ABSTRACT
Eye muscle antibody (EMAb) testing represents a possible means of diagnosing and characterizing thyroid-associated ophthalmopathy (TAO). In particular, antibodies against
flavoprotein (Fp), the ‘‘64 kDa protein’’ and G2s, the terminal fragment of the winged-helix transcription factor Fox p1, may be markers of eye muscle damage in patients with Graves’ hyperthyroidism. Here, we report upon the sensitivity and specificity of EMAb testing in patients with thyroid disorders with and without ophthalmopathy from a single center. Patient charts were reviewed and EMAb results correlated with clinical diagnosis and features of ophthalmopathy. A single endocrinologist assessed each patient and serum was tested for eye muscle antibodies and levels of free thyroxine (T4) and thyrotropin (TSH). Medical records, laboratory reports, and EMAb test results were reviewed and relevant clinical and biochemical findings extracted and entered into a database. One hundred and sixty-three EMAb tests were carried out on 99 patients. A statistically significant association between anti-G2s antibodies and clinical features of the ocular myopathy subtype of TAO, but not of the congestive ophthalmopathy subtype, was demonstrated. Anti-Fp antibody test results were not found to be significantly associated with any eye findings. We also report preliminary data on the first 15 patients with newly diagnosed Graves’ hyperthyroidism treated with radioiodine or antithyroid drugs and followed for 1 year or more. In the first 15 patients followed for 1 year or more, serum antibodies against both Fp and G2s were found to be significantly associated with Graves’ disease, but not other thyroid diagnoses. None of the four patients treated with antithyroid drugs developed autoantibodies or demonstrated features of extraocular disease. On the other hand, eye muscle antibodies were detected in eight of the nine patients treated with radioiodine, in five cases after therapy. Of the six patients who had eye muscle involvement as defined by increased intraocular pressure on upgaze, diplopia or restricted motility, all received radioiodine and had detectable serum autoantibodies. None of the results were statistically significant, possibly due to the small numbers of patients so far analyzed.
