Radioiodine treatment for hyperthyroidism: information for patients

What is hyperthyroidism?

Your thyroid gland is in your neck, in front of your windpipe. It produces a hormone called thyroxine which acts as your ‘body clock’, keeping your body working properly. Thyroxine has a direct effect on your heart rate, brain function, bowel activity, skin and other vital organs. Hyperthyroidism (also known as Graves’ disease, thyrotoxicosis and overactive thyroid) develops when your thyroid gland produces too much thyroxine making your body clock run too fast.

What is radioiodine treatment?

Radioiodine treatment uses radioactive iodine to cure hyperthyroidism. The radioactivity destroys the overactive thyroid tissue and slows down the amount of thyroxine your body produces. We would usually advise patients who have nodules in their thyroid which are producing too much thyroxine or patients with Graves’s disease which has not got better with tablets to have this treatment. Sometimes radioiodine is recommended as the first treatment for hyperthyroidism The thyroid gland uses most of the iodine, so you will only need a small amount of radioactivity.

How is the radioiodine given?

The radioiodine is given as a capsule or rarely as a drink. The drink tastes just like water and only contains a small amount of radioiodine. The capsule looks like those used for many other medicines and you swallow it whole with a drink of water.

How long does the radioiodine take to work?

It can take between a few weeks and several months for the treatment to work. Most people with hyperthyroidism (80–90% of people) are cured by a single dose of radioiodine. If the treatment has not worked, it may be repeated after a minimum gap of 6 months.

Is radioiodine treatment dangerous?

No, its safety record is excellent. Radioiodine treatment has been given to millions of people since it was introduced in the early 1940s.

Where else in the body does radioiodine go?

Most of the radioiodine goes to the thyroid gland within a few hours. The rest will pass out of your body in your urine during the first few days after treatment. How long this will take depends on how much you are given.

Are there any risks in having children afterwards?

No effects on the unborn babies of women who have been treated with radioiodine more than six months before they got pregnant, or on the health of those children, have been shown in over sixty years of experience in using radioiodine treatment. The treatment does not affect a woman’s fertility.

Can I father children after radioiodine treatment?

Men should be careful not to father children for four months after radioiodine treatment. The treatment does not affect a man’s fertility.

Will there be any danger to my family or friends?

After your radioiodine treatment, your body will contain some radioactivity, which will get less every day. If you follow the advice you are given, other people may receive a tiny radiation dose from you which is not dangerous at all. You will be able to continue shopping, cooking and doing other day-to-day household activities as normal. However, you will need to take some simple precautions for some time after your treatment to stop your family, friends and other people coming into contact with too much of the radiation.

How long you will need to do these things will depend on the amount of radioiodine you have been given. Your specialist will give you advice on the precautions at least a week before your treatment. If you are given a large dose of radioiodine, you may have to stay in hospital for a few days after the treatment to reduce the risk of other people coming into contact with radiation. You can travel home by public transport, as long as you do not spend more than one hour sitting next to the same person on the bus, train or tube. You can drive yourself home. If someone else is driving you home, you should sit on the back seat, as far away from them as possible.

Hygiene

• Most of the radioiodine leaves your body in your urine and sweat during the first few days after your treatment. Drinking plenty of fluids and going to the toilet a lot will speed this up process.
• Men should urinate (wee) sitting down on the toilet to avoid getting radioiodine on the edge of the toilet.
• After going to the toilet, you should flush it twice.
• Always wash your hands well after going to the toilet.
• Make sure that no one else uses your towels and face cloths.
• Wash all your crockery and cutlery thoroughly.

Other precautions

Your specialist will advise you about the following activities at least a week before your treatment is given. The length of time you will have to do this for will depend on the amount of radioiodine you receive.

Different precautions may apply for different lengths of time, but some may be for up to two to four weeks.

• Stay at least 1m away from children under 3: for 21 days after your treatment.
• Stay at least 1m away from children under 5: for 16 days after your treatment.
• Stay away from adults at home (and children under 5): for 11 days after your treatment.

For the time advised:

• Limit your contact with children, especially children under 3 years of age. For children above 3 years see information above.
• Stay more than an arm’s length or one meter away from other people and sleep alone.
• Depending on what you do for work, your doctor will advise you how much time you need to take off after you’ve had the radioiodine treatment.
• Don’t go to places like cinemas, theatres, pubs and restaurants, where you may be in close contact with other people for a long time.
• Don’t make any unnecessary journeys.

Carry the card

Your specialist will give you a card with the details of your treatment. This will also tell you how long you need to follow the precautions for.

You should carry this with you until you no longer have to follow any of these instructions.

You should also carry the card with you if you are travelling through ports or on international flights for six months after treatment.

Some security devices at airports are so sensitive that they may detect that you have had radioiodine treatment even after this length of time.

Will I need to see my healthcare team after the radioiodine treatment?

Yes, you will need to see either the doctor or specialist nurse you saw at the clinic 6-8 weeks after the treatment. Your doctor or nurse will then advise you if you need to start thyroid tablets. Most patients need seen 2-3 times after radioiodine, and then discharged from hospital care.

Are there any short-term side effects?

Most people don’t have any side effects from the treatment. A few people develop symptoms of an overactive thyroid (such as a racing heart and sweating), usually five to ten days after the treatment. For this reason, your doctor may tell you to take a tablet called a beta- blocker for a few weeks after the treatment, and they may tell you to start taking your antithyroid tablets again.

Your thyroid gland may become underactive at a time ranging from a few months after treatment to many years later, causing ‘hypothyroidism’. This is where your thyroid gland does not produce enough hormones. In a small number of people, this
happens quite soon after radioiodine treatment. The blood tests will show whether this has happened.

If your thyroid gland does become underactive, your doctor will give you thyroxine tablets to replace the thyroxine that your thyroid gland is no longer producing. The tablets are very safe and contain a man-made version of the natural thyroxine that your body is unable to produce enough of. It may take a little time to find the right dose of thyroxine for you.

Thyroid eye disease (which can develop in Graves’ disease) may get worse after the treatment. The doctor will discuss this with you before you have the treatment and may suggest that you take a steroid called prednisolone for a month or two after the treatment.

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