What is a thyroid scan?

A thyroid scan is a procedure in which the doctor examines the thyroid gland using radioactive iodine and x-rays.

When is it used?

This procedure is used to diagnose problems with the thyroid gland.

There may be some alternative diagnostic studies you could consider such as CT scan (special x-rays) and ultrasound (sound waves), depending on the problem and your condition. However, the thyroid scan provides information on how the gland is functioning, information that no other test can offer.

An alternative is to choose not to have treatment, recognizing the risks of not knowing if you have a problem with your thyroid. You should ask your doctor about these choices.

How do I prepare for a thyroid scan?

The doctor will give you capsules containing radioactive iodine or another isotope to take 4 to 24 hours before the test. Tell the doctor if you are allergic to shellfish or other things that contain iodine. Also, tell the doctor if you have had other contrast-dye tests done in the past few months such as a CT scan.

What happens during the procedure?

After taking the capsules, you will lie on an examining table while a scanner is held near your neck. The scanner measures the amount and distribution of radiation in the thyroid. This information will help the doctor understand how well the thyroid is working. You may have more than one scan done. The doctor may also use a scanning device that produces a picture of the thyroid gland, showing areas where there may be a problem.

What happens after the procedure?

The doctor will give you the test results when the complete report is available. You can go home after the test is completed.

Ask your doctor what other steps you should take and when you should come back for a checkup.

What are the benefits of this procedure?

This procedure will help the doctor make a more accurate diagnosis.

What is a risk associated with this procedure?

The amount of radioactivity given in this test is so small that it does not pose a risk.

You could be allergic to the dye. You should ask your doctor how this risk applies to you.

When should I call the doctor?

Call the doctor immediately if you develop a skin rash following the test.

Call the doctor during office hours if:

• You have questions about the procedure or its result.

• You want to make another appointment.