Clinical and Surgical Predictors of Postoperative Hypocalcemia After Thyroid Surgery: A Comprehensive Multicenter Evaluation
Abstract
Background: Hypocalcemia is the most common complication after thyroid surgery and may lead to prolonged hospitalization and long-term morbidity. Identifying reliable perioperative predictors is essential for early risk stratification and prevention. Objectives: This study aimed to address these gaps by evaluating the incidence and predictors of transient and permanent hypocalcemia after thyroid surgery in a large cohort from three major hospitals. Methods: This retrospective multicenter cohort study included 6,124 patients who underwent thyroid surgery between January 2020 and December 2025. Demographic, biochemical, operative, and postoperative data were extracted from the electronic medical records. Hypocalcemia was defined as corrected serum calcium < 8.5 mg/dL and/or compatible clinical symptoms requiring calcium supplementation and was classified as transient if it resolved within 6 months or permanent if calcium and/or active vitamin D supplementation remained necessary beyond 6 months. Separate multivariable logistic regression analyses were performed to identify independent predictors of transient and permanent hypocalcemia. Results: Postoperative hypocalcemia occurred in 1,756 (28.7%) patients, including 1,578 (25.8%) with transient hypocalcemia and 178 (2.9%) with permanent hypocalcemia. Patients with hypocalcemia had lower preoperative calcium levels and more frequent vitamin D deficiency. Independent predictors of both transient and permanent hypocalcemia included lower preoperative calcium, vitamin D deficiency, central neck dissection, accidental parathyroid removal, parathyroid tissue on pathology, parathyroid autotransplantation, and lower immediate postoperative parathyroid hormone (PTH) levels. The strongest predictors of transient hypocalcemia were parathyroid tissue on pathology (adjusted odds ratio [aOR] 3.11, 95% CI 2.12 - 4.21) and lower postoperative PTH (aOR 2.44 per 10 pg/mL decrease, 95% CI 2.09 - 2.76). For permanent hypocalcemia, the strongest predictors were parathyroid tissue on pathology (aOR 3.67), accidental parathyroid removal (aOR 3.08), and lower postoperative PTH (aOR 2.79). Conclusions: Post-thyroidectomy hypocalcemia is associated with preoperative biochemical status and parathyroid-related operative factors. Immediate postoperative PTH measurement is useful for early risk stratification and for targeted postoperative management.