Amiodarone-induced thyrotoxicosis: clinical presentation and expanded indications for thyroidectomy.

Abstract

Amiodarone-induced thyrotoxicosis (AIT) is a rare disorder that is frequently refractory to conventional pharmacologic therapy. An analysis of seven patients who underwent thyroidectomy for control of AIT between 1987 and 1993 was completed to examine the clinical manifestations and the indications for surgical therapy. Five men and two women, 53 to 72 years of age, had AIT after 3 to 55 months of amiodarone treatment (mean, 21 months). The primary manifestations of AIT were ventricular tachycardia (five), exacerbation of chronic pulmonary disease (one), and occult hyperthyroidism (one). Medical therapy included propylthiouracil in doses up to 1200 mg/day in five patients, a beta-receptor antagonist in three, and withdrawal of amiodarone in five. Near-total or total thyroidectomy resulted in resolution of thyrotoxicosis in all patients. Morbidity included pneumonia (one) and cardiac dysrhythmias (two). One patient died of ventricular dysrhythmias 4 months after thyroidectomy. The mean thyroid weight was 50 gm (range, 17 to 216 gm). Microscopic examination showed destructive follicular lesions with fibrosis in all patients. Associated thyroid pathologic condition included multinodular goiter in four patients and a follicular adenoma in one. AIT may be clinically occult or manifested by unusual symptoms requiring a high index of suspicion for diagnosis. Near-total thyroidectomy is safe and effective in producing rapid resolution of AIT and is indicated for the initial treatment of patients who present with a resurgence of life-threatening cardiac arrhythmias and for all patients with AIT refractory to medical therapy.