Radioactive Iodine (RAI) Treatment for Hyperthyroidism

Your doctor has requested a Radioactive Iodine (RAI) treatment. This booklet will answer some of the questions you may have.

When is Radioactive Iodine treatment used?

Radioactive iodine is used as a treatment in the following cases:

To treat hyperthyroidism (too much thyroid hormone) due to Graves’ disease.
To treat hyperthyroidism (too much thyroid hormone) due to a thyroid nodule that is overactive.
To shrink an enlarged thyroid gland (called a goiter) that is compressing your airways or esophagus, without needing surgery.

What is a Radioactive Iodine Treatment?

Radioactive iodine (I-131) has been used to treat over-active thyroid disorders (hyperthyroidism) since the early 1940s. It is an effective method of treatment. Radioactive iodine is given either as a capsule or in liquid form. It is taken up by the thyroid and destroys the cells in the thyroid gland. This has the effect of reducing the amount of thyroid hormone made by the thyroid gland and reduces the size of the gland.

What is involved?

Before your radioactive iodine therapy, your doctor will order a thyroid and uptake scan. This is used to determine the cause of your hyperthyroidism and provide information about your thyroid tissue to determine your treatment dose. Radioactive iodine therapy is targeted to treat only your thyroid gland, so there is very little radiation exposure to the rest of your body’s cells. When the thyroid cells absorb the radiation, they are damaged or destroyed.

Approximately 90% of patients need only one dose to be cured of their hyperthyroidism. Though you may only need a single dose, it may take up to six months before the medication fully destroys all or part of the thyroid for complete effect. If your symptoms persist 6 months after treatment, you may need a second dose.

Before your therapy is scheduled, you will be consulted by a Nuclear Medicine physician regarding the risks and benefits of having the radioactive iodine treatment. At this time, you will be given specific instructions about all the precautions that need to be followed and you will be asked to sign a consent form. When you arrive in the department for your therapy, a technologist will explain the entire procedure to you and give you the opportunity to ask any questions. A Nuclear Medicine physician will ensure that you are receiving the correct amount of radioactive iodine that was ordered for you. The technologist will then give you the dose either in the form of a capsule or liquid. Once you have received this dose, you will be able to leave the department with no ill effects. The entire procedure will take about 30 minutes.

Do I need to prepare for the treatment?

Bring your Health card.
There are certain medications that interfere with the therapy. You will be given specific instructions regarding which medications need to be stopped.
Women of childbearing age will be required to get a blood test done shortly before the treatment, often on the morning of their therapy, to ensure that they are not pregnant. The nuclear medicine department will give you specific instructions about when and where to have this blood work done. Hysterectomy and menopause are the only acceptable reasons not to have this blood test done.
Breastfeeding: Iodine is excreted in breast milk. Breastfeeding must be stopped following treatment. In order to minimize radiation dose to the breasts, RAI therapy should be delayed until lactation ceases for breastfeeding women (typically 4-6 weeks after breastfeeding stops).

Side Effects of Radioactive Iodine:

A common side-effect of radioactive iodine treatment is an underactive thyroid gland (hypothyroidism), so it is very important to have regular thyroid blood tests starting from four to six weeks after the treatment to identify and treat this early.

Other side effects of radioactive iodine include:

Sore throat: this can last for a week
Metallic taste in the mouth: This can last for a few weeks.
Nausea: This usually subsides one to two days after treatment.
Swollen salivary glands: This can last for a few weeks. It is caused by iodine absorbed by the salivary glands, though stimulating saliva flow a day after treatment (by sucking a lemon drop, for instance) is an effective remedy.
A very rare potential serious complication is temporary worsening of hyperthyroidism within the first two weeks following RAI therapy. Inform your doctor if you experience worsening of your hyperthyroid symptoms after treatment, or present to the emergency department.
If you have existing thyroid eye disease (which can occur in Graves’ disease), this may sometimes be aggravated by radioactive iodine treatment. Inform your doctor of any eye symptoms you have, to check if these might be thyroid related. Your doctor will advise ways to minimize the risk of worsening the eye disease and you may require assessment by an eye specialist.

Is it safe to conceive after radioactive iodine treatment?

There is no evidence of reduced fertility or genetic abnormalities in patients’ offspring after RAI. However, as a general precaution following radioactive iodine treatment, men should avoid fathering a child for at least four months, and women should avoid conceiving for at least six months. Your treatment center will give you detailed information on this. After that time there is no problem with having a baby or with the development of the baby and many people have gone on to conceive and have healthy children following treatment with radioactive iodine.

Is the radiation dangerous?

There is no increased risk of thyroid cancer or leukemia after RAI. For most patients, the benefit of treating the overactive thyroid gland far outweighs the extremely low cancer risk. The specialist doctors who will be treating you will be able to answer any questions you have about the safety of treatment in your situation.

