RELATION BETWEEN THERAPY FOR HYPERTHYROIDISM AND THE COURSE OF GRAVES-OPHTHALMOPATHY

Background The chief clinical characteristics of Graves' disease are h yperthyroidism and ophthalmopathy. The relation between the two and th e effect of treatment for hyperthyroidism on ophthalmopathy are unclea r. Methods We studied 443 patients with Graves' hyperthyroidism and sl ight or no ophthalmopathy who were randomly assigned to receive radioi odine, radioiodine followed by a 3-month course of prednisone, or meth imazole for 18 months. The patients were evaluated for changes in the function and appearance of the thyroid and progression of ophthalmopat hy at intervals of 1 to 2 months for 12 months. Hypothyroidism and per sistent hyperthyroidism were promptly corrected. Results Among the 150 patients treated with radioiodine, ophthalmopathy developed or worsen ed in 23 (15 percent) two to six months after treatment. The change wa s transient in 15 patients, but it persisted in 8 (5 percent), who sub sequently required treatment for their eye disease. None of the 55 oth er patients in this group who had ophthalmopathy at base line had impr ovement in their eye disease. Among the 145 patients treated with radi oiodine and prednisone, 50 (67 percent) of the 75 with ophthalmopathy at base line had improvement, and no patient had progression. The effe cts of radioiodine on thyroid function were similar in these two group s. Among the 148 patients treated with methimazole, 3 (2 percent) who had ophthalmopathy at base line improved, 4 (3 percent) had worsening of eye disease, and the remaining 141 had no change. Conclusions Radio iodine therapy for Graves' hyperthyroidism is followed by the appearan ce or worsening of ophthalmopathy more often than is therapy with meth imazole. Worsening of ophthalmopathy after radioiodine therapy is ofte n transient and can be prevented by the administration of prednisone. (C) 1998, Massachusetts Medical Society.