Amiodarone-induced thyrotoxicosis in patients with multinodular goiter: type 1 or type 2 AIT?
Luca Tomisti, Enrica DellUnto, Sandra Brogioni, Chiara Cosci, Enio Martino & Fausto Bogazzi
Introduction: Type 2 amiodarone-induced thyrotoxicosis (AIT) is a form of destructive thyroiditis, commonly responsive to glucocorticoids. On the contrary, type 1 AIT is an iodine-induced hyperthyroidism, occurring in patients with underlying thyroid disease often responding to thionamides.
Aim of the study: To compare the effectiveness of methimazole (MMI) or prednisone (GLU) in the treatment of AIT patients with multinodular goiter with biochemical features of destructive thyroditis.
Patients and methods: We enrolled 22 untreated AIT patients with multinodular goiter in a historical prospective study. The patients showed similar biochemical findings; particularly all patients showed low thyroidal radioactive iodine uptake (24th h RAIU <5%) and an estimated thyroid volume with conventional ultrasonography >25 ml. Eleven patients were treated with metimazole (initial dose 40 mg/day) (MMI GROUP) and 11 patients were treated with prednisone (initial dose, 0.5 mg/kg per day) (GLU GROUP) for 4 months (120 days).
Results: After 120 days euthyroidism was restored in 9/11 patients treated with glucocorticoids (81.8%) and in 4/11 patients treated with MMI (36.3%) (P 0.03). Furthermore, patients in GLU GROUP reached euthyroidism more rapidly than those in MMI Group (median cure time GLU GROUP 33 days versus median cure time MMI GROUP >120 days, P=0.01).
Conclusion: This data suggest that AIT patients with multinodulare goiter but biochemical features of destructive thyroiditis could respond more favorable to glucocorticoids therapy than to thionamides therapy.