Clinical significance of urinary enzymes and beta 2-microglobulin following ESWL

To examine the renal damage caused by shock waves, urinary excretion of enzymes and beta 2-microglobulin were determined before and after ESWL. Urine samples were obtained from 35 patients with renal stone and 26 patients with ureteric stone treated with ESWL. Urinary lactate dehydrogenase (LDH) levels significantly increased on day 0, just after ESWL, in both groups. In the ureteric stone group the kidneys received less shock waves than in the renal stone group. Increased urinary lactate dehydrogenase was considered to have derived from erythrocytes in urine. Elevated urinary N-acetyl-beta-D-glucosaminidase (NAG) levels were also observed on day 0 after ESWL in both groups, due to unknown reasons. Indirect effect of ESWL through the sympathetic nervous system or humoral factors may contribute to increases in the urinary excretion of NAG. No significant increase was found in urinary gamma-glutamyl-transpeptidase (GGTP) levels for 5 days after ESWL. Urinary beta 2-microglobulin (BMG) levels increased on day 0 in the renal stone group alone. In our present study, the clinical significance of urinary enzymes and BMG was not well evaluated, because urinary excretion of these indicators following ESWL were transient and mild.