Influence of short-term interruption of antithyroid drugs on the outcome of radioiodine therapy of Graves' disease: results of a prospective study.
OBJECTIVE
The factors influencing success of treating Graves' disease with radioiodine ( (131)I) are discussed controversially. This study analyses prospectively the influence of discontinuing antithyroid drugs (ATD) immediately prior to treatment with radioiodine on the therapeutic outcome.


METHODS
We studied 141 patients with Graves' disease. In 73 of them (group A) treatment was performed under medication with ATD, in 68 patients (group B) ATD were discontinued for 3 - 7 days starting at the time of therapy. We performed a statistical analysis of the influence of ATD and other factors potentially influencing treatment results.


RESULTS
In group A 49/73 patients were treated successfully (67 %) vs. 58/68 (85 %) in group B (p < 0.01). Characteristic changes in the kinetics of radioiodine were observed: after discontinuing ATD specific uptake was higher (2.0 %/ml in group A vs. 2.6 %/ml in group B, p = 0.004), and the effective half life was longer (5.1 +/- 1.3 d in group A vs. 5.5 +/- 1.1 d in group B, p = 0.076) resulting in a significantly higher radiation dose in group B (200 +/- 61 Gy in group A vs. 236 +/- 72 Gy in group B, p = 0.002).


CONCLUSIONS
We conclude that short-term interruption of ATD improves the success rate of treating Graves' disease with radioiodine significantly.
Eschmann
S M
SM
University of Tuebingen, Department of Nuclear Medicine, Germany. susanne-martina.eschmann@med.uni-tuebingen.de
Thelen
M H
MH
Dittmann
H
H
Bares
R
R
D000368:Aged; D013956:Antithyroid Agents / Q000627:therapeutic use*; D005260:Female; D006111:Graves Disease / Q000188:drug therapy* / Q000532:radiotherapy*; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D016896:Treatment Outcome; D028761:Withholding Treatment
D013956:Antithyroid Agents; D007457:Iodine Radioisotopes