Treatment for Grave's Disease

[ecl39]

Hello everyone, I have two main questions:
1. Do you have to be euthyroid in order to have radioactive iodine treatment done for Grave's disease?
2. Is it possible for your thyroid to build up an immunity/tolerance to Methimazole?

I'm 24 years old, female. I was diagnosed with Grave's 2.5 years ago. It was pretty bad when I was first diagnosed. My ft4 exceeded what the test was able to measure (40). I was taking 90 mg of Methimazole a day for a while until my symptoms became less severe. I gradually decreased it to 15mg and my TSH, while still in the normal range, became quite a bit higher. My ft4 levels decreased to about 0.6. At that point I was feeling hypothyroid, so my endo decreased me to 10mg. Almost immediately my hyperthyroid symptoms reappeared, so she increased me back to 15mg. Over the course of about 2 or 3 months, I noticed my symptoms were reappearing again, even at the 15mg. My labwork confirmed that I was becoming hyperthyroid again; my ft4 was above 2, exceeding the normal range. So I recently increased my methimazole yet again to 20mg and I am seeing a new endo this week to get a second opinion. Should I be worried that my thyroid suddenly stopped responding to the 15mg? Could my symptoms reappear even after increasing it again? And do I have to wait for everything to stabalize before radioactive iodine is an option?

Any help is greatly appreciated. Thank you!!

[Red_Star]

Anything that affects the immune system (eg: stress) could be a cause. Stress worsens my thyroid symptoms that's for sure! :)

[ecl39]

Thank you for your reply and for the suggestion & helpful information/links! I had never heard of block and replace therapy before; I'll definitely have to look into it. I'm just so confused as to why my thyroid, which had previously been regulated just fine at 15 mg of Methimazole, would suddenly start to become overactive again at the very same amount of Methimazole.

[Red_Star]

I'd say no to both questions. You could also try 'block and replace' therapy where you take a high dosage of anti-thyroid medication which stops your thyroid gland making any thyroxine and then take thyroid medication to keep your blood level normal.

Excerpts from MyThyroid - Frequently Asked Questions on Radioactive Iodine...

"The principle advantage of Radioactive Iodine treatment for hyperthyroidism is that it tends to have a much higher success rate than medications. Depending on the dose of radioactive iodine chosen, and the disease under treatment (Grave's vs toxic goitre, vs hot nodule etc), success rate in achieving definitive resolution of the hyperthyroidism may vary from 75-100%. A major expected side effect of radioactive iodine in patients with Graves disease is the development of life long hypothyroidism requiring daily treatment with thyroid hormone."

"What are the factors associated with a positive outcome after radioactive iodine? The amount of radioactive iodine administered, severity of existing hyperthyroidism, size of the thyroid, and gender are all factors that influence success of treatment, and provide guidance for the suggested dose of radioactive iodine to be administered."