The Relationship between Bilirubin Levels and Patients with Lupus Nephritis

Background: Bilirubin acts as an antioxidant. In this study, we assessed the relationship between the bilirubin level and lupus nephritis (LN). Methods: We included 50 newly diagnosed LN patients and 74 healthy individuals. Patients with LN were divided into three groups according to pathological classification. According to the activity index (AI), 42 LN patients were divided into two additional groups: AI < 4 and AI >= 4. We evaluated the changes in the bilirubin levels in 4 LN patients after glucocorticoid treatment. Results: The bilirubin levels in the LN patients were significantly lower than those in the controls. The bilirubin levels in the patients with active LN were lower than those in the patients with non-active LN. The levels of bilirubin in the AI >= 4 group were lower than those in AI < 4 group. Moreover, bilirubin was negatively correlated with the 24-hour urine protein, but it was positively correlated with the glomerular filtration rate. The glucocorticoid treatment reduced the 24-hour urine protein level, and it increased the bilirubin level. Conclusions: The serum bilirubin level in the LN patients was decreased significantly, and this was related to the disease activity.