Plasma ferritin (ft), transferrin receptors (tffi) and log tfr/ft ratio as indices of iron deficiency in infants randomized to formulas with 1.5, 3, 7 or 12 mg iron/l

To determine the most sensitive index of iron deficiency in infants, a subset of samples was taken from a study of 267 Caucasian term infants recruited from Hamilton hospitals and randomized to standard term formulas containing 1.5, 3, 7 or 12 mg iron/L fed from birth to 12 mo with solid foods fed after 4 mo. Heel prick blood samples at 6 (n=76), 9 (n=78) and 12 (n=59) mo were analyzed for plasma Ft (RIA, Biorad, CAN), plasma TfR (ELISA, Ramco, …