RAI causes the thyroid gland to prematurely age and die, but unless you’ve had an ablative dose, your thyroid isn’t completely gone at first, even if you’re hypo and on replacement hormones.
Mine has died out gradually over a period of nearly three years, and my replacement dose has been continually raised. What you’re experiencing isn’t at all unusual, but it would be helpful if more doctors think to warn people of this possibility, which can prolong the adjustment period and subsequent return to health.
Hopefully this answers your question.
Dianne W
AOLF, NGDF