Renal tubular damage after renal stone treatment

50 patients were studied with respect to renal tubular damage related to open operative, percutaneous and extracorporeal shock wave treatment of renal stones. Preoperative and postoperative urinary N-acetyl-glucosaminidase (NAG) levels were measured as a marker of renal damage. There was no significant evidence of renal tubular damage in patients who underwent a conventional or percutaneous nephrolithotomy; urinary NAG excretion was significantly increased after ischaemic surgery. After extracorporeal shock wave lithotripsy (ESWL) serum NAG levels increased, probably because a damage of the white blood cells in cutaneous and renal circulation, but a slight increase of urinary NAG excretion could suggest a mild renal tubular damage especially in case of more than 2,000 shocks.