Enzymatic evaluation of renal damage caused by different therapeutic procedures for kidney stone disease.

In an attempt to evaluate renal injury relative to open surgery, percutaneous nephrolithotripsy (PCN) and extracorporeal shock wave lithotripsy (ESWL) were studied in 52 patients with renal calculus disease. Preoperative and postoperative urinary levels of N-acetyl-glycosaminidase (NAG), a sensitive marker of renal tubular damage, were studied. No significant changes were noted in posttreatment urinary NAG values among patients who underwent ESWL or PCN. Although statistically nonsignificant, a constant mild increase of urinary NAG was observed after PCN, that has to be evaluated with long-term follow-up studies. The shock wave number or power in cases treated with ESWL as well as the number of renal punctures in the PCN group did not change the effect on renal tubular function. Diabetics and patients with chronic renal disease treated by ESWL did not show any significant change in posttreatment urinary NAG levels. In contrast to that, all patients treated by open surgery had significant, intense and prolonged increase of the postoperative NAG values, especially those treated by ischaemic nephrolithotomy. Comparing the three different therapeutic modalities, open surgical procedures had the most significant effect on renal function and this difference was statistically significant. We therefore suggest that ESWL does not endanger renal function, while open surgery must be reserved for selected cases.