Excretion of urinary protein induced by extracorporeal piezoelectric lithotripsy.

An investigation was carried out into renal injury caused by extracorporeal piezoelectric lithotripsy (EPL) using an EDAP lithotriptor. Four urinary proteins, with a molecular weight range of 160000-14500, immunoglobulin G (IgG), N-acetyl-beta-glucosaminidase (NAG), albumin and lysozyme, were monitored in 27 patients 1 day before and 1, 7, 30, 90 and 180 days after unilateral EPL treatment. All patients had non-obstructive renal stones, previously untreated. Apart from 5 patients with stablised hypertension and 6 with persistent urinary infections due to the infected stones, all patients appeared healthy, as confirmed by clinical, haematological and biochemical investigations. Only albumin levels increased significantly 1 day after treatment; statistically nonsignificant increases and decreases were recorded in the levels of NAG and lysozome respectively. IgG was beyond the limit of detection (less than 0.5 mg%) in all patients. The albumin level returned to normal 7 days after treatment. The EPL-induced increase in albumin was recorded in 88% of patients, compared with increased levels of NAG in 46% and lysozyme in 64%, mainly in those with infected stones. These findings indicated a transient glomerular injury after EPL treatment.