Shock wave therapy for kidney stones linked to increased risk of
1 May 2006
Researchers at Mayo Clinic in the USA have issued an alert about the side
effects of shock wave lithotripsy, a treatment for breaking up kidney stones
using high energy pressure waves propagated through water.
The researchers found the treatment significantly increased the risk for
diabetes and hypertension later in life. The risk for diabetes was related
to the intensity of the treatment and quantity of the shock waves
administered; hypertension was related to treatment of stones in both
The shock waves break up an impassable kidney stone into smaller,
sand-like pieces that can be passed spontaneously, usually within a month.
The patient and the lithotriptor, the device that emits the shock waves, are
placed in a water bath. Water allows easier conduction of the shock waves
through the patient’s tissue and to precisely focus on the kidney stone.
“This is a completely new finding,” says Amy Krambeck, M.D., Mayo Clinic
urology resident and lead study investigator. “This opens the eyes of the
world of urology to the fact that hypertension and diabetes are potential
side effects. We can’t say with 100% certainty that the shock wave treatment
for the kidney stones caused diabetes and hypertension, but the association
was very strong. The risk of developing diabetes after shock wave
lithotripsy is almost four times the risk of people with kidney stones
treated with medicine, and the risk of developing hypertension is one and
one-half times, which is a significant risk increase.”
The study, which is the first examination of the effects of shock wave
lithotripsy over the long term, involved reviewing charts of 630 patients
treated with shock wave lithotripsy in 1985 at Mayo Clinic. The researchers
sent those still alive a questionnaire; almost 60% responded. The
researchers matched the patients treated with lithotripsy to patients
similar in age, gender and initial time of seeing a urologist for kidney
stones who received a different treatment, medicine. Nineteen years
post-treatment, those treated with lithotripsy had 3.75 times the risk of
having diabetes as those given the other kidney stone treatment. The degree
of increased risk rose with greater number and intensity of shocks
administered. Those treated with lithotripsy also had 1.47 times the risk of
having hypertension — high blood pressure — than those who received the
other kidney stone treatment; risk was highest for those who had both
The researchers hypothesize that the increase in risk for diabetes
associated with shock wave therapy for kidney stones relates to damage
inflicted to the pancreas, a previously known risk of lithotripsy, which may
affect the islet cells in the pancreas that make insulin. They believe the
increased risk for hypertension may relate to scarring, which the treatment
may cause to the kidneys and could alter the secretion of hormones centred
in the kidneys like renin, which influence blood pressure.
Drs. Krambeck and Joseph Segura, M.D., Mayo Clinic urologist and study
investigator, say that they continue to use shock wave treatment, among
other alternative treatments for kidney stones.
“Despite the risks, shock wave therapy still can save the day for
patients, and it would be a mistake to put it on the shelf,” says Dr.
The researchers indicate that they now counsel patients about the
potential risk for diabetes and hypertension prior to shock wave treatment.
Dr. Segura stresses the need for kidney stone patients and their
physicians to weigh the pros and cons of shock wave treatment according to
individual situations. “It’s a trade-off about whether the risks are worth
taking,” he says.
“We’re assuming doing nothing is not the right thing to do for patients.
You have to look at it in terms of treatment alternatives — percutaneous
stone removal (removing a kidney stone through a small incision in the
patient’s back using an instrument called a nephroscope) or ureteroscopy
(snaring a stone with a small instrument passed into the ureter through the
bladder and then breaking up the stone with ultrasound or laser energy) —
each of which has its own set of risks.”
Early shockwave therapy, introduced in the 1980's used electrohydraulic
energy, in which an electrical discharge in a water-filled container created
a vaporization bubble that rapidly expanded then collapsed, generating a
pressure wave. Newer models use high frequency electrical signals in
piezoelectric crystals or an electromagnetic coil connected to a membrane to
produce the shockwave. Newer models have a smaller focus zone, which could
result in less side effects.
The Mayo Clinic researchers examined the long-term effects of lithotripsy
for patients treated with a 1985 lithotriptor, one of the early models, in
this study. Drs. Krambeck and Segura say additional research studies,
including research on newer machines and different models, are needed on
shock wave therapy and risk for diabetes and hypertension later in life.
Prior to age 70, approximately 10% of men and 5% of women will experience
a kidney stone, according to the National Institutes of Health. About 1
million people in the United States have had shock wave lithotripsy, says