Radioactive Iodine Treatment Procedure
Pre-Treatment Preparation
- The National Comprehensive Cancer Network recommends radioactive iodine (RAI) treatment is administered 2-12 weeks post-thyroidectomy using 30-200 mCi of I-131, with the dose determined by clinical indication, preceded by TSH stimulation via either recombinant human TSH (rhTSH) injection or thyroid hormone withdrawal 1, 2
- The preferred method of TSH stimulation is recombinant human TSH (rhTSH) administration while the patient continues levothyroxine therapy, as it demonstrates equal efficacy to thyroid hormone withdrawal but with better patient acceptance and quality of life 3
- Administer 0.9 mg rhTSH intramuscularly for two consecutive days, with blood sampling for thyroglobulin measurement occurring 72 hours after the second injection 4
Dosing Protocols
- For remnant ablation, the American College of Endocrinology recommends a low-dose ablation of 30-100 mCi, which is appropriate for low to intermediate risk patients without known residual disease 1, 2, 3
- For residual or metastatic disease, the National Comprehensive Cancer Network recommends a higher-dose treatment of 100-200 mCi, which is used for suspected or proven radioiodine-responsive residual tumor 1, 2, 5
Post-Treatment Protocol
- Post-treatment whole body scan (WBS) imaging is performed to detect residual thyroid tissue or metastatic disease, and helps guide further management decisions 1, 2, 3
Risk-Stratified Indications
- The American Thyroid Association recommends RAI for all patients with known distant metastases, documented lymph node metastases, gross extrathyroidal extension, primary tumor >2 cm, and high-risk patients based on pathology and staging 3, 7
- RAI is not recommended for unifocal cancer <1 cm without other higher risk features, multifocal cancer when all foci are <1 cm without other higher risk features, and very low-risk patients (pT1a, N0/NX) 3, 7