Endocrine Abstracts

The aim of our study was to assess the effectiveness of radioiodine therapy (RIT) on the reduction of thyroid volume after pre-treatment adjunct of rhTSH in patients with non-toxic goitre with low RAIU.

Material and methods: We treated 36 patients; (28 female, 8 male) aged 35–77 years. Initial 24 h RAIU was ranged between 5 and 17%, and thyroid volume ranged between 42 and 128 ml. Twelve patients had compressive symptoms. Malignant changes were excluded in all nodules by FNAB. All the patients received a single dose of 0.05 mg rhTSH given intramuscular. About 24 h later diagnostic dose of ¹³¹I was administered and RAIU after 24, 48 and 72 h was estimated. Therapeutic dose of ¹³¹I was given on the third day of rhTSH administration. Serum TSH, fT4 and fT3 were determined, 24 h, 72 h after rhTSH administration and on the 3rd day after RIT. The activity dose calculated by Marinelli’s formula and ranged between 400 and 800 MBq. The absorbed dose ranged between 160 and 300 Gy. Follow up control was done every 6 weeks. Thyroid ultrasound, and thyroid scan were done again after12 months of RIT.

Results: A significant 4-fold increase in 24 h RAIU from 12.2 to 54% was observed. The significant increase in serum TSH from 1.4±0.5 to a peak level 12.21±4.62 was seen after 24h . After 12 months 91% of patient were in euthyroidism, 9% (3 patients) develop hypothyroidism. Thyroid volume reduced to about 45% average. In all of the patients the compressive symptoms relieved and exercise tolerance improved.

Conclusions: Pre-treatment with rhTSH allows the therapeutic dose of ¹³¹I to be reduced by 50–58% without compromising the result of thyroid volume reduction. This mode of therapy can be recommended, especially when RAIU is low and the dose of radioiodine to be administered is high.