Perdomo CM, García‐Goni M, Sancho L, et al. - This study was carried out to assess the first‐generation thyrotropin receptor antibodies (TRAb) values to thyroid radionuclide scintigraphy (TRSt) in the differential diagnosis of hyperthyroidism. Researchers performed a retrospective study of 201 untreated outpatients with overt or subclinical hyperthyroidism on whom first‐generation TRAb and TRSt had been conducted at the time of diagnosis. They examined histological specimens in patients who had previously undergone thyroid surgery at our centre. SPSS 20.0 was applied in statistical analysis. This research endorses that initial differential diagnosis of thyrotoxicosis should not be based solely on first‐generation TRAb as this method may leave nearly 20% of the patients misdiagnosed and, consequently, improperly treated. This study’s findings demonstrate that thyroid scintigraphy should also be conducted when only first‐generation TRAb assays are available during the initial differential diagnosis of thyrotoxicosis.