Hyperbilirubinemia, Augmentation of Endothelial Function and Decrease in Oxidative Stress in Gilbert Syndrome
Background—Patients with Gilbert syndrome have mild unconjugated hyperbilirubinemia. It has been shown that bilirubin is an endogenous antioxidant. We evaluated the role of oxidative stress in endothelial function in patients with Gilbert syndrome under normal conditions without cardiovascular risk factors.
Methods and Results—A total of 108 young men with Gilbert syndrome without cardiovascular risk factors and 108 age-matched healthy men (normal controls) were enrolled in this study. Serum concentrations of bilirubin were higher in patients with Gilbert syndrome than in control subjects (29.2±11.6 vs. 9.4±2.7 μmol/L, P<0.001). Serum concentrations of malondialdehyde-modified low-density lipoprotein (MDA-LDL) and urinary excretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG), as indices of oxidative stress, were lower in patients with Gilbert syndrome than in control subjects (61.8±24.5 vs. 72.5±21.8 U/L, P=0.034, 7.8±2.4 vs. 10.4±3.2 ng/mg creatinine, P=0.001, respectively). Flow-mediated vasodilation (FMD) was greater in patients with Gilbert syndrome than in normal control subjects (7.2±2.2% vs. 5.9±1.7%, P<0.001). Vascular responses to nitroglycerine were not significantly different between the two groups. FMD correlated with serum concentration of bilirubin (r=0.44, P<0.001), MDA-LDL (r=-0.25, P=0.01), and urinary excretion of 8-OHdG (r=-0.27, P=0.004) in patients with Gilbert syndrome but not in control subjects. In addition, serum concentration of bilirubin correlated with MDA-LDL (r=-0.20, P=0.04) and 8-OHdG (r=-0.21, P=0.02) in patients with Gilbert syndrome but not in control subjects.
Conclusions—Patients with Gilbert syndrome had low levels of oxidative stress associated with hyperbilirubinemia and enhancement of endothelium-dependent vasodilation.
Clinical Trial Registration Information—http://www.umin.ac.jp; Identifier: UMIN000003409.
- Received March 14, 2012.
- Accepted May 22, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited