Role of the underlying thyroid disease on the phenotype of graves' orbitopathy in a tertiary referral center

BACKGROUND: Clinically overt Graves' orbitopathy (GO) is associated with Graves' disease (GD) in approximately 95% of cases, whereas the remaining 5% is observed in patients with hypothyroid autoimmune thyroiditis (AT) or without overt thyroid dysfunction (euthyroid GO). However, it is not known whether there is a difference in terms of GO phenotype between patients with GD and those with hypothyroid AT or without thyroid dysfunction, and hence this is investigated here. METHODS: The study design was to evaluate retrospectively all consecutive patients with a recent manifestation of GO, seen at their first visit to a tertiary referral center over a period of 10 years. In total, 358 GO patients were studied, and all of them underwent GO assessment. RESULTS: Of the 358 patients studied, 341 had hyperthyroid GD, 10 had AT with hypothyroidism, and seven had euthyroid GO. Age, sex, and smoking habits were similar in the three groups, as was the time since GO was first noticed (GO duration). The vast majority of patients had moderate to severe, active GO, as expected in a tertiary referral center. Exophthalmometry, eyelid width, clinical activity score (CAS), diplopia, and visual acuity did not differ between patients with GD and those with AT or euthyroid GO, suggesting that the GO phenotype was similar. Accordingly, the NOSPECS score did not differ between the three groups. CONCLUSIONS: The phenotype of GO is similar regardless of the underlying thyroid disease. Because this study was performed in a tertiary referral center, this conclusion can be restricted only to patients who develop moderate to severe GO.