BackgroundThe role of serum TSH concentrations as a predictor of malignancy of thyroid nodule remains unclear.ObjectiveTo prospectively evaluate the usefulness of serum TSH levels as a predictor of malignancy in thyroid nodules.MethodsPatients with thyroid nodule(s) who underwent fine-needle aspiration biopsy under ultrasonographic guidance in a tertiary, university-based hospital were consecutively evaluated. Patients with known thyroid cancer and/or patients receiving thyroid medication were excluded. Serum TSH levels were measured by two differents methodologies, chemiluminescent (CLIA) and electrochemiluminscent immunoassay (ECLIA). Anatomopathological exam of tissue samples obtained at thyroidectomy was considered the gold standard for the diagnosis of thyroid cancer.ResultsA total of 615 patients participated in the study. The mean age was 55.9±14.7 years, and 544(88.5%) were female. The median TSH values were 1.48 and 1.55 μU/mL, using CLIA and ECLIA, respectively. One-hundred-sixty patients underwent thyroidectomy and the final diagnoses were malignant in 47(29.4%) patients. TSH levels were higher in patients with malignant than in those with benign nodules in both TSH assays: 2.25 vs. 1.50; P = 0.04 (CLIA) and 2.33 vs. 1.27; P = 0.03 (ECLIA). Further analysis using binary logistic regression identified elevated TSH levels, a family history of thyroid cancer, the presence of microcalcifications, and solitary nodule on US as independent risk factors for malignancy in patients with thyroid nodules. Additional analyses using TSH levels as a categorical variable, defined by ROC curve analysis, showed that the risk of malignancy was approximately 3-fold higher in patients with TSH levels ≥2.26 μU/mL than in patients with lower TSH levels (P = 0.00).ConclusionsHigher serum TSH levels are associated with an increased risk of thyroid cancer in patients with thyroid nodules. Using TSH levels as an adjunctive diagnostic test for stratifying the risk of malignancy associated with a thyroid nodule may help on defining the best therapeutic approaches.

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Background: Thyroglobulin measurements in the washout of fine needle aspiration (FNA-Tg) are an excellent tool to detect lymph node (LN) metastases of differentiated thyroid carcinoma (DTC). Nevertheless, how to define the best cutoffs and the influence of potential confounders are still being discussed. Objective: To evaluate the accuracy of FNA-Tg measurement to detect DTC metastases and the influence of thyroid status and anti-thyroglobulin antibodies (TgAb). Methods: One hundred thirty-eight patients with DTC and suspicious cervical LN were included. Patients underwent ultrasound (US)-guided FNA for cytological examination and FNA-Tg measurements. Final diagnoses were confirmed by histological examination or clinical and US follow-up for at least 1 year. Results: Data from 119 subjects with suspicious LN were evaluated. The median value of FNA-Tg in patients with metastatic LN (n = 65) was 3,263.0 ng/mL (838.55–12,507.5), while patients without LN metastasis (n = 54) showed levels of 0.2 ng/mL (0.2–0.2). According to the ROC curve analysis, the best cutoff value to predict metastasis was 4.41 ng/mL for FNA-Tg, with a sensitivity of 98% and specificity of 96%. There were no differences in the median of FNA-Tg measurements between those on (TSH 0.16 mUI/mL) and those off levothyroxine (TSH 99.41 mUI/mL) therapy (47.94 vs. 581.15 ng/mL, respectively; p = 0.79). Interestingly, the values of FNA-Tg in patients with LN metastasis (n = 65) did not differ between patients with positive and those with negative TgAb (88.8 vs. 3,263.0 ng/mL, respectively; p = 0.57). Conclusion: US-guided FNA-Tg proved to be a useful examination in the follow-up of patients with DTC, independently of TSH status and the presence of TgAb.