Thyroid Cancer Treatment Radioactive Iodine

Radioactive iodine treatment is often prescribed for thyroid cancer patients after they’ve had surgery for papillary or follicular cancer. It is widely considered a very effective way to remove any remaining, potentially cancerous thyroid cells.

Even if you had a complete thyroidectomy as part of your thyroid cancer treatment, your surgeon may have left some thyroid tissue behind in order to avoid damaging your laryngeal nerve, which affects your voice box, and your parathyroid glands, which regulate your body’s use of calcium.

These microscopic “leave-behinds” may be cancerous, so your oncologist might recommend radioactive iodine treatment to destroy or abate them.

How Radioactive Iodine Treatment Works

Thyroid cells are the only ones in the body that absorb iodine to produce thyroid hormones. However, when the cells absorb radioactive iodine, they die, making it a very effective tool in thyroid cancer treatment.

Before radioactive iodine treatment — also called RAI — you’ll be instructed to go through a variety of steps to prepare your body to absorb the radioactive iodine. You’ll prepare by increasing your levels of TSH (thyroid stimulating hormone) and depleting your body’s iodine stores.

To increase your TSH levels, you’ll stop taking thyroid hormone replacement medication. This may cause a temporary return of thyroid problems, including:

  • Concentration problems
  • Depression
  • Fatigue
  • Muscle aches
  • Weight gain.

You’ll also be required to follow a low iodine diet, eliminating things such as:

  • Salty foods
  • Seafood
  • Tea
  • Vitamins.

Talk to your physician or oncologist for specific instructions on how to prepare for radioactive iodine treatment.

Radioactive Iodine Treatment Precautions

Although RAI is a safe and effective form of thyroid cancer treatment, you’re still dealing with radioactivity, so you need to take special steps to help your body flush out the iodine and protect those around you.

Depending on the dosage, radioactive iodine treatment can be administered in isolation rooms in cancer research facilities or on an outpatient basis. It generally takes about three days for most of the radioactivity to be excreted from your body through your bodily fluids, such as urine, feces, sweat and saliva. Your oncologist or physician will provide you with specific instructions on how to minimize the radiation exposure to your family and friends. Sample precautionary measures include:

  • Avoiding close physical contact, especially with pregnant women and children
  • Flushing the toilet two or three times after use
  • Using separate dishes.

Side Effects Of Radioactive Iodine Treatment

Patients may experience the following after RAI treatment:

  • Dry eyes
  • Dry mouth
  • Mild nausea
  • Sore salivary glands
  • Tender neck.

More serious long-term problems include fertility problems and a possible increased risk of leukemia. Talk to your doctor if you have specific questions about thyroid cancer treatment.


American Cancer Society Staff. (2009). Thyroid cancer: Radioactive iodine (radioiodine) therapy. Retrieved March 28, 2010, from the American Cancer Society Web site:

New York Thyroid Center Staff. (n.d.). Thyroid cancer: Radioactive iodine preparation and precautions. Retrieved March 28, 2010, from the Columbia University Medical Center Web site:

Van Nostrand, D. (2004). Radioiodine ablation and treatment for papillary and follicular thyroid cancer. Retrieved March 28, 2010, from the ThyCa: Thyroid Cancer Survivors’ Association, Inc. Web site:

National Cancer Institute Staff. (2007). Radioactive iodine therapy. Retrieved March 28, 2010, from the National Cancer Institute Web Site: