How To Prepare
Tell your doctor if you:
- Take any medicines regularly. Be sure your
doctor knows the names and doses of all your medicines. Your doctor will
instruct you if and when you need to stop taking any of the following medicines
that can change the thyroid scan test results:
- Thyroid Reference hormones Opens New Window
- Antithyroid medicines
- Medicines that have iodine, such as iodized salt, kelp, cough syrups, multivitamins, or the heart medicine amiodarone (such as Cordarone or Pacerone)
- Are allergic to any medicines, such as iodine. But even if you are allergic to iodine, you will likely be able to have this test because the amount used in the tracer is so small that your chance of an Reference allergic reaction Opens New Window is very low.
- Have ever had a serious allergic reaction (Reference anaphylaxis Opens New Window) from any substance, such as the venom from a bee sting or from eating shellfish.
- Have had any test using radioactive materials or iodine dye (such as a CT scan with contrast) 4 weeks before the thyroid scan. These other tests may change the results of the thyroid scan.
- Are or might be pregnant.
- Are breast-feeding.
Before a thyroid scan, blood tests may be done to measure the amount of thyroid hormones (Reference TSH Opens New Window, T3, and T4) in your blood.
To prepare for a thyroid scan:
- Do not eat for 2 hours before the test.
- Do not take any antithyroid medicine for 5 to 7 days before the test.
Your doctor may ask you to eat a low-iodine diet for several days if this test is being done to check for thyroid cancer.
For a thyroid scan, you will either swallow a dose of radioactive iodine or be given technetium in a vein (Reference intravenously Opens New Window) in your arm. When and how you take the radioactive tracer depends on which tracer is used.
- Iodine can be taken as a capsule or a fluid 24 hours before the test. Iodine has little or no taste.
- Technetium is given 2 hours before the test.
Just before the test, you will remove your dentures (if you wear them) and all jewelry or metal objects from around your neck and upper body.
Before a thyroid scan, you need to sign a consent form that says you understand the risks of the thyroid scan and agree to have it done. Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form (What is a Reference PDF Opens New Window document?).
|By:||Reference Healthwise Staff||Last Revised: Reference May 31, 2011|
|Medical Review:||Reference E. Gregory Thompson, MD - Internal Medicine
Reference Matthew I. Kim, MD - Endocrinology