Abstract: Objective To determine intact parathyroid hormone (iPTH) levels at 24 hours after total thyroidectomy, to predict the occurrence of permanent hypoparathyroidism (pHPP), and to analyze the clinical value of parathyroid hormone as an independent risk factor for predicting hypoparathyroidism. Methods Totally 622 patients with thyroid cancer and benign thyroid lesions who underwent total thyroidectomy at Department of General Surgery, Beijing Chaoyang Hospital, Capital Medical University from December 2008 to December 2019 were studied retrospectively. Independent sample t test and Chi-square test were used to analyze and compare serum iPTH levels, and multivariate Logistic regression analysis was applied to evaluate the correlation between each data and the occurrence of permanent hypoparathyroidism after surgery. The area under the receiver operating characteristic (ROC) curve (AUC) was used to calculate iPTH levels to predict the accuracy of permanent hypoparathyroidism. Results Among the 622 cases of total thyroidectomy, 25 cases of permanent hypoparathyroidism occurred, with an incidence of 4.02% (25/622). Multivariate analysis showed that iPTH level on postoperative day 1(OR=2.815, 95% CI:1.169-6.781,P=0.021) was independent risk factor for postoperative permanent hypoparathyroidism. The concentration of iPTH threshold value was 5.45 pg/mL (AUC 0.974, 95%CI: 0.958-0.985,P<0.001) at 24 hours after total thyroidectomy. Conclusions Serum iPTH level measured on the first day after total thyroidectomy was closely related to the occurrence of permanent hypoparathyroidism postoperatively, It was an independent predictor of risk factors.

Key words: total thyroidectomy, postoperative hypocalcemia, permanent hypoparathyroidism