I had RAI and I had a few problems at the start of the Thyroxin absorbing so my Doctor recommended taking
/D3 combination and since taking Calcium
/D3, my levels evened out and I am doing great.
I even tried taking the thyroxine at night and it did help somewhat but am now back to taking Thyroxin when I wake and Calcium before bed.
It is also important to get checked for any vitamin deficiences.
Zinc, magnesium, calcium, B vitamins, Selenium, Cortisol levels too.