radioactive iodine-131 (I-131) ablation

Indications

• benign conditions of the thyroid
  • Graves' disease (toxic diffuse goiter)
  • toxic multinodular goiter or nontoxic nodular goiter
  • autonomously functioning toxic or non-toxic thyroid nodules
  • hyperthyroidism
• thyroid cancer (radioiodine uptake +)

Contraindications

• pregnancy
• lactation
• may aggravate Graves ophthalmopathy

Procedure

• pretreatment with glucocorticoids to mitigate increase in thyroid-stimulating immunoglobulin if Grave's ophthamopathy

Complications

• overall cancer risk not increased
• excess risk for thyroid cancer (RR=1.86)
• excess mortality risk for breast cancer & other solid cancers with higher radioactive iodine doses (400-500 vs 100-200 megabecquerels)*

* typical treatment dose is 200-300 megabecquerels

Management

• levothyroxine after ablation to maintain serum TSH below normal*

* thyroid follicular cells, the origin of papillary thyroid carcinoma & follicular thyroid carcinoma, are TSH-responsive

More general terms

• radioablation (photodynamic ablation)