The reason you have to have Lithium levels checked regularly is to ensure you don't have a toxic level of Lithium in your system. Lithium toxicity can be as mild as a stomachache or as serious as kidney or liver damage/failure. I've been on Lithium for almost a year now, and I get bloodwork done every three months. The only thing I have to be careful of is to not over exert myself, because getting overheated can cause you to go toxic as well.

Depakote can affect the kidneys and liver as well, but not to the extent of Lithium. When I was on Depakote, I think I only had one blood draw in 6 months, and that was at 6 weeks to make sure the dose was proper.

As far as Lamictal, that was one I was never prescribed. I've been given pretty much everything under the sun until I was properly diagnosed bi-polar, and Lithium is my miracle drug.