Predicting Hypocalcemia and Identifying Supplementation Needs After Total Thyroidectomy: The Role of Perioperative PTH Measurements

<b>Background</b>: Post-thyroidectomy hypocalcemia is a common complication, yet the optimal perioperative markers for identifying high-risk patients and guiding supplementation remain debated. This study aimed to evaluate factors associated with hypocalcemia at 24 h after total thyroidectomy, identify independent predictors, and assess the reliability of early PTH measurement in determining supplementation needs. <b>Methods</b>: We conducted a single-center prospective cohort study including 200 patients undergoing total thyroidectomy at Genesis Hospital, Thessaloniki, between November 2022 and March 2025. PTH was measured preoperatively, 10 min post-resection, and at 24 and 72 h; calcium and phosphorus were measured preoperatively and postoperatively. <b>Results</b>: Independent predictors of hypocalcemia at 24 h were female sex, preoperative calcium, and PTH at 10 min. Age, pathology, incidental parathyroid excision, and extent of surgery were not significantly associated with hypocalcemia. ROC analysis showed that a preoperative calcium cutoff of 9.47 mg/dL yielded an AUC of 0.73, with 70.1% sensitivity and an NPV of 82%. PTH at 10 min with a cutoff of 24.6 pg/mL yielded an AUC of 0.66, with 70.1% sensitivity and an NPV of 79%. For supplementation needs, PTH at 10 min demonstrated excellent discrimination, with a cutoff of 16.3 pg/mL at 24 h and 14.1 pg/mL at 72 h. <b>Conclusions</b>: Preoperative calcium and PTH measured 10 min after thyroid removal are useful markers for predicting hypocalcemia after total thyroidectomy, with early PTH also accurately identifying supplementation needs.