Endocrine Abstracts

Introduction: Graves’ disease (GD) is a common autoimmune endocrinopathy where autoantibodies that activate TSH receptor (TRAb) cause clinical hyperthyroidism. Graves’ Orbitopathy (GO) is one of the major complications of GD that results from the inflammation of retro-orbital tissues. Although the clinical usefulness of TRAb determination in the diagnosis of GD is well established, recent studies have shown that TRAb levels may also be helpful in assessing the activity and the clinical course of GO.

Aim: The aim of this study was to define the diagnostic cut-off point of TRAb at which we could indentify patients with active GO.

Methods: We studied 124 females and 46 males with GD who were on treatment with antithyroid drugs and were euthyroid for at least 3 months. Disease duration varied from 6 to 72 months. According to the Clinical Activity Score (CAS), 50 patients had active and 120 non-active GO. Serum FT₄, T₃ (Axsym Abbot), TSH (electrochemiluminescence (ECL) method on Elecsys 2010 Roche), TRAb (DYNOtest TRAb Human kit Brahms Ria kit), anti-TPO and anti-Tg (ECL Elecsys 2010 Roche) were measured in all patients.

Results: Patients with active GO had significantly higher TRAb levels compared to patients with non-active GO (P<0.001) while no difference was found for anti-TPO and anti-Tg levels. Area under the sensitivity (true positives) versus 1-specificity (false positives) curve for TRAb±S.E.M. was 0.85±0.032 and the corresponding 95% confidence interval ranged from 0.79 to 0.91 indicating that TRAb is a useful marker in GO activity assessment. TRAb values higher than 4.7 IU/l (sensitivity 74%, specificity 74.2% and efficiency 74%) can discriminate patients with active GO.

Conclusion: In patients with GO, a TRAb cut-off value of 4.7 IU/l could be applied for anti-inflammatory treatment decisions during the course of the disease.