Lack of association between high serum thyroid-stimulating hormone level and risk of papillary thyroid microcarcinomas.

BACKGROUND High serum thyroid-stimulating hormone (TSH) is associated with thyroid carcinoma in patients with thyroid nodules. However, previous studies suggests that TSH is not involved in the pathogenesis of small thyroid carcinomas. We performed this study to evaluate serum TSH as a malignancy predictor in the assessment of small thyroid nodules. METHODS We retrospectively analyzed 3791 patients who underwent thyroidectomy. We classified all patients into 3 to 5 groups by serum TSH or nodule size and analyzed the association of serum TSH and risk of papillary thyroid carcinoma (PTC). RESULTS The frequency of PTC increased as serum TSH increased. Serum TSH and older age were associated with the risk of PTC in multivariate analysis (p < .0001). In subgroup analysis, the risk of PTC increased as serum TSH increased with thyroid nodules > 1 cm (p < .05). CONCLUSIONS Serum TSH may not be useful for clinical risk assessment of small thyroid nodules.