NEW YORK (Reuters Health) Oct 14 - Once patients have had kidney stones they seem to have a heightened risk of gallstones -- and vice versa, according to a new study. Even after adjustment for weight, diabetes status and diet, the link remained.
The report "raises our antenna to this shared relationship between these two disorders," said Dr. Brian Matlaga, a urologist at the Johns Hopkins University School of Medicine in Baltimore.
"From an anecdotal standpoint, certainly it's not an uncommon scenario that a patient would have had both," Dr. Matlaga, who wasn't involved in the new research, told Reuters Health.
But he described himself as "a little bit at a loss trying to define what that relationship would be," since kidney stones are usually formed of calcium and gallstones of cholesterol.
Data for the current analysis came from three different long-term health studies of more than 240,000 nurses and doctors who were followed for between 14 and 24 years.
Over that time, about 5,100 people had new-onset kidney stones and close to 18,500 had new cases of gallstones.
On multivariate analysis, depending on the population -- male or female, older or younger -- people with a history of gallstones were between 26% and 32% more likely to get a kidney stone than people who hadn't ever had gallstones.
The link also went in the opposite direction. A history of kidney stones meant study participants were 17% to 51% more likely to report a new gallstone.
The researchers, led by Eric Taylor from the Maine Medical Center in Portland, said it's possible that a shift in gut flora might somehow predispose people to both kidney stones and gallstones. But, Dr. Taylor told Reuters Health, "the fairest thing is that we just don't know" why the two would be linked.
In their report September 23rd in the Journal of Urology the researchers echoed Dr. Matlaga's call for more detailed research into any explanations for a common cause.
"They are really two different kinds of stones, so the relationship is not going to be simple between the two conditions," Dr. Taylor said.
SOURCE: bit.ly/pMoRpk
J Urol 2011.