Thyroid Scan

What is a thyroid scan?

A thyroid scan is a procedure in which your health care provider examines your thyroid gland using radioactive iodine that gives off a type of x-ray.

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.

How do I prepare for a thyroid scan?

Your health care provider will give you capsules containing radioactive iodine or another isotope to take 4 to 24 hours before the test. Tell your provider if you are allergic to shellfish or other things that contain iodine. Also, tell your provider 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 your health care provider understand how well the thyroid is working. You may have more than one scan done. Your provider 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?

Your health care provider will give you the test results when the complete report is available. You can go home after the test is completed.

Ask your health care provider 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 your health care provider 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.

Allergic reactions are uncommon for this test, but discuss any allergies you have with him or her before the test.

When should I call my health care provider?

Call your health care provider immediately if you develop a skin rash after the test.

Call your health care provider during office hours if:

  • You have questions about the procedure or its result.
  • You want to make another appointment.

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Published by iMcKesson Clinical Reference Products.
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Adapted from content provided by iMcKesson, LLC
Review Date: 6/10/01