Association between Serum Ferritin and Cognitive Function in Early Childhood

In infants 1-3 years of age, we found higher serum ferritin values associated with higher cognitive function, as measured by the Mullen Scales of Early Learning (P = .02 for the nonlinear relationship). A serum ferritin of 17 μg/L corresponded to the maximum level of cognition, beyond which there was no meaningful improvement. TRIAL REGISTRATION: Clinicaltrials.gov NCT01481766 and NCT01869530.