Measurement of urinary N-acetyl-β-D-glucosaminidase to assess renal ischemia during laparoscopic operations

Background: Oliguria during laparoscopy is a well-documented phenomenon of unknown etiology. Experimental evidence suggests that renal perfusion is reduced during pneumoperitoneum. N-acetyl-β-D-glucosaminidase (NAG), which is present in renal tubular cells, is released into the urine in response to tubular insults. In this study, urinary NAG was measured before and after procedures to assess for ischemic renal injury. Methods: A total of 31 patients underwent laparoscopic procedures while 28 patients had conventional surgery. Urine was obtained first at the time of preoperative Foley catheter placement and later during the recovery room stay. NAG levels were measured and indexed to urinary creatinine. Results: Operative time for the laparoscopy group was 105 min (range, 15-255); for the conventional group, it was 179 min (range, 75-385) (P < 0.05). No differences were noted between pre- and postoperative NAG levels or between the groups. There was no correlation between urinary NAG levels and operative time. Conclusion: Pneumoperitoneum is not associated with a change in the urinary concentration of NAG. This finding suggests that there is no significant renal tubular injury associated with laparoscopic surgery.