What is radioactive iodine?
This is also called internal radiotherapy. The treatment uses a radioactive form of iodine called iodine 131 or I-131. The radioactive iodine circulates throughout your body in your bloodstream. Thyroid cancer cells will pick up the iodine wherever they are in your body. The radiation in the iodine will then kill the cancer cells.
This is a targeted treatment. It will not affect other body cells as it is only thyroid cells that pick up iodine. The treatment is only suitable for some types of thyroid cancer. It is used for
Even if you have one of these types of thyroid cancer, this treatment may not be suitable for you. You will be given a test dose to see if your cancer cells pick up iodine. Not all do.
Radioactive iodine treatment is given
- After surgery to kill any cancer cells left behind
- To treat thyroid cancer that has spread
- To treat cancer that has come back after it was first treated
What do I do to prepare for this?
Before you are treated, your doctor will ask you to stop taking thyroid hormone tablets. This will be for 4 weeks if you are taking T4 (thyroxine) or 2 weeks if you are on T3 (tri-iodothyronine). This is because the I-131 works best when the levels of another hormone called TSH (thyroid stimulating hormone) are high. The levels of this hormone in your blood will begin to rise as soon as you stop taking thyroid hormone tablets.
In some situations, you may not be started on thyroid tablets until after surgery and radioactive iodine treatment have been completed.
3 weeks before you have this treatment, you will be asked to start eating a low iodine diet. This is because too much iodine in your body can mean that the treatment does not work so well. You should cut out any food coloured pink with the additive E127. So, do not eat
- Spam or salami
- Tinned strawberries
- Glace cherries
- Pink pastries or sweets (look on the labels for E127)
You should also not have
- Iodised table salt or sea salt
- Cough medicine
- Fish and seafood
- Vitamin supplements that say they contain iodine
Dairy products contain some iodine, so cut down on eggs, cheese, milk and milk products. You do not have to cut these out altogether but have as little as you can.
What happens when you have the treatment
To have the treatment, you will have to come in to hospital for a few days. You will be looked after in a single room. The treatment will make you slightly radioactive for a few days, so the time that the staff and your visitors spend with you will be limited for their protection. Your sweat and urine will be radioactive during this time. The hospital may have rules about changing your sheets daily and may ask you to flush the toilet more than once after you have used it.
To have the treatment, you are given a drink or capsule or the iodine can be injected into a vein in your arm. Your nurse will ask you not to eat or drink for a couple of hours so that your body can absorb the iodine. After that, you can eat normally. You should try to drink a lot to flush any excess radioactive iodine out of your system.
You will have to stay in your single room for a few days until your radiation levels have fallen. A radiation monitor (Geiger counter) may be used to monitor you or test anything that is taken out of your room. You can bring videos, tapes and books in to keep you entertained. Anything that comes out of the room will be monitored and it may be that some of your possessions are kept on the ward for a couple of days if they have been contaminated. After that time, they will be safe again and will be given back to you.
After your treatment
After a few days, you will have a scan to see if the radiation has dropped to a safer level. Once it has, you will be able to go home. You may be told that you shouldn't be in contact with children or breastfeeding mothers for a short time when you get home. Check this with the staff before you go home. So that you're sure about what you can and can't do and how long you have to take any precautions for. Your nurse will tell you when you can start to take your thyroid tablets again. Usually, this is 3 days after you had your treatment.