Urinary Neutrophil Gelatinase- Associated Lipocalin in Children with Idiopathic Nephrotic Syndrome: A Biomarker to Differentiate Between Steroid Sensitive and Resistant Forms of Disease

Abstract

Background: Objectives of the study were to find out the ability of urinary neutrophil gelatinase- associated lipocalin (NGAL) as a biomarker to differentiate between steroid resistant nephrotic syndrome (SRNS) and steroid sensitive nephrotic syndrome (SSNS), and also to observe variation in levels, if any, between focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) in SRNS patients.Methods: The study included 63 patients of idiopathic nephrotic syndrome (19 SSNS in relapse, 19 SSNS in remission and 25 SRNS), aged 2.5-16 years, along with 17 controls. Urinary NGAL was measured by ELISA and the values were normalised with urinary creatinine.Results: Median urinary NGAL/creatinine level was significantly raised in SRNS as compared to SSNS relapse, SSNS remission and controls (p 18.3 ng/mg had sensitivity of 84%, specificity of 97.4% and area under the curve of 0.935 (p< 0.001, 95% confidence interval 0.871-0.998) to differentiate SRNS from SSNS patients. Median urinary NGAL/creatinine value was significantly raised in children with FSGS as compared to MCD (p=0.003) in SRNS patients. It had significant positive correlations with duration of illness (r=0.342, p=0.006), urine protein creatinine ratio (r=0.594, p< 0.001) and negative correlation with serum albumin (r=0.470, p<0.001).Conclusion: Urinary NGAL/creatinine level correlated with activity of the disease and it can distinguish not only SRNS from SSNS but also FSGS and MCD histopathological sub-types of SRNS in children.