BONE MINERALIZATION IN PRETERM INFANTS FED HUMAN MILK

Abstract

Bone mineral status was assessed in 20 healthy, appropriately grown infants <1600g birthweight assigned randomly to one of 2 diets: 1. Preterm human milk (PT milk) pooled by postpartum week and fed corresponding to infants postnatal age, providing calcium 22-26 mg/dl, phosphorus 13-17 mg/dl. 2. Supplemented PT milk, an equal mixture of premature infant formula and PT milk providing calcium 72-74 mg/dl, phosphorus 37-38 mg/dl. All infants were fed by gavage at 180 ml/kg/day and received 400 IU Vitamin D daily. Infants fed PT milk had significantly lower serum phosphorus levels at 4 and 5 wk (4.6±0.4 and 4.1±0.4 mg/dl) than infants fed supplemented PT milk (6.1±0.2 and 6.0±0.2 mg/dl), p<.005. They also had significantly higher serum alkaline phosphatase levels at 4 and 5 wk (569±81 and 824±127 IU/1) than the supplemented group (340±40 and 347±49 IU/1), p<.02. The serum differences were reflected in lower bone mineral content (BMC) of humerus by photon densitometry at 5 wk (PT milk, .084±.005 vs supplemented PT milk .107±.007 g/cm, p<.05). At 35-37 postconceptual wk, infants in both groups were discharged on standard infant formula (calcium 51 mg/dl, phosphorus 39 mg/dl). At 44 postconceptual weeks, infants initially fed either PT milk or supplemented PT milk, had similar serum phosphorus (6.7±0.2 and 7.2±0.2 mg/dl) and alkaline phosphatase (301±33 and 285±23 IU/1; BMC in both groups (.252±.021 and .246±.014 g/cm) was comparable to that of healthy term infants (.223±.006). Preterm infants fed unsupplemented PT milk show bone demineralization. BMC increases significantly after routine formula feeding irrespective of PT milk supplementation.