The diagnostic accuracy of urinary neutrophil gelatinase-associated lipocalin in assessing kidney function in severe hydronephrosis.

Background: Up to now, there is no perfect indicator to evaluate the renal function of severe hydronephrosis, which poses difficulties in the selection of clinical treatment decisions. This study investigates the role of neutrophil gelatinase-associated lipocalin (NGAL) in urine drained from the nephrostomy tube shortly after nephrostomy to evaluate the renal function of patients with severe hydronephrosis caused by ureteral obstruction.

Methods: The clinical data, and blood and urine samples of 24 patients with severe hydronephrosis due to ureteral obstruction were retrospectively collected. The NGAL in the urine drained from the nephrostomy tube on the morning of the first day after the procedure was measured. The glomerular filtration rate (GFR) was determined using a nuclear scan, and the clearance rate of creatinine was calculated based on nephrostomy drainage. The correlation between the NGAL level, urine volume post-nephrostomy, affected side GFR, and creatinine clearance rate (Ccr) was assessed. Moreover, the relationship between the urinary NGAL levels and prognosis was analyzed based on whether the patients underwent nephrectomy.

Results: There was a significant correlation between the urine NGAL from the nephrostomy of the affected side and the Ccr and urine volume post-nephrostomy (both P<0.05). Compared with the patients in the kidney preservation group, those who underwent nephrectomy had significantly increased NGAL levels, and significantly reduced Ccrs and nephrostomy drainage urine output. Through the receiver operating characteristic (ROC) curve evaluation, the efficacy of NGAL in predicting nephrectomy was found to be superior to both the Ccr and urine output, with an area under the curve (AUC) of 0.845.

Conclusions: The NGAL in the urine shortly after nephrostomy may indicate severe renal functional deterioration.