Utility of Recombinant Human Thyrotropin for Augmentation of Radioiodine Uptake and Treatment of Nontoxic and Toxic Multinodular Goiters

Abstract

To report our results in treating 16 patients with low radioiodine uptake (RAIU) multinodular goiter who had obstructive symptoms or suppressed thyroid-stimulating hormone (TSH or thyrotropin), indicating mild hyperthyroidism. Six patients were treated with 0.3 mg of recombinant human thyrotropin (rhTSH) followed by 30 mCi of (131)I 72 hours later. Ten patients were treated with 0.9 mg of rhTSH followed by 30 mCi of (131)I 24 hours later. Of the 16 treated patients, all 10 with compressive symptoms and both patients with weight loss had remission or improvement, as did 1 of 2 patients with atrial fibrillation. All patients with suppressed TSH had a return to normal levels or became hypothyroid. During the next 3 to 7 months, estimated gland size reduction was 30 to 40%. Three of the 6 patients who received 0.3 mg of rhTSH and 6 of the 10 patients who received 0.9 mg of rhTSH, in conjunction with (131)I therapy, ultimately had TSH levels indicative of hypothyroidism. Mild radiation thyroiditis developed in only one patient, and no other side effects occurred. The 0.3-mg dose of rhTSH seemed to be as efficacious as the 0.9-mg dose. The greater than fourfold increase in RAIU at 72 hours after administration of rhTSH in our study is more than twofold higher than the 24-hour RAIU results previously reported in normal subjects and in patients with multinodular goiter. These findings have implications for future expanded studies and alternative dosing regimens in treating patients with both multinodular goiter and subclinical hyperthyroidism.