MON-736 Effects of High-Dose Vitamin D Supplementation on Bone Mineral Density in Very Low Birth Weight Preterm Infants

Abstract Disclosure: M. Yoo: None. J. Seo: None. K. Lee: None. J. Choi: None. Y. Choe: None. S. Yang: None. Background: Vitamin D deficiency is highly prevalent among very low birth weight (VLBW) preterm infants owing to challenges in achieving adequate enteral nutrition and reduced trans-placental transfer. Daily vitamin D supplementation at a dose of 800 IU safely and effectively increases the proportion of VLBW infants with 25-hydroxy vitamin D (25(OH)D) levels above 30 ng/mL, starting from 2 weeks of age until hospital discharge. Objective: This study aimed to evaluate whether a daily vitamin D supplement of 800 IU significantly enhances bone mineral density, as measured by dual-energy X-ray absorptiometry (DEXA), in VLBW infants at the time of discharge, compared to a supplement of 400 IU/day. Methods: We retrospectively reviewed medical records of 215 VLBW infants with birth weights under 1,500 g admitted to the neonatal intensive care unit of Hanyang University Seoul Hospital between January 2010 and December 2023. The study population was divided into two groups based on their vitamin D intake of either 400 IU/day or 800 IU/day, starting 14 days after birth if trophic feeds were tolerated. Bone mineral apparent density (BMAD) was assessed using total body densitometry via a commercially available DEXA (Hologic QDR-4500; Hologic, Waltham, Mass., USA) in infant whole-body mode at discharge. Results: In the demographic analysis, the 800 IU vitamin D group had a higher maternal age (32.01±3.43 vs. 33.34±4.39, p=0.017) and birth weight (812.86±141.19 vs. 883.76±260.09 g, p=0.01) than the 400 IU group. However, the 800 IU group experienced a longer duration of total parenteral nutrition days than the 400 IU group. Correcting for birth weight and total parental nutrition days, BMAD of the total body was significantly higher in the 800 IU group (p=0.008) than in the 400 IU group. Further analysis using a general linear model revealed that 800 IU vitamin D supplementation was associated with BMAD at the left femur (β=0.267, p=0.001) at discharge. Conclusion: Daily supplementation of 800 IU of vitamin D was associated with improved bone mineralization, as measured by DEXA, at discharge in VLBW infants. Presentation: Monday, July 14, 2025