A prospective study of the effects of radioiodine therapy for hyperthyroidism in patients with minimally active graves' ophthalmopathy.

CONTEXT Radioiodine is an effective and safe treatment for hyperthyroidism but has been implicated as a risk factor for deterioration or new presentation of Graves' ophthalmopathy (GO). Prophylactic glucocorticoids appear to prevent this effect. OBJECTIVE The objective of this study was to document the course of GO after radioiodine therapy. DESIGN This was a prospective observational study. Patients were assessed at baseline and 2, 4, 6, and 12 months after radioiodine therapy. SETTING The study was conducted at a tertiary referral center. PATIENTS Seventy-two GO patients with minimally active eye disease participated in the study. INTERVENTION A fixed dose of radioiodine was administered. T(4) was commenced 2 wk later to prevent hypothyroidism. MAIN OUTCOME MEASURES Change in activity and severity of GO were analyzed. RESULTS Exophthalmometer readings, the width of the palpebral aperture, diplopia scores, and the clinical activity score improved significantly. By clinically significant criteria, the eye disease improved in four patients (transiently in three of the four cases), most likely attributable to the natural course of the disease. No patient's eyes deteriorated. CONCLUSIONS Radioiodine is not associated with deterioration of GO in patients with minimally active eye disease when postradioiodine hypothyroidism is prevented.