I believe it. The ONLY side-effect I have with Lamictal is related to dehydration, which is probably related to my kidneys working extra hard.
My side-effects are: dry-mouth, easily dehydrated, increased thirst, increased urination. Basically all the same, the lamictal is dehydrating. I try to drink as much water as possible, but I still get dehydrated fairly often. I need to drink even more water.

My dad used to drink sweet tea all year every day, instead of water. He got real bad kidney stones, and the doctors told him to drink plain water, and cut out the sugary drinks.