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April 10, 1967


JAMA. 1967;200(2):162-163. doi:10.1001/jama.1967.03120150118028

From 1946 to 1956 radioactive iodine, because of its low cost, ease of administration, adequate control of symptoms, and lack of known complications, seemed an excellent treatment for hyperthyroidism. The surprisingly high incidence of hypothyroidism (20%) following this therapy was first reported in 1956.

Briefly summarizing a large volume of more recent reports, the following facts appear: One year after131I treatment of hyperthyroidism, 7% or more of the patients will be hypothyroid; the incidence of hypothyroidism rises inexorably thereafter at an annual increment of 2.5% or more for as long as the patients are followed up. In a recent report the cumulative incidence after ten years was 70%.1 Hypothyroidism has resulted from doses as small as 2 mc. Every major center uses repeated doses of131I until remission is secured, and this often requires doses in excess of 100 mc and four or more doses. After