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

Objective: 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.

Methods: 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.

Results: 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).

Conclusions: 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.