Predictive factors for permanent hypoparathyroidism following total thyroidectomy: A retrospective cohort study of 5,671 cases

Objective: To evaluate the rates of permanent hypoparathyroidism based on demographic variables, patient comorbidities, clinical staging of the disease, surgery performed, and severity of transient hypoparathyroidism. Subjects and methods: This is a retrospective cohort study with patients who underwent total thyroidectomy with or without neck dissection between January 2014 and December 2021. Results: 5,671 patients were analyzed, 966 (17%) presented transient hypoparathyroidism and 106 (1.8%) developed permanent hypoparathyroidism. The logistic regression model analyzing the cohort of patients with transient hypoparathyroidism demonstrates that the number of dissected lymph nodes from the central compartment, immediate postoperative PTH levels, the necessity of postoperative intravenous (IV) calcium supplementation and the duration of IV calcium supplementation are significant predictors. When applied to the original dataset, this model presents a NPV of 1.0000 and a PPV of 0.9594 with an overall accuracy of 0.9624. Conclusion: The incidence of permanent hypoparathyroidism was closely associated with the extent of level VI dissection, particularly regarding the number of lymph nodes removed and whether the dissection was bilateral. Furthermore, the severity of post-operative hypocalcemia was demonstrated by the decrease in PTH levels, as well as the need for and duration of intravenous calcium supplementation.