Association between urinary adiponectin level and renal involvement in systemic lupus erythematous

To assess association between urinary levels of adiponectin and severity of renal involvement in SLE patients. Also, this study aims to determine the value of urinary adiponectin levels to discriminate renal involvement in these patients.

In a multi-center cross-sectional survey, 50 consecutive patients diagnosed as having systemic lupus erythematosus (SLE) according to American College of Rheumatology criteria were classified into two groups with or without renal involvement (microscopic hematuria, reduced glomerular filtration rate < 25% of normal value, and proteinuria > 500 mg/24 h) which was confirmed by renal biopsy. Urinary adiponectin was measured by enzyme-linked immunosorbent assay. SLE disease activity levels were assessed by SLE Disease Activity Index (SLEDAI) score.

Comparing urinary levels of adiponectin between the two groups indicated considerable discrepancy in this index between the groups with and without renal involvement (146.33 ± 258.83 ng/mL vs. 22.96 ± 44.33 ng/mL, P = 0.023). Also, urinary adiponectin/creatinine ratio was significantly higher in the former group (221.72 ± 414.58 vs. 19.99 ± 41.19, P = 0.019). Our study showed a higher mean SLEDAI score in those with renal involvement than others (23.60 ± 2.53 vs. 9.12 ± 3.03, P < 0.001). Multivariable linear regression analysis with the presence of potential confounders showed that the level of urinary adiponectin was significantly higher in those with renal involvement than other patients (β = 0.470, P = 0.023). The optimal cut-off point for urinary adiponectin levels to discriminate renal involvement from normal renal state was 7.5 ng/mL, yielding a sensitivity of 80% and specificity of 52%.

Urinary levels of adiponectin are significantly elevated in SLE patients with renal involvement. The measurement of this biomarker can be helpful to discriminate impaired from normal renal function in SLE patients.