Radioactive iodine (RAI) therapy can treat hyperthyroidism (overactive thyroid) and certain types of thyroid cancer.

The term “radioactive” may sound frightening, but it’s a safe, generally well-tolerated treatment. It targets thyroid cells specifically to permanently destroy them. There’s little exposure to the rest of your body’s cells. Still, there are certain precautions you’ll have to take because you can emit (give off) small amounts of radiation that could affect other people.

Your thyroid gland needs iodine to make thyroid hormones. You typically get the iodine you need naturally through the foods you eat and iodized salt. In RAI therapy, your thyroid takes up radioactive iodine, which kills thyroid cells using radiation. It’s a type of nuclear medicine treatment.

Procedure Details

• Blood tests to check your thyroid hormone levels.
• Stopping any thyroid-suppressing medicines (propylthiouracil or methimazole) at least one week before the procedure.
• Following a low-iodine eating plan for one to two weeks before the procedure. Your healthcare provider will let you know which foods to avoid. 
• Receiving injections of thyroid-stimulating hormone (TSH) to increase how much radioactive iodine your thyroid will absorb.
• If you’re currently breastfeeding and are willing to stop, you’ll need to stop at least six weeks before the procedure.