Radioactive Iodine Treatment
Radioactive iodine treatment (RAI), also called radioiodine therapy, is a medical procedure used to treat hyperthyroidism (and thyroid cancer). A dose of radioactive iodine-131 (¹³¹I) is administered orally; the thyroid gland preferentially absorbs iodine, causing the radioactive dose to destroy overactive thyroid tissue.
Indications
- graves-disease (most common use)
- Toxic multinodular goitre
- Toxic adenoma
Pre-Treatment Dietary Requirements
To maximise the effectiveness of RAI:
- low-iodine-diet: Patients follow a diet with <50 mcg iodine/day for 1–2 weeks before treatment to deplete the thyroid’s iodine stores, forcing it to avidly absorb the radioactive dose.
- soy avoidance: Soy has been shown (in animal studies) to interfere with radioactive iodine uptake; patients are advised to avoid soy products before the procedure.
- kelp and iodine supplements: Must be discontinued well in advance.
Outcome
RAI typically results in hypothyroidism (underactive thyroid) requiring lifelong levothyroxine replacement therapy. This is an expected and manageable outcome.
Post-Treatment Considerations
After RAI, iodine balance in the diet remains important. Bone health (calcium, vitamin-d) is also a long-term concern given the prior hyperthyroid state.