Hemoglobin (Hb), mean cell volume (MCV) and erythrocyte protoporphyrin (EP) tests are commonly used to screen for iron deficiency (ID) but systematic evaluation of their performance is limited.We evaluated the sensitivity and specificity of Hb, MCV and EP in predicting ID (defined as total body iron stores <0 mg/kg) in preschool children aged 3-5 years, non-pregnant women aged 15-49 years, and pregnant women.
Data from National Health and Nutrition Examination Surveys (NHANES) on children (2003-2006: n=861), non-pregnant women (2003-2006: n=3112), and pregnant women, (1999-2006: n=1150) were examined. Children or women with blood lead >10 µg/dL or C-reactive protein (CRP) >5.0 mg/dL were excluded. The receiver operating characteristic (ROC) area under the curve (AUC) was used to evaluate the performance of Hb, MCV and EP measurements in screening for ID.
In detecting ID in children 3-5 years, EP (AUC 0.80) was superior to Hb (AUC 0.62) [P<0.01] but not statistically different from MCV (AUC 0.73). In women, EP and Hb were comparable (non-pregnant AUC 0.86 and 0.84, respectively; pregnant 0.77 and 0.74, respectively) and both were better than MCV (non-pregnant AUC 0.80; pregnant 0.70) [P<0.01].
The performance of EP in screening for ID was superior or at least as effective as that of Hb and MCV in all groups. For children 3-5 years, EP screening for ID is better than Hb and similar to MCV. For both non-pregnant and pregnant women, the performance of EP and Hb are comparable and both are superior to MCV.