Actually, it is not to increase your salt intake, but decreasing it can be a problem, my brother tends to salt his food, I don't, we thought he shouldn't use salt if food is already salted, but he said his pdoc told him not to stop using salt.
I do not remember how it goes, Larry Hoover could probably explain or look up stuff by "Mougens?" I'll get back to you if interested, my mind can't remember the pdoc/researcher's name. Anyhow, reducing salt (sodium) intake can be a problem, something to do with the body/brain grasping or bonding onto a sodium (molecules) upsets the balance,
"Larry, help me with this", y'all know Larry Hoover and his expertise right?
So that is where the salt intake/reduction thing comes in.
100mg per day? wow, that is really low and shouldn't present any problems. I had been on a total per day 900mgs (300mgs 3x a day) then gradually was lowered to 1 (300mgs) per day, then switched.
It is an excellent med for Bipolar disorder, hs the longest track record, if prescribebd properly, titrated gradually, the risk of side effects can be mild or nothing.
I wish you all lots of luck with meds and/or treatment, we can get through this
Oh, some of the books I listed at the top have explanation on Lithium and sodium intake, I am sure there are some med sites on the internet that can explain some things you may want to know about.
Take good care now,
DE

(((((((((( Bama )))))))))))