Journal of Korean Endocrine Society 2000;15(4-5):532-541.
Published online January 1, 2001.
The Efficacy of Thyroxine Suppression Therapy in Benign Thyroid Nodules.
Seog Ki Yun, Chul Hee Kim, Young Sun Kim, Dong Won Byun, Kyo Il Suh, Myung Hi Yoo
Department of Internal Medicine, College of Medicine, Soonchunhyang University, Korea.
Benign pathologic findings are shown in 800% of thyroid nodules by fine needle aspiration cytology (FNAC) or needle biopsy. About half of these benign nodules are follicular lesions which are presented only as thyroid follicles or thyroid cell clumps. Differential diagnosis of follicular adenoma, follicular carcinoma and adenomatous goiter is impossible by FNAC or needle biopsy. Thyroxine suppression therapy has been performed traditionally in order to discriminate malignant nodules, but few studies are available which confirmed the efficacy of thyroxine suppression therapy in thyroid nodules of those the initial pathologic findings were follicular lesions. So we tried to evaluate the efficacy of thyroxine suppression therapy in benign thyroid nodules and also the incidence of thyroid cancer of the thyroid nosules which were not decreased on thyroxine suppression therapy after surgical resection. METHODS: Total 1027 patients with thyroid nodules were evaluated by FNAC or needle biopsy at Soonchunhyang university hospital from 1990 to 1996. Among 1027 patients, 507 patients showed follicular lesions in FNAC or needle biopsy and they received thyroxine suppression therapy. Thyroid nodule volume was measured before and after thyroxine suppression therapy using ultrasonography. We studied 184 patients who were followed up for more than 1 year. Serial changes of thyroid function tests, thyroid nodule volume, serum thyroglubulin (Tg) level before and after therapy were analyzed. RESULTS: l. In 80 (43.5%) of the 184 patients, nodule volumes decreased more than 50 percent after thyroxine suppression therapy. 2. There was no significant difference in serum T3, T4, TSH levels before and after thyroxine suppression therapy between group I (nodule volume decreased less than 50%) and group II (nodule volume decreased more than 50%). 3. In group II patients, thyroid nodule volumes were decreased continuously at 12 month, 18 month and 30 month after thyroxine suppression (p<0.05). 4. There was no significant difference between the group I and group II in the frequency of multiple thyroid nodules on ultrasonography. 5. Among 37 patients who underwent thyroidectomy, 19 cases (51.4%) were revealed as malignant thyroid nodules (papillary cancer 4 cases, follicular cancer 15 cases). Eighteen cases (48.6%) were revealed as benign thyroid nodules (follicular adenoma 10 cases, adenomatous goiter 8 cases). 6. There was no significant difference in the frequency of multiple nodules on ultrasonography between benign and malignant nodules. CONCLUSION: Our data suggested thyroxine suppression therapy was effective in discriminating malignant thyroid nodules from benign nodules, especially in selecting follicular carcinoma from follicular lesion by FNAC or biopsy.
Key Words: Thyroid nodule, Follicular lesions, Thyroxine suppression therapy

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