Bilirubin as an anti-oxidant for surgical stress: a preliminary report of bilirubin oxidative metabolites.

Bilirubin has been recognized as an anti-oxidant. The purpose of this study was to examine whether bilirubin would act as an antioxidant for surgical stress in humans. Serum bilirubin and urinary bilirubin oxidative metabolites (BOM) were measured in 96 patients who underwent surgery. The antioxidant activity of bilirubin was assessed using BOM measured by enzyme-linked immunosorbent assay with an anti-bilirubin monoclonal antibody. Serum bilirubin levels increased after surgery in all 96 patients (p < 0.01), but did not correlate with operation time or blood loss (p = 0.53 and p = 0.28, respectively). BOM increased only in patients with major surgeries (p = 0.048). Significant correlations between BOM and operation time and blood loss were found (p < 0.01). Bilirubin appears to act as an antioxidant for invasive surgery in humans. Urinary BOM could be a reliable marker for the degree of surgical stress.