ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 P797

The effect of radioiodine therapy in patient with subclinical hyperthyroidism

Saeid Abdelrazek1, Franciszek Rogowski1, Malgorzata Szelachowska2, Adam Parfienczyk1, Anna Zonenberg2, Emilia Wojno1, Piotr Szumowski1, Urszula Karpinska1 & Marta Marciniak1


1Department of Nuclear Medicine, Medical University of Bialystok, Bialystok, Poland; 2Department of Endocrinology, Diebatology and Internal Medicine, 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 skeletal systems and prevent evolvement to overt hyperthyroidism.

Material and methods: We treated 630 patients, aged 30–70 years; 85% of them were female and 15% male; 220 patient with multinodular goitre (MNG), and 310 patient with autonomous nodule (ATN). Some of the patients were treated with antithyroid drugs for 6 to 24 months before I131 therapy (110 patient). 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 150 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 95% of MNG; 1% of patient with ATN and 5% of patient 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 (up to 10 years) to evaluate the long term effect of RIT.

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