Kidney stones are on the increase in children, and the experts can only guess why.
And at Children's Hospital of Philadelphia, the number of children with kidney stones has gone from ten a year to five a week in just the past four years.
And it's about the same at four other hospitals across the country, according to a survey by the Associated Press.
No one knows exactly why, but one researcher is investigating whether it's the salt in kids' food. A diet high in salty foods like fries and packaged noodles can lead to too much calcium, which can turn into kidney stones. The best way to avoid kidney stones is to drink lots of water. For an average 10-year-old, that's about four cups of water a day.
"What I like to tell kids," said Dr. Hatch, "is that they should drink enough water to keep their pee almost clear"
Most of the kidney stones in children are small, but they still can be incredibly painful. Treatment begins with pain medication to see if the stones will pass. If they don't, then surgery is required.