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:
- Medicines that have iodine, such as iodized salt, kelp,
cough syrups, multivitamins, or the heart medicine amiodarone (such as Cordarone or
- 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
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
- 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 (TSH, T3, and T4) in your blood.
To prepare for a thyroid scan:
- Do not eat for 2 hours before the
- Do not take any antithyroid medicine for 5 to 7 days before
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 (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
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?).
E. Gregory Thompson, MD - Internal Medicine
Matthew I. Kim, MD - Endocrinology
May 31, 2011
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