Radioiodine Treatment

Radioiodine Treatment for Thyroid Disorders

Radioiodine therapy (RAI), also known as radioactive iodine therapy (I-131 therapy), is a widely used treatment for various thyroid conditions, including hyperthyroidism and thyroid cancer. It involves the use of radioactive iodine (I-131), which is selectively absorbed by the thyroid gland, leading to targeted destruction of thyroid tissue.

Indications for Radioiodine Therapy

1. Hyperthyroidism (Overactive Thyroid)

   • Graves’ disease (most common indication)

   • Toxic multinodular goiter

   • Toxic adenoma

2. Thyroid Cancer

   • Used after thyroidectomy to destroy remaining thyroid tissue or metastases in differentiated thyroid cancer (papillary & follicular types).

How Radioiodine Therapy Works

• I-131 is taken orally (capsule or liquid form).

• It is selectively absorbed by thyroid cells, where it emits beta radiation.

• The radiation destroys thyroid cells over weeks to months, reducing thyroid hormone production.

• The treatment does not affect other body tissues significantly due to iodine's natural thyroid selectivity.

Preparation for Radioiodine Therapy

1. Low-Iodine Diet (for thyroid cancer patients)

   • Followed for 1-2 weeks before treatment to maximize iodine uptake by thyroid cells.

   • Avoid iodine-rich foods (e.g., dairy, seafood, iodized salt).

2. Stopping Thyroid Hormone Medications (for cancer patients)

   • Levothyroxine (T4) may be stopped and replaced with liothyronine (T3) before treatment.

   • Alternatively, recombinant TSH (Thyrogen®) injections may be used to stimulate thyroid cells.

3. Thyroid Function Tests

   • TSH levels should be elevated for better iodine uptake.

4. Pregnancy and Breastfeeding Precautions

   • Contraindicated in pregnancy – Must avoid pregnancy for at least 6 months after treatment.

   • Breastfeeding should be discontinued before therapy.

Post-Treatment Precautions (Radiation Safety Guidelines)

• Limit close contact with others, especially pregnant women and children, for 3-7 days.

• Use separate utensils and wash them thoroughly after use.

• Flush the toilet twice after use and wash hands thoroughly.

• Drink plenty of water to help flush out excess radioiodine.

• Avoid sharing a bed with others for a few days.

• Airport security radiation detectors may detect radioactivity – Carry a medical certificate if traveling soon after treatment.

Expected Outcomes & Side Effects

• Hyperthyroidism Treatment:

  • Most patients become hypothyroid within 3-6 months, requiring lifelong levothyroxine replacement therapy.

• Thyroid Cancer Treatment:

  • Remaining thyroid tissue is destroyed, reducing the risk of recurrence.

  • Periodic whole-body scans may be required to monitor for cancer recurrence.

• Common Side Effects:

  • Temporary neck pain or swelling

  • Dry mouth or altered taste (especially in high-dose therapy for cancer)

  • Fatigue

  • Sore throat (rare)