Screening for Iron Deficiency in Early Childhood Using Serum Ferritin in the Primary Care Setting

OBJECTIVES: The American Academy of Pediatrics recommends universal screening for anemia using hemoglobin at 12 months. However, hemoglobin lacks diagnostic accuracy for iron deficiency, and the optimal age for screening has not been determined. Our objective was to assess a screening strategy for iron deficiency using serum ferritin. METHODS: We conducted a cross-sectional study of children 1 to 3 years old attending a health supervision visit. We examined the relationship between child age and serum ferritin, age and hemoglobin, hemoglobin and serum ferritin, and the prevalence of elevated C-reactive protein (CRP). RESULTS: Restricted cubic spline analysis (n = 1735) revealed a nonlinear relationship between age and serum ferritin (P < .0001). A linear spline model revealed that from 12 to 15 months, for each 1-month increase in age, serum ferritin levels decreased by 9% (95% confidence interval [CI]: 5 to 13). From 15 to 24 months, the rate of change was nonsignificant. From 24 to 38 months, for each month increase in age, serum ferritin increased by 2% (95% CI: 1 to 2). For hemoglobin, from 12 to 24 months, the rate of change was nonsignificant. From 24 to 38 months, for each 1-month increase in age, hemoglobin increased by 20% (95% CI: 9 to 32). Compared with the serum ferritin cutoff of <12 g/L, the hemoglobin cutoff of <110 g/L had a sensitivity of 25% (95% CI: 19 to 32) and a specificity of 89% (95% CI: 87 to 91). Elevated CRP >= 10 mg/L occurred in 3.3% (95% CI: 2.5 to 4.2). CONCLUSIONS: Screening for iron deficiency using serum ferritin at 15 or 18 months may be a promising strategy. For children at low risk for acute inflammation, concurrent measurement of CRP may not be necessary.