Hyperthyroidism

I-131 Thyroid Therapies

One of the very earliest radionuclide therapies used in clinical medicine radioiodine therapy of thyroid disorders uses high-energy beta minus particles from the decay of I-131, administered orally as NaI. This is a useful therapy for both benign and malignant thyroid diseases.

Benign Thyroid Disease

(Therapy is typically administered as an outpatient basis.)

Graves’ Disease.

I-131 is the treatment of choice for symptomatic patients. The desired dose of I-131 to be administered can be calculated using the following formula: Dose = (Thyroid mass[grams] x 100-200 uCi/gram)/Percent uptake. Thyroid mass estimates can be unreliable, affecting the accuracy of the calculated dose. Many centers treat patients with an empiric dose of eight to 12 mCi.

Autonomously Functioning Nodules: Multinodular Goiter and Plummer’s Disease.

Therapeutic doses are typically larger than for Graves’ Disease, according to state-specific regulations, up to a maximum of 33 uCi in NRC-regulated states. Treatment goals are to locally disable autonomously functioning nodules and to decrease the size of the thyroid gland. Non-toxic Nodular Goiter. I-131 therapy is used for the reduction of thyroid volume in patients with nontoxic multinodular goiter.