Extracorporeal shock wave lithotripsy (ESWL) is an effective method to treat kidney stones. The soft tissues surrounding the kidney may be damaged as the shock wave passes through on its way to the stone. We measured serum myoglobin concentration to assess skeletal muscle damage as a side effect of ESWL in patients treated for stones in a solitary kidney using shock waves generated at 19 kV with two different total impulse counts - 4000 or 2000 -applied in one session. Sixty-six patients, aged 35-65, were studied. Twenty four patients were excluded with signs of urinary tract infections. Patients were randomly assigned to either 2000 or 4000 impulse count treatment groups. Serum myoglobin concentration was measured by RIA. In the 4000 impulse treatment group, mean serum myoglobin was 75.2±29.8 ng/ml before ESWL, was 82.2±33.7 ng/ml(9.3% increase from baseline) on day 1 after ESWL, and was 93.0±44.9 ng/ml (23.7% increase from baseline) on day 3 after ESWL. In the 2000 impulse treatment group, mean serum myoglobin was 86.6±27.2 ng/ml before ESWL, was 96.2±41.2 ng/ml (11.1% increase from baseline) on day 1 after ESWL, and was 78.9±36.9 ng/ml (8.9% decrease from baseline) on day 3 after ESWL. Changes within and between treatment groups were not statistically significant (p>0.05). These small increases in serum myoglobin concentration after ESWL may indicate skeletal muscle damage. Greater and more persistent increases in serum myoglobin seen after a greater number of impulses applied may indicate more muscle damage. Normalization of serum myoglobin concentration indicates that this damage is transient and ESWL produced no evidence of permanent skeletal muscle damage at the doses used. Moreover, we found no statistical difference in serum myoglobin concentration within groups or between groups.

Keywords: kidney stones, treatment, extracorporeal shock wave lithotripsy (ESWL), complications