Abstract 75: Unilateral thyroid association ophthalmopathy in Hashimoto's thyroiditis: A case report

Background: Thyroid-associated ophthalmopathy (TAO) is an array of symptoms caused by an autoimmune process involving the orbital tissue. Most TAO is reported in hyperthyroid Grave's disease and in euthyroid and hypothyroid Graves' patients with positive thyroid receptor antibodies. But TAO is rarely reported in Hashimoto's thyroiditis (HT) and is a poorly understood entity. Here we report a unilateral TAO in a patient withhypothyroidHTwith negative TSH-R antibodyand high TPO antibody. Hewas treated with pulse methyl-prednisolone, levothyroxine, and artificial teardrops. Case Report: A 43-year-old non-smoker, non-alcoholic male with a complaint of fatigue and lethargy with mild swelling of both legs. On evaluation, his TSH was 180 miu/ml in 2016, and levothyroxine 50 mcg was initiated, then gradually increased throughout three months to 150 mcg daily. He became euthyroid. In January 2021, he noticed pain and protrusion in the right eye, so he consulted an ophthalmologist. On investigation, his TSH was 70 miu/ml; on asking, he agreed that he was not consistently on thyroid hormone replacement. So, he restarted 100 mcg of LT4. In March 2021, he noticed further aggravation of eye symptoms despite taking LT4 replacement with TSH of 8 miu/l, so he consulted endocrinology. Details of hormonal test in table-1. General physical and systemic examination was unremarkable. The degree of exophthalmos on the Hertelexophthalmometers was 18 mm for the left eye and 25 mm for the right eye. Intraocular pressure was normal in both eyes. The CAS SCORE was 4 in March 2021, then improved over six months to 2. Magnetic resonance imaging of orbits revealed unilateral right eye proptosis with a mild increase in bulk of inferior rectus (IR) (maximum thickness 6.5 mm) with sparing of the anterior part of tendons. Treatment and follow-up: He hadbeen given pulse methyl-prednisolone 500 mg weekly for five weeks and advised to continue LT 150 mcg once daily. At the discharge, he was euthyroid biochemically, and there was an improvement in eye symptoms. He had followed up on Aug 20th; his CAS was 2 with stable eye disease and was euthyroid on LT150 mcg. CT orbit showed enlargement of IR and MR. Discussion: Pathogenesis of TAO in Hashimoto thyroiditis is poorly understood. We have reported TAO in a patient with hypothyroidism and negative TRAb with a high anti-TPO antibody. HEwas managed with LT, and pulse methylprednisolone on March 2021, and subsequent follow-up showed stable unilateral eye disease. Conclusion: Thyroid-associated ophthalmopathyisrarebut can sometimes occur in Hashimoto's thyroiditis. Awareness of this atypical form is essential for appropriate treatment because prompt recognition and management can prevent corneal involvement and blindness due to optic nerve compression.