LONG-TERM TREATMENT OF GRAVES' HYPERTHYROIDISM WITH IPODATE

Abstract

We have previously reported that ipodate (1g, q.d.) compares favorably to PTU (200 mg, t.i.d.) in the treatment of Graves' hyperthyroid patients in 3-wk therapy (J Clin Endocrinol Metab 54:630, 1982). This report presents the results of five newly diagnosed Graves' hyperthyroid patients who were given 500 mg ipodate daily for 23 to 35 wks. Mean baseline serum T3, T4 and rT3 were 780 ng/dl, 25.4 ug/d1 and 118 ng/dl, respectively. One day after the first dose of ipodate, serum T3 decreased by 62% (P<0.005) and stayed within the normal range throughout the treatment. The serum T4 concentration decreased by 20% (P=0.09) at 24 h, 35% at 3 d(P<0.02) and 54% (P<0.005) at 21 d. Subsequently serum T4 was 41–65% lower than baseline throughout the study; it was within the normal range in four patients from 10 wks of treatment on. Serum rT3 increased at 24 h following the first dose of ipodate (118% above baseline, P<0.05 and remained elevated (97–109%) for 10 wks and then gradually decreased to baseline level. A significant decrease of resting pulse rate and marked gain in body weight (11±2.4 1b) were observed in all patients. Following the discontinuation of ipodate, thyroid radioiodine uptake in four patients was not different from baseline value: baseline, 74 ±6%; 7 d 66±8%; 14 d 71±7%; 28 d 69±7%. The fifth patient's RAI uptake Fell to 12–16% (vs. baseline value of 48%) from 7–28 d after the end of a 26-wk course of ipodate. In conclusion: (1) long term use (for 23–35 wks) of ipodate for the treatment of Graves' hyperthyroidism is clinically feasible; and (2) RAI uptake returns to baseline level as early as 7 d following the discontinuation of ipodate.