Use of recombinant human thyrotropin increases the thyroid radioiodine (iodine 131 [131I]) uptake and may have a role in the context of 131I therapy of benign goiter.
In a double-blind, placebo-controlled trial, 57 patients with nodular nontoxic goiter (51 women and 6 men) were randomized to receive either 0.3 mg of recombinant human thyrotropin (n = 28) or placebo (n = 29) 24 hours before 131I therapy. The 131I dose was calculated based on thyroid size (measured by ultrasound), thyroid 131I uptake, and 131I half-life. The follow-up period was 1 year and included measurements of thyroid size and function and patient satisfaction.
Baseline median goiter volume was 51 mL (range, 20-99 mL) in the placebo group and 59 mL (range, 25-92 mL) in the thyrotropin group (P = .75). At 12 months, the mean ± SEM relative goiter reduction was 46.1% ± 4.0% in the placebo group and 62.1% ± 3.0% in the thyrotropin group (P = .002 between groups). The difference was most pronounced among patients with large goiters. Within each group, there was no significant correlation between retained thyroid 131I dose and goiter reduction. Adverse effects were significantly more frequent in the thyrotropin group (34 vs 12 events; P<.001). Permanent hypothyroidism developed in 3 patients (11%) in the placebo group compared with 16 patients (62%) in the thyrotropin group (P<.001). Patient satisfaction was high and uninfluenced by the use of recombinant human thyrotropin.
Stimulation with recombinant human thyrotropin prior to 131I therapy improves thyroid size reduction by 35%, with a 5-fold higher rate of hypothyroidism. These effects are, at least partially, mediated through mechanisms other than an increase in retained 131I thyroid dose. Further recombinant human thyrotropin dose-finding studies are warranted before routine use.
clinicaltrials.gov Identifier: NCT00145366