCV of 86 microns3 or greater. It is concluded that the MCV has strong predictive value positive (and negative) when below (or above) the values just cited, but that serum iron studies do not have sufficient predictive value to justify their use in the routine differentiation between iron deficiency anemia and the ACD in hospitalized patients when no other cause for anemia is likely.