Thyroid Research Thyroid Research Archive Hyperthyroidism

Prednisone is better therapy than iopanoic acid in amiodarone-induced hyperthyroidism

(July 2003)

The background of the study. Amiodarone, a drug for treating abnormal heart rhythms, causes two types of hyperthyroidism, iodine-associated hyperthyroidism and thyroid inflammation (thyroiditis)-associated hyperthyroidism. In this study the efficacy of prednisone and iopanoic acid (an x-ray dye used to visualize the gall bladder) was compared in patients with hyperthyroidism caused by amiodarone-induced thyroiditis.

How the study was done. The study subjects were 12 patients taking amiodarone who had thyroiditis-associated hyperthyroidism. They had taken amiodarone for an average of 30 months, and it was stopped on study entry. The patients were randomly assigned to receive prednisone, given in decreasing doses for three months, or iopanoic acid, given until the patient's serum thyroxine (T4) and triiodothyronine (T3) concentrations were normal. Serum free T4, free T3, and thyrotropin (TSH) were measured at base line, weekly for one month, and monthly thereafter.

The results of the study. There were six patients in each group. Their base-line serum free T4 and free T3 concentrations were similar, and all had undetectable serum TSH concentrations (<0.005 mU/L). During therapy, serum T3 concentrations decreased to normal in seven days and remained normal thereafter in both groups. Serum T4 concentrations decreased promptly in the prednisone group, reaching normal in 14 days, whereas they changed little in the iopanoic acid group until 180 days. The serum TSH concentrations were normal in 40 days in the prednisone group and in 84 days in the iopanoic acid group. Symptoms of hyperthyroidism improved as serum T3 concentrations decreased. All the patients in the prednisone group had normal serum T4 and T3 concentrations by 90 days, as compared with 360 days in the iopanoic acid group.

The conclusions of the study. Prednisone is more effective therapy than iopanoic acid in patients with hyperthyroidism caused by amiodarone-induced thyroiditis.

The original article. Bogazzi F, Bartalena L, Cosci C, Brogioni S, Dell'Unto E, Grasso L, Aghini-Lombardi F, Rossi G, Pinchera A, Braverman LE, Martino E. Treatment of type II amiodarone-induced thyrotoxicosis by either iopanoic acid or glucocorticoids: a prospective, randomized study. J Clin Endocrinol Metab 2003;88:1999-2002.