Low-Dose 131 I in Treatment of Graves' Disease

One hundred and sixty-four patients with Graves' disease were treated with low-dose radioiodine (2 mCi), with a mean follow up of 4 1/2 years. At this time 74 (45%) were euthyroid having had a single dose, with a total of 131 (80%) being controlled with one or more doses. Three (2%) were still toxic but their mean follow up was only 3 years. Thirty (18%) were rendered hypothyroid, two-thirds of these after a single dose of 2 mCi 131I. The one-year incidence of hypothyroidism was 6%, with an incidence at 6 years of 20%. Previous surgery, medical treatment and thyroid antibody status appeared to have no influence on the outcome.