How does radioiodine work?
The thyroid gland accumulates iodine from the food you eat. The thyroid gland uses this iodine to perform its normal function, which is to make thyroid hormone. Radioiodine is used to treat overactive thyroid glands and certain kinds of thyroid cancer. It is mainly taken up by the thyroid gland. In the treatment of hyperactive thyroid glands, radiation from the radioactive I-131 damages a portion of the thyroid gland to reduce its activity. Larger doses of I-131 may be used after thyroid cancer surgery to destroy any remaining diseased thyroid tissue. Radioactive iodine treatment may be given:
- after surgery, follicular thyroid cancer and papillary thyroid cancer
- to treat thyroid cancer that has spread
- to treat thyroid cancer that has come back after it was first treated
- treatment of hyperthyroidism
You may only need to have this treatment once. But it can be repeated every 3 months if needed, until there is no sign of any thyroid cancer on your scans.
How safe is radioiodine?
The practice of treating one’s thyroid with radioiodine or I-131 is a common, well accepted form of treatment. Most of the radiation from the I-131 will be taken up by the thyroid gland. However, the other tissues in your body will receive some incidental radiation. This small amount of radiation does not produce any adverse effects. Radioiodine is never given to pregnant or nursing individuals. Radioactive iodine has been used to treat hyperthyroidism for more than 60 years. There is no evidence that radioactive iodine causes cancer, infertility, or birth defects.
How long does the radioiodine stay in your body?
Within a few days after treatment, the radioactive iodine will leave your body in your urine and saliva. but very small amounts can be found in your saliva, sweat and bowel movements. How long it takes will depend on your age and on the dose you received. Young people get rid of radioactive iodine faster than older adults. Drink plenty of fluids during this time to help your body get rid of the radioactivity.
Tips to know before and after iodine therapy.
Time: You will be advised to minimize the time spent in close contact with others.
Distance: The greater the distance you are from others, the less radiation they will receive.
Hygiene: Good hygiene will minimize the possibility that others will be contaminated with radioiodine that leaves your body.
Before iodine therapy:
- You stop taking the tablets for 4 weeks if you are taking T4 (thyroxine) or 2 weeks if you are taking T3 (liothyronine). This is because the I-131 works best when the levels of another hormone called TSH (thyroid stimulating hormone) are high. The levels of TSH in your blood start to rise as soon as you stop taking thyroid hormone tablets.
- In some situations, your doctors may not ask you to take thyroid hormone tablets until after your surgery and radioactive iodine treatment have finished.
- You’ll need to follow a low-iodine diet for at least 1 week before you start treatment. A low-iodine diet will make your radioactive iodine therapy more effective. If you have too much iodine in your diet, it can stop the thyroid cells from taking up the radioactive iodine.
The day you receiving the radioiodine, do not eat after midnight. No solid foods for two (2) hours after swallowing the radioiodine
References
https://www.augustahealth.com/radiology/radioactive-therapy-with-i-131-for-thyroid-diseasehttps://www.uofmhealth.org/health-library/hw148148https://www.cancerresearchuk.org/about-cancer/thyroid-cancer/treatment/radiotherapy/radioactive-iodine-treatment/preparing-radioactive-iodine-treatmenthttps://www.snmmi.org/AboutSNMMI/Content.aspx?ItemNumber=5609https://www.mskcc.org/cancer-care/patient-education/radioactive-iodine-therapy-thyroid-outpatient-treatment
