Lamictal plus Lithium works very well for many people - if you have to go on Synthroid, it is a small price to pay for stability. Lithium, unlike Depakote, does not increase the effect of Lamictal, so you will just titrate Lamictal up until you reach what is clinically an optimum dose for you. Lamictal does not come with a blood level test / range, unlike Lithium and Depakote, but you will know when you hit the sweet spot and it might even be that 75 mg is enough or that 100 mg is your sweet spot. Sex and swimming are wonderful things to do!!