Serum TSH Levels as a Predictor of Thyroid Malignancy in Euthyroid Patients with a Thyroid Nodule- A Cohort Study

Abstract

Introduction: Palpable thyroid nodules are a common disorder in the general population. In many cases, the initial presentation of thyroid cancers can be a thyroid nodule. Hence, this is important to distinguish between a benign and a malignant nodule. Fine Needle Aspiration Cytology (FNAC) is the gold standard for evaluating a thyroid nodule. Currently, FNAC is a much more reliable diagnostic technique. However, there are certain limitations of FNAC, which makes the serum Thyroid Stimulating Hormone (TSH) an essential marker in evaluating the thyroid nodule. It has been observed that the frequency of malignancy varies by the serum TSH levels within its normal range itself. Hence, in the present study, authors aim to assess the role of preoperative serum TSH in predicting the malignancy associated with thyroid nodules. Aim: To evaluate the usefulness of preoperative serum TSH levels in patients with ‘nodular thyroid disease’, in prediction of malignancy. Materials and Methods: This is a cohort study conducted over 7 years from January 2014 to December 2020 by the surgery Department of Gandhi Medical College and associated Hospital, Bhopal, India. A total of 50 patients with thyroid nodule(s) having preoperative serum TSH levels within the normal range were included in this study. Serum TSH levels were measured by Electrochemiluminscent Immunoassay (ECLIA). In additaion, patients’ postoperative tissue biopsies were analysed and associated with preoperative serum TSH levels statistically using student’s t-test, Wilcoxon Mann Whitney U-test, Fisher’s exact test, or Chi-square test. Results: A total of 50 patients were included in the study. The age (years) ranged from 19 to 70. Out of 50 patients who participated in the study, 46 (92%) were female. All 50 (100%) patients had thyroid swelling as their initial presentation. Authors subdivided the sample into three groups by the TSH level distribution of the study (category A 0.4-1.4, category B 1.41- 2.5, and category C 2.51-4.0 mIU/L). The serum TSH category C participants had the largest proportion of biopsy impressions as malignant (p-value <0.001). A cut off level of TSH 2.86 mIU/L showed a sensitivity of 58.8% and specificity of 100%. Conclusion: In patients with thyroid nodule/s having serum TSH levels within their normal range, the higher limits of serum TSH levels are associated with an increased risk of thyroid cancer. Preoperative serum TSH levels can be used as an adjunctive diagnostic test for identifying the risk of malignancy associated with a thyroid nodule. It may aid in decision making on diagnostic approaches and may help in making the best therapeutic plans.