sometimes hypothyroidism is caused by not enough iodine in one's system.
i take iodoral each day -- 1 - 12.5 mg tablet when i get up -- and another half a pill later during the day. i also eat seaweed -- to make sure there is enough iodine in my system each day.
hope that helps
Do you mean that you took the radioactive iodine pill years ago, and your thyroid was ablated?