Radioactive Iodine Imaging

Also known as: radioactive iodine uptake test, RAIU test.

What is radioactive iodine imaging?

Radioactive iodine imaging is a medical test that helps your pediatrician diagnose how well your child’s thyroid gland functions. It uses a short acting dose of radioactive iodine to determine how much the thyroid can take in over a certain period of time. If the thyroid gland takes in too much or too little iodine, it could be indicative of a medical problem.

What happens during the procedure?

  1. The patient takes a pill or liquid form with a small amount of radioactive iodine in it.
  2. After 4 to 6 hours, a scanner called a gamma probe is used to scan the thyroid gland and the area around it. It measures how quickly the thyroid gland is taking in the iodine.
  3. Then another scan is done 24 hours later.

Is any special preparation needed?

No special preparation is needed for this test though, your child may be advised not to eat or take some medications for some hours prior to the test. Patients should tell the doctor if they have diarrhea or have had recent computed tomography (CT) scans or iodine-based tests performed.

What are the risk factors?

The radiation exposure that occurs during this test is fairly small and doesn’t usually cause any problems.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: March 04, 2021 11:10 AM

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