Absence of serum thyroid hormone autoantibodies in patients chronically treated with amiodarone.

The role of iodine in the pathogenesis of thyroid hormone autoantibodies (THAA) was evaluated in a large series (n = 223) of patients submitted to chronic treatment (3-36 months) with the iodine-rich drug, amiodarone. Positive anti-T3 autoantibody (AbT3) tests were found only in one patient, whereas tests for anti-T4 autoantibody (AbT4) were negative in all cases. Likewise, the incidence of THAA in the control groups of patients with spontaneous thyroid disorders was low. The overall prevalence of THAA in the present series of 803 patients was 1.2% for AbT3 and 0.1% for AbT4. The present data strongly suggest that iodine plays a minor role, if any, in the occurrence of THAA.