Abstract Introduction Thyroid eye disease (TED) is most often associated with Graves’ hyperthyroidism and bilateral involvement, whereas presentation with hypothyroidism or as a unilateral process is uncommon. Even more rarely, autoimmune hypothyroidism may evolve into Graves’ hyperthyroidism due to a shift in TSH receptor antibody (TRAb) activity. Clinical Case A 48-year-old man with hypertension, dyslipidemia, and a current smoker was referred by an ophthalmologist for progressive right eye bulging, ocular pain, and redness. Examination revealed right-sided unilateral proptosis and lid retraction, with a Clinical Activity Score (CAS) of 5, consistent with active thyroid eye disease (TED) and severe disease according to the European Group on Graves’ Orbitopathy (EUGOGO) classification. Laboratory evaluation demonstrated overt hypothyroidism with strongly positive TPO and total TRAb antibodies. Thyroid ultrasound showed mild diffuse enlargement with heterogeneous echotexture, and orbital MRI confirmed hypertrophy of the right extraocular muscles (Figure 1). The patient received high-dose intravenous methylprednisolone (total 4.5 g over 12 weeks) and levothyroxine 50 μg/day. Smoking cessation was achieved. At follow-up, thyroid function initially improved, but TED remained active. Subsequently, while TED stabilized, the patient developed biochemical hyperthyroidism; levothyroxine was discontinued. On further follow up, overt hyperthyroidism was confirmed, and methimazole was initiated and titrated to 10 mg/day, resulting in biochemical stabilization and maintenance of stable TED without optic nerve involvement. At the last follow-up, the patient was maintained on carbimazole 10 mg/day with good clinical outcomes. Table 1 summarizes the follow-up stages of the patient. In fact, as we are in a resources-limited area, TRAb blocking and stimulating antibodies are not available Conclusion This case highlights a rare presentation of severe unilateral TED initially associated with autoimmune hypothyroidism, later evolving into Graves’ hyperthyroidism. It emphasizes the importance of close biochemical monitoring, awareness of possible immune conversion, and multidisciplinary management to prevent sight-threatening complications, especially in high-risk patients such as smokers with elevated TRAb titers.Figure 1:CT scan of orbits showing extraoccular muscles enlargement Table 1:Patient follow up visits
Zeid Faeik Zwain (Thu,) studied this question.