Thyroid Scan: How To Prepare

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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 hormones
  • Antithyroid medicines
  • Medicines that have iodine, such as iodized salt, kelp, cough syrups, multivitamins, or the heart medicine amiodarone (Cordarone, Pacerone)
• Are allergic to any medicines, such as iodine. However, 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 allergic reaction is very low.
• Have ever had a serious allergic reaction (anaphylaxis) from any substance, such as the venom from a bee sting or from eating shellfish.
• Have had bleeding problems or take blood thinners, such as aspirin or warfarin (Coumadin).
• Have had any test using radioactive materials or iodine dye 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 (TSH, T3, and T4) in your blood.

To prepare for an RAIU test, do not:

• Eat for 2 hours before the test.
• Take any antithyroid medicine for 5 to 7 days before the test.

Your doctor may ask you to eat a low-iodine diet, especially 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 (intravenously) 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 PDF document?).

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Last updated:	September 15, 2006
Author:	Jan Nissl, RN, BS
Reviewed By:	Caroline S. Rhoads, MD - Internal Medicine, David C.W. Lau, MD, PhD, FRCPC - Endocrinology & Metabolism
Editors:	Susan Van Houten, RN, BSN, MBA, Tracy Landauer