Prediction of early postoperative hypocalcemia and hypoparathyroidism after thyroidectomy for papillary thyroid carcinoma: dual-outcome prediction models

Background Postoperative hypocalcemia and hypoparathyroidism are two common complications after total or subtotal/near-total for papillary thyroid carcinoma (PTC). This study aimed to identify significant predictors of early postoperative hypocalcemia and hypoparathyroidism and develop prediction nomograms for risk stratification in PTC patients. Methods A total of 1036 PTC patients who underwent total or subtotal/near-total thyroidectomy were retrospectively enrolled. Multivariable logistic regression with prespecified variables was performed to identify independent predictors for two outcomes: (1) early postoperative hypocalcemia, and (2) hypoparathyroidism. Nomograms were constructed for each outcome. Model performance was assessed by area under the receiver operating characteristic curve (AUC), calibration plots and decision curve analysis (DCA). Bootstrap internal validation (500 resamples) was used to correct for optimism. Results Among 1,036 patients, 325 (31.4%) developed early postoperative hypocalcemia, and 228 (22.0%) met criteria for hypoparathyroidism. For hypocalcemia, independent predictors were preoperative calcium (per 0.1 mmol/L: OR 0.298, 95% CI 0.234-0.374, P < 0.001), thyroidectomy extent (subtotal vs. total: OR 0.75, 95% CI 0.025-0.709, P = 0.033), lateral neck dissection (LND) (OR 3.197, 95% CI 1.742-5.852, P < 0.001), and ultrasound risk score (central lymph node involvement: OR 4.013, 95% CI 2.559-6.323, P < 0.001; lateral lymph node involvement: OR 3.387, 95% CI 1.700-6.825, P < 0.001; primary nodule only: OR 1.899, 95% CI 1.119-3.198, P = 0.016). For hypoparathyroidism, independent predictors were preoperative calcium (per 0.1 mmol/L: OR 0.417, 95% CI 0.330-0.519, P < 0.001) and ultrasound risk score (central lymph node involvement: OR 3.388, 95% CI 2.137-5.360, P < 0.001; lateral lymph node involvement: OR 3.468, 95% CI 1.712-7.218, P<0.001; primary nodule only: OR 1.677, 95% CI 0.942-2.926, P = 0.073). The hypocalcemia model showed good discrimination (AUC 0.836, 95% CI 0.810-0.861), as did the hypoparathyroidism model (AUC 0.768, 95% CI 0.752-0.816). Conclusions Simple models integrating preoperative calcium, surgical extent, and ultrasound findings effectively predict early postoperative hypocalcemia and hypoparathyroidism in PTC patients undergoing total or subtotal/near-total, which may assist in preoperative risk stratification and guide prophylactic management.