Association of serum uric acid with lupus nephritis in systemic lupus erythematosus.

The aim of the present study is to assess the association of elevated serum uric acid (UA) with lupus nephritis (LN) in systemic lupus erythematosus (SLE) patients. A total of 130 SLE patients were recruited, of whom 73 patients developed LN. Blood samples were obtained for determination of uric acid, complement 3 (C3), C-reactive protein (CRP) and some autoantibodies including anti-double-stranded DNA, -Smith, -SSA, -SSB, -U1RNP, SCL-70, and -Jo-1 antibodies. Correlations of UA with LN were assessed. UA was an independent risk factor for LN [odds ratio (95% CI): 1.01 (1.005-1.014); P=0.0000]. The best cut-off value for UA using the ROC curve was 330 μmol/L (sensitivity 78.1% and specificity 75.4%) and the area under the ROC curve was 0.803±0.039 (95% CI: 0.727-0.878, P=0.000). Spearman's correlation coefficient analysis showed negative association of UA with C3 in SLE patients with LN (r=-0.356, P=0.002), but no association in those without LN. No correlations were found between UA and age, SLEDAI, CRP, IgG, IgM or IgA. Furthermore, analysis of covariance demonstrated that anti-Sm (β=-0.218, P=0.004) and -U1RNP (β=0.177, P=0.008) autoantibodies were independent determinants of serum UA. The UA level is independently associated with the development of LN in SLE patients.