Differences in Urine NGAL Levels in Patients Undergoing RIRS With or Without Ureteral Access Sheath

This study will include patients aged between 18 and 65 who will undergo retrograde infrarenal surgery (RIRS) due to renal stone(s). A total of 60 patients (male or female) will be recruited, and will be randomized into 2 groups consisting of 30 patients in each group. The first group of patients will undergo RIRS with a ureteral access sheath (UAS) positioned prior to surgery; and the second group will undergo RIRS without UAS. As use of UAS decreases the pressure in the renal pelvis during RIRS, it is aimed to evaluate whether using UAS or not affects the kidney functions. besides the routine kidney function tests, namely urea and creatinine, neutrophil gelatinase-associated lipocalin (NGAL) (a more specific and early marker of kidney function) will be used to assess the differences in the kidney functions. Preoperative blood urea and creatinine levels and urine NGAL levels will be studied for all patients. After the surgery, blood urea and creatinine levels will be again studied as well as urine NGAL levels at postoperative 2nd hour, 72nd hour and 1st week.