My Pdoc did a baseline blood test for Thyroid prior to starting Lithium as it can wreck your thyroid function and you could need Thyroid medication for life.

I did a blood test 2 weeks after starting then was increased to 600mg 2 weeks later had blood work and I was in the low range and I stayed there. After that point I did blood work every 4-6 months.

Every Pdoc has there own way of managing people on Lithium.

I am no longer on Lithium.