Systemic Lupus Erythematosus activity and serum bilirubins

Background: Serum bilirubins play an important role in controlling oxidative stress; there is increased oxidative stress during activity of rheumatic diseases such as systemic lupus erythematosus (SLE). Objective: To study bilirubin levels in SLE (Systemic Lupus Erythematosus) patients and relate them to disease activity. Methods: We analyzed levels of total bilirubins (TB), direct bilirubins (DB) and indirect bilirubins (IB), sedimentation rate (ESR) and C reactive protein (CRP) in 143 SLE patients. Data were collected on the clinical and autoantibody profiles and patients underwent measurement of SLEDAI and SLICC . Results: Correlation of indirect bilirubin values with SLEDAI was negative (p=0.02; Spearman rho=-0.18). Comparing the levels of IB according to the clinical activity profile we observed associations with increase of anti DNA titer (p=0.027) and with decrease in complement levels (p=0.017). ESR correlated negatively with IB levels (p=0.01) but CRP did not (p=0.15). In a multiple linear regression analysis only the increase in ESR titer remained significant. SLICC values were not correlated with TB (p=0.30), DB (p=0.12) or IB (p=0.31). Conclusions: We conclude that IB levels in SLE correlate negatively with disease activity. IB levels are lower in patients with higher ESR.