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Radioiodine therapy (I-131) for thyroid cancers & thyrotoxicosis

Overview

Radioiodine therapy uses radioactive iodine (I-131) to target and treat thyroid-related conditions, such as hyperthyroidism (overactive thyroid) and thyroid cancer. Radioactive iodine is absorbed by the thyroid gland and works by destroying thyroid cells, either to reduce thyroid hormone production or eliminate cancerous tissues.

Your doctor may recommend radioiodine therapy for:

  • Hyperthyroidism: To reduce the overproduction of thyroid hormones, often due to conditions like Graves’ disease or hyperactive thyroid nodules.
  • Thyroid Cancer: To destroy any remaining cancerous thyroid tissue after surgery or to treat thyroid cancer that has metastasized to other areas.

  • The thyroid gland naturally absorbs iodine. Radioiodine therapy uses this property to deliver radioactive iodine (I-131) directly to the thyroid gland.
  • Once absorbed, the radioactive iodine destroys overactive or cancerous thyroid cells, reducing thyroid activity or eliminating cancerous tissue.

  • Low-iodine diet: You may be asked to follow a low-iodine diet for 1-2 weeks before treatment to help the thyroid gland absorb the radioiodine more effectively. This involves avoiding foods like dairy products, seafood, iodized salt, and processed foods that contain iodine.
  • Medications: Inform your doctor about any medications you are taking, especially thyroid medications. Some medications may need to be stopped temporarily before treatment.
  • Pregnancy and breastfeeding: Radioiodine therapy is not suitable for pregnant or breastfeeding women. You should avoid trying to conceive for at least 6 months after the treatment, and breastfeeding should be stopped prior to therapy.
  • Plan for isolation: After treatment, you may need to limit close contact with others, especially children and pregnant women, for a few days due to the radiation. The exact duration will depend on the dosage of radioiodine.

  • Radioiodine dose: Radioiodine is usually taken as a pill or liquid, which you will swallow in a single dose. It is tasteless and well tolerated by the body.
  • Absorption by Thyroid: The radioactive iodine is absorbed by your thyroid gland over the next few days to months, where it destroys the targeted thyroid cells.
  • Follow-up: You may be asked to come back for follow-up blood tests or scans to assess how well the therapy is working.
  • Radiation precautions: After receiving radioiodine therapy, you will emit small amounts of radiation. You need to follow specific safety guidelines for a few days to minimise radiation exposure to others.

Radiation Safety Guidelines: To protect those around you, follow these precautions for a few days after treatment:

  • Limit close contact: Avoid prolonged physical contact with others, especially pregnant women and young children.

    Specific duration of this will be conveyed by your treating Nuclear Medicine Physician.

  • Sleep separately: Sleep in a separate bed, if possible, for a few days.
  • Use separate utensils and dishes: Wash your utensils and dishes separately from others.
  • Flush the toilet twice: After using the bathroom, flush the toilet twice and wash your hands thoroughly.
  • Avoid public places: Stay away from crowded areas and public transportation to reduce exposure to others.
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