Endocrine Abstracts

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.

Materials and methods: We treated 1600 patients refered to our department during the last 8 years, aged 23–77 years; 89% of them were females and 11% males; 520 patients with multinodular goitre (MNG), and 1080 patients with autonomous nodule (ATN). Some of the patients were treated with antithyroid drugs for 1–3 months before ¹³¹I therapy (148 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 800 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 93% of MNG; 1% of patients with ATN and 6% of patients with MNG develop hypothyroidism. One percentage of patients with MNG were in subclinical hyperthyroidism and received second dose of radioiodine therapy. 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).

Conclusions: 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 to evaluate the long-term effect of radioiodine therapy.

Subclinical hyperthyroidism, and long period of follow-up to evaluate the long-term effect of radioiodine therapy.