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Radioactive Iodine (RAI) Therapy in Thyroid Cancer

Adjuvant ablative or therapeutic I-131 administered after total thyroidectomy in differentiated thyroid carcinoma to eradicate remnant tissue and treat metastatic disease.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

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This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Endokrinoloji department. Book Appointment →

What is Radioactive Iodine (RAI) Therapy in Thyroid Cancer?

Radioactive iodine therapy (RAI) is the use of beta-emitting I-131 to ablate or destroy thyroid follicular cells in differentiated thyroid carcinoma (DTC) - papillary and follicular subtypes. It is administered after total/near-total thyroidectomy. Iodine is selectively concentrated in thyroid tissue via the sodium-iodide symporter (NIS); medullary and anaplastic thyroid cancers do not concentrate iodine.

Indications by ATA risk: low-risk (microcarcinoma, intrathyroidal, no extension): RAI not routinely recommended; intermediate-risk (lymphovascular invasion, microscopic extrathyroidal extension, lymph node metastasis): selective RAI 30-100 mCi; high-risk (gross extrathyroidal extension, distant metastasis, R1/R2 resection): RAI 100-200 mCi. Pulmonary or skeletal metastases require repeated cycles.

Preparation: TSH stimulation >30 mU/L is mandatory - either thyroid hormone withdrawal (4-6 weeks levothyroxine cessation, 2 weeks T3) or recombinant human TSH (rhTSH/Thyrogen) injection. Low-iodine diet (LID) for 1-2 weeks (avoid iodized salt, seafood, dairy, contrast). Pretreatment whole-body scan and stimulated Tg measurement. Pregnancy and breastfeeding are absolute contraindications.

Symptoms

Acute neck pain and swelling (radiation thyroiditis)
Sialadenitis and dry mouth (parotid/submandibular)
Nausea and gastritis (within 24-48 hours)
Bone marrow suppression (transient)
Taste alterations and loss of taste
Fatigue and hypothyroid symptoms (during withdrawal)

Risk Factors

Cumulative dose >600 mCi (secondary malignancy risk)
Pregnancy (absolute contraindication)
Lactating breast tissue (uptake risk)
Severe xerostomia history
Pulmonary metastases (radiation pneumonitis)
Bone marrow reserve compromise

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Persistent neck pain after RAI
  • Severe nausea and vomiting (>72 hours)
  • Acute parotid swelling and pain
  • Rising thyroglobulin during follow-up
  • New imaging-detected metastases
  • Suspected radiation pneumonitis (cough, dyspnea)

Treatment Methods

01
Total thyroidectomy first (RAI is adjuvant)
02
TSH stimulation (rhTSH or hormone withdrawal)
03
Low-iodine diet 1-2 weeks pre-RAI
04
Risk-stratified I-131 dose (30-200 mCi)
05
Post-therapy whole-body scan (5-7 days)
06
Tg and anti-Tg surveillance (every 6-12 months)

Which Department to Visit?

You can visit our Endokrinoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.