Long term treatment of Graves' disease with iopanoic acid (Telepaque).

To investigate the long term utility of the cholecystographic contrast agent iopanoic acid (Telepaque) for treatment of Graves' hyperthyroidism, we studied 40 patients treated with 500 mg, orally, daily for 1-12 months. We measured thyroid size; body weight; serum T3, T4, and free T4 concentrations; and antithyroglobulin and antimicrosomal antibody levels at monthly intervals. Based on the effects of the therapy, the patients were divided into 3 groups: 6 patients had excellent responses with return of serum thyroid hormone levels to normal (group A); 12 patients had fair responses, but 1 thyroid hormone test remained elevated (group B); and 22 patients had minimal benefit (group C) with only slight clinical improvement and transient reduction of serum T3 concentration. Mean serum T3 levels decreased significantly after 1 month of therapy in all 3 groups and became normal in groups A and B, but the reduction in group C was not sustained. Mean serum T4 and free T4 levels remained above normal during the course of therapy in groups B and C. Sixty-eight percent of patients in group C had large goiters compared with 33% of group A and 25% of group B, and those in group C tended to have more severe biochemical hyperthyroidism initially. There were no significant changes in antibody titers during therapy. These data indicate that iopanoic acid is not effective therapy for many hyperthyroid patients.