ACETYLCHOLINE-RECEPTOR ANTIBODIES IN PATIENTS WITH GRAVES OPHTHALMOPATHY

Objectives: To determine the frequency and clinical correlates of acetylcholine receptor (AChR) antibody seropositivity in patients with Graves' ophthalmopathy. Materials and Methods: Fifty consecutive new patients with Graves' ophthalmopathy diagnosed in an outpatient neuro-ophthalmology practice underwent determination of AChR-binding antibodies. Clinical and biochemical thyroid variables were compared between seropositive and seronegative patients. Clinical variables included age, sex, thyroid disorder, and duration and course of illness. Biochemical variables included thyroid hormone levels and thyroid antibodies. Seropositive patients were followed clinically to identify signs of myasthenia gravis. Results: Four of 50 (8%) patients had definitely elevated levels of AChR-binding antibodies. No obvious differences existed between the seropositive and seronegative groups in regards to age, sex, underlying thyroid disorder, biochemical thyroid state, presence of thyroid antibodies, or duration and course of their disease. None of the four seropositive patients developed signs of myasthenia gravis during the median follow-up period of 4.5 years. Conclusion: AChR-binding antibody seropositivity occurs in a small proportion of patients with Graves' ophthalmopathy but, by itself, does not necessarily identify an individual with concurrent myasthenia gravis or an individual at risk to develop myasthenia gravis.