Transient goiter enlargement after administration of 0.3 mg of recombinant human thyrotropin in patients with benign nontoxic nodular goiter: A randomized, double-blind, crossover trial

Abstract

Background: Recombinant human (rh) TSH, in doses from 0.01 to 0.9 mg, has been used to augment the effect of radioiodine (131I) therapy in patients with a benign nontoxic nodular goiter. Transient thyroid enlargement and thyrotoxicosis may be seen following 131I therapy. Aim: The aim of the study was to investigate whether rhTSH per se causes goiter enlargement, until now an issue evaluated only in healthy nongoitrous subjects. Methods: In random order, 10 patients with nontoxic nodular goiter [mean 39.8 ± 20.5 (SD) ml] received either 0.3 mg rhTSH or isotonic saline in a double-blinded crossover design. Thyroid volume (by ultrasound) and function were closely monitored during the following 28 d. Results: Saline injection did not affect thyroid function or size. After rhTSH, median serum TSH increased from baseline 0.97 mU/liter (range 0.39-1.56) to 37.0 mU/liter (range 18.5-55.0) at 24 h (P < 0.01), with a subsequent decline to subnormal levels at d 7. Mean free T4 and free T3 increased significantly from baseline to a maximum at 48 h. Twenty-four hours after rhTSH, the mean goiter volume was significantly increased by 9.8 ± 2.3% (SEM) (P = 0.01) and after 48 h by 24.0 ± 5.1% (P = 0.002). The goiter enlargement had reverted at d 7. Nine patients had symptoms of hyperthyroidism and/or cervical compression after rhTSH, as opposed to one during placebo treatment (P < 0.02). Conclusions: A transient average goiter enlargement of up to 24% is seen after 0.3 mg rhTSH. This may lead to a significant cervical compression when used for augmentation of 131I therapy in patients with goiter. The use of lower doses of rhTSH needs to be explored. Copyright © 2006 by The Endocrine Society.