Information Living with thyroid disorders Radioactive iodine therapy for children with hyperthyroidism Radioactive iodine treatment (RAI) involves giving your child a pill or drink of radioactive iodine in a hospital or clinic. RAI treatment has been safely used for over seventy years but it isn’t usually given to children under around ten years of age. The radioactive iodine goes straight to the over-active thyroid gland where it destroys the cells in the thyroid gland. It does not affect any other parts of the body. After radioactive iodine treatment your child will be able to go home, but there are rules that need to be followed in the two to three weeks following treatment, such as avoiding close contact with children. This will mean that your child will need to be off school during this time. More specific details will be provided by the hospital at the time of treatment. Your child is likely to develop hypothyroidism after treatment with RAI. This means that their thyroid gland can’t produce enough thyroid hormones and they will need to take levothyroxine for the rest of their life. Even if your child doesn’t become hypothyroid immediately, they should have a thyroid function test (TFT) every six to twelve months.