Bilirubin levels in patients with systemic lupus erythematosus: increased or decreased?

The aim of this study was to investigate the serum bilirubin levels in SLE patients and their associations with clinical and laboratory characteristics of SLE. There were 198 SLE patients in this study, of whom 7 cases with tobacco smoking or alcohol intake were excluded. Some clinical and laboratory characteristics of the patients were obtained by medical record review. In addition, 154 age- and sex- matched healthy volunteers with no histories of SLE, liver diseases, and other autoimmune or inflammatory diseases were randomly recruited into this study. The serum bilirubin levels were lower in SLE patients without liver diseases than in healthy controls (P = 0.000). Univariate logistic analysis demonstrated that hypertension, lupus renal involvement, positive anti-dsDNA antibody, C3, C4, hsCRP, and albumin remained as impact factors of total bilirubins; lupus renal involvement, ESR, IgG, globulin, and ALT, as impact factors of direct bilirubins; and lupus renal involvement, positive anti-dsDNA antibody, C3, C4, hsCRP, and albumin, as impact factors of indirect bilirubins. However, multivariate logistic analysis showed that only hsCRP remained as an independent positive impact factor of total bilirubins, lupus renal involvement as an independent negative impact factor of direct bilirubins, and hsCRP and albumin as independent positive impact factors of indirect bilirubins. In conclusion, serum bilirubin levels are decreased in SLE and the decreased bilirubin levels could be associated with inflammatory process and lupus renal involvement of SLE.