Incidence of Zinc Toxicity as a Complication of Phototherapy Authors

1 Associate Professor, RMMCH 2 Post Graduate, RMMCH Abstract Background: Neonatal jaundice is one of the common newborn illness for which existing therapies are not only costly, time-consuming but also has some inherent risks. Phototherapy duration can be reduced by adding zinc salts. Uunconjugated bilirubin in the intestine (bilirubin and zinc can form a complex in physiologic pH) is precipitated by zinc salts; however, zinc toxicity is an issue that must be considered since theoretically bilirubin reduction by phototherapy may increase serum zinc levels, making additional zinc supplementation the potential cause of zinc toxicity. Objective: Estimation of serum zinc level alterations before and after phototherapy, in jaundiced newborns Materials and Methods: A prospective cohort study was performed at the newborn department of RMMCH. 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 >18mg/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.