Endocrine Abstracts

Objective: 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 hormone (FT4) blood level.

Methods: In this study 131 cytological benign AFTNs in 116 pts (100 female and 16 male) with normal FT4 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 61 (range 35 - 90) years. AFTNs were located more frequently in the right thyroid lobe (73 nodules) than in the left lobe (58 nodules). In 19 pts a solitary AFTN has been found on ultrasonography and the other 97 patients had AFTNs in multinodular goiter. 15 pts had two AFTNs. On post I-131 therapy thyroid scan in 80 AFTNs complete therapy effect has been observed, but in 51 AFTNs a scintigraphycally partial effect has been noted. Statistical analysis showed a significant reduction in the thyroid (P = 2,8179E-24) and AFTNs (P = 4,0351E-06) volume after J-131 therapy. TSH value significantly increased (P = 3,0081E-05) and FT4 value significantly decreased (P = 3,1438 E-05) after I-131 therapy. FT3 (P = 0,3757), anti-TPO (P = 0,7615) and anti-Tg (P = 0,1412) and anti-TSH receptor (P = 0,1182) values did not change significantly.

Conclusion: This study shows that radionuclide therapy with I-131 in pts with AFTN and normal FT4 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.