Thyroid scan

A thyroid scan checks the function of the thyroid gland. It can help find out if your thyroid is working normally, or is overactive or underactive.

Thyroid scans are done in the nuclear medicine department, using a gamma camera.

Preparing for a thyroid scan

There is no special preparation for this scan. You can eat and drink as normal. We will ask you to keep well hydrated by drinking more than usual between the injection and the scan. A staff member will give you more details when you come in for your scan.

You should be prepared to be at the hospital for up to 1 hour.

Please contact us as soon as you receive your appointment if you:

  • currently take levothyroxine medicine (you must stop taking this medicine for the 4 weeks before your scan)
  • have had a CT scan using contrast in the 4 weeks before your thyroid scan appointment
  • are breastfeeding (we’ll give you some more information before you come for your scan)

During a thyroid scan

You will meet our team of technologists, or radiographers and they will explain the procedure to you. You can ask any questions about the scan.

You will be injected with a tracer. This is a radioactive fluid that helps us to see your scans clearly. This gets absorbed in the thyroid.

After the injection you will be asked to sit in the waiting area for 15 minutes and drink a glass of water. Just before the scan, we will ask you to pee (empty your bladder) and then we’ll take you to the camera room.

You will be asked to remove any metal items, such as mobile phones, wallets or belts, but clothes with small metal zips and fastenings are OK. You will be lying on a camera bed and you need to keep as still as you can. The cameras will be above and below your head and come quite close, but will not touch you.

The scan will take about 10 minutes.

Pregnancy and breastfeeding

As the scan involves an injection of a radioactive tracer, you must tell us if you are, or think that you might be, pregnant, or if you are breastfeeding. If possible, please tell us as soon as you receive your appointment.

For all nuclear medicine studies we check your pregnancy status with you before using any radioactive tracer.

Pain during a thyroid scan

The injection is similar to a blood test and there is no pain associated with tracer.

After a thyroid scan

There are no side effects from this scan and you can carry on with your normal activities.

After the scan you will still have some radioactivity left in your body. For the rest of the day, avoid any non-essential prolonged, close contact with children, and anyone who might be pregnant. This is to reduce the amount of unnecessary radiation to babies and children

Risks of a thyroid scan

We feel that the potential benefits of the test outweigh the very small risks. We make sure the amount of radiation you receive is as small as possible.

You can read government information about radiation exposure from medical imaging.

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. It is possible that the very small amount of radioactivity left in your body could set off a detector as you pass through security. If you plan to travel abroad in the week after your scan, it could be helpful to take your appointment letter with you.

Follow-up appointments

If you already have an appointment booked in clinic to discuss the results of the test, please let our team know.

Your images will be reviewed by our doctors and a report will be sent to the doctor that referred you. You will get the test results from them

Resource number: 5370/VER1
Last reviewed: July 2023
Next review due: July 2026

Trusted Information Creator. Patient Information Forum

Contact us

If you have any questions about your test in the nuclear medicine department, please contact us

Phone 020 7188 4112, Monday to Friday, 9am to 5pm

Email [email protected]

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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