Iodine treatment for thyroid cancer uses a radio-active chemical called radio-iodine. The radio-iodine is concentrated in thyroid tissue and is also taken up by some types of thyroid cancer cells. This treatment gives a high dose of radiation to those cancer cells, and normal thyroid cells, but a low dose to all other normal tissues.

Radio-iodine therapy is often an important part of the treatment of the two commonest types of thyroid cancer, papillary and follicular carcinomas of the thyroid gland. This therapy destroys any stray cells that have not been removed by the surgery and therefore reduces the risk of the cancer coming back.

The radio-iodine is taken as a capsule and treatment is usually given as an in-patient in hospital. This is because you will be quite radio-active for a few days afterwards as the radio-iodine stays in your body for a little while. This radio-activity will not make you feel ill in any way but it does mean that your visitors will be limited to spending only a few minutes each day with you. Also, young children and pregnant women will not be allowed to visit you.

The hospital team will measure your radioactivity and as soon as this has dropped to a safe level you will be allowed home. Even then you will usually be told not to go back to work and to avoid contact with small children and pregnant women for about two weeks, while the final traces of radioactivity disappear from your system.

As the radio-iodine is concentrated in the thyroid gland the dose of radiation to the reproductive organs is very small indeed, although there is a little radiation from traces of the radio-iodine passed out through the bladder. This can be further reduced by drinking plenty to insure the urine is kept dilute. So there would be no long term effect on fertility. Fertility may be reduced for a few months after treatment, and you should avoid pregnancy in the first few months. Many women go on to have children after radioactive iodine treatment.