Amiodarone, a type III anti-arrhythmic agent, has a high iodine concentration which can induce thyroid dysfunction (reported in up to 24% of the users). Amiodarone-induced thyrotoxicosis (AIT) is more associated to male young patients, being a therapeutic challenge that requires antithyroid and/or corticosteroids agents and, in some cases, surgery.

We report a clinical case of a 24-years-old male patient, medicated with amiodarone, who developed mixed AIT, refractory to medical treatment, being ultimately proposed to total thyroidectomy.

A 24-years-old male patient, with a clinical history of hypertrophic cardiomyopathy and auricular flutter, was medicated with amiodarone. Nine months after the patient developed an AIT, with no therapeutic alternative to amiodarone and therefore no possibility to suspend it. Thyroid ultrasound demonstrated a slightly enlarged thyroid and Sestamibi thyroid scintigraphy showed a pattern compatible with mixed AIT. The patient initiated therapy with antithyroid and corticosteroid agents, requiring various dosage adjustments and difficult normalization of thyroid hormones, and developed a Cushing-like syndrome. Thereby, it was decided to proceed to surgery - total thyroidectomy - with no surgical or post-operative complications. The histologic examination revealed hyperplasic lesions induced by medication. In the post-operative period corticosteroids were weaned. The thyroid hormones are being maintained in the normal range with appropriate levothyroxine replacement.

AIT is a serious complication of amiodarone use and can exacerbate the underlying cardiac conditions. In cases where the thyrotoxicosis is refractory to medical treatments, it is indicated to proceed to surgery in order to restore the euthyroid state.