NEW YORK (Reuters Health) – In the treatment of nodular goiter, the effect of radioiodine (I-131) therapy is potentiated by neoadjuvant administration of recombinant human thyroid stimulating hormone (TSH). A protocol based on this strategy substantially reduces radiation exposure compared with I-131 monotherapy, investigators in Denmark report.

In a double-blinded study, patients treated with TSH stimulation received 70% less radiation without compromising goiter volume reduction.

“This approach is attractive in terms of minimizing post-therapeutic restrictions and in reducing the potential risk of radiation-induced malignancy,” Dr. Soren Fast and colleagues at Odense University Hospital write in the Journal of Clinical Endocrinology and Metabolism published online on June 2nd.

They randomly assigned 60 adult patients to treatment with 0.1 mg intramuscular recombinant human TSH followed by an absorbed thyroid dose of 50 Gy I-131, and 30 patients to placebo treatment followed by 100 Gy I-131. The median administered I-131 activity was 170 MBq and 559 MBq, respectively (p < 0.0001). At 12 months, goiter volume was reduced by a mean of 35% in both groups. Mean scores on a 10-point visual analog scale rating cervical obstructive symptoms fell by 4 points in the placebo group and 3.4 points in the TSH group (p = 0.43). The authors note that in Denmark, the maximum I-131 activity that can be employed without any patient restrictions is 200 MBq. Thirty-seven patients in the TSH group could be treated without any post-therapeutic restrictions, versus none of the patients in the placebo group (p < 0.0001). One patient treated with TSH and 14 treated with placebo required hospitalization (p < 0.0001). Four patients in the placebo group and two in the TSH group had to undergo surgery because of therapeutic failure. Adverse effects were similar in the two groups, as were the patterns of early and late alterations in thyroid function. The authors had also randomized patients to receive TSH or placebo 24, 48 or 72 hours before I-131 therapy. TSH stimulation resulted in increases in the 24-hour I-131 uptake of 111%, 83%, and 62%, respectively, although they say this was not a major determinant of goiter volume reduction. However, they caution, timing of the TSH injection is critical for keeping administered I-131 activity as low as possible. Although these results “support a future role of rhTSH in the context of I-131 therapy” for nontoxic nodular goiter, Dr. Fast and associates recommend large-scale studies focusing on eligibility criteria, cost and quality of life as well as an evaluation of the optimal TSH dose. Reference:
http://jcem.endojournals.org/cgi/content/abstract/jc.2010-0634v1


J Clin Endocrinol Metab 2010;95.