Radioiodine for the treatment of hyperthyroidism

Introduction

This leaflet has been written to provide information for patients and their relatives. We hope this will answer your questions, but it may give rise to others which we are happy to answer. The multi-professional team that will be caring for you consists of the consultant, a physicist and technicians from the nuclear medicine department. We hope you find this helpful and welcome your comments, should you have any.

What is the thyroid gland and what does it do?

The thyroid gland is situated in the neck and produces hormones that are necessary for controlling various internal bodily functions.

What is hyperthyroidism?

The thyroid sometimes releases higher than normal quantities of the thyroid hormones, which can produce various physical symptoms. This condition is called hyperthyroidism or thyrotoxicosis.

What is radioiodine therapy and how does it work?

Radioiodine therapy uses a form of iodine (Iodine-131) that is radioactive. Like normal iodine, radioiodine is specifically concentrated in the thyroid and thereby has a local radiotherapy effect, which reduces thyroid gland over-activity. This selective effect means that the dose of radiation is very low.

What are the risks of radioiodine therapy?

This procedure uses ionising radiation to provide treatment. Ionising radiation can cause cell damage that may turn cancerous after many years or decades.

We are all at risk of developing cancer during our lifetime. One in two people living in the UK will be diagnosed with cancer at some point in their life. This procedure will add only a very small chance of this happening to you and the benefits of having this treatment outweigh its risks.

How do I prepare for my appointment?

Ordinary iodine (in food, for example) can interfere with the uptake of radioiodine by the thyroid, so it is important that you go on a ‘low iodine’ diet for seven days before your appointment, and for four days after. A ‘low iodine’ diet means avoiding all fish, seafood, multi-vitamins, nutritional supplements (such as kelp) and any other food or medication (for example cough linctus) with high iodine content.

If you are taking Carbimazole (Neomercazole), Propythiouracil and/ or Thyroxine tablets, please stop these seven days before your appointment. You do not need to stop any other medication that you normally take.

Depending on your exact domestic circumstances, you may need to arrange child care, time off work, or help with daily tasks if you are a full-time carer. Please see the section on ‘Will my radioiodine therapy be dangerous for others?’

On the day of your appointment, you should not eat for at least two hours prior to attending.

Please bring all medicines and tablets you may be taking with you and show them to the nurse who receives you.

Please phone the nuclear medicine department prior to your appointment if you have recently received any x-ray contrast media (an x-ray involving an injection such as CT scan, myelogram) as you may not be able to go ahead with your treatment.

Please contact the nuclear medicine department at least a week before your appointment if you need to cancel your treatment.

Are there any side effects from stopping my thyroid medication?

You may feel tired or weak when not taking your tablets. This is normal and the effects will disappear once you start taking them again. However, not all patients will need to restart their tablets. The consultant will advise you about this on the day of your appointment.

I’m pregnant and/ or breast feeding, what should I do?

The treatment will have to be postponed if you are pregnant or breast feeding, so please phone us immediately so we can rearrange your treatment.

How long will the whole procedure take?

You should allow up to three hours, which includes the time taken for a pre-therapy scan (see below) and consultation, as well as the treatment itself.

What will happen at my appointment?

Initially you will be seen by one of our nurses or technologists who will weigh you and check that you have followed the instructions in this leaflet, regarding diet, medications, etc.

If you need to have a pre-treatment thyroid scan, the nurse or technologist will inject a small amount of radioactivity into an arm vein at this time. A few minutes later you will have some pictures of your neck area taken using a special scanner called a gamma camera.

Next, you will be seen by one of our consultants who will go through your medical history and explain the therapy procedure to you in detail. You will be asked to provide ‘informed consent’ (for example you have to sign a consent form) before the therapy can take place.

Finally, you will be taken through to see one of our physicists who will inform you about restrictions to be followed when you go home, plus any other radiation protection advice deemed appropriate to you (please see the section ‘Will my radioiodine therapy be dangerous for others?’). The physicist will then give you the radioiodine in the form of a small amount of liquid or a capsule, which has a gelatine shell.

Is a thyroid uptake scan always performed on the day of treatment?

Not always. This may be because you have already had one, either in the department of Nuclear Medicine at Addenbrooke’s Hospital or in a different hospital.

Will I need to stay in hospital after my appointment?

No, you will be able to go home almost immediately, but do not use public transport for journeys of over one hour unless absolutely necessary (also see ‘Will my radioiodine treatment be dangerous to others?’)

Where does the radioactivity go?

Some of the radioiodine swallowed is concentrated in the thyroid. The rest mainly passes out of your body in urine, saliva and sweat.

Will I have any side effects after the therapy?

Most patients do not notice any side effects after the treatment. However, a small number of patients experience some neck ache two to five days after treatment. If troublesome this can be treated with paracetamol or ibuprofen. Also a small number of patients notice a gritty feeling in their eyes in the first 48 hours after treatment. If this happens just wash your eyes with sterile lukewarm water, and if you wear contact lenses change to spectacles until the discomfort has eased (normally lasts one to two days at most).

When can I start eating normally again?

You can begin eating normally (stop the ‘low iodine’ diet) 24 hours after your treatment.

Do I need to restart my thyroid tablets?

Every patient is different so you will be advised individually about this by your doctor. Some patients restart thyroid tablets one week after the radioiodine treatment, but some patients stop their medication after the treatment. If you do continue your medication it will be reviewed when you come back to the outpatient clinic after the radioiodine treatment.

Will my radioiodine therapy be dangerous to others?

No, provided you follow the simple instructions contained in this leaflet, as well as some specific advice given to you on the day of treatment.

