Abstract
PURPOSE: Serum thyrotropin (TSH) is a well-established growth factor for thyroid nodules and suppression of TSH concentrations by administering exogenous thyroxine may interfere with the growth of established nodules as well as the formation of new thyroid nodules. The aim of this study was to investigate whether serum TSH at presentation is a predictor of thyroid malignancy in patients with thyroid nodules. METHODS: A total of 565 patients without overt thyroid dysfunction, who presented with palpable thyroid nodule(s) between 1988 and 2004 and underwent at least one fine-needle aspiration biopsy, were retrospectively evaluated. RESULTS: The final diagnostic outcome was established after surgery (n = 122) or after a minimum of 1-year clinical follow-up period. Higher rates of malignancy were observed in patients with serum TSH in the upper tertile of the normal range (P = 0.026). Binary logistic regression analysis revealed significantly increased adjusted odds ratios for the diagnosis of malignancy in patients with serum TSH 1.5-4.0 mIU/l when compared to those with either TSH 0.4-0.8 mIU/l (P = 0.005) or TSH 0.9-1.4 mIU/l (P = 0.007). CONCLUSIONS: The risk of malignancy in thyroid nodules increases in parallel with TSH concentrations within the normal range. TSH concentration at presentation is an independent predictor of thyroid malignancy.