my experience after being on 450mg. for more than 35 yrs. suggest you become as informed as you can, esp. in the areas of thyroid issues (put on synthroid)..had a great endocrinologist yrs. ago who connected parathyroid issues due to lithium and had most of the parathyroids removed (can't be totally w/o parathyroids) but take 500mg. calcium 3x day; and now, after being off lithium for 35 yrs., my blood work indicates some renal/creatin issues so i have to pee in a bottle for 24 hrs. and if the results are not good, then i'm to be referred to a nephrologist for kidney issues. i only had hypomania, no depression and that's why i was on such a low dose for many yrs. it worked for me, but i do have fears now about kidney damage which i understand is irreversible, even when off lithium. do your research. not many drs. know about the parathyroid issues tho most know about the thyroid issues caused by lithium.