title: Low serum bilirubin concentration is associated with coronary artery calcification (CAC).
abstract: BACKGROUND
  Bilirubin is a potent antioxidant and previous studies have reported the relationship between low serum bilirubin concentration and atherosclerosis. The purpose of this study was to assess the correlation between serum bilirubin concentration and coronary artery calcification (CAC).
  
  
  METHODS
  This study consisted of 637 participants and we evaluated the relationship between CAC score determined by multislice computed tomography and serum bilirubin concentration.
  
  
  RESULTS
  An inverse correlation was found between serum bilirubin concentration and log(CAC+1) (r=-0.361, P<0.0001). Multiple regression analysis also demonstrated that age (beta=0.261, P=0.0125), systolic blood pressure (beta=0.153, P=0.0237), uric acid (beta=0.126, P=0.0441), estimated glomerular filtration rate (beta=-0.139, P=0.0416) and serum bilirubin concentration (beta=-0.281, P<0.0001) were independent determinants of log(CAC+1). An increment of 1 micromol/L in serum bilirubin concentration was associated with 14% decrease in the odds for CAC score > or =400 after adjustment for several risk factors. Both age and SBP were also positively associated with CAC score > or =400, but the odds ratio for CAC score > or =400 was greater for every 1 micromol/L increment in serum bilirubin concentration than for every 1-year increment in age and 1-mmHg increment in SBP.
  
  
  CONCLUSIONS
  Low serum bilirubin concentration is associated with coronary artery calcification. Serum bilirubin concentration can be measured easily in the clinical laboratory and applied in medical practice, and low serum bilirubin concentration would be useful as a provisional new risk factor of CAC.
authors.affiliation: Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, 465 Kajii cho, Hirokoji, Kawaramachi dori, Kamikyo ku, Kyoto, Japan.
authors.forename: Muhei
authors.initials: M
authors.lastname: Tanaka
authors.forename: Michiaki
authors.initials: M
authors.lastname: Fukui
authors.forename: Ki-ichiro
authors.initials: K
authors.lastname: Tomiyasu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Akabame
authors.forename: Koji
authors.initials: K
authors.lastname: Nakano
authors.forename: Goji
authors.initials: G
authors.lastname: Hasegawa
authors.forename: Yohei
authors.initials: Y
authors.lastname: Oda
authors.forename: Naoto
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000150:complications*; D001663:Bilirubin / Q000097:blood*; D002114:Calcinosis / Q000209:etiology*; D003324:Coronary Artery Disease / Q000097:blood / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D001663:Bilirubin