Radioiodine Treatment – Treatment for Overactive Thyroid

The thyroid is a gland in your neck that produces hormones. An overactive thyroid produces more thyroid hormones than your body needs, which may cause you to have symptoms such as weight loss, mood swings and feeling too hot. This is also known as thyrotoxicosis.

Your doctor believes radioiodine (radioactive iodine) therapy is the best treatment for your overactive thyroid. This leaflet includes advice for you when receiving the treatment.

Before your appointment, someone from the Medical Physics Department will contact you to talk about your appointment.

This leaflet should answer most of the questions you may have about radioiodine. If you have more questions, please ask (see contact details below).

What does the treatment involve?

You will have to swallow a small (paracetamol sized) capsule with some water. You must stay in the department for half an hour after taking the medication before you can go home, so we can ensure the body has absorbed the tablet.

How does it work?

Iodine is a chemical element which can be found in nature and as a mineral in some foods. Most iodine in your diet goes to your thyroid gland. Radioiodine (which is normal iodine that has been made radioactive) will go to your thyroid in the same way. 

Once in the thyroid, the radiation given off has the effect of “slowing down” your thyroid.

Is there any preparation before the treatment?

Your hospital doctor will give you instructions about your tablets.  You may need to stop taking some of your medication before your treatment and to resume after.  Please continue to take your present medication unless told otherwise.

It is important that you are not pregnant when you have your treatment, as radioiodine is harmful to unborn babies. At your appointment, we will ask about the possibility of you being pregnant, any contraception used and the date of your last period. We may also need to perform a pregnancy test if you are of childbearing age.

If you are currently breast-feeding, you will need to stop and not restart.

It is recommended that you follow a Low Iodine Diet for 1 week before treatment and 2 hours after administration. The purpose of the Low Iodine Diet is to reduce the amount of iodine in your body before your treatment begins. This helps the radioiodine to be absorbed correctly.

What foods are rich in iodine?

You can avoid high levels of iodine in your diet by preparing meals from ingredients and foods listed in the ‘OKAY TO EAT’ column, according to your preference. Only the foods in the ‘TRY NOT TO EAT’ column need to be avoided.

Regular table salt and sea salt (with no added iodine) may be used if required but avoid high quantities of salt for general healthy eating.

The British Thyroid Foundation (BTF) website provides some meal suggestions and recipes for the Low Iodine Diet at:

https://www.btf-thyroid.org/low-iodine-diet-suggested-meals

Do your best to follow the Low Iodine Diet, but it is not possible or necessary to follow a diet that has no iodine. The aim is to avoid having high iodine levels.

What happens after the treatment?

There are no side effects from the capsule and you can drive yourself home as normal. If someone else is driving you to your appointment, we ask that you sit in the backseat furthest away to reduce radiation dose to the driver.

It is ok to return home by public transport provided the journey is no more than 1 hour, avoid sitting next to anyone who is pregnant or small children.

You should arrange a thyroid function blood check 6 to 8 weeks after treatment and see your consultant 1 week after your blood check. The thyroid function check can be arranged via the haematology department at the hospital or via your GP.

You should start to feel some benefit within a few weeks of treatment.  Your GP will continue to check your thyroid function for the rest of your lifetime, with advice from your consultant where necessary.

What if I start feeling unwell?

It is extremely unlikely that the radioiodine treatment would cause you to feel unwell.

You should seek medical help as normal if you feel unwell and tell them you have had “radioiodine therapy for overactive thyroid.”

If you vomit within 48 hours of treatment, please contact the Medical Physics Department immediately for further advice and instruction as the vomit will be radioactive.

Is the radiation harmful?

There is no evidence of harmful effects from the radiation.  Radioiodine has been a successful treatment for overactive thyroid for over 80 years; the patients receiving this treatment are monitored carefully.

There is no recorded increased risk of developing cancer because of this therapy. The benefits of treatment vastly outweigh any risk.

How many treatments will I need?

There is no evidence of harmful effects from the radiation.  Radioiodine has been a successful treatment for overactive thyroid for over 80 years. The patients receiving this treatment are monitored carefully.

