Diagnostic thyroid uptake and/or thyroid scan

What is this test?

The thyroid uptake test is done to find out how your thyroid gland is working. The thyroid scan is done to see if there are overactive or underactive parts within your thyroid gland.

The most common reasons for these tests are to look for overactive (hyper) thyroid, underactive (hypo) thyroid or inflammation of the thyroid. If you have an overactive thyroid, the uptake and scan results may be used to plan radioactive therapy.

Your appointment

If you make any changes to your insurance before your appointment please call Registration at 1-866-309-0832. This will help prevent delays and the need to reschedule your test, as many radiology services need a pre-authorization. 

Take Elevator H or I to Level 3 Nuclear Medicine Clinic. It is between elevators H and I.

Please call Nuclear Medicine at 1-319-356-1911 if you:

  • Have questions
  • Need to cancel your appointment
  • Are unable to do the prep listed or think you may be pregnant
    • You may not be able to have the test, or it may need to be rescheduled

Getting ready for your test

Before your test, tell your doctor or nurse if:

  • You are pregnant or think you may be pregnant, or if you are breastfeeding.
    • You may have to give a urine sample if a pregnancy test is needed.

Skin Prep

  • Do not use iodine tincture two weeks or betadine one month before your test.

Food

  • Do not eat or drink for four hours before or two hours after your thyroid test. You may drink water.
  • If you have any other test today where you are told not to eat or drink for a longer amount of time, please follow those instructions.

Medicine

  • Stop taking dietary supplements with iodine, such as vitamins. minerals or kelp, at least one week before your test.
  • Talk with your doctor about how to take thyroid or antithyroid medicine. Most often you will stop these medicines before your thyroid uptake test:
    • Antithyroid medicines, such as PTU and Methimazole one week before
    • Synthroid four to six weeks before
    • Cytomel one to two weeks before
  • Six to eight weeks before your test, do not have:
    • Diagnostic X-ray studies where you are given dyes by mouth
    • CT studies where you are given contrast in an IV
    • Intravenous Pyelogram (IVPs)

What to expect

Thyroid Uptake and Scan

You will come for three visits over 24 hours for this test.

  1. Your first visit will take about 30 minutes. You will take a capsule with a small amount of radioactive material. The level of radioactivity is very low and does not have side effects.
  2. Your second visit will also take about 30 minutes. You will come back three to six hours after you take the capsule to have the uptake (absorption) measured.
    • You may also have a scan after the uptake
  3. Your third visit will take about 1 hour and 30 minutes. You will come back 24 hours after you take the capsule to have the uptake measured again. Then you will be given a radioactive medicine into your vein through an intravenous catheter (IV). You will wait 30 minutes and then have the scan.
    • The uptake is measured using an uptake probe.
    • The scan is done using a special machine called a gamma camera. It will take about one hour to take all the pictures that are needed. The camera:
      • Does not emit any radiation.
      • Will be closer ot your body while the pictures are taken.

Thyroid Scan Only

If you are only haveing a thyroid scan, you will:

  1. Be given a radioactive medicine into your vein through an IV.
  2. Wait 30 minutes
  3. Have the scan

It will take about one hour to take all the pictures that are needed.

Last reviewed: 
August 2018

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