This definition was based on the results from a previous Korean nationwide survey that showed that anti-thyroid drugs were the preferred treatment regimen for first-time and recurrent Graves’ disease and that most patients chose either anti-thyroid drugs (97.1%) or radioactive iodine (2.9%) rather than surgery (0.0%) [19], notwithstanding the fact that thyroid hormone replacement is essential for treating overt clinical hypothyroidism [20]. Here, TG is linked to thyroid gland disorder.