[Radioiodine therapy of functional autonomy of the thyroid gland. Treatment results in view of pretreatment scintigraphic diagnosis and early response of triiodothyronine levels to treatment]

Effectiveness of Radioiodine Treatment for Toxic Nodular Goiter

OBJECTIVE

The aim of this retrospective study is to evaluate the treatment outcomes in patients with toxic nodular goiter (TNG) that received radioiodine treatment (RAIT) and to determine the influence of age, gender, nodule size, I-131 dose, underlying etiology and antithyroid drugs on the outcomes of RAIT.

METHODS

Two hundred thirty three patients (mean 64±10 years old) with TNG that received RAIT were included in the study. Treatment success was analyzed according to demographic (age and gender) and clinical data (thyroid function tests before and after RAIT, thyroid sonography and scintigraphy, I-131 dose, antithyroid drugs). A fixed dose of 555 MBq was administered to patients with nodules smaller than 2 cm in diameter and of 740 MBq to patients with nodules larger than 2 cm. Hyperthyroidism treatment success was defined as achieving hypothyroidism or euthyroidism six months after RAIT.

RESULTS

In our study, the cure rate was 93.9% six months after RAIT. Hypothyroidism was observed in 74 (31.7%) patients, and euthyroidism was achieved in 145 (62.2%) patients while 14 (6%) patients remained in hyperthyroid state. Age and gender did not affect treatment outcomes. No correlation was found between underlying etiology or antithyroid drugs and therapeutic effectiveness. The effectiveness of RAIT was better in patients with nodules smaller than 2 cm.

CONCLUSION

We observed that high cure rates were obtained in patients with TNG with 555 MBq and 740 MBq doses of I-131. While nodule diameter and RAI dose are important factors for treatment efficacy; age, gender, underlying etiology and antithyroid drugs do not affect the outcome of RAIT.

Influence of Propylthiouracil and Methimazole Pre-treatment on the Outcome of Iodine-131 Therapy in Hyperthyroid Patients with Graves' Disease

There is ongoing controversy about potential differences in the influence of the anti-thyroid drugs propylthiouracil (PTU) and methimazole (MMI) on radioiodine treatment of Graves' hyperthyroidism. This retrospective study investigated the influence of PTU and MMI pre-treatment, individually or sequentially, on the outcome of iodine-131 (131I) therapy in 199 patients with Graves' disease who had been treated with 131I for the first time and followed up at 3 and 6 months after treatment. Pre-treatment with PTU, or sequential PTU and MMI pre-treatment, increased the failure rate of 131I therapy and reduced the rate of hypothyroidism. MMI pre-treatment alone had no significant influence on the results of 131I therapy. Logistic regression analyses indicated that PTU pre-treatment and having a thyroid gland of > 60 g were both significantly related to 131I therapy failure.