There is no recorded increased risk of developing cancer because of this therapy. The benefits of treatment greatly outweigh any risk.

Will I be any danger to my family or friends?

The amount of radioiodine in your body will reduce with time. Some will also leave your body in bodily fluids such as sweat and urine.

People who are very close to you will receive a small radiation dose. You will still be able to perform your usual daily activities such as shopping, cooking and caring for pets.

It is important to keep the radiation dose to other people, especially young children and pregnant people, as low as possible.

One of the team will discuss this guidance with you on the telephone and at the treatment appointment. Please raise any concerns or difficulties you may have with the restrictions, and we will work through them with you. This may mean special arrangements that differ from the below.

Please share this information with close family members sharing your home so that they will be aware of these small risks and the precautions we have asked you to take.

If anyone has any concerns, please raise them – we will be happy to discuss concerns with anyone you choose to accompany you for your treatment.

To reduce risk you should:

• Try to stay at least 2 metres away from people, especially pregnant people and children, for up to 25 days. Where this is not possible then try to maintain a distance of at least 1 metre. You are allowed up to 15 minutes per day within 1 metre.

• Sleep alone for up to 22 days.

Your urine will be radioactive, with additional radioactivity in sweat, mucus, and saliva for the first 4 days following treatment.

In addition to the above, for the first 4 days, you should:

• Use the toilet sitting down and after using the toilet, shut the lid before flushing it twice.

• Use separate towels and face cloths to other people in the household.

• Keep your toothbrush separate from others in the household.

• Do not share cutlery and crockery unless it has been washed first.

• Avoid food preparation that involves a lot of handling of the food, e.g. making bread.

• Pay extra care to hand washing after using the toilet and before touching any food and drink.

Please change your bedsheets and towels at the end of the 4 days and then at the end of restrictions before you resume sharing with anyone else.

Clothing, sheets, towels etc. can be washed with the rest of the household’s items, similarly cutlery and crockery can be washed with the rest of the household’s items.

Will having this treatment stop me going to work?

If your work involves routinely sitting or standing within 1 metre of the same person or handling food items, you may need to stay off work for a number of days. A member of the Medical Physics team will discuss this with you prior to treatment. 

If you work closely with children or pregnant people, use photosensitive material, or work with certain radiation equipment you may need to stop work for up to 2 to 3 weeks.

Are there any other potential restrictions?

For people you see rarely (in shops, on public transport etc.) there are no restrictions.

• If you regularly car share with the same person you may need to avoid this for a number of days.

• You must not donate blood for at least 6 months after treatment to maintain steady thyroid levels.

• Individuals of childbearing capacity must avoid becoming pregnant for 12 months following the treatment. If you do become pregnant within this time, you must seek advice from your GP immediately and inform them you have had radioiodine treatment. It is VITAL you have a blood test to check your thyroid hormone levels as this MUST be controlled during pregnancy. 
  
  Please be assured this treatment will not affect your fertility.

• You must stop breastfeeding before treatment and not restart.

• Individuals should avoid fathering children for 4 months following treatment.

You will receive exact details of your personal restrictions when you have your treatment.

We also provide a yellow card to remind you about the restrictions and how long they apply. Please carry the card on your person until the end of the restrictions (up to 25 days).

Travelling or working in an airport or port?

Some airports and ports have sensitive radiation detectors installed. The very small amount of radioiodine still in your body (even when all close contact restrictions have ended) may cause such a detector to alarm. 

We advise you to keep your yellow restriction card and take it with you if you are travelling by aeroplane or entering a port in the 6 months following your treatment. The Medical Physics Department may be contacted to confirm your treatment should you trigger any radiation alarm.

Contact Details

If you have any queries before or after the treatment telephone the Medical Physics Department.

Medical Physics Department
University Hospital of Hartlepool  
Telephone: 01429 522680

Further Information

You can get more information about radioiodine treatment and thyroid disease from:

British Thyroid Foundation
Telephone:  01423 810093
Website: www.btf-thyroid.org/  

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