Urinary neutrophil gelatinase-associated lipocalin as a marker for disease activity in lupus nephritis

The neutrophil gelatinase-associated lipocalin (NGAL) has been emerging as a novel biomarker of acute kidney injury while its value in lupus nephritis is uncertain. The aim of this study was to assess urinary NGAL levels as a marker for disease activity in patients with lupus nephritis.This study included 70 systemic lupus erythematosus (SLE) patients; 50 with active lupus nephritis (LN) and 20 without as well as 20 matched controls. The neutrophil gelatinase-associated lipocalin (NGAL) in both serum and urine samples was measured by enzyme-linked immunosorbent assay (ELISA). Patients with active LN received standard treatment then assessed for response as well as the value of urinary NGAL (uNGAL). Our results revealed that, The SLE patients with or without LN had an elevated urinary NGAL as compared to controls (p < 0.000) and the mean of uNGAL was (20.67 ± 5.34),(10.63 ± 3.53),(5.65 ± 2.49) respectively. Furthermore,Urinary NGAL levels in LN patients were significantly higher than those in non-LN patients (P < 0.0001). In the ROC curve analysis , the diagnostic performance of uNGAL for discriminating patients with nephritis from those without nephritis showed that the best cutoff value was 13.66 ng/ml ,sensitivity 92%,specificity 75%,area undercurve (0.959) and (P < 0.0001). Measurement of urinary NGAL levels showed an excellent diagnostic performance for discriminating patients with LN from SLE without nephritis.