title: Association of systemic lupus erythematosus with low serum bilirubin levels.
abstract: OBJECTIVE
  Systemic lupus erythematosus (SLE) is accompanied by severe oxidative stress. Bilirubin has been reported as a strong negative predictor of oxidative stress-mediated diseases, such as atherosclerosis. The objective of our study was to evaluate the association between serum bilirubin levels and SLE manifestation.
  
  
  METHODS
  The study was performed with 259 SLE patients, diagnosed according to American Rheumatism Association (ARA) criteria. A subset of these patients, having normal hepatic function (n = 218, mean age 39.5 years), was studied in greater detail to eliminate the possible confounding effects of any underlying or drug-induced liver disease on the serum bilirubin levels. Age-matched healthy subjects (n = 180) served as the control group. A standard biochemical and immunological work-up was performed on all subjects.
  
  
  RESULTS
  Compared to the controls, substantially lower levels of serum bilirubin were detected in SLE patients (p < 10⁻⁵); these were inversely correlated with disease activity and extent (p < 0.05). Furthermore, each 1 μmol/L decrease in serum bilirubin was associated with a 37% increase in the odds for a positive SLE status [odds ratio (OR) 1.37, 95% confidence interval (CI) 1.28-1.47, p < 10⁻⁵]. Simultaneously, the odds of unconjugated hyperbilirubinaemia (a phenotypic sign of Gilbert's syndrome) were more than four times lower in SLE patients (OR 0.235, 95% CI 0.072-0.764, p = 0.016).
  
  
  CONCLUSIONS
  Low serum bilirubin represented a strong predictor of the manifestation of SLE symptoms. The most likely explanation for this finding is the increased consumption of bilirubin due to the severe oxidative stress accompanying SLE. Subjects with higher serum bilirubin levels, such as those with Gilbert's syndrome, might be protected from the development of SLE.
authors.affiliation: Institute of Clinical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University in Prague, Praha, Prague, Czech Republic. vitek@cesnet.cz
authors.forename: L
authors.initials: L
authors.lastname: Vítek
authors.forename: L
authors.initials: L
authors.lastname: Muchová
authors.forename: E
authors.initials: E
authors.lastname: Jančová
authors.forename: S
authors.initials: S
authors.lastname: Pešičková
authors.forename: D
authors.initials: D
authors.lastname: Tegzová
authors.forename: V
authors.initials: V
authors.lastname: Peterová
authors.forename: K
authors.initials: K
authors.lastname: Pavelka
authors.forename: V
authors.initials: V
authors.lastname: Tesař
authors.forename: Ha
authors.initials: H
authors.lastname: Schwertner
mesh_terms: D000328:Adult; D001663:Bilirubin / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D005878:Gilbert Disease / Q000097:blood / Q000175:diagnosis; D006801:Humans; D008107:Liver Diseases / Q000097:blood / Q000175:diagnosis; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D001663:Bilirubin