The therapeutic efficacy of oral cholecystographic agent (iopanoic acid) in the management of hyperthyroidism.

Five randomly chosen patients with thyrotoxicosis were administered 1 gm of the oral cholecystographic agent iopanoic acid daily for 21 days. There was a marked fall in T3 levels by 75% of the pretherapy value by 96 hr; values remained normal over the 21-day period. T4 values fell significantly by seven days of therapy, and the decreased values were sustained. FT3 and FT4I also showed corresponding decreases in value. All subjects showed clinical improvement by both subjective and objective criteria. During therapy, escape from the effect of iopanoic acid was not encountered. However, after stopping the drug for 2-4 wk, the patients' iodine-131 uptake become as high as the pretherapy level, enabling them to undergo radioiodine treatment for thyrotoxicosis. The treatment strategy can be aimed at achieving quick euthyroidism and in planning radioiodine treatment as early as possible in high risk patients. This treatment may also be useful in preoperative control of thyrotoxicosis.