Iodine-131 therapy:
(1) permits post-ablative I-131 total body scanning
(2) makes measurement of serum thyroglobulin more specific for detecting persistent or recurrent tumor
(3) should not be used in low risk patients
(4) decreases both recurrence and death rates in high risk patients
Indications for Iodine-131 Ablative Therapy
(1) distant metastases
(2) incomplete excision of tumor
(3) complete excision of tumor but a high risk of mortality associated with thyroid carcinoma
(4) complete excision of tumor but high risk of relapse
(4a) due to age: < 16 years or > 45 years of age
(4b) histologic subtype:
• papillary variants: tall cell, columnar cell, diffuse sclerosing
• follicular subtypes: widely invasive or poorly differentiated
• Hurthle cell carcinoma
(4c) extent of tumor: large tumor mass, extension beyond thyroid capsule, or lymph node metastases
(5) elevated serum thyroglobulin concentration more than 3 months after surgery
