Ultrasonographic Characteristics of the Hyperfunctioning Thyroid Nodule and Predictive Factors for Thyroid Stimulating Hormone Suppression

Abstract

Background and Objectives: Thyroid scan is a good tool for diagnosis of hyperfunctioning thyroid nodules (HNs), however it has been limited in use in a primary clinical practice, because of its inconvenience and low accessibility. This study aimed to analyze ultrasonographic (US) characteristics of HNs and to predict HNs by US. Materials and Methods: We included 114 patients who exhibited results of ‘hot’ nodule in the thyroid scan from 2008 to 2017. Analysis for US characteristics included 73 patients without unclear US images and other inevitable reasons. We compared US characteristics of HNs with cold nodules that showed “cold” in the thyroid scan. Additionally, we compared US characteristics of HNs between suppressed thyroid-stimulating hormone (TSH) (＜0.25 uIU/mL) or normal TSH, and analysis receiver operating characteristics (ROC) curve for prediction of suppressed TSH among HNs. Results: The HNs showed more partially cystic nodule, isoechoic echogenicity, hypervascularity and presence of halo in the US finding than the cold nodule. In subgroup analysis of nodules with TSH suppression among HNs, the TSH suppression nodules was lager in max size and volume than the normal TSH nodules. In ROC analyses for prediction of the TSH suppression among HNs, area under receiver operating characteristics curves was 0.736 in max size, 0.761 in volume. Conclusion: HNs showed more frequently partially cystic contents, isoechoic echogenicity, hypervascularity, and peripheral halo sign in US finding. Thyroid nodule size and volume were associated with suppressed TSH level of HNs, and optimal cutoff levels for prediction of TSH suppression among HNs were 2.6 cm and 1.13 cm3, respectively.