Using ferritin levels to determine iron-deficiency anemia in pregnancy.

BACKGROUND

Standard obstetrical practice has included iron therapy for patients with anemia without requiring the determination of iron deficiency. However, the proportion of pregnant women with anemia who have such a deficiency may be relatively modest. We instituted a practice protocol using serum ferritin levels to determine the proportion of women undergoing prenatal care who had both anemia and iron deficiency.

METHODS

We evaluated consecutive women entering prenatal care. Those with anemia (hemoglobin level <11 mg/dL) underwent testing for serum ferritin level and other hematologic variables.

RESULTS

A total of 182 patients entered prenatal care. Hemoglobin data were available for 173 (95%). Thirty-eight (22%) had anemia (hemoglobin level <11 mg/dL); 1 of those women was excluded from the study. Using a ferritin level of 12 mg per dL as the cutoff for iron deficiency, 54% (20) of the 37 remaining patients with anemia had an iron deficiency, and 46% (17) had anemia not related to such a deficiency. Use of hematologic indices provided on complete blood count were not useful in predicting iron deficiency based on serum ferritin levels.

CONCLUSIONS

In our population of prenatal patients with anemia, only approximately half had an iron deficiency. Diagnostic and therapeutic approaches to screening for anemia in pregnancy should be reconsidered and further evaluated.