Radiology and Imaging
Thyroid Uptake and Scan
Below is a list of some frequently asked questions, but feel free to contact us if you need additional information. We are always pleased to assist you.
Why did my doctor order a Thyroid Uptake and Scan?
Your doctor may suspect that your thyroid is not functioning properly. The thyroid regulates thyroid hormones in the blood and a simple blood test could show that the hormones are high or low. Another reason your doctor may have sent you for this test is if he or she felt a lump during an external examination of the neck.
Is there anything I need to do to prepare for the test?
There are a few things that you need to make sure of before you come in for the test. You should make sure that you have not had CT contrast for 6 weeks before taking the pill because the contrast could alter the results of your test. Usually, your endocrinologist stops all thyroid medications. We usually try to lead people away from eating diets high in iodine, such as, shellfish, seaweed, and multi-vitamins with iodine, in order to better our results. We also advise patients not to eat 1 hour after taking the pill so that it can be absorbed without competition from other foods.
How is a Thyroid uptake and scan performed?
A pill containing a very small amount of radioactive iodine is measured and then given to you to swallow. The next day (20 to 26 hours) the patient returns and the thyroid is measured to see exactly how much of the iodine accumulated in the thyroid. We also take some images of the thyroid to see exactly how and where the iodine is taken up. The uptake of the iodine correlates directly with the metabolism of the thyroid and can show if the thyroid is normal, overactive or underactive. If there is a nodule, it will also tell us information about the metabolism of that nodule.
What are the risks of the Thyroid Uptake and Scan?
An allergic reaction to the tracer is extraordinarily rare, even if you are allergic, because of the extremely low amount. By taking the pill, the patient is exposed to a very small dose of radiation, less than that obtained from an X-ray study.
What are the alternatives to a Thyroid Uptake and Scan?
The doctor could rely on a blood work alone. They can also do a sonogram but these tests are usually done along with the Thyroid Uptake and Scan.
Will other tests be ordered?
Depending on what the results of this test show, your doctor could order a sonogram, CT scan or MRI. They may also order radioactive iodine therapy. In the rare cases that involve thyroid cancer, surgery may also be necessary.
What can I expect after the test is done?
There are no after-affects from this test. The radioactive tracer will disappear quickly and will be out of your system in 3-4 days.
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