Postoperative parathyroid hormone (PTH) is equivalent to perioperative PTH drop in predicting postsurgical hypoparathyroidism

Introduction Postoperative surgical hypoparathyroidism (PoSH) following thyroid surgery is an established complication. Several predictive factors have been identified including perioperative parathyroid hormone (PTH) levels. The aim of the study is to compare the drop in perioperative PTH to postoperative day 1 PTH in predicting hypocalcaemia and hypoparathyroidism. Methods Records of consecutive patients who had either total or completion thyroidectomy with or without central neck dissection in a 3-year period in a single thyroid surgery unit were accessed to retrieve data on demographics, pathology, surgery, perioperative biochemistry and management. Results Of 295 included patients, there were 227 (76.9%) females. Forty-five (15.3%) had completion thyroidectomy, and the rest had total thyroidectomy. Seventy-eight (26.4%) had concomitant central neck dissection. Sixty-four (21.7%) had hypocalcaemia on the day after surgery. Hypoparathyroidism persisted in 10.5% of patients at 6 months. Both day 1 PTH and a drop in PTH predicted day 1 hypocalcaemia (p < 0.001) and 6-month hypoparathyroidism (p < 0.001). The area under the receiver operating characteristic (ROC) curves for day 1 PTH and drop in PTH for the prediction of day 1 hypocalcaemia (0.729 vs 0.726, respectively) and for 6-month hypoparathyroidism (0.964 vs 0.958, respectively) were similar, albeit slightly better for day 1 PTH. Conclusions Day 1 PTH is equivalent to (if not better than) drop in PTH in predicting short- and long-term PoSH. Preoperative PTH measurements may not be needed in the detection and/or management of PoSH after thyroid surgery.