In the early 1980s, getting a kidney stone removed often meant painful open surgery. Then came shock wave lithotripsy. This revolutionary technology uses sonic waves to blast kidney stones into tiny grains of sand. No surgery is needed.
It has always seemed to be safe. But now there's disturbing new data from a Mayo Clinic study. The study appears in the May issue of the Journal of Urology.
Shock Wave Damage
The study compared kidney stone patients treated in 1985 with shock wave lithotripsy to patients given other nonsurgical kidney stone treatments that same year. Nineteen years later, the shock wave patients were nearly four times more likely to get diabetes. And, if both kidneys were treated, the patients were 47 percent more likely to have high blood pressure.
It's not yet clear how shock wave treatment might cause these problems, says researcher Amy E. Krambeck, M.D. What seems to be happening is collateral damage from the shock waves.
"The theory is that the shear forces related to shock wave lithotripsy can cause tissue damage," Krambeck tells WebMD. "Damage to the pancreas could put patients at risk for diabetes."
Patients who got the most shock wave treatments — at the highest intensity — had the highest risk of diabetes.
Don't Suspend Treatment
The shock wave machine used in 1985 is an older model. It's still in use at the Mayo Clinic, Krambeck says. Newer shock wave machines give a more focused shock — but also provide stronger shock waves. Because the Mayo Clinic study is the first to link diabetes to shock wave treatment, it's not at all clear whether newer machines provide less risk, the same risk, or more risk.
Krambeck says much more study is needed. In the meantime, she says, there's no reason to stop using the machines for patients with large kidney stones.
There's no immediate danger for people who've had their kidney stones treated by shock wave, says Glenn Preminger, M.D. Preminger chairs the American Urologic Association's kidney stone treatment panel. He's professor of urologic surgery and director of the comprehensive kidney stone center at Duke University.
"Prudence — and the need for surveillance — is warranted," Preminger tells WebMD. "But we do not need to suspend shock wave lithotripsy or rush to the doctor at this point. Any stone-forming patients should have routine follow-up with their physicians. As part of that routine care, we would look for the possibility of high blood pressure and diabetes. So what I recommend is prudent follow-up care."
There are different kinds of kidney stones — and different treatment options.
"There are 101 ways to form a kidney stone," Krambeck says. "It all has to do with genetic makeup, diet, and lifestyle. Once a person forms a stone, he or she needs a complete metabolic evaluation to understand why. Then we can give medication to prevent a second stone."
Some kinds of kidney stones can be prevented with medication or proper diet. But when a stone can't be prevented or easily passed in the urine, treatment is necessary. The options:
The surgical options are a lot less invasive than in the past — but they are still more invasive than shock wave lithotripsy," Preminger says. "It is a terrific alternative to standard surgery. It is essential that patients be made aware of these possible new risks. But we should not discontinue shock wave treatment."
SOURCES: Krambeck, A.E. Journal of Urology, May 2006; Vol. 175: pp 1742-1747. Amy E. Krambeck, M.D, Mayo Clinic, Rochester, Minn. Glenn Preminger, M.D, professor of urologic surgery and director, comprehensive kidney center, Duke University, Durham, N.C.; and chairman, nephrolithiasis panel, American Urologic Association.
By Daniel J. DeNoon
Reviewed by Louise Chang, M.D.
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