Vitamin D, bone density, and nephrocalcinosis in preterm infants: a prospective study

Area of Science:

• Neonatal Medicine
• Pediatric Nephrology
• Nutritional Science

Background:

• Vitamin D (VitD) supplementation is recommended for preterm infants to enhance bone density.
• Potential complications include hypercalciuria and nephrocalcinosis (NC), particularly in infants with low gestational age (GA) or birth weight (BW).
• The precise relationship between VitD, serum levels, bone density, and NC in preterm infants remains unclear.

Purpose of the Study:

• To investigate the effects of recommended Vitamin D supplementation on bone mineral density (BMD) and the incidence of nephrocalcinosis (NC) in preterm infants.
• To explore the associations between VitD intake, serum 25-hydroxy VitD levels, and NC development.
• To identify risk factors for NC in this vulnerable population.

Main Methods:

• A prospective, observational cohort study involving 56 preterm infants (GA ≤ 32 weeks or BW ≤ 1800 g).
• Data collected included demographics, dietary intake, serum 25-hydroxy VitD, and weekly urinalyses.
• Bone mineral density (BMD) and content (BMC) were assessed via DEXA scan, and NC was diagnosed using kidney ultrasound.

Main Results:

• 41% of infants (23/56) developed NC.
• Infants with NC had significantly lower GA and BW and a higher prevalence of calcium oxalate crystals.
• No significant differences were observed in VitD intake, urine calcium/creatinine ratios, BMD, or BMC between infants with and without NC.

Conclusions:

• Current Vitamin D supplementation guidelines achieve adequate serum levels but do not appear to improve BMD or BMC in preterm infants.
• Preterm infants born at earlier GA and lower BW receiving recommended VitD doses face an elevated risk of NC.
• Close monitoring of VitD supplementation and serum levels is essential in high-risk preterm infants to mitigate NC risk.