Radioactive Iodine Treatment for Hyperthyroidism

What is hyperthyroidism?

The thyroid gland, located at the front of your neck, makes hormones that control your metabolism—the way your body uses energy.  Hyperthyroidism, also called overactive thyroid, occurs when your thyroid gland makes too much thyroid hormone. Too much thyroid hormone speeds up many of the body’s functions. If untreated, an overactive thyroid can lead to other health concerns, such as heart problems.

The most common cause of hyperthyroidism is Graves’ disease, in which the immune system stimulates the thyroid gland. Less often, hyperthyroidism occurs when the thyroid has one or more nodules (lumps) that make too much thyroid hormone.

Thyroid glandWhat is the treatment of hyperthyroidism?

The goal of treatment is to lower the amount of thyroid hormones in the body. Treatment options include:

  • Radioactive iodine (RAI). Also called radioiodine. RAI is a common and long-used treatment for hyperthyroidism.
  • Surgery. This treatment removes the thyroid gland with surgery (called thyroidectomy).
  • Antithyroid drugs. These medicines are given for months or even years to lower the levels of thyroid hormone.  Sometimes, patients are prescribed these medications in preparation  for RAI or surgery. 

How does radioactive iodine treatment work?

 The thyroid gland uses iodine to make thyroid hormone. It absorbs the iodine from the foods we eat. Similarly, the thyroid gland absorbs the RAI when it swallowed. Then, the radiation attached to the iodine damages the thyroid cells. Over time, the thyroid gland produces less thyroid hormone. Because no other organ in the body use iodine, the RAI does not affect any other part of the body. 

RAI, also called iodine 131 (I-131), is given as a single-dose capsule or liquid. Most often, you will not need to stay in the hospital. It can take 6 weeks to 6 months to see the full effects of RAI treatment. During this time, your thyroid blood levels will be monitored regularly. You may also need to take antithyroid drugs. 

Who should not receive RAI?

For safety reasons, these people should not get RAI treatment:

  • Pregnant and breastfeeding women or those planning to become pregnant in the next six months
  • People who cannot follow radiation safety precautions
  • Young children who haven’t tried other treatment options first
  • Some people with active Graves’ ophthalmopathy (thyroid eye disease)

How should I prepare for RAI?

If you are taking antithyroid drugs, stop these medications five to seven days before treatment. Do not stop taking beta blockers (drugs such as atenolol) if your doctor has prescribed them.

Avoid drugs and foods that contain high levels of iodine for as long as your doctor instructs. Foods high in iodine include iodized salt, seaweed and other seafood, and dairy products. Multivitamins often contain iodine, so check the labels.

Some radiation stays in your body for a few days after RAI treatment. Your health care provider will give you a list of precautions to take after treatment to minimize others’ exposure to the radiation. The radiation is eliminated in your urine, stool, and saliva. So, good hygiene is most important. 

Follow these safety measures after RAI treatment:

  • Sleep in a separate bed (more than six feet away) from other adults for three or more days after treatment. Sleep apart from children and pregnant women for two weeks or longer.
  • In daytime, keep more than six feet away from children and pregnant women for at least one day.
  • Avoid prolonged time in public places or transportation (planes, trains, buses) for at least three days. 

What are the side effects of RAI?

RAI is generally safe. Sometimes neck pain can develop right after the treatment. This does not last long, and pain medicine can help relieve the discomfort.

Most people will develop hypothyroidism (underactive thyroid) after treatment. This drop in the amount of thyroid hormones in the body may be temporary, but it is often permanent. It is easily treated with synthetic (manmade) thyroid hormone, levothyroxine.

The risk of thyroid cancer does not increase in patients who receive RAI as a treatment of hyperthyroidism.

Is RAI treatment a cure?

In most patients, one does of RAI cures hyperthyroidism. Some patients, will need a second dose of RAI. 

Questions to ask your doctor

  • What are the pros and cons of RAI compared with other treatments?
  • How long should I stay on a low-iodine diet before RAI treatment?
  • What side effects are possible? 
  • When may I return to work after RAI treatment?
  • After treatment, how long should I avoid close contact with my family members and pets?
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