Significance of Urinary Neutrophil Gelatinase-Associated Lipocalin Detection in Patients with Lupus Nephritis

Introduction: Clinical and laboratory markers have limited specificity and sensitivity for predicting renal disease in Systemic Lupus Erythematosus (SLE) patients. Aim of the Work: In this study we investigated whether urinary neutrophil gelatinase associated lipocalin (uNGAL) predicts active nephritis with or without history of biopsy-proven lupus nephritis (LN), also to find the correlation between uNGAL with serum creatinine level, creatinine clearance, anti-double-stranded (dsDNA) anti body and disease activity score in SLE patients. Methods: Sixty-three SLE patients based on the American College of Rheumatology (ACR) criteria in this cross sectional study were divided into two groups: patients with and without nephritis. For each group disease activity was measured by SLEDAI and then divided to low (SLEDAI 8) and high activity (SLEDAI ≥ 8) according to Annett et al., 2003. 24 hours uNGALvalues were measured to each group. uNGAL sensitivity and specificity for identifying biopsy-proven nephritis were calculated, and a receiver operating characteristic (ROC) curve was constructed. Results: The mean±SD of 24-hours uNGAL in patients with LN was significant higher (24.61±3.44mg/24hours) compared to patients without nephritis (16.80±3.54mg/24 hours) with p-value of (p=0.000). A significant positive correlation was found between serum creatinine and uNGAL (r=0.324; p=0.030), while there was significant negative correlation between Creatinine clearance and uNGAL (r=–0.310; p=0.013). uNGAL had high sensitivity (82%) and moderate specificity (67%) in patients with biopsy proven LN in comparison to that of anti-dsDNA which had low sensitivity (50%) and specificity (37%) in detection of renal flare in LN patients.Conclusions: uNGAL predicts renal flare in LN patients with high sensitivity and specificity. Furthermore, uNGAL is a more sensitive and specific for renal flare in patients with a history of LN than anti-dsDNA antibody. So uNGAL may help in earlier diagnosis and treatment of LN with good outcomes in these patients.