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Radioactive Iodine for Thyroid Cancer

Treatment for Thyroid Cancer

Radioactive iodine therapy, often referred to as RAI, is used following surgery for certain types of thyroid cancer; specifically, follicular and papillary and may also be useful for some differentiated types.

Read about other treatments for thyroid cancer in our Patients' Guide to Thyroid Cancer.

A thyroidectomy is a type of thyroid surgery used to remove the thyroid when cancer is present. However, some thyroid cells may remain after the procedure To prevent thyroid cancer recurrence, RAI is done to kill any remaining, possibly cancerous, thyroid cells.

Should thyroid cancer spread to other parts of the body,  radioactive iodine is often recommended to distroy those cells, as well.

How Radioactive Iodine Therapy Works

Thyroid hormone-producing cells are the only cells in your body that absorb iodine. The cells collect and concentrate iodine from our diets (such as from iodized salt, which is common in processed foods, deli meats, fast food and dairy products, to name a few) and use the iodine to make thyroid hormones (T3 and T4—read more about thyroid hormones in our thyroid gland overview).

Since no other cells in the body can absorb iodine, doctors can give an individual radioactive iodine to destroy  thyroid cells, while not harming cells from other organs. The majority of radioactive iodine, therefore, will be absorbed by any remaining thyroid cells.

Very small amounts of radioactive iodine may be absorbed by your salivary glands, and the lining of your stomach, which may cause side effects such as a sore throat or hoarseness. If this occurs, it is usually goes away as the body heals.

A certain form of radioactive iodine is used: I-131. That is the form that has been found to be the most effective in eliminating remaining thyroid cells.

Radioactive Iodine Therapy Basics

Your doctor will walk you through step-by-step what will happen in your radioactive iodine therapy. Here are some basics to keep in mind, though:

  • Radioactive iodine therapy is usually planned for a few weeks (14 days or so) after thyroid surgery. The swelling that occurs after surgery can affect how well blood flows to that part of your neck, and good blood circulation is necessary to get as much radioactive iodine as possible to any remaining thyroid cells. 
  • You may need to go on a low-iodine diet for avout four weeks before receiving radioactive iodine therapy. A low iodine diet is recommended before and during RAI therapy to clear your body of this nutrient so the therapy is more thoroughly absorbed by any remaining thyroid cancer cells. The Thyroid Cancer Survivors' Association has an excellent low-iodine cookbook you may want to consult. 
  • To help your remaining thyroid cells respond best to the RAI therapy, you may need to become hypothyroid for several weeks. This means stopping your thyroid replacement medication (levothyroxine) or receiving injections of recomginant TSH (Thyrogen). Of course, if your doctor recommends this procedure, it will be explained in much more detail to you so that you understand its importance and how it will be done. 
  • Another option to withholding thyroid replacement medication is to receive Thyrogen®. Thyrogen allows you to keep taking your thyroid hormone replacement medication before, during and after radioactive iodine therapy so you can avoid becoming hypothyroid.

  • You take radioactive iodine (RAI) in a pill.

  • This is an outpatient procedure, but there are special requirements for when you return home. However, you will be given very special instructions about keep a distance from other people in your house for a few days, and taking other precautions until the radioactive substance wears off. This is something else your medical team will thoroughly explain.

Radioactive iodine therapy has been used since the 1950s. The risk is low, and the benefits are important for a good recovery. RAI is a very common and accepted treatment for thyroid cancer patients following thyroid surgery.