Thyroid Scan

What is a Thyroid Scan?

A Thyroid scan looks at the function of the thyroid gland in your neck. Additionally, with the Thyroid scan, one can also assess the significance of Thyroid nodules.


You may eat and drink normally before your appointment.

You will be required to stop taking the following medication if you are on it:

  • Carbimazole/propylthiouracil, stop 3 days prior to test.
  • Thyroxine (T4), stop 4 weeks prior to test.
  • Tri-iodothyronine (T3), stop 2 weeks prior to test.
  • Please contact us if you have had a CT scan with contrast in the last 2 months as this could affect your test.

If you are pregnant or breastfeeding it is essential that you let us know before your appointment date. If you are a female of child bearing age (12-55 years old). You will be asked about your pregnancy and breastfeeding status. If you are unable to confirm you are not pregnant a pregnancy test may be performed.


All patients are entitled to have a chaperone present for any consultation, examination or procedure where they feel one is required. This chaperone may be a family member or friend.

The examination

Upon your arrival a radiographer will explain the procedure to you and will ask you a few questions about your health records. You will then have a small amount of radioactive tracer injected into a vein in your arm.

This substance takes 20 minutes to concentrate in the thyroid gland and during this time you will be asked to drink a glass of water as this will help to produce better quality images. After the 20 minute waiting period you will lay on a scan table with the camera placed above your head/neck to view your thyroid and a series of images will be taken. The machine is very quiet and you do not go through a tube or tunnel.

Is radioactivity dangerous?

The amount of radiation involved is similar to that from an x-ray examination. The radioactivity naturally disperses from the body and is largely gone in 24 hours. The very low risk involved is balanced against the benefit of the information the examination provides for your doctors.

After the examination

You will be asked to drink more than usual for the rest of the day to help clear the substance from your body. Otherwise you can continue as normal.