For the treatment to work, the radioiodine needs to remain in your thyroid for a few weeks, and people physically close to you will therefore receive a very small radiation dose that we wish to keep to a minimum. It is therefore important not to remain physically close (such as within touching distance) for ‘prolonged periods’ (such as sitting next to someone on the sofa watching TV for several hours, sharing a bed), although normal ‘everyday contact’ is fine.

In addition to this general advice in relation to adults, we ask you to avoid all non-essential close contact with young children and pregnant women for the stated period.

You should also arrange for any very young children (under the age of three years) to be looked after by someone else for a period following your treatment (see below). Our departmental consultant and physicist will talk to you about this in more detail at your appointment.

We will need to provide information and advice to anyone caring for you following your treatment. Friends or family that act as your carer are advised to attend your appointment with you so that our team can have this discussion in person.

However, if you have paid carers come to your home, or if you will be returning to a care home or retirement village after your appointment, we will need to provide staff with advice and information prior to your treatment.

Please contact the nuclear medicine department prior to your appointment if you receive care from others or have any concerns regarding this advice.

How long will my restrictions last?

The length of time that the restrictions apply varies from person to person, which depends on your personal, home and work circumstances as well as the amount of radioiodine that you have received. However, it is important to note that:

You will need to avoid prolonged close contact with children under the age of five, and pregnant women, for three to four weeks. This includes, kissing, cuddling, sharing a seat, sharing a bed etc.

You will also need to avoid prolonged close contact with children over five and other adults for 11 – 16 days. This includes going to places of entertainment, travelling on public transport for more than one hour, sharing a bed with a partner and possibly returning to work (see below).

Avoid sharing bodily fluids for a week after treatment. This includes not sharing towels or water bottles, the use of barrier contraception, and using disposable tissues when you sneeze and washing your hands thoroughly afterwards.

Please note that the duration of restrictions described above are just a guide to help you make the necessary arrangements prior to your appointment. The consultant and physicist will decide on the exact length of your restrictions, based on your personal circumstances, at the time of your appointment. The time periods applying to the various restricted activities will be written down for you on a special ‘yellow card’ that you can take away with you.

Can I prepare food during the restricted period?

Yes, but you must follow good hygiene guidelines. Remember to wash your hands regularly while handling and cooking food. Do not put anything near your mouth whilst cooking, which includes tasting the food and returning the spoon to the cooking pot. It is also good practice to set aside cutlery and crockery for your own use for the first week after your treatment.

Will I be able to return to work after my therapy?

Whether or not you can return to work immediately after your treatment depends on the amount of radioiodine you received and the type of job you do. If you work in close proximity to other adults, or in the preparation of food, you may need to take time off work for up to 16 days. If you work with children or pregnant women this could be increased to up to 27 days. The consultant and physicist will advise you accordingly during your appointment. The ‘yellow card’ that will be given to you will include a date that you may return to work. If this is insufficient documentation for your employer, please ask for a ‘fit to work’ certificate at your appointment.

Can I travel abroad after my treatment?

It is advisable to avoid all overseas travel for the full duration of your restriction periods. Please phone the department of nuclear medicine if you have a holiday planned within a month of your appointment as we may need to postpone your treatment.

Please also be aware that very sensitive radiation detectors are now being used at ports and airports and there is a possibility that you could activate one of these for up to six months after your radioiodine therapy.

Please make the physicist aware of your travel plans at your appointment and he/ she will provide you with a formal letter to show to airport security staff.

Also try to avoid (if possible) any car/ bus/ train journeys where you will need to sit next to the same person for more than an hour for at least a week after your treatment

Are there any risks with having children after the therapy?

There have been no effects on the heath of the offspring of patients who have received radioiodine treatment. However, if you are female we do ask you to avoid becoming pregnant for six months after radioiodine treatment. If you are male, you are advised to avoid fathering children for at least six months after your therapy.

Will I need to see a doctor after my therapy?

You should be seen by your endocrine doctor within six weeks after your treatment to have blood tests. These are to check how your thyroid gland has responded to the radioiodine treatment. It takes between two and three months for radioiodine to have its full effect. If you do not have an appointment with your endocrinologist you should arrange for them to see you six weeks after your treatment.

How many treatments will I need?

Usually one, but occasionally a second (or even third) treatment is necessary. You will be monitored with blood tests to determine whether you require further radioiodine treatment. If you require a second treatment, it will be given about six to twelve months after your first treatment.

Are there any long term side-effects?

Radioiodine has been used for over 70 years to treat hyperthyroidism and the treatment is considered low risk and extremely effective, often avoiding the need for surgery or long term medication.

However, your thyroid gland may become underactive after your treatment. This could happen within a few months or after several years.

That is why periodic blood tests to check the function of your thyroid are important and will be required for the rest of your life.

If your thyroid becomes underactive, your doctor will prescribe a drug called thyroxine, which replaces the main hormone produced by the thyroid. Thyroxine has no side effects and needs to be taken only once a day in tablet form.

Medication

Bring all of your medicines (including inhalers, injections, creams, eye drops or patches) and a current repeat prescription from your GP

Please tell the ward staff about all of the medicines you use. During your stay If you wish to take your medication yourself (self-medicate) please speak with your nurse. Pharmacists visit the wards regularly and can help with any medicine queries.

My Chart:

We would encourage you to sign up for MyChart. This is the electronic patient portal at Cambridge University Hospitals that enables patients to securely access parts of their health record held within the hospital’s electronic patient record system (Epic). It is available via your home computer or mobile device

More information is available on our website: My Chart

Contacts/Further information

Nuclear Medicine Department

012233 217145