A Risk Scoring System Integrating Clinical and Ultrasonographic Parameters for Predicting Hypothyroidism After...

Background/Objectives: Postoperative hypothyroidism is a common complication following hemithyroidectomy and may necessitate lifelong levothyroxine replacement therapy. Although several clinical predictors have been identified, clinically applicable risk models integrating both clinical and ultrasonographic parameters remain limited. This study aimed to identify independent predictors of postoperative hypothyroidism and to develop practical risk scoring systems with and without ultrasonographic parameters based on these predictors. Methods: This observational cohort study included 95 patients who underwent hemithyroidectomy and were followed for at least 6 months. Clinical characteristics, thyroid autoantibodies, and ultrasonographic features of the remnant thyroid lobe were evaluated. Independent predictors of postoperative hypothyroidism were identified using multivariable logistic regression analysis, and two simplified risk scoring systems were developed based on the regression coefficients. Results: Postoperative hypothyroidism developed in 39 of the 95 patients (41.1%). In the model incorporating ultrasonographic parameters, preoperative TSH, a low remnant thyroid volume-to-body surface area ratio, and heterogeneous remnant thyroid parenchyma were independent predictors of postoperative hypothyroidism. The corresponding score stratified patients into low-, intermediate-, and high-risk categories with observed hypothyroidism rates of 9.1%, 44.7%, and 100.0%, respectively, and showed an AUC of 0.858. In the model without ultrasonographic parameters, preoperative TSH and thyroid autoantibody positivity were independent predictors; the corresponding score showed an AUC of 0.745. Conclusions: The proposed risk scoring systems may serve as practical tools for identifying patients at increased risk of postoperative hypothyroidism following hemithyroidectomy according to the availability of ultrasonographic assessment. External validation in independent cohorts is warranted before routine clinical implementation.