Antithyroid antibodies as an early marker for thyroid disease induced by amiodarone.

Changes in thyroid function may occur during treatment with amiodarone. A double blind prospective trial of amiodarone and placebo was performed in 37 patients in the subacute phase of myocardial infarction. Though none of the patients assigned to receive placebo developed any antibody, six of 13 patients treated with amiodarone developed antithyroid microsomal antibodies. There was no difference in triiodothyronine and thyroxine concentrations between the two groups, but a significant difference in concentrations of thyroid stimulating hormone was noted on day 30 (p less than 0.05). Six months after the withdrawal of amiodarone autoantibodies could not be detected and concentrations of thyroid stimulating hormone were normal. These antibodies have not previously been reported to develop during short term treatment with amiodarone. They could have an important role in the detection of early thyroid changes in patients given amiodarone.