Context: Telepaque (iopanoic acid) is believed to rapidly ameliorate hyperthyroidism, however, may preclude subsequent ¹³¹I therapy, possibly delaying it for several months.

Objective: To see how early patients, made euthyroid with Telepaque, can be treated with ¹³¹I and to compare their short/long-term outcome with patients treated with ¹³¹I, after making them euthyroid with carbimazole and -blockers.

Design: Randomized Controlled Trial.

Setting: Tertiary care teaching institute.

Patients: Two hundred hyperthyroid patients.

Interventions: Iopanoic acid group (IA-group)-Telepaque 500 mg/day orally for 7 days, no medication for 1 week followed by ¹³¹I therapy if radioiodine neck-uptake had recovered. Control group (controls)- received 30-40 mg oral carbimazole daily until patients became euthyroid followed by ¹³¹I.

Main outcome: After one week of Telepaque therapy and 6 weeks of carbimazole almost all patients became clinically and biochemically euthyroid. Eighty-six and 94% patients were ready for ¹³¹I therapy after 1 & 2 weeks off Telepaque, respectively. The cure rate, defined as euthyroid plus hypothyroid, after the first dose of ¹³¹I in controls & IA-group was 80% and 76.2%, respectively (p-0.54). Thirty-two percent among controls and 25% in IA-group became hypothyroid within one year (p-0.33); thereafter annual rate of hypothyroidism was about 2% in both the groups. After mean follow-up duration of 11 yr, 58% patients in controls and 51% in IA-group were hypothyroid.

Conclusions: Telepaque rapidly ameliorates hyperthyroidism without jeopardizing the subsequent radioiodine therapy and the outcome of radioiodine therapy in this subset of patients is no way different compared with those prepared by carbimazole.