Endocrine Abstracts

Objectives: The purpose of this study was to evaluate the results of radionuclide therapy with iodine-131 (I-131) in patients (pts) with autonomously functioning thyroid nodules (AFTNs) and a normal thyroid stimulating hormone (TSH) blood level.

Methods: In this study 127 cytological benign AFTNs in 113 pts (98 female and 15 male) with normal TSH level have been treated with a fixed I-131 doses (370 MBq). Clinical exam, ultrasonography with color Doppler (US), fine needle aspiration biopsy (FNAB), TSH, FT4, FT3, anti-TPO, anti-Tg, anti-TSH receptor and thyroid scan (scintigraphy) have been performed in all pts before and 6 months after I-131 therapy.

Results: The median age of the pts was 60 (range 35 - 90) years. AFTNs were located more frequently in the right thyroid lobe (71 nodules) than in the left lobe (56 nodules). In 18 pts a solitary AFTN has been found on ultrasonography and the other 95 patients had AFTNs in multinodular goiter. 14 pts had two AFTNs. On post I-131 therapy thyroid scan in 79 AFTNs complete therapy effect has been observed, but in 48 AFTNs a scintigraphycally partial effect has been noted. Statistical analysis showed a significant reduction in the thyroid (P = 2,2516E-10) and AFTNs (P = 0,0038) volume after J-131 therapy. TSH value significantly increased (P = 3,734E-05) and FT4 value significantly decreased (P = 5,2476 E-05) after I-131 therapy. FT3 (P = 0,3743), anti-TPO (P = 0,7633) and anti-Tg (P = 0,1947) and anti-TSH receptor (P = 0,1166) values did not change significantly.

Conclusion: This study shows that radionuclide therapy with I-131 in pts with AFTN and normal TSH blood level is a very effective modality. The effect of the I-131 therapy on AFTNs can be evaluated with a thyroid scan 6 months after I-131 therapy.