Markantes GK, et al. - Since amiodarone-induced thyrotoxicosis (AIT) is a common and deleterious side effect of amiodarone use and it is often very difficult to discriminate between Type 1 (AIT1) and Type 2 (AIT2) AIT, researchers sought to explore whether determining the plasma activity of β-G would be helpful in separating AIT1 from AIT2. Participants in the study were 67 subjects: 9 with AIT1, 9 with AIT2, 14 with hyperthyroidism due to Grave’s disease or toxic multinodular goiter, 14 with subacute thyroiditis, and 21 euthyroid controls. In distinguishing AIT1 from AIT2, plasma β-G activity (expressed as mean ± SD in nmol 4-methylumbelliferone [4-MU]/mL plasma/h) was performed well. Between AIT1 and controls, β-G activity did not differ significantly.