This week I visited the Children's Hospital of Philadelphia and spent time in their pediatric urology clinic. The doctors there have seen a sudden rise of kidney stones in children -- increasing from five cases a month to now four cases a week. That is a dramatic change!

What I expected to see in the clinic were overweight teenage boys who eat too much junk food and get too little exercise. What I saw and heard from the doctors was something all together different: I met teenage girls who were athletic and skinny, and on the surface didn't look like they would be at risk for anything.

But the culprit lingered just below the surface. These girls love junk food, sports drinks, and soda. The common denominator? Salt.  They are exchanging water for drinks high in salt.

For all of us, our kidneys filter our blood, clear the impurities, and make urine. When we don't drink enough water, calcium leaches out and can cause stones. If the stones aren't passed through the system they may have to be removed surgically. None of the options are great and the pain these kids feel is tremendous.

This is one of those times when prevention is even more important than treatment. Now pediatricians are urging all kids to drink at least four tall glasses of water a day. And the best test is one that is tried and true: look at the color of your or your child's urine. If it is pale yellow or clear...that's good. If it is straw colored, the system is down some....and you need to make your way to a water fountain.