Shock-wave lithotripsy (SWL), a noninvasive technique that uses sound waves to sonically disintegrate stones within the urinary track, appears to increase the risk of diabetes and hypertension (high blood pressure), suggests a long-term follow-up study.

“This is a completely new finding,” lead author Dr. Amy Krambeck, from the Mayo Clinic in Rochester, Minnesota, said in a statement. “We can’t say with 100 percent certainty that the shock wave treatment for the kidney stones caused diabetes and hypertension, but the association was very strong.”

The findings are based on a study of 578 kidney stone patients who were treated with SWL in 1985 and sent a follow-up questionnaire in 2004. Roughly 59 percent of the subjects responded to the questionnaire. The control group consisted of 288 matched patients who had their stones treated nonsurgically.

At follow-up, SWL-treated patients were 47 percent more likely to have hypertension than were controls. The risk of hypertension was strongest with bilateral SWL, the report indicates.

SWL was also linked to diabetes. Nearly 17 percent of SWL-treated patients developed diabetes during follow-up and treatment with SWL more than tripled the risk of diabetes. The risk of diabetes was directly related to both the number of shocks given and the intensity of treatment.

SWL may promote hypertension by causing scarring in the kidneys and altering the secretion of blood pressure-modulating hormones, the authors hypothesize. The link with diabetes may relate to damage inflicted upon the pancreas, they add.

Senior author Dr. Joseph W. Segura, also from the Mayo Clinic, emphasized that the current findings do not mean that SWL should be abandoned. “Despite the risks, SWL still can save the day for patients, and it would be a mistake to put it on the shelf,” he added, noting that other therapies for stone removal carry their own risks as well.

SOURCE: Journal of Urology, May 2006.