Gilbert syndrome and ischemic heart disease: a protective effect of elevated bilirubin levels

Background: Oxidation processes play an important role in atherogenesis. Bilirubin IX is recognised as a potent antioxidant. In the present study, we assessed the role of elevated serum bilirubin levels in the prevention of ischemic heart disease (IHD). Methods: The occurrence of IHD was determined in Gilbert syndrome (GS) patients above 40 years (n=50). The diagnosis was based on past medical history and ECG criteria. The occurrence was related to that of the comparable general population (n=2296). Serum biochemistry, including the total antioxidant status was evaluated in the GS subjects, IHD patients (n=38) and control subjects (n=38). Results: The prevalence of IHD in GS subjects (aged 49.7±9.0 years) was 2% (0.05–10.7%, 95% confidence interval), compared to 12.1% in a general population (P<0.05). Bilirubin, total antioxidant capacity and high density lipoprotein (HDL) cholesterol were found to be significantly higher in GS subjects compared to control groups (P<0.05). According to linear discriminant analysis, hyperbilirubinemia rather than elevation of HDL cholesterol levels seemed to be more important in protection from IHD. Conclusions: In the present study, low prevalence of IHD in GS subjects was detected. It may be presumed that chronic hyperbilirubinemia prevent the development of IHD by increasing the serum antioxidant capacity.