According to an article in the NYTimes.com, more kids-- even as young as five or six--are getting kidney stones. Why the steep rise in kidney stones? Kids are consuming more salt in their diet and not drinking enough water.
I think it is a tough sell to convince school-age kids to drink more water. They'll tell you they don't have time to go to the bathroom. However, waiting until you are thirsty to drink could create problems later. Keeping hydrated is important to preventing kidney stones. Kids who play sports or are very active need to pay even more attention to how much water they drink.
Extra salt in the diet is also a problem. Stones form when substances like calcium crystallize in the urine. According to the NYT, "Excess salt has to be excreted through the kidneys, but salt binds to calcium on its way out, creating a greater concentration of calcium in the urine and the kidneys."
Excessive salt is hidden in many foods: chips, french fries, processed foods such as canned meats, soups, packaged meals. Parents and kids need to read the food and drink labels to see the salt concentration. Did you realize even the sport drink Gatorade contains more salt than kids need? Now researchers are also looking into the link between sucrose in sodas and kidney stones.
I used to think dairy foods could be a problem because of the calcium. According to the NYT, "Dairy products have been shown to reduce the risk of stones, because the dietary calcium binds with oxalate before it is absorbed by the body, preventing it from getting into the kidneys."
I also used to think kidney stones was a disease only involving older people. Obviously the trend is changing. A rise in the incidence of kidney stones is also happening to younger women in their 20s and 30s.
I am not a doctor or a medical professional. For more information on this health topic talk to your doctor.