Early change of thyroid hormone concentration after 131I treatment in patients with solitary toxic noudule

ABSTRACT

In spite of extensive use of 131I for treatment hyperthyroidism, the results of early outcome are variable. To test whether 131 I induced necrosis causing clinical aggravation of hyperthyroidism and increasing the free thyroid Hormone concentration in the serum of patients with solitary nodule not pretreated with antithyroid drugs. Thirty consecutive patients were treated with 925 MBq 131 I. Serum concentration of thyrotropin [SH] free thyroxine [fT4], free triiodothyronine [fT3], Thyroglobuline [Tg], and interleukin-6 [IL-6] were measured A'lure and after application of 131 I. After application of 131 I no clinical worsening I was observed. FT4 and fT3 concentration did not change significantly within the first five days, whereas both of them significantly decreased after 12 days [p<0.0001]. Slight and clinically irrelevant increase in the level of the two thyroid innones was observed in 9 patients. Furthermore, we observed a prolonged increase in Tg concentration and a transient [iirrease in IL-6 concentration. Neither evidence of any clinical aggravation hyperthyroidism nor any significant increase in thyroid inrmone concentration by 131 I induced necrosis of thyroid cells was found. Therefore, the application of 131 I may be concidered as a safe and effective treatment for patients with typerthyroidism due to toxic adenoma.