Amiodarone. The dilemma of hyperthyroxinaemia and the treatment of thyrotoxicosis.

The use of amiodarone, a drug which is prescribed increasingly as an anti-anginal and anti-arrhythmic agent, necessitates a high index of suspicion for the development of thyroid disorders, especially thyrotoxicosis. Two cases, which illustrate the diagnostic dilemma of hyperthyroxinaemia and the poor response to antithyroid medication, are described. During amiodarone therapy, the clinical features of thyrotoxicosis may be masked or atypical, and the choice of therapy is complicated by a delayed response to thioamide drugs and possible contraindication for beta-blocking agents which necessitates the use of glucocorticoid drugs in some patients.