evaluation of serum zinc levels in hyperbilirubinemic neonates before and after phototherapy

Background: the existing therapeutic methods for neonatal jaundice are costly, time-consuming and potentially risky. zinc salts can reduce phototherapy duration by precipitating unconjugated bilirubin in the intestine (bilirubin and zinc can form a complex in physiologic ph); however, zinc toxicity isanissue thatmustbe considered since theoretically bilirubin reduction by phototherapy may increase serum zinc levels, making additional zinc supplementation the potential cause of zinc toxicity. objectives: so, our purpose was evaluating the serum zinc level alterations before and after phototherapy, in hyperbilirubinemic newborns. materials and methods: a prospective cohort study was performed at the children’s medical center of tehran university of medical sciences from 2012 to 2014. healthy, full-term exclusively breast fed newborns with non-hemolytic jaundice were enrolled in the study. participants were divided into two groups based on serum bilirubin levels (tsb < 18 mg/dl and tsb≥ 18 mg/dl) at admission. pre- and post-phototherapy total serum zinc level was measured before and 12 - 24 hours after termination of phototherapy. results: phototherapy was associated with a significant increase in the serum zinc level in neonates with severe hyperbilirubinemia (tsb ≥ 18 mg/dl) but not in those with mild-moderate hyperbilirubinemia (tsb < 18 mg/dl). in addition, phototherapy caused a significant increase in the rate of zinc with potentially toxic levels (zinc > 200) in only neonates with severe hyperbilirubinemia. conclusions: phototherapy increases serum zinc level by reducing bilirubin level so that additional supplementation of this element can lead potentially to zinc toxicity.