What is a Thyroid scan?

A thyroid scan is a nuclear medicine test of the thyroid gland. It can be used to assess any unusual lumps in your thyroid or to measure how well your thyroid is working.  

Is it safe for me to have the scan?

For this scan it is necessary to inject or drink a small amount of radioactive tracer, called a radiopharmaceutical, in order to take the pictures. The small risk from this (less than a CT scan) is outweighed by the information that will be gained by taking the scan. A doctor will have checked the request to make sure this is the appropriate test for you.  

If you have any concerns or would like further information, please contact the department where you are having your thyroid scan. If you don’t understand why you need to have this scan please speak to the doctor who referred you.

For female patients aged 12 to 55 

If you know that you are pregnant, or there is any chance that you might be pregnant, please contact the department where you will be having your scan. Do this as soon as possible as the scan can be postponed if it is not urgent. 

Also, contact the department if you are breast-feeding, as they may give you special instructions. 

Preparation for your scan

You may need to stop some of your usual medicine before your scan. Therefore, your appointment letter may ask you to contact the nuclear medicine department where you will be having your scan in order to discuss your medication. 

Your injection or drink

There are two different tracers that can be used for the thyroid scan. The nuclear medicine department will select the one that is most appropriate for you. 

One tracer is given as an injection into a vein in your arm or hand. You may have had a blood test in the 
past; this is much the same. The ‘pinprick’ of the needle may hurt a bit but that is all. With this tracer the scan pictures can be taken 20 minutes later. 

The alternative tracer is given as a drink, so no injection is involved. However, you will then have to wait for between 2 and 4 hours before the scan can be taken. 

Your scan

You will not have to get undressed, but you will be asked to remove any jewellery from around your neck. You 
will be asked to lie on your back on a special couch with your chin up so that the camera can see your neck. 

The pictures are taken by a special machine called a gamma camera. This is not a tunnel, but the camera detector will come very close to you.  

You will not be left on your own – there will always be someone immediately available, either in the room or behind a screen. The scan usually takes about 30 minutes. 

It may be necessary to take more pictures after a further wait. Sometimes it may also be necessary to take an additional picture the next day.

After your scan

It is very unlikely that you will feel any side-effects after the scan, but if you think that you have please let the nuclear medicine department know.  

You may continue all your normal activities unless you have been advised otherwise. 

After your scan there will be some radioactivity left in your body but this will not present a significant risk to other people around you. However, for the rest of the day, we suggest that you try to keep any time that you spend within arm’s length of pregnant women, babies and small children as short as possible; but there is no need 
to stop giving children essential love and care. 

The radioactivity in your body will soon disappear.

Travelling abroad

It is perfectly safe for you to travel abroad after your scan, but many airports and sea ports are now equipped with very sensitive radiation detectors. So it is possible that the very small amount of radioactivity left in your body could set off a detector as you pass through security. Therefore, if you intend to travel abroad within a week 
following your scan, it could be helpful to take with you something to explain that you have recently had a nuclear medicine scan. This could be your appointment letter or some other official confirmation from the department where you had your scan. 

Your results

Your thyroid scan will be looked at by a specialist who will issue a report. The report will be sent to the doctor who requested your scan rather than to your GP. This is because the doctor who requested your scan will have all the results from other tests and will be able to tell you how the result of your thyroid scan affects your care. 

Information about you

As part of your care, information will be shared between clinical staff, some of whom you may not meet. It may also be used to help train other staff. Information collected may also be used later on to help the department improve their quality of care, plan services or to research into new developments. 

The pictures from your scan may be used to teach other healthcare workers, but your name and all other identification will be removed first. It won’t be possible to identify you from the scan pictures. 

All information will be treated as confidential and is not given to anyone who does not need it. If you have any concerns, please discuss these with the department. 

More information

All the staff would like to make your visit as pleasant as possible. If you have any concerns please talk to a member of the nuclear medicine staff.

A printable version of this leaflet can be found here