title: Higher serum total bilirubin concentration is associated with lower risk of renal insufficiency in an adult population.
abstract: BACKGROUND
  Chronic inflammation is proposed to play a central role in the pathogenesis of chronic kidney disease (CKD), and serum bilirubin has antioxidant and anti-inflammatory effects. We investigated the association between serum total bilirubin (Tb) concentration and renal function in an adult population.
  
  
  METHODS
  We conducted a cross-sectional study and collected anthropometric measurements, fasting blood tests, lifestyle habits and medical history of 3876 subjects attending a health examination. Renal insufficiency was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) calculated by using the CKD-EPI equation.
  
  
  RESULTS
  Serum Tb concentrations were higher in subjects without renal insufficiency than in those with renal insufficiency. Multivariable linear regression analysis showed that Tb concentration was positively associated with eGFR after adjusting for important CKD risk factors (P=0.04). Multivariable logistic regression analysis also revealed that higher Tb concentration (each increment of 1.71 μmol/L) (0.1 mg/dL) was associated with a reduced risk of renal insufficiency: odds ratios were 0.94 (P=0.005) for men and 0.90 (P=0.015) for women, respectively. When subjects were divided into quartiles of serum Tb, multivariable-adjusted odds ratios for renal insufficiency comparing the fourth to the first Tb quartile were 0.49 (P=0.001) for men and 0.35 (P=0.003) for women. A stepwise exclusion of subjects, first those with possible liver disease and second, those with CKD stage 4 and 5, showed consistent results.
  
  
  CONCLUSIONS
  Higher serum Tb concentration was associated with lower risk of renal insufficiency, regardless of other conventional CKD risk factors.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Taichung Veterans General Hospital Taichung, Taiwan.
authors.forename: Ang-Tse
authors.initials: AT
authors.lastname: Lee
authors.affiliation: Department of Family Medicine, Taichung Veterans General HospitalTaichung, Taiwan; Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing UniversityTaichung, Taiwan; School of Medicine, National Yang Ming UniversityTaipei, Taiwan.
authors.forename: Ya-Yu
authors.initials: YY
authors.lastname: Wang
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Taichung Veterans General HospitalTaichung, Taiwan; School of Medicine, National Yang Ming UniversityTaipei, Taiwan; Center for Geriatrics and Gerontology, Taichung Veterans General HospitalTaichung, Taiwan.
authors.forename: Shih-Yi
authors.initials: SY
authors.lastname: Lin
authors.affiliation: Division of Biochemistry, Department of Pathology and Laboratory Medicine, Taichung Veterans General Hospital Taichung, Taiwan.
authors.forename: Jiin-Tsae
authors.initials: JT
authors.lastname: Liang
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Taichung Veterans General HospitalTaichung, Taiwan; School of Medicine, National Yang Ming UniversityTaipei, Taiwan; School of Medicine, National Defense Medical CenterTaipei, Taiwan.
authors.forename: Wayne Huey-Herng
authors.initials: WH
authors.lastname: Sheu
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Taichung Veterans General Hospital Taichung, Taiwan.
authors.forename: Yuh-Min
authors.initials: YM
authors.lastname: Song
authors.affiliation: Department of Family Medicine, Taichung Veterans General Hospital Taichung, Taiwan.
authors.forename: Wen-Dau
authors.initials: WD
authors.lastname: Chang
keywords: Bilirubin; cardiovascular disease; chronic kidney disease; kidney function