If papilliary or follicular (but not medullary) cancer are diagnosed then the surgery will be followed by Radioactive iodine (RAI) treatment. Normal thyroid cells and thyroid cancer cells are unique because they are the only cells in the body to store radioactive iodine. This means radioactive iodine can be used to treat thyroid cancer. It is called radioactive iodine ablation (RAI). The radiation in the iodine destroys thyroid cells but is harmless to the rest of the body. ‘Ablation’ literally means destruction. Radioactive iodine treatment destroys any remaining thyroid cells in the body after surgery.

If your child is already taking levothyroxine or propylthiouracil (PTU) they will be asked to stop taking these several weeks before they have RAI therapy. This is to ensure they have a high TSH level as this allows any cancer cells to absorb the radioactive iodine better.

You can help your child’s RAI treatment by preparing foods with a low-iodine content for about two weeks before ablation, and avoiding vitamins and food supplements containing high levels of iodine. This is because thyroid cells take up iodine from food, so by emptying the thyroid cells of iodine beforehand the radioactive iodine can be better absorbed by any thyroid cells. The hospital staff will be able to give you further information.

Radioactive iodine is taken either as a drink or as a capsule. Your child will need to stay in hospital for a few days in a single room as the treatment will make them radioactive. The number of visitors who see them and the length of time that they can stay will be restricted during this time. This is to stop you and other visitors being exposed to radioactivity. As parents you may be able to share in their care and to be with them during the day so that they are not so isolated.

The hospital should provide you with a list of what your child will need to take with them, and should tell you what policies it has for the retention or disposal of your child’s belongings. If items, such as clothing, toothbrush, toys, books etc have been contaminated with radiation they may have to be disposed of, so be sure to ask before your child takes a favourite toy or activity with them as it may not return home with them!

Girls and young women must not have radioactive iodine if they are pregnant and must avoid getting pregnant for at least six months after the treatment. This means that girls who have gone through puberty are routinely given a pregnancy test before they receive radioactive iodine therapy. Boys and young men must avoid fathering a child for at least six months after the treatment.

After radioactive iodine treatment, your child will be monitored by blood tests, a thyroglobulin test and scans just to make sure that there are no remaining thyroid cancer cells.