Early Postoperative Parathyroid Hormone as a Predictor of Hypocalcemia After Total Thyroidectomy

Abstract

Background: Hypocalcemia is a common complication following total thyroidectomy, primarily due to transient or permanent hypoparathyroidism. Early postoperative parathyroid hormone (PTH) measurement has been proposed as a predictor of post-thyroidectomy hypocalcemia. This study aims to assess the predictive value of early postoperative PTH levels for hypocalcemia in patients undergoing total thyroidectomy. Methods: A cross-sectional study was conducted at the General Surgery and Otolaryngology Department, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, from July 2022 to July 2023. A total of 103 patients who underwent total thyroidectomy were included. Preoperative and postoperative PTH and serum calcium levels were measured. The correlation between immediate postoperative PTH levels and the development of hypocalcemia was analyzed. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal PTH cutoff value for predicting hypocalcemia. Results: The mean age of the study population was 41.72±12.12 years, with a female predominance (76.7%). The most common preoperative diagnosis was multinodular goiter (70.87%), followed by papillary carcinoma (22.33%). The mean preoperative PTH level was 45.41±15.56 pg/mL, significantly decreasing immediately after surgery to 37.63±20.22 pg/mL (p=0.001). Hypocalcemia developed in 20.39% of patients, all of whom had a postoperative PTH level ≤14.4 pg/mL. The ROC curve analysis identified this threshold with a sensitivity of 94.6% and specificity of 100% (AUC=0.987, p=0.001). Conclusion: Early postoperative PTH measurement is a reliable predictor of hypocalcemia following total thyroidectomy. A ≤14.4 pg/mL cutoff value can effectively identify at-risk patients, enabling timely calcium supplementation and preventing symptomatic hypocalcemia.