Background and aim: Very premature newborns have an increased risk of low bone mass and metabolic bone disease. Most longitudinal studies report a significant decline in bone strength in the first weeks after birth. The aim of the study was to evaluate whether higher early calcium (Ca) and phosphorus (P) intake delivered by parenteral nutrition (PN) can prevent bone strength decline in preterm infants, within the first weeks after birth.
Patients and methods: This was a randomized controlled trial of consecutively admitted neonates born with ≤ 33 weeks of gestational age, assigned to receive either Ca 45 mg · kg⁻¹ · day⁻¹ (low dose [LD]) or Ca 75 mg · kg⁻¹ · day⁻¹ (high dose [HD]) by PN. P was added to the PN solutions at a fixed Ca:P ratio (mg) of 1.7:1. Bone strength was assessed by the speed of sound (SOS) using the quantitative ultrasound method. Measurements were performed weekly from birth until discharge. Low bone strength (SOS < 10th centile of reference values) was the main outcome.
Results: Eighty-six infants were enrolled, 40 assigned to LD group and 46 to HD group. Mean (standard error) gestational age was 29.6 weeks (2.1) and birth weight was 1262 g (0.356). In the HD group, the SOS values never fell below those recorded at birth and, up to the sixth week of life, low bone strength was significantly less frequent as compared with that in the LD group, in spite of progressive reduction in parenteral mineral intake and/or establishment of full enteral feeding.
Conclusions: Early assigned parenteral intake of Ca 75 mg · kg⁻¹ · day⁻¹ and P 44 mg · kg⁻¹ · day⁻¹ significantly contributed to preventing short-term bone strength decline in preterm infants.