Endocrine Abstracts (2012) 29 P1601

The effect of radioiodine therapy in 950 patients with subclinical hyperthyroidism

S. Abdelrazek, F. Rogowski, M. Szelachowska, M. Mojsak, A. Kraszynska, M. Kornas & M. Gorska


Medical University of Bialystok, Bialystok, Poland.


The aim of our study was to assess the influence of radioiodine (131I) therapy on the achievement of euthyroidism, prevention of adverse effects on the cardiovascular and prevent evolvement to overt hyperthyroidism. Material and methods: We treated 950 patients, aged 30–70 years; 87% of them were female and 13% male; 320 patients with multinodular goitre (MNG), and 630 patients with autonomous nodule (ATN). Some of the patients were treated with antithyroid drugs for 1 to 3 months before I131 therapy (90 patients). Malignant changes were excluded in all nodules by fine needle aspiration biopsy. All the patients had serum TSH levels <0.1 mU/l and effective T-half was more than 3 days at the time of treatment. The activity dose was calculated by the use of Marinelli’s formula and ranged between 200 and 600 MBq. The absorbed dose (Gy) ranged between 180 and 300, and was proportional to thyroid volume. Follow up control was done every 6 weeks. Results: Euthyroidism achieved in 99% of patient with ATN and 94% of MNG; 1% of patients with ATN and 6% of patients with MNG develop hypothyroidism. In all of the patients, the symptoms and signs of subclinical hyperthyroidism disappeared (palpitation, tachycardia, atrial fibrillation, exercise tolerance improved, the blood pressure normalised and the quality of life improved). One percent of the patients received 2nd dose of radioiodine. Conclusions: Our result is good and is in the range of the existing literature. The achievement of euthyroidism and the remission of the symptoms and signs of subclinical hyperthyroidism, were due to good diagnosis, well preparation of the patients; accurate measurement of administered activity, effective half-life, and well-organised follow up. We recommend early treatment of subclinical hyperthyroidism, and long period of follow up visits in our department to evaluate the long term effect of radioiodine therapy.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

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