Any treatment that removes or destroys much of the
thyroid ( such as surgery or radioactive iodine) does require treatment
for life with T4 hormone. However in certain situations, Hypothyroidism is temporary, you may need thyroxine for a time, but can later stop taking it. Sometimes, the fact that you no longer need the medication is obvious. but other times you and your doctor may decide to attempt a trial period off thyroid hormones for four to six weeks to see if you still need it.