Association between serum 25-hydroxy Vitamin D and bilirubin levels in term neonates with hyperbilirubinemia: A cross-sectional, observational study

Introduction: Neonatal jaundice is a common cause of hospital admission among neonates in the 1st week of life. The condition results from an imbalance between oxidative stress and antioxidant mechanisms. Considering the fact that the metabolism of both bilirubin and 25-hydroxy Vitamin D occurs in the liver and 25-hydroxy Vitamin D being a potent antioxidant, we hypothesized that there exists an association between 25-hydroxy Vitamin D and serum bilirubin levels. Methods: A total of 174 neonates were enrolled in the study and were further subclassified into 4 groups: Group A (no clinical jaundice), Group B (clinical jaundice with the value of serum bilirubin <10 mg/dl), Group C (clinical jaundice with the value of serum bilirubin >10 mg/dl but not in phototherapy range), and Group D (clinical jaundice with serum bilirubin value requiring initiation of phototherapy). 25-hydroxy Vitamin D and serum bilirubin levels along with parathyroid hormone, calcium, phosphorus, and alkaline phosphatase levels were estimated. Results: The mean 25-hydroxy Vitamin D levels were highest in Group A and lowest in Group D (21.92 ± 20.85 vs. 14.38 ± 8.52, P = 0.020) and vice versa for serum bilirubin levels (15.08 ± 0.93 vs. 4.28 ± 0.97, P < 0.001). There was a nonsignificant negative correlation between serum 25-hydroxy Vitamin D and bilirubin levels (correlation coefficient: −0.113 [−0.257–0.0364], P = 0.138). Conclusion: The present study suggests a lack of association between serum 25-hydroxy Vitamin D and bilirubin levels. However, the results need to be confirmed by further prospective studies to conclude that 25-hydroxy Vitamin D has no role in the pathogenesis of neonatal hyperbilirubinemia.