3Neonatology, University of Miami, Miami, FL, USA Vitamin D Status among Preterm Infants with Metabolic Bone Disease and Cholestasis Supamit Ukarapong, MD1, Walter Zegarra, MD2, Cristina Navarrete, MD3 and Gary Berkovitz1 1Pediatric Endocrinology, University of Miami, Miami, FL, USA, 2Pediatrics, Jackson Memorial Hospital, Miami, FL, USA, 3Neonatology, University of Miami, Miami, FL, USA Background Results Results Metabolic bone disease (MBD) is a common problem among premature infants . Preterm infants often require prolonged parenteral nutrition, which can lead to cholestasis. Our previous study identified cholestasis as an important risk factor in the development of MBD1. We investigated the vitamin D level in preterm infants with MBD and cholestasis. Table 1 Patient Characteristics Cholestasis N=24 No-Cholestasis N=29 Median BW (IQR) 582 grams (411-753) 675 grams (494-856) P= 0.06 Median GA 25 weeks (24-26) 26 weeks (25-27) p = 0.63 Figure 1. Comparison of Vitamin D level at 1st measurement (6 weeks) and 2nd Measurement (12 weeks) Study Methods The proportion of infants with vitamin D deficiency was also similar in both groups both at 1st (C vs. NC; 12.5% vs. 13.7%, p-value= 0.89) and 2nd measurement (C vs. NC; 15% vs.9%, p=0.55). Serum calcium and phosphorus level determined between first and second vitamin D measurement were also similar in both group (time x group effect p-value = 0.23 and 0.81 respectively) Study Design : Retrospective Case -Control study Medical records of preterm infants admitted to the NICU between Jan 2014 to May 2016 were reviewed. Definitions: 1. MBD: was defined as peak alkaline phosphatase above 500 U/L and characteristic radiographic changes. 2. Cholestasis: Elevated direct bilirubin (>2 mg/dl) for more than 2 weeks. 3. Vitamin D deficiency: Serum 25-OH vitamin D less than 20 Laboratory Values: Serum 25-hydroxy vitamin D, PTH Calcium and Phosphorus Statistical Analyses : -Mann Whitney U test for birthweight, gestational age, serum 25-OH vitamin D and PTH - Chi-square for proportion of patients with vitamin D deficiency - Two-way repeated measure ANOVA for serum calcium and phosphorus Median serum 25-hydroxyvitamin D level at the time MBD was diagnosed, average  postnatal age 6 weeks, was similar (p= 0.41) in C (29.1 ng/ml, IQR 24.4–33.5) and NC (28.7 ng/ml, IQR 22.7-34.6) group. Figure 2. Comparison of serum PTH at the time of diagnosis Conclusion Our study suggests that vitamin D does not play an important role in the etiology of MBD. Reference: 1 Venkatarayappa SK et al., Risk Factors for Metabolic Bone Disease of Prematurity, PAS meeting 2016. Median serum PTH was slightly lower in C (60.1pg/ml, IQR 25.1- 95.1) than in NC (84.8pg/ml, IQR 49.2-119.6), p=0.05