• Chloe McElmury

What’s RAI and how does it work?

Radioactive-iodine (RAI) is a common treatment and scanning method for thyroid cancer survivors, especially after your thyroidectomy. RAI can be a little confusing and scary. RAI can refer to 1) a scan uptake dose you may have to check for thyroid tissue anywhere in your body and 2) a treatment dose to fight thyroid cancer.

Scan Uptake Dose

Your thyroid is the main part of your body that uses iodine. Before receiving your RAI dose, you will most likely be put on a low-iodine diet (LID). LID makes it so that your remaining thyroid cells are starving for iodine. So, when you take the RAI dose, those cells will suck up a ton of that radio-active iodine. This means that when you have a scan, it will be easy to see where the iodine has gone in your body. Maybe you will have no uptake, but the scans will be able to show if you’ve got uptake anywhere in your body where there are thyroid cells. This is helpful to identify recurrence after many years, or even to find some thyroid tissue that was possibly missed during surgery. This dosage strength is usually fairly low, and you might not have to take any precautions such as isolating yourself from others. Always follow your doctor’s orders on what you can and can’t do when radioactive! The scan used with RAI is usually a whole body scan.


During a whole body scan, you will most likely be lying on your back. I always ask for a warm blanket during mine! You might be strapped in around the waist and feet, to make sure you don’t wiggle around during the scan. It’s very important to stay still so a clear image is taken. Usually the scan will start at your head, getting very close to your face. Then, the scanner slowly moves down your body. Sometimes you can also ask for music to be played to help pass the time.


Treatment Dose

For treating cancer or suspected cancer, your RAI dose will be higher than what you received for your scan. For both types of doses, you’ll take radioactive iodine as either a liquid or a capsule you swallow. It’s the same idea as the scan uptake dose; the radioactive iodine will be absorbed by any thyroid tissue anywhere in your body. The radiation then destroys the cancer cells.


Because you are getting more radiation with this method, there are things to be aware of. First of all, any other RAI history of yours should be taken into consideration. It’s very hard to hit the lifetime limit you should get of radiation, but past RAI treatments should be used to gauge how successful it was before. Sometimes you can wait and watch, but other times it’s really best to zap that cancer right away! Sometimes a surgery might be more appropriate, so always talk it out with your doctor to ensure this is the best route.


Another consideration after RAI are the potential side effects and isolation period. Depending on your dose, you may need to be isolated from others, especially pregnant women, children, the elderly, and those with compromised immune systems. You will have special rules to follow, like drinking as much water as you possibly can to flush the radiation from your body and flushing the toilet multiple times after you go with the lid closed. For some, you may have to be in isolation at the hospital. If you have small children or a family, that will also require some crafty ways to keep your distance.



Sometimes, RAI might cause some symptoms, but usually they are not serious and are temporary. However, trust your body and if something doesn’t feel right, call your doctor right away. Make sure to drink lots of water and suck on hard candy like lemon drops after your RAI to flush the radiation from your salivary glands. You may get salivary gland swelling.


After your RAI treatment dose, you may have to get an additional scan to see if there is less or no uptake; aka, is the thyroid tissue that was there all gone?


In some cases, RAI may not be appropriate for your treatment. For example, if you have RAI-resistant metastatic thyroid cancer.


What questions do you still have about RAI? I hope this post answered some basic questions about it.

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