Urinary neutrophil gelatinase-associated lipocalin level as a biomarker of acute kidney injury following extracorporeal shock wave lithotripsy

INTRODUCTION: Although extracorporeal shock wave lithotripsy (ESWL) is minimally invasive and highly efficient for the management of kidney stones, adverse effects have been described. Available indicators of renal function exhibit insufficient sensitivity in acute renal injury (AKI). We aimed to evaluate the severity of the kidney tissue response to ESWL injury by measuring the urinary neutrophil gelatinase-associated lipocalin (uNGAL), which can indicate AKI in its early phase. MATERIAL AND METHODS: The prospective, controlled study included 62 patients with nephrolithiasis undergoing single ESWL treatment. uNGAL level was measured before the procedure, and 6 h and 12 h after. RESULTS: The median uNGAL level increased by 126.0%, 6 h after ESWL (p <0.001). The growth rate continued and 12 h after was higher by 583.7%, compared to the pre-treatment level (p <0.001). The median value of estimated glomerular filtration rate (eGFR) dropped by 15.3% 12 h after the treatment (p <0.001). It increased by 5.0% in the period 7 days to 3 months after (p <0.001) and after 3 months it was lower by 10.1% compared to pre-ESWL values (p <0.001). uNGAL level after 12 h was significantly negatively associated with eGFR, 12 h, 7 days and 3 months after the ESWL. The sensitivity of uNGAL 12 h after ESWL was 60.6%; its specificity was 75.0%, with a positive predictive value of 74.0% and negative predictive value of 61.7%. CONCLUSIONS: uNGAL appears to be a useful biomarker for the assessment and prediction of AKI. It was noticed that uNGAL had the highest predictive value 12 h after the ESWL treatment.