Burden and Nutritional Determinants of Metabolic Bone Disease of Prematurity in Very Low Birth Weight Infants: A Prospective Cohort Study from a Tertiary Neonatal Unit

Objectives To characterize the biochemical profile of metabolic bone disease of prematurity with specific emphasis on hypophosphatemia in very low birth weight (VLBW) or < 32 weeks’ infants in response to current practices of calcium, phosphate and vitamin D supplementation at 40 weeks of postmenstrual age. Methods This prospective cohort study was conducted in a tertiary care neonatal unit. VLBW or preterm infants < 32 weeks of gestation were enrolled. Serum calcium, phosphorus, alkaline phosphatase, and 25-hydroxyvitamin D levels were assessed at 4 weeks of postnatal age and at term-equivalent age (40 weeks postmenstrual age). Results A total of 102 neonates were enrolled, of whom 99 completed follow-ups. No infant developed hypocalcaemia at either assessment point. Hypophosphatemia was observed in 45 (44.1%) infants at 4 weeks and persisted in 35 (35.4%) infants at 40 weeks postmenstrual age. Vitamin D insufficiency and deficiency were present in 13.7% and 19.6% of infants at 4 weeks, respectively. Metabolic bone disease of prematurity was diagnosed in 19 (18.6%) infants. Lower average daily phosphorus intake was associated with a higher prevalence of metabolic bone disease, while calcium and vitamin D intake showed similar unadjusted associations (p < 0.001). Conclusion Hypophosphatemia was the most frequent biochemical abnormality observed in infants with metabolic bone disease of prematurity.. Despite routine supplementation, hypophosphatemia remained prevalent and was the strongest independent predictor of metabolic bone disease, underscoring phosphorus inadequacy as the primary driver of disease in VLBW infant.