The pathogenesis of thyroid-associated ophthalmopathy (TAO) and the mechanism for its unique link with thyroid autoimmunity are poorly understood, in part due to the absence of specific diagnostic clinical signs and confirmatory “gold standard” laboratory tests. We report a patient who highlights the potential clinical role for eye muscle and collagen XIII antibody testing in the diagnosis and management of thyroid-related eye, eyelid and orbital disorders. A healthy euthyroid woman member of the Thyroid Research Laboratory presented with the incidental finding of positive calsequestrin and collagen XIII antibody tests carried out in the context of our research. She was pregnant at the time. Examination revealed marked upper eyelid retraction (UER) and a small goitre. Seven months after an uneventful pregnancy, which was 12 months after the initial blood test, she re-presented with overt hypothyroidism. Thyroglobulin and microsomal antibodies were strongly positive (25,600, > 25,600, respectively) and TSH was 40. We then tested the earlier serum sample for thyroid antibodies, which were positive at a low titre (1600, 1600, respectively) indicating that she had Hashimoto’s thyroiditis at that time. The hypothyroidism persisted, requiring long term management with L-thyroxine. UER can occur in the absence of other features of ophthalmopathy except for mild protopsis in patients with Hashimoto’s thyroiditis in whom antibodies targeting eye muscle or collagen XIII antibodies are detected in about 50% of cases. Overall about 20% of patients with Hashimoto’s thyroiditis have eye signs. Calsequestrin antibodies are specific and sensitive markers for extra ocular and upper eyelid muscle inflammation and damage in patients with thyroid autoimmunity and collagen XIII antibodies appear to be good markers for the congestive ophthalmopathy subtype of TAO.
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