8176 An Unusual Case of Thyroid Eye Disease (TED) Occurring in Autoimmune Hypothyroidism

Abstract Disclosure: K. Prasongdee: None. C.M. Tessier: None. Background: It is unusual for TED to present in patients with autoimmune thyroid disease who are euthyroid or hypothyroid. Clinician recognition of this rare presentation is important in ensuring proper treatment and improving patient outcomes. Clinical Case:Our patient is a 57-year-old female with a past medical history of COPD, hypothyroidism presenting with several months of blurry vision. She reports double vision when looking down, and eye pain at rest and with eye movement. She was diagnosed with hypothyroidism one year prior to presentation, and her TSH subsequently normalized after titration to levothyroxine of 112 mcg daily. She reported no history of head or neck radiation. No family history of thyroid disease. She smoked for 30 pack years but stopped 2 years prior. Physical exam showed eye lid swelling and redness, pain and diplopia on end-lateral gaze, no chemosis, no conjunctival injection, or inflammation of the caruncle, lids closed completely, proptosis with Hertel ophthalmometer measured 23 mm on the right eye and 22 mm in the left eye (normal range < 18 to 20 mm for Caucasians), thyroid not enlarged with no palpable nodules, no thyroid bruits. The initial Clinical Activity Score (CAS) was 4, which indicated active TED. A thyroid ultrasound showed Inhomogeneous echogenicity with increased vascularity consistent with autoimmune thyroiditis. An MRI of the orbits revealed diffuse extraocular muscle enhancement and enlargement with tendinous insertion sparing, increased T2 hyperintensity findings which favored thyroid eye disease. Further laboratory testing confirmed the presence of multiple thyroid autoantibodies: Thyrotropin binding inhibitory immunoglobulin 2.76 IU/L (normal range < 1.75 IU/L), Thyroid peroxidase antibody 1135 IU/mL (normal range <9 IU/mL), Thyroglobulin antibodies 157 IU/mL (normal range < 116 IU/mL), thyroid-stimulating immunoglobulin 447% (normal range <140 % Baseline). She was referred to ophthalmology for management of TED and was started on teprotumumab. Her CAS improved to 0 and her diplopia resolved. Her proptosis remained stable. This case illustrates an unusual clinical course in a patient who initially presented with autoimmune hypothyroidism, later developed Thyroid Eye Disease. A study by Kahaly GJ et al showed that in Hashimoto’s thyroiditis (HT), thyroid-stimulating autoantibodies are highly correlated with thyroid eye disease (TED) with positive thyroid-stimulating autoantibodies detected in 5.5% of the patients with HT and 68.2% in the patients with HT and TED. Even though it is less common, up to 6% of patients with HT may be affected by TED. Rare presentations such as this case emphasizes the need to be vigilant when evaluating eye symptoms in patients with autoimmune thyroid disease. Teprotumumab that showed improvement in patients with Grave’s and thyroid eye disease, was also successful in treating our patient symptoms. Presentation: 6/3/2024