What is Radioiodine (I-131) Therapy for Hyperthyroidism

Radioiodine (I-131) therapy is a procedure to treat an overactive thyroid gland (hyperthyroidism). The thyroid is a gland in the neck that uses iodine to help control how the body uses food (metabolism).

In this procedure, you swallow a pill or liquid that contains I-131.

I-131 is manufactured (synthetic) iodine that gives off radiation. This destroys thyroid cells and reverses hyperthyroidism.

Tell a health care provider about:

• Any allergies you have.
• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any problems you or family members have had with anesthetic medicines.
• Any blood disorders you have.
• Any surgeries you have had.
• Any medical conditions you have.
• Whether you are pregnant, may be pregnant, or have gone through menopause, if this applies.
• Whether you currently have children.
• Whether you plan to have children in the next 2 years.
• Any contact you have with children or pregnant women.
• Your travel plans for the next 3 months.
• Whether you pass through radiation detectors for work or travel.

What are the risks?

Generally, this is a safe procedure. However, problems may occur, including:

• Damage to other structures or organs, such as the salivary glands. This could lead to dry mouth and loss of taste.
• Low sperm count, if this applies. This may lead to temporary infertility.
• Sore throat or neck pain. This is temporary.
• Slightly increased risk of thyroid cancer.
• Nausea or vomiting.

What happens before the procedure?

• Ask your health care provider about changing or stopping your regular medicines. This is especially important if you are taking diabetes medicines, blood thinners, or thyroid medicines.
• Women may be asked to take a pregnancy test.
• Women who are breastfeeding should plan to stop at least 6 weeks before the procedure.
• Follow instructions from your health care provider about eating or drinking restrictions.
• Plan to avoid contact with others for 1 week after your treatment. It is most important to avoid contact with children and pregnant women. To do this, plan to stay home from work, arrange child care, and sleep alone, if these things apply to you.
• Plan to drive yourself home after treatment. Do not take public transportation. If you need someone to drive you home, sit as far away from the driver as possible.

What happens during the procedure?

• You will be given a dose of I-131 to swallow. It may be a pill or a liquid.
• Your thyroid gland will absorb the I-131 over the next 3 months. The treatment process will be complete in about 6 months.

What happens after the procedure?

• You may need to stay in the hospital for 24 hours after your treatment. This depends on the requirements in your state.
• Follow instructions from your health care provider about:
  • How to take care of yourself after the procedure.
  • How to protect others from exposure to radiation as it leaves your body.

Radioiodine (I-131) Therapy for Hyperthyroidism, Care After

Refer to this sheet in the next few weeks. These instructions provide you with information about caring for yourself after your procedure. Your health care provider may also give you more specific instructions. Your treatment has been planned according to current medical practices, but problems sometimes occur. Call your health care provider if you have any problems or questions after your procedure.

What can I expect after the procedure?

After your procedure, it is common to have a sore throat or mild neck pain for several months.

Follow these instructions at home:

For the First 48 Hours After the Procedure:

• Do not use public bathrooms.
• Flush twice after using the toilet.
• Take a bath or shower every day.
• Do not make food for other people.
• Wash your sheets, towels, and clothes each day, by themselves.

Pregnancy and Breastfeeding

• Do not attempt to have children for as long as you are told by your health care provider. This may be for up to 1 year after your procedure. Use a method of birth control (contraception) to prevent pregnancy. Talk to your health care provider about what form of contraception is right for you.
• Do not breastfeed for as long as you are told by your health care provider, if this applies.

General instructions

• Avoid close contact with other people. It is most important to avoid contact with pregnant women and children. Do this for 1 week after your procedure.
  • Try to keep a distance of about 3 feet from others.
  • Sleep alone. Do not have intimate contact.
  • If you have children, arrange for child care.
  • Do not ride in vehicles with other people.
  • Do not stay in a hotel.
• Take over-the-counter and prescription medicines only as told by your health care provider. This includes any thyroid medicines.
• When traveling, carry a note from your health care provider to explain that you have had radioiodine therapy. This is because radioactivity may set off detectors in airports or other places.
• Do not share utensils, such as silverware, plates, or cups. Use disposable utensils, or clean your utensils separately from those of others.
• Wash your hands often. If soap and water are not available, use hand sanitizer.
• Drink enough fluid to keep your urine clear or pale yellow.
• Keep all follow-up visits as told by your health care provider. This is important. Follow-up visits may be required every 1–2 months after treatment.

Contact a health care provider if:

• You have pain that gets worse or does not get better with medicine.
• You have a dry mouth.
• You lose your sense of taste.
• You become pregnant within 1 year of your procedure, if this applies.
• You feel unusually tired (fatigued).
• You have very dry skin.
• You start to lose your hair.
• You have bowel movements that are less frequent or more difficult than usual (constipation).
• You have unexplained weight gain.
• You always feel cold.