Correlation of TIRADS Classification and Nodule Size with Serum TSH in Adults with Thyroid Incidentalomas

Background: A thyroid incidentaloma (TI) is an unexpected, asymptomatic thyroid lesion inadvertently discovered during an investigation of an unrelated condition. Although most TIs are benign, there is a significant potential for malignancy. The prevalence of TI is increasing due to the increased detection using increasingly available high resolution modern ultrasound machines. This study aims to address the need for increased precision in separating benign from malignant lesions by using serum TSH estimation as an adjunct to standardized ultrasound categorization of these lesions for more accurate prediction of their benignity or malignancy, hence reducing the frequency of the need for invasive FNAC. Materials and Methods: This was a prospective cross-sectional study of 400 adult subjects, carried out over a period of six (6) months (January 2023 - June 2023). Each was first scanned, and then blood sample taken from those with incidental thyroid nodules for estimation of serum thyroid-stimulating hormone. The data obtained from the study was analyzed using the Statistical Package for Social Sciences (SPSS), Version 25.0 (IBM Corp. Released 2017, IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.). Sociodemographic characteristics (e.g. gender) of patients were presented in frequency tables and charts where necessary and age was represented as mean ± SD and also displayed in charts. Chi-square analysis was used to determine the relationship between serum TSH levels and the TIRADS classification of the detected TIs. Pearson correlation analysis was used to determine the level of linear correlation between the size of the TIs and serum TSH levels. All P-values ≤ 0.05 were considered statistically significant. Results: The prevalence of incidentalomas in this study was higher than values from older studies. Raised TSH levels were noted in very few subjects and were seen with the; higher TIRADS categories, nodule sizes above 1.5cm, and patients with malignant thyroid nodules. TSH was proportionally increased in more aggressive tumors. Chi Square showed statistically significant association between; the TSH levels and ACR-TIRADS categories (p-value = 0.003), and between TSH levels and the sizes of the TIs (p-value ˂0.001). Pearson’s correlation test showed statistically significant linear correlation between serum TSH levels and the size of the TIs (p-value ˂0.001). Conclusion: The use of high-frequency ultrasound has led to an increase in the detection of incidental thyroid nodules during imaging of the neck. Establishing the use of TSH measurements with ultrasound algorithms in identifying high-risk thyroid nodules in routine clinical practice represents an exciting, cost-efficient and non-invasive approach to optimize thyroid cancer diagnosis.