ClinicalTrials.gov Identifier: NCT00150124
A randomized trial evaluating a block-replacement regimen during radioiodine therapy
Article first published online: 22 DEC 2010
© 2010 The Authors. European Journal of Clinical Investigation © 2010 Stichting European Society for Clinical Investigation Journal Foundation
European Journal of Clinical Investigation
Volume 41, Issue 7, pages 693–702, July 2011
How to Cite
Bonnema, S. J., Grupe, P., Boel-Jørgensen, H., Brix, T. H. and Hegedüs, L. (2011), A randomized trial evaluating a block-replacement regimen during radioiodine therapy. European Journal of Clinical Investigation, 41: 693–702. doi: 10.1111/j.1365-2362.2010.02452.x
Randomized clinical trial
- Issue published online: 9 JUN 2011
- Article first published online: 22 DEC 2010
- Received 15 September 2010; accepted 22 November 2010
- 131I kinetics;
- Graves’ disease;
- radioiodine therapy;
- thyroid hormones;
- toxic nodular goitre
Eur J Clin Invest 2010; 41 (7): 693–702
Background Lack of consensus regarding the antithyroid drug regimen in relation to radioiodine (131I) therapy of hyperthyroidism prompted this randomized trial comparing two strategies.
Design Patients with Graves’ disease (GD, n = 51) or toxic nodular goitre (TNG, n = 49) were randomized to 131I either 8 days following discontinuation of methimazole (−BRT, n = 52, median dose: 5 mg) or while on a continuous block-replacement regimen (+BRT, n = 48, median dose 15 mg methimazole and 100 μg levothyroxine).
Results Patients in the +BRT group required more radioactivity. In this group, thyroid function did not change in the early post 131I period, while serum-free T3 index was higher in the −BRT group (P < 0·05). One year posttherapy, the fraction of cured patients (euthyroid or hypothyroid) was 48% and 61% in the +BRT and −BRT group, respectively (P = 0·014 unadjusted; P = 0·004 adjusted), but the outcome depended on the type of disease. In GD, treatment failure in the +BRT group correlated positively with the 24-h thyroid 131I uptake (P = 0·017), while no correlations existed in the −BRT group. In addition to +BRT allocation, patients with TNG were at higher risk of treatment failure with lower thyroid radiation doses (P = 0·048), higher doses of methimazole (P = 0·026) and lower levels of serum TSH (P = 0·009).
Conclusions A continuous block-replacement regimen results in a stable thyroid function during 131I therapy but is hampered by the higher amounts of radioactivity required. The study demonstrates that the outcome in GD is highly unpredictable, while treatment failure in patients with TNG is correlated with a number of factors.