A thyroid scan shows how your thyroid is working, using a small amount of radioactivity, known as a "tracer". The tracer localises in the thyroid gland and the distribution is scanned using a gamma camera. The scan gives information on the size, position and function of the gland. 

How does it work?

The tracer will be injected into a vein, usually in your arm or hand; 20 minutes after the injection you will be asked to lie on a scanner couch. The gamma camera will be positioned over your neck and will take a series of pictures of the thyroid. Each picture will take about five minutes and the whole scan will take around 30 minutes. 

How do I prepare?

You will be asked to provide a list of your medications, if your doctor has not already advised us of them, as the uptake of the tracer may be affected by certain medications. Before your appointment we may ask you to stop taking some of your medicines, especially any thyroid medication you may be taking.

After the procedure

Once the scan has finished the doctor will check the quality of your scan while you wait, and the technologist will then let you go home. The radiation dose from this procedure is very small and there is no need to make any change to your routine.

There are no side effects from the injection; it will not make you feel sleepy or affect your ability to drive.