However, even though kidney stones are also increasing in many areas in the world, for many reasons, the results should not be generalized beyond the United States, he noted.

“This study is an important step forward in understanding the changing epidemiology of kidney stone disease,” Dr. Charles D. Scales, of Duke University Medical Center in Durham, North Carolina, told Reuters Health by email. The underlying causes of the increase are unclear. “In adults, it may be related to the tidal wave of obesity and diabetes in the United States,” said Dr. Scales, an expert in kidney stones who was not involved with the study.

These epidemiologic trends provide more support for the concept that “chronic and poorly understood metabolic derangements are likely causing all of these new stones in previously low-risk individuals,” he said.

Increased consumption of high-sodium processed food and dehydration also may be contributing factors, he added. “Emerging evidence suggests that a kidney stone may foreshadow future medical problems, such as heart disease, bone density loss, and chronic kidney disease,” Dr. Scales said. “So from the public-health perspective, the worst may be yet to come as these teenagers with stones become adults.”

The study had no commercial funding and the authors reported no disclosures.