Acute myopathy secondary to amiodarone-induced thyrotoxicosis

A 60-year female with no preceding thyroid disease presented in August 2020 with severe debilitating progressive motor weakness of her lower limbs. Initial investigations revealed an acute myopathy secondary to thyrotoxicosis. On further review it was noted that the patient had ceased amiodarone treatment for rhythm control of atrial fibrillation and associated tachyarrhythmia-induced cardiomyopathy 10 days prior to admission to hospital. The patient was treated with high dose carbimazole and prednisone with marked improvement in mobility over the next 2 weeks. Her weekly thyroid function tests continued to ameliorate with progressive improvement in her mobility and return to functional baseline over a two-month period.