Radioactive Iodine Uptake Test
How To Prepare continued...
To prepare for an RAIU test:
- Follow your doctor's instructions about not eating before the test. Most often, you will need to stop eating 8 hours before the test.
- Tell your doctor about all of the medicines, vitamins, and supplements you are taking. You may need to stop taking some medicines or supplements for a while before the test.
Your doctor may ask you to eat a low-iodine diet.
For an RAIU, you will swallow a dose of radioactive iodine. Iodine can be taken as a capsule or a fluid 4 to 24 hours before the test. Iodine has little or no taste.
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.
You will be asked to sign a consent form that says you understand the risks of the test 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?).
How It Is Done
A radioactive iodine uptake (RAIU) test is done in the nuclear medicine section of a hospital's radiology department by a person trained in nuclear medicine (nuclear medicine technologist).
For this test, you will lie on your back with your head tipped backward and your neck extended. It is important to lie still during this test. A special machine is placed over your thyroid gland to measure the amount of tracer absorbed by the thyroid gland. This is not an X-ray machine-it is a scanner that detects the radiation given off by the tracer. This test takes about 10 minutes and is done 3 to 6 hours after you are given the tracer. Another scan may be done in 24 hours.
After an RAIU test, you can do your regular activities. But you will be asked to take special precautions when you urinate. This is because your body gets rid of the radioactive tracer through your urine. This takes about 24 hours. During this time, it is important to flush the toilet twice each time you use it and wash your hands thoroughly after each time you urinate.