Abstract: TH-PO442

Vitamin D Supplementation Increases Nephrocalcinosis but Not Bone Density in Preterm Infants

Session Information

Category: Nutrition, Inflammation, and Metabolism

  • 1401 Nutrition, Inflammation, Metabolism

Authors

  • Malone jenkins, Sabrina R, University of Utah, Salt Lake City, Utah, United States
  • Grinsell, Matthew M., University of Utah, Salt Lake City, Utah, United States
  • Weaver lewis, Kimberlee A, Intermountain Medical Center, Murray, Utah, United States
  • Chan, Gary M, University of Utah, Salt Lake City, Utah, United States
Background

Vitamin D (VitD) supplementation is recommended for infants to maintain VitD status and improve bone density. One possible complication of VitD supplementation is nephrocalcinosis (NC), which is the calcification of renal tissue and is reported in 7-64% of infants with gestational age (GA)<32 wks or birth weight (BW)<1500g. Hypercalciuria and urine calcium crystal formation may also be complications of VitD supplementation. The relationship between VitD supplementation, NC, and the effect on bone density in preterm infants remains unknown. We hypothesize that VitD supplementation is associated with higher incidence of NC and hypercalciuria without improving bone density in preterm infants.

Methods

Prospective observational cohort study of 56 infants with GA≤32wks or BW≤1800g. We collected data on demographics, dietary intakes, and serum VitD levels until 40 wks corrected GA. Weekly urinalyses with microscopy were performed from 2 wks of age. NC was identified by renal ultrasound (US). Bone mineral density and content was assessed using DXA scan. Bone strength and elasticity was assessed by measuring speed of sound (SOS) through tibial US.

Results

26/56 (46%) infants were diagnosed with NC. Infants with NC had a lower GA (28±2 vs 31±2wks, p<0.01) and BW (1102±305 vs 1449±428g, p<0.01) compared to Non-NC. There were no differences in VitD intake or urine calcium/creatinine ratios in NC vs NonNC infants. However, 69% of NC infants vs 40% NonNC had urinary calcium oxalate (CaOx) crystals on microscopy (p<0.03; PPV=60% & NPV=60%). Near discharge, 25-OH VitD levels were higher in the NC group compared to the NonNC group (46±24 vs 34±20ng/ml, p=0.03). DXA scan showed no difference in bone mass and density. However, tibial bone US demonstrated lower SOS (2774±159 vs 2910±158 m/s, p<0.01) and percentile (9±15 vs 28±27, p<0.01) in the NC group consistent with reduced bone strength and elasticity.

Conclusion

Infants born at an earlier GA and lower BW are at increased risk of NC. Our study shows that infants with NC had higher VitD levels and more frequent urine CaOx crystals. VitD supplementation did not increase bone density or mass on DXA but did have lower bone elasticity and strength on tibial US. We speculate that VitD supplementation may not improve bone density but may increase the risk for development of NC in preterm infants.

Funding

  • Private Foundation Support