Does phototherapy induce an oxidative stress in preterm neonates?

ABSTRACT

Of this study was to investigate whether phototherapy leads to oxidative stress in preterm newborns. Lipid peroxidation products as indicated by the thiobarbituric acid reacting substances [TBARS] in blood and urinary 8-Hydroxydeoxyguanosine [8-OHdG] as a protein peroxidation product in urine were assessed before and after exposure to phototherapy. Meanwhile, antioxidant activity in terms of plasma vitamin E and erythrocyte-glutathione peroxidase [GSH-PX] was assessed. The study group enrolled 24 preterm infants with physiological hyperbilirubinemia categorized according to the used modality of phototherapy into single and double phototherapy groups. Their mean gestational age was 31.22 +/- 2.63 weeks, and birth weight was 2.175 +/- 0.86 kg. Blood samples were collected immediately before and after 72 hours of phototherapy. Samples were analyzed for total serum bilirubin [TSB], serum albumin, blood TBARS, plasma vitamin E and erythrocyte-GSH-PX. Urine samples were collected before and after phototherapy for analysis of 8-OHdG. Levels of blood TBARS, Urine 8-OHdG were significantly elevated after phototherapy while plasma vitamin E and erythrocyte GSH-PX did not significantly change. Blood TBARS showed a negative correlation to TSB before phototherapy. The percent increase in serum TBARS or Urine 8-OHdG after phototherapy did not significantly correlate to gestational age or birth weight. Phototherapy induces oxidative stress in preterm neonates with unconjugated hyperbilirubinemia, regardless of their birth weight or gestational age. In face of this stress, antioxidant defense may be inadequate, requiring vitamin E supplementation. No significant photo-oxidant hazard is added in proceeding with double phototherapy in neonates under single phototherapy