Urine neutrophil gelatinase-associated lipocalin (NGAL) measurement is not predictive for ureteral patency in pediatric patients following pyeloplasty: a pilot study

Objective: To evaluate the benefit of urine neutrophil gelatinase-associated lipocalin (NGAL) measurement to predict the ureteral patency in pediatric patients undergoing pyeloplasty. Materials and Methods: Ureteropelvic junction obstruction patients who underwent unilateral dismembered pyeloplasty had urine NGAL measurements taken intraoperatively during pyeloplasty and postoperatively at six months following surgery. All patients were evaluated preoperatively and postoperatively with renal scans. Pairwise comparisons and correlation analyses were performed to determine the dynamics and benefits of urine NGAL measurement. Results: Thirteen patients were included in this pilot study with a mean age of 3.2 years at surgery. Mean intraoperative bladder urine level was 4.43 ng/mL, and median intraoperative renal pelvic urine NGAL level was 3.70 ng/mL. There was no significant difference between these two levels (p-value = 0.76). Six months after pyeloplasty, 9/13 patients demonstrated significant reduction in the bladder urine NGAL level (at least 50% reduction), and 5/13 patients showed ureteral patency based on postoperative renal scan (more than 5% improvement in differential renal function or the conversion of diuretic half time. However, the finding of significant reduction of urine NGAL level did not correlate with ureteral patency (r = -0.50, p-value = 0.08). Conclusion: Although bladder urine NGAL level reduces in most pediatric patients following pyeloplasty, this decline is not reflective of the finding of ureteral patency from renal scanning. The benefits of urine NGAL measurement in this context remain unclear and require further large-scale investigation.