Neutrophil gelatinase-associated lipocalin is a urine-based biomarker for diagnosing active lupus nephritis

Background: Lupus nephritis is one of the most serious complications of systemic lupus erythematosus (SLE). Urinary neutrophil gelatinase-associated lipocalin (NGAL) is a non-invasive biomarker that may aid in diagnosing active lupus nephritis. This study seeks to evaluate NGAL as a urine-based biomarker to diagnose active lupus nephritis. Methods: This cross-sectional study was conducted in the Department of Laboratory Medicine, Rheumatology, and Nephrology at Bangabandhu Sheikh Mujib Medical University. Urine samples were collected to estimate NGAL levels using the ELISA method in the Department of Laboratory Medicine. Participants were divided into three groups: patients with SLE and active lupus nephritis, patients without nephritis, and healthy controls. Each group was comprised of 24 individuals. Patients with active lupus nephritis were classified into six categories (I to VI). ANOVA was performed to compare urinary NGAL values across the groups or categories. A receiver operating characteristic curve was created to establish the cut-off point for NGAL. Results: The mean urinary NGAL level was 19.5 (SD 6.9), 7.2 (3.8), and 1.7 (6.5) ng/mL in SLE patients with active lupus nephritis, SLE patients without active lupus nephritis, and healthy individuals, respectively. Increasing mean levels were observed across the classes of lupus nephritis. The cut-off point for urinary NGAL in active lupus nephritis was 11.6 ng/mL, demonstrating a sensitivity of 83.3% and a specificity of 93.8%. Conclusion: The level of urinary NGAL was elevated in SLE patients with active lupus nephritis. It could serve as a valuable biomarker for diagnosing active lupus nephritis.