RESUMEN
OBJECTIVES: A subtype of patients with thyroid eye disease (TED) were found to be euthyroid without prior thyroid dysfunction or treatment, known as Euthyroid Graves' Ophthalmopathy (EGO). We report the prevalence, clinical and serological phenotypes of EGO in a Chinese population. METHODS: A cross-sectional follow-up study. Ethnic Chinese TED patients were managed at the Thyroid Eye Clinic(TEC), Prince of Wales Hospital and TEC, the Chinese University of Hong Kong between September 2007 and July 2021. RESULTS: A total of 66 (5%) patients among the 1266 ethnic Han Chinese TED cohort were diagnosed as EGO, and 6 (9%)of them become dysthyroid over an average of 74-month follow-up. EGO patients were associated with a longer duration between onset of the symptoms to our first consultation (P < 0.0001), a higher male-to-female ratio (P = 0.0045) and a higher age of disease onset (P = 0.0092). Family history of thyroid disease was more common in TED patients (P = 0.0216) than in EGO patients. EGO patients were more likely to present unilaterally (P < 0.0001), and they have a larger difference in MRD1 (P < 0.0001), and extraocular motility (P < 0.0001) between the 2 eyes when compared to the TED patients. Notably, the extraocular motility restriction of the worst eye was more affected in EGO patients (P = 0.0113). The percentages of patients who received IVMP, ORT and emergency or elective surgeries(decompression or squint operation) between EGO and TED were similar. CONCLUSIONS: Understanding the important clinical phenotypes of EGO may help the clinician to make the correct diagnosis. Further study to compare EGO and TED is warranted.