Detecting iron deficiency in anemic patients with concomitant medical problems

To determine the sensitivity and specificity of mean corpuscular volume, transferrin saturation, total iron-binding capacity, and ferritin level in determining iron deficiency in a population of anemic veterans with a wide variety of general medical diagnoses.

Retrospective chart review.

Hospitals of the Department of Veterans Affairs in Madison and Milwaukee, Wisconsin.

One hundred one anemic veterans with any medical condition who underwent bone marrow aspiration and serum iron studies.

Using the presence or absence of bone marrow hemosiderin as the reference standard, the sensitivity and specificity of the following serum iron indicators were calculated: mean corpuscular volume, transferrin saturation, total iron-binding capacity, and ferritin level. Of these patients, 41 (40.6%) were categorized as iron deficient, with no stainable bone marrow hemosiderin. A serum ferritin level < or =100 microg/L provided the best sensitivity (64.9%) and specificity (96.1%) for evaluating iron stores in this patient population. When performed within 24 hours of bone marrow examination, a serum ferritin level < or =100 microg/L was 100% accurate in separating iron-deficient from iron-sufficient patients. None of the other serum iron indicators alone or in combination performed better than ferritin level alone.

In a population of anemic veterans with a wide variety of concomitant medical problems, a serum ferritin level < or =100 microg/L was optimal for determining iron deficiency. This is higher than the ferritin level of < or =50 microg/L cited in standard textbooks as evidence of iron deficiency in patients with inflammation, infection, or malignancy.