Value of urinary neutrophil gelatinase-associated lipocalin in evaluation of renal tubulointerstitial injury of type 2 diabetic nephropathy

Objective To investigate the value of urinary neutrophil gelatinase-associated lipocalin (NGAL) in evaluation of renal tubulointerstitial injury of type 2 diabetic nephropathy (DN). Methods 167 patients with type 2 diabetes and 50 patients without diabetes were recruited in this study from the Department of Nephrology of Daping Hospital from January of 2012 to December of 2015. The diabetic patients were categorized into normoalbuminuria group (n=56), microalbuminuria group (n=58), and macroalbuminuria group (n=53), among whom 51 patients received renal biopsies. Urinary NGAL levels were measured by ELISA, and urinary NAG levels were measured by the spectrophotometric method. Analysis was made for correlation of urinary NGAL with renal function parameters, and with renal histopathological sores. The value of urinary NGAL in evaluation of renal tubulointerstitial injury of DN was also analyzed. Results Urinary NGAL levels were elevated in diabetic patients compared with the non-diabetes control. Urinary NGAL levels were positively associated with both urinary NAG (r=0.528, P<0.001) and ACR (r=0.578, P<0.001), and negatively associated with eGFR (r=-0.637, P<0.001). Urinary NGAL levels were significantly correlated with scores of renal tubular atrophy and interstitial fibrosis (r=0.652, P<0.001) in DN. Urinary NGAL had the largest area under the curve (AUC=0.868), with a specificity of 94.7% and a sensitivity of 71.9%. Conclusion Urinary NGAL could serve as one of the most ideal biomarkers for evaluating the tubulointerstitial injury in DN. Key words: Neutrophil gelatinase-associated lipocalin; Diabetic nephropathy; Renal tubulointerstitial injury; Biomarker