What should I think about if I have radioiodine for hyperthyroidism?

Most people—depending on their ages, how much thyroid hormone their bodies make and other health conditions they have—are treated first with radioactive iodine.

Radioactive iodine is often recommended if you have Graves' disease and are older than 50, or if you have thyroid nodules (toxic multinodular goiter) that are releasing too much thyroid hormone. Radioactive iodine is not used if:

• You are pregnant or you want to become pregnant within 6 months of treatment.
• You are breast-feeding.
• You have thyroiditis or another kind of hyperthyroidism that is often temporary.

You may take antithyroid medicine for several weeks or months before treatment with radioactive iodine. The antithyroid medicine will lower thyroid hormone levels in your body and will also lower your chances of having a more serious problem called thyroid storm. You may also take additional medicines that can make you feel better and help your thyroid return to normal before you are given radioactive iodine.

Radioactive iodine has been used to treat hyperthyroidism for more than 60 years. There is no evidence that radioactive iodine causes cancer, infertility or birth defects.

If you have had radioactive iodine treatment and you want to travel within a few days after treatment, prepare for any problems you may have at airport security. People who have had radioactive iodine treatment can set off the radiation detection machines in airports.

If you plan to travel within 5 to 7 days of your radioactive treatment:

• Check with local authorities about special procedures or considerations.
• Ask your doctor to write a letter describing the radiation isotope used, the date and time of treatment, the dose and its biological half-life (how long it takes for half of the radioactive iodine to be eliminated from the body). The letter should include your doctor's 24-hour telephone numbers so that authorities can call your doctor if they need to verify the information in the letter.
• Keep in mind that you will have to wait for permission to travel.