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.