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ABSTRACT
Objective: We aimed to determine whether the ratio of thyrotropin (TSH) to thyroglobulin (Tg) (TSH/Tg) would be able to asist in predicting malignancy in thyroid nodules.
Material and Methods: Euthyroid patients operated between the year 2007 and 2014 were retrospectively reviewed. Patients who previously had thyroid disease or surgery and those with increased levels of anti-thyroglobulin antibodies were excluded from this study. Clinicopathological features, as well as serum TSH, Tg, and TSH/Tg were compared between histopathologically benign and malignant groups.
Results: Data related to 370 (60.3%) benign and 244 (39.7%) malignant patients were analyzed. The malignant patients exhibited significantly higher TSH, TSH/Tg, and total thyroid volume, and a lower Tg compared to the benign patients (p<0.001 for each). There were 924 (74.2%) benign and 321 (25.8%) malignant nodules. Cytological distribution of the nodules was observed to be as follows: 343 (27.6%) nondiagnostic, 637 (51.2%) benign, 121 (9.7%) atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), 39 (3.1%) follicular neoplasm/suspicious for follicular neoplasm (FN/SFN), 64 (5.1%) suspicious for malignancy (SM), and 41 (3.3%) malignant. TSH, Tg, and TSH/Tg were significantly different in different Bethesda categories (p<0.001 for each). Median TSH/Tg was the lowest in benign (0.013), and highest in SM (0.054) and malignant (0.086) cytologies. TSH/Tg was significantly higher in the malignant nodules compared to benign nodules, in AUS/FLUS, FN/SFN, and SM categories (p=0.001, p<0.001, and p=0.003, respectively). In the regression analysis, TSH/Tg demonstrated higher diagnostic performance compared to TSH and Tg (p<0.001).
Discussion: Preoperative TSH/Tg could be used as a novel marker for differentiating between benign and malignant thyroid nodules. It could also assist in the prediction of risk of malignancy and management decisions when the cytology is indeterminate.