Do I need to do anything after the Treatment?

In the days following radioactive iodine therapy, you will need to take certain precautions to prevent radiation exposure to others. Keep in mind that the precautions listed below are general, and your doctor will be more specific about how many days and what kinds of precautions you need to follow tailored to your individual needs and medical circumstances.

The radioactive iodine used for your treatment will remain in your body only temporarily. Most of the iodine not taken up by your thyroid gland will be eliminated during the first few days after your treatment. The iodine leaves your body mainly in your urine, but small amounts also leave in your saliva, sweat and feces. Although there is no evidence that the radiation from this amount of iodine will cause harmful effects, it makes sense to avoid any unnecessary exposure to others. The following simple precautions should be taken following your treatment:

When travelling home after treatment, preferably travel alone in a private vehicle or if that is not possible, with one other driver. Maintain as large a distance as possible between you and the driver.
Keep distance from others, including mealtimes.
Remain in your home for 2 days post-treatment.
Delay returning to work unless you can satisfy the above conditions both at work and while traveling to work.
Sleep in a separate room.
Avoid personal contact with others (hugging/kissing/sexual intercourse).
Avoid prolonged physical contact with babies, young kids, pregnant women and pets.
Drink plenty of fluids. This will help the radioactive iodine to leave your body more rapidly.
Urinate as often as possible. Men should sit to urinate. Use a separate bathroom. Flush the toilet twice (with lid down) after each use. If you do not have a separate bathroom, clean thoroughly before returning it for use by others. Wash your hands with plenty of soap and water after you go to the toilet.
Do not share items (food utensils, towels and personal use items) with anyone else.
Wash all clothes and bed linens separate from household laundry.

People who have recently had radioactive iodine treatment can trigger radiation detectors used for security purposes, for example at airports and border crossings. This can occur for up to three months after treatment. If you are travelling within this time period, you should carry a travel letter provided by the nuclear medicine department.

Follow-up after radioactive iodine treatment is essential. There is no single correct dose and about 10% of patients need a further dose. There are no additional problems associated with having more than one dose. Some patients will still require treatment with antithyroid medication for some weeks or months until the radioactive iodine has been effective, and the overactivity has settled.

Over two-thirds of those who have radioactive iodine treatment will develop hypothyroidism (an underactive thyroid). This can occur anytime from one month after the treatment and is most common within the first 12 months after treatment but can occur later. This will be monitored by your doctor by regular blood tests.

What about radioactive iodine treatment for children and teenagers?

Radioactive iodine is an effective and safe treatment option for children and teenagers with an overactive thyroid gland but will usually be given as a second-line treatment after a reasonably long course of antithyroid medication. It is used less commonly in younger children.

What about breastfeeding?

Breastfeeding must be discontinued entirely. It is vital that you ensure that we are aware if you are pregnant and/or breastfeeding.

Will this treatment cost me money?

No. This test is paid for by the healthcare system. This treatment costs over one thousand dollars, so please notify the department at 613-761-4831 if you cannot make your appointment.

What should I do if I cannot make my appointment?

If you cannot make your appointment, it is important that you notify the department at 613-761-4831 as soon as possible. Failure to make your appointment results in wasting of expensive materials that are ordered especially for your appointment and also reduces availability to other patients. Missed appointments may also result in delays of your treatments.

Directions and Parking

Civic Campus 1053 Carling Avenue – 1st Floor Tel.: 613-761-4831, option 8 Hours: Mon. – Fri., 8:00 a.m. – 4:00 p.m. Directions: From within the Civic Campus, take the “C” elevators to the 1^st Floor and follow the signs to Nuclear Medicine. Patients may also ask for directions at the patient information desk.	General Campus 501 Smyth Road – Main level Tel.: 613-761-4831, option 8 Hours: Mon. – Fri., 7:00 a.m. – 4:00 p.m. Directions: From the main entrance, follow the signs on the main level (located at the public elevators). Patients may also ask for directions at the patient Information desk.
Park in either parking lot off Carling Avenue (P7) or in the multistory parking garage (P1).	Park in the parking garage which is located beside the main entrance just off Smyth Road.

Parking instructions

All parking lots are automated
Take the parking ticket with you inside.
When you have completed your appointment, you can pay by cash or credit card at one of our pay stations, or you can pay by credit card with express exit at the parking lot exit gates (the grace period after payment to leave facility is 20 minutes).
Payment methods:
- Pay stations: Cash or credit card (Visa, MasterCard or American Express).
Maximum parking fee is $13.00

Visit The Ottawa Hospital’s website for additional directions and parking instructions and maps

Last updated on: April 21st, 2022

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