Endocrine Abstracts

Aim: The aim of our study was to evaluate the influence of recombinant human thyroid-stimulating hormone (rhTSH) on the efficacy of radioiodine therapy in patients with non toxic nodular goitre with low RAIU.

Materials and methods: The study was performed on 50 patients with non toxic nodular goitre (36 females and 14 males, aged 34–75 years) referred for radioiodine therapy. All patients had low RAIU (8–16%), 24 h after a diagnostic dose of I-131 (4 MBq). All the patients received a single intramuscular dose of 0.05 mg rhTSH (thyrogen). 24 h later diagnostic dose of ¹³¹I was administered and thyroid scan with RAIU after 24 and 48 h was estimated. Therapeutic dose of I-131 was given on the third day of rhTSH administration. Serum levels of TSH, fT4 and fT3 were determined, 24 and 72 h after rhTSH administration and on the 3rd day after radioiodine therapy. The therapeutic activity of I-131 calculated by Marinelli’s formula and ranged between 280 and 600 MBq. The absorbed dose ranged between 150 and 220 Gy. Follow up control was done every 6 weeks. Thyroid ultrasound, and thyroid scan were done again after 6 and 12 months of radioiodine therapy.

Results: A significant increase (2 11 fold) in 24 h RAIU was observed after rhTSH administration. The distribution of radioiodine was more homogeneous 48 h after rhTSH administration. After 12 months 92% of patient were in euthyroid state and 8% develop hypothyroidism. After 6 months the mean reduction in goitre volume was 22 and 45–55% after 12 months. The medium therapeutic activity of I-131 was 280 MBb.

Conclusions: Pre-treatment with rhTSH reduce the therapeutic dose of I-131 by 50–58% without compromising the result of thyroid volume reduction. rhTSH makes radioiodine therapy more effective in the patients with non toxic nodular goitre with low RAIU.