Iodine-131 Therapy for Thyroid Ablation

About Iodine-131 Therapy

Iodine-131 therapy is given to patients with thyroid cancer who have had a total thyroidectomy (surgery) and have stopped all thyroid medications for several weeks, but a iodine body scan shows that they still have activity in the residual thyroid tissue and/or in metastatic lesions.

The purpose of Iodine-131 for thyroid ablation is to destroy all functioning thyroid tissue.

It has been shown that the use of thyroid hormones after surgery decreases the recurrence rate of cancer — a rate that is further decreased when radioiodine is used postsurgically.

How Does this Treatment Work?

Given in capsule form, Iodine-131 will dissolve in the stomach and travel systemically throughout the body, being absorbed by whatever thyroid tissue is remaining. The Iodine-131 that is not absorbed will be excreted from the body by either or all of the following three routes:

  • Saliva
  • Urine
  • Sweat

How Long Does the Radioiodine Stay in the Body?

The radioiodine from your treatment will remain in your body only temporarily. Most of the radioiodine not collected by your thyroid gland will be eliminated during the first two days after your treatment. It leaves the body primarily through your urine, but very small amounts may leave in your saliva, sweat and during a bowel movement. The amount of radioiodine remaining in your thyroid tissue is responsible for the desired medical effect. However, this amount also decreases rapidly. This means that the possibility of radiation exposure to you and others is reduced with time. At the end of treatment, no radioiodine remains in your body.

How Can Radiation Exposure Be Reduced to Others?

The amount of radioiodine in your body during treatment is small. Although there is no evidence that the radiation from this amount will cause any problems, it makes sense to take steps to minimize exposure, no matter how small. If you take these simple precautions during the first few days after your treatment, you can reduce or eliminate the possibility of radiation exposure to others.

There are three basic principles to remember:

  • Distance. The greater the distance you are from others, the less radiation they will receive. Even an increase in distance of a few feet will greatly reduce the exposure. So try not to remain in close contact with others for longer than necessary.
  • Time. Radiation exposure to others depends on how long you remain close to them. You should try to minimize the time spent in close contact with others.
  • Hygiene. Good hygiene minimizes the possibility that other people will be contaminated with the radioiodine that leaves your body. Since most of it leaves your body in the urine, good toilet hygiene and careful and thorough washing of your hands will reduce the possibility of contamination.

Guidelines to Help You Apply the Basic Principles of Radiation Exposure

Below are guidelines, recommended by the Society of Nuclear Medicine, that will help you reduce exposure to others. Your physician can best recommend which guidelines are important for you and how long they should be followed. Ask your doctor for more information.

  • Sleep alone for the first few days after your treatment. During this period, avoid kissing or sexual intercourse. Also avoid prolonged physical contact, particularly with children and pregnant women; the thyroid glands of children and fetuses are more sensitive to the effects of radioiodine than those of adults.
  • If you have a baby or are taking care of one, your doctor can best instruct you on the following guidelines. You probably can do what is necessary to care for your baby, but it is preferable not to have the baby too close, such as sitting in your lap, for more than a short time during the first two days after treatment.
  • If you have been breastfeeding your baby, you must stop because radioiodine is secreted in breast milk. Discuss with your doctor when you will be able to resume breastfeeding.
  • If you are pregnant or think you may be, tell your doctor because radioiodine treatment should not be given during pregnancy. Also, if you are planning to become pregnant, ask your doctor how long you should wait after treatment.
  • Wash your hands with soap and plenty of water each time after you go to the toilet.
  • Keep the toilet especially clean. Flush it two or three times after each use.
  • Rinse the bathroom sink and tub thoroughly after you use them. Clean bathroom practices will reduce the chances of others becoming contaminated from the radioiodine in your salvia and sweat.
  • Drink plenty of liquids such as water and juices. This will make you urinate more frequently and help the radioiodine to leave your body more rapidly, thus lowering the amount in your body.
  • Use separate (or disposable) eating utensils for the first few days and wash them separately. This will reduce the chance of contaminating other family members with the radioiodine in your saliva.
  • In most cases, normal activities may be resume 72 hours after treatment.

Based on Nuclear Regulatory Commission requirements, your release from the hospital will be based on the amount of exposure you are likely to give to any individual with whom you may come in contact. This will be calculated by the our medical physicist. In most cases, patients receiving this treatment return home on the same day of administration of Iodine-131.

If you have any questions regarding your treatment, please contact our medical physicist at 732-923-6811, or your nuclear medicine physician at 923-6690.

Click here for the informational brochure (pdf), available as a PDF (portable document format) file.