Refractory amiodarone-induced thyrotoxicosis requiring adjunctive cholestyramine treatment

Amiodarone is an antiarrhythmic drug which may be associated with thyroid dysfunction. Type I amiodarone-induced thyrotoxicosis (AIT) is treated with thionamides and type II AIT is treated with glucocorticoids. Combined therapy is used in mixed or indeterminate forms. When medical treatment is unsuccessful, radioiodine ablation or thyroidectomy is considered. This report reviews a case of AIT refractory to conventional treatment. Despite high doses of methimazole and prednisone, the patient remained clinically and biochemically thyrotoxic. Cholestyramine, a bile salt sequestrant, was used as an off-label adjunctive treatment resulting in significant improvement and achievement of euthyroidism that may also be in part due to the expected natural timeline of recovery from AIT after several months. The patient subsequently trended towards hypothyroidism with symptomatic weight gain and cold intolerance for which he was initiated on levothyroxine.