BOSTON -- Doctors are noticing a painful trend among children. Many think kidney stones is just a grownup problem.

But as NewsCenter 5's Heather Unruh reported Monday, there is a rise in the number of children being treated for kidney stones.

The pain began when Kara Cabana was 12-years-old, but it took doctors two years to figure out she had developed kidney stones.

"They were like, kids aren't supposed to have kidney stones at such a young age," said Kara Cabana, of Bellingham, Mass.

Dr. Avi Traum, a pediatric nephrologist with MassGeneral Hospital for Children, says kidney stones in kids has become a painful trend.

"Typically we think of middle-aged adults who develop stones, or pregnant women who get stones. But this is certainly a problem in pediatrics as well," Traum said.

Traum said two of the biggest risk factors for kidney stones is too much salt and not enough water.

"Kids aren't drinking as well. So, whatever is in your urine, like calcium, is going to be more concentrated," Traum said.

Most kidney stones form when minerals like calcium bind with the excess salt on the way out of your body. And passing a stone can be very painful.

"Sometimes it can be so severe that they go to the E.R., because they think it's appendicitis," Traum said.

Traum said one of the most important things you can do to prevent kidney stones from forming is to increase fluids.

"Anywhere from 1.5 to 2 liters of fluids in a teenager. In a school-aged kid, you can scale that down a bit to probably 1 to 1.5 liters," he said.

Cabana drinks a lot more water now, and watches what she eats. Even with medication, she still gets kidney stones, but less frequently.

"For now, it's help," she said. "I feel better."