Radioactive Iodine TreatmentIn the United States, Radioactive Iodine (RAI) is a common treatment for most people with Graves' disease and hyperthyroidism. Some other terms sometimes used to describe RAI include:
- radioiodine ablation
- radioactive iodine ablation
- thyroid ablation
- ablation therapy
- chemical thyroidectomy
- chemical surgery
- radioactive cocktail
Whether or not to continue using antithyroid drugs right up until RAI is controversial. Some practitioners recommend using the antithyroid drugs right up until the surgery, to keep the thyroid somewhat suppressed so that there is not a flare-up on hyperthyroidism post-RAI. Others discontinue antithyroid drug use prior to RAI, because of evidence that antithyroid drugs may reduce the effectiveness of RAI. Specifically, according to research, methimazole and carbimazole can be taken up to 3 to 5 days before RAI without reducing the effectiveness of the RAI, but because PTU takes longer to clear out of your system, it should be stopped at least two weeks before RAI. (Note: Some practitioners will switch their PTU patients over to Tapazole in the weeks prior to RAI, so that antithyroid drug therapy doesn't need to be stopped quite so early.)
In the United States, patients receiving doses of RAI less than 30 millicuries are not hospitalized. In Europe, most RAI patients are hospitalized to avoid exposing others to radiation.
If you have RAI in the United States, your doctor will discuss the radiation level and any precautions you might need to take to protect your family or the public.
Generally, however, in the first 24 hours after RAI, avoid intimate contact and kissing. In the first five days or so after RAI, limit exposure to young children and pregnant women, and, in particular, avoid carrying children in a way that they will be exposed to your thyroid area. Also avoid any thyroid-to-thyroid contact. Experts recommend that you drink a lot of water -- some say at least 4 glasses a day -- to help flush the RAI out of your system, sleep alone and use a bathroom apart from the rest of your family, if possible.
A very small percentage of patients are at risk of life-threatening thyroid storm after RAI. Read this article on Thyroid Storm for an overview of the risks and symptoms.
RAI can have some side effects, including nausea, vomiting, sore throat and swelling of saliva glands, but they are usually temporary.
The effects of RAI on the thyroid may begin to be felt as early as four weeks after treatment, and some patients become hypothyroid soon thereafter. It usually takes two to three months for the RAI to effectively slow down the thyroid in most patients.
Ultimately, most patients do become hypothyroid. Research has shown that, in fact, 25 to 50% of patients are hypothyroid a year after RAI, and 5% more become hypothyroid each year, for 10 years; 90% are hypothyroid. Periodic evaluation of thyroid function is, therefore, important, and once hypothyroidism is detected, patients should start thyroid hormone replacement to prevent symptoms of an underactive thyroid.
An estimated 30% of patients who receive RAI will actually need a second RAI treatment later. Typically, these patients had a small initial dose, had a very enlarged thyroid or other complicating factors.
There is a degree of controversy over RAI. The majority of North American endocrinologists tend to prefer RAI -- almost always as a permanent, irreversible treatment -- versus antithyroid drugs. Many also believe it is safe to use in women of childbearing age and children. This is in contrast to Europe, where antithyroid drugs are the preferred first treatment, and RAI and surgery are used for those patients who don't respond to the medication. European endocrinologists also tend to be more cautious and are far less likely to use RAI in women of childbearing age and children. Some more cautious practitioners in the United States, however, recommend that the first episode of Graves' disease should always be treated with antithyroid drugs. The key exception is in the case of patients 50 and older, who frequently should have RAI to reduce the possibility of hyperthyroidism-induced atrial fibrillation.
Additional information on the controversies over RAI is featured in the following articles: