association of urinary lipocalin-2 with lupus nephritis

objective(s): lupus nephritis (ln) is the main cause of mortality and disability in systemic lupus erythematosus (sle) patients. therefore, utilizing a reliable and non-invasive method for serial measurements of renal function seems to be necessary. the aim of this study was to evaluate the role of urinary lipocalin-2 as a biomarker of renal involvement in sle patients.   materials and methods: fifty two lupus patients in this cross sectional study were divided into two groups: patients with and without nephritis. for each group, urinary lipocalin-2, values were measured and reported according to urinary lipocalin-2/creatinine. urinary lipocalin-2/creatinine sensitivity and specificity for identifying biopsy-proven nephritis were calculated, and a receiver operating characteristic (roc) curve was constructed. results : the mean urinary lipocalin-2/creatinine value of patients with biopsy-proven ln was 2.99 ± 4.1 ng/mg, and in non-ln patients was 1.16 ± 1.27 ng/mg. urinary lipocalin-2/creatinine levels in ln patients were significantly higher than those in non-ln patients (p- value = 0.03). in ln patients, urinary lipocalin-2/creatinine significantly correlated with proteinuria (r = 0.68; p = 0.0001). using a cutoff value of 0.896 ng/mg, urinary lipocalin-2/creatinine had a sensitivity of 89.7% and a specificity of 39.1% for identifying sle patients with biopsy-proven ln. the area under the roc curve was 0.664 ± 0.076 with a 95% confidence interval of 0.52-0.81 (p=0.04). analysis of variance showed that urinary lipocalin-2/creatinine is the same in different classes of ln (p-value=0.28). conclusion: an important clinical conclusion is that measurement of urinary lipocalin-2 may result in earlier diagnosis of ln.