There are rising instances of children and teens with kidney stones, particularly girls, according to research data, leading doctors to question why.

The age-old reasons for kidney stones — metabolic syndrome, obesity, hypertension, and diabetes — are not factors either, piquing the interest of the medical researchers, NBC News reported.

"In children, we're not seeing that," Children's Hospital of Philadelphia Dr. Gregory Tasian told NBC. "They're otherwise healthy and simply come in with their first kidney stone for unclear reasons.

"Clearly something has changed in our environment that is causing this rapid shift."

About 30 years ago, kidney stones were more of an middle-aged white man concern, according to the report.

Kidney stones are hard deposits that cause problems and pain when they get caught in the urinary tract.

Medical researchers are pointing to a number of dietary factors causing the uptick in kidney stones among the young, including ultra-processed foods, early life antibiotics use, and even climate change. The latter is being blamed under the belief that dehydration is causing kidney stones, according to the report.

There is data showing increased cases in the summer months and warmer areas, including the southern U.S. states, becoming known as the "kidney stone belt."

But that does not explain the increased risk of young girls.

Kidney stone cases rose 16% from 1997 to 2012, with 15- to 19-year-olds seeing the highest increases, and incidences being 52% higher among girls and young women, according to research published in the Clinical Journal of the American Society of Nephrology.

Data shows the men 25 and older then being at higher risk.

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