Abstract
BACKGROUND: Iron deficiency peaks in prevalence in early childhood and is associated with poor neurodevelopmental outcomes which may be irreversible. The American Academy of Pediatrics recommends universal screening for anemia with measurement of hemoglobin at 12 months of age. There are two limitations to this strategy. First, hemoglobin lacks sensitivity and specificity for iron deficiency. Second, the optimal age for screening has not been studied. Our objective was to examine a screening strategy using serum ferritin (SF) and to determine the relationship between child age and SF levels. OBJECTIVES: Our objective was to examine a screening strategy using serum ferritin (SF) and to determine the relationship between child age and SF levels. DESIGN/METHODS: Healthy children 12-36 months of age were recruited from a primary care research network. Blood samples for SF and C-reactive protein (CRP) were obtained during scheduled health supervision visits at 12, 15, 18, 24, or 36 months. We excluded children with CRP ≥10 mg/L. Restricted cubic spline (RCS) regression analysis was performed to test for a non-linear relationship between age and SF. Linear spline models were used to examine the rate of change between each age. Mean SF levels and the proportion of children with SF levels <12 µg/L were calculated for each age. RESULTS: 1470 children met eligibility and were included in the analysis; 48% were females. 28 children (2%) were excluded due to elevated CRP. The RCS regression analysis confirmed a U-shaped non-linear relationship between age and SF. SF was highest at 12 months, reached the lowest inflection point at approximately 20 months, and rose again to 36 months. The linear spline models showed that from 12-15 months, for each 1-month increase in age, SF decreased by 11.5% (p<0.0001); the rate of change was not significant from 15-18 months (p=0.3) or from 18-24 months (p=0.3); from 24 to 36 months, for each 1-month increase in age, SF increased by 1.95% (p<0.0001). At each age, the SF mean (± SD) and proportion with <12 µg/L were: