Reduction in serum paraoxonase level in newborns with hyperbilirubinemia as a marker of oxidative stress

Indirect bilirubin exerts an antioxidant effect when increased mildly. This study aimed to investigate whether increased bilirubin levels lead to an oxidant effect in newborns with hyperbilirubinemia requiring phototherapy.The study included 30 term newborn infants aged 0-7 days with indirect hyperbilirubinemia requiring phototherapy and no comorbid disease as the study group. In addition, 30 term healthy newborn infants aged 0-7 days without indirect hyperbilirubinemia were employed as a control group. Serum triglyceride, total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), serum paraoxonase (PON) levels and malondialdehyde (MDA) levels were compared between the groups.Serum MDA, total bilirubin, and LDL and HDL levels were significantly higher and the serum PON level was significantly lower, in the study group compared with the controls (p < 0.05).In newborns with hyperbilirubinemia requiring phototherapy, an increased bilirubin level causes oxidative stress by decreasing the level of serum PON and increasing the level of MDA.