Abstract

Radioiodine (¹³¹I), a radioactive isotope of iodine, permanently suppresses thyroid function and is widely used in the UK for the treatment of patients with hyperthyroidism (thyrotoxicosis). It is used either as first-line treatment or when a patient has relapsed after thyroidectomy or an antithyroid drug. Radioiodine is also a standard part of treatment for some kinds of thyroid cancer.