April 29, 2012
“I have a 5mm caclculi stone in my left kidney (non-obtrusive). Unfortunately, I have not been able to pass this naturally by drinking large amounts of water each day. I am considering having shockwave treatment for this since I don’t want surgery. Could please outline some of the risks with this option (such as diabetes and hypertension)?”
A paper which was published in 2006 (Krambeck and colleagues) first reported on a worrisome potential link between shockwave lithotripsy and the development of diabetes or hypertension. In their study, they compared patients with kidney stones who underwent shockwave versus another group of kidney stone patients who did not receive surgery but were instead observed. Those who underwent shockwave lithotripsy were found to have a higher occurrence of diabetes and hypertension than those that were observed. However, an important flaw of the study was that the two groups aren’t necessarily that comparable. The patients that were observed for their stones were observed for a reason- they typically had smaller stones or other reasons why their urologists felt that surgery was not needed. Because stone disease is itself more common in patients with diabetes or hypertension, what the study may have been actually measuring is that those with larger or more symptomatic stones are more likely to have hypertension or diabetes – not that shockwave lithotripsy is actually causing hypertension or diabetes. Indeed, some subsequent studies on this subject reported opposite results that suggest that shockwave lithotripsy is not associated with the development of diabetes or hypertension.
Based on the available data, the risk of developing diabetes or hypertension because of shockwave lithotripsy is likely slim to none. Unfortunately, we all really can’t know for sure unless long term studies can be completed in which large numbers of patients with stones are randomized into observation, shockwave lithotripsy, or ureteroscopy. These patients would then have to be followed for 10 to 20 years to see who develops diabetes or hypertension. As you can guess, this type of study would be difficult to complete.
The common mistake that can occur with assuming that things that are associated with each other is equivalent to saying that one thing causes another has been called the “correlation fallacy“. (Correlation is a technical term for association). A simple example of this involves ambulances and car accidents. If you visited a lot of car accident scenes, you’d probably notice that there are often ambulances there. If you knew nothing about car accidents, you might then make the wrong assumption that just because ambulances were highly associated with car accidents, that they are actually the cause of the accidents.
In our “Ask KidneyStoners.org” section, we field questions from stone formers or their family members. See previous questions and answers here.