Abstract #1401671: Hashimoto’s Disease with Thyroid Eye Disease, Negative TRAB and Positive TPO Antibodies Treated with Teprotumumab

Abstract

Thyroid Eye Disease (TED) is most commonly associated with hyperthyroidism secondary to Graves’ disease (GD). The disease activity of TED is positively correlated with the presence of thyrotropin receptor antibodies (TRAB). Some with TED are euthyroid at presentation but have positive TRAB. Less frequently, patients with Hashimoto’s disease have TED, the majority of which are TRAB positive. We present a unique case of euthyroid TED with negative TRAB but positive thyroid peroxidase antibodies (TPO Ab) treated with teprotumumab. A 65-year-old African-American male presented with a 9-day history of gradually worsening vision, ocular pain, and bilateral eye bulging. His best-corrected visual acuity at near was 20/200 right eye and 20/400 left eye with full peripheral vision by confrontation. Pupils were equal and reactive to light with normal intraocular pressure. There was bilateral upper eyelid retraction, diffuse conjunctival injection, proptosis, and diffuse external ophthalmoplegia. His clinical activity score was 7. The thyroid exam was normal. Computed Tomography (CT) scan of the orbits showed significant, tendon-sparing enlargement of all extraocular muscles along with bilateral orbital apex crowding. Bilateral compressive optic neuropathy from severe TED was suspected. TSH, free T4, and T3 were normal. TPO Ab was positive but TRAB was negative by both binding inhibitory and Thyroid Stimulating Immunoglobulin (TSI) assays. He was treated with high-dose intravenous methylprednisolone for 5 days followed by 2 weeks of oral prednisone. One month after presentation treatment was initiated with 8 infusions of teprotumumab with complete resolution of all ocular symptoms and restoration of normal vision. Six months after the last dose of teprotumumab he remains euthyroid with negative TRAB and positive TPO Ab. TED is uncommon in euthyroid individuals. Most have positive TRAB and many ultimately develop hyperthyroidism. Even less common are those with Hashimoto’s thyroiditis (HT) presenting with TED. Teprotumumab is the only Food and Drug Administration-approved medication to treat TED. Our patient with vision-threatening TED had a remarkable response to teprotumumab with the restoration of normal vision and resolution of TED. We could not identify any other reports of a patient with euthyroid HT with positive TPO Ab but negative TRAB treated with teprotumumab. Physicians should be mindful of this unusual presentation to detect cases early and institute appropriate treatment to prevent visual complications.