An evaluation of red blood cell heterogeneity (increased red blood cell distribution width) in iron deficiency of pregnancy.

A new classification of anemias, which is based on mean corpuscular volume and quantitative anisocytosis (red blood cell distribution width), was evaluated in 331 pregnant women on initial presentation for prenatal care. Seventy-four of them had severe iron depletion (serum ferritin level less than or equal to 10 ng/dl). Contrary to the above classification, early iron deficiency without anemia was infrequently identified by an increase in distribution width (4 of 25 patients). The distribution width was not consistently increased in the 49 anemic, iron-deficient patients; 34 were normal and would have been considered to have thalassemia minor or anemia of chronic disease according to the new classification. The distribution width was no more sensitive than the mean corpuscular volume in suggesting iron deficiency. This study does not confirm the usefulness of the new classification in the diagnosis of iron deficiency in this patient population.