Abstract: Objectives Parathyroidectomy (PTX) is an effective treatment for severe secondary hyperparathyroidism (SHPT). However, persistent SHPT may occur because of the presence of supernumerary and ectopic parathyroids. This is a diagnostic accuracy study of preoperative and postoperative serum intact parathyroid
hormone (iPTH) to predict the effects of PTX. Methods Intraoperative and perioperative serum iPTH values were recorded in 501 SHPT patients treated with total PTX+autotransplantation and without thymecto-my. Patients with serum iPTH ≤50 pg/mL in the first week after PTX were classified as successful PTX. Patients with serum iPTH＞50 pg/mL in the first week after PTX were followed up for 6 months; successful PTX was defined if the follow-up iPTH level was ＜300 pg/mL, and persistent SHPT was considered if the iPTH was ＞300 pg/mL. Results A total of 433 (86.4%) patients were defined as successful PTX, 49 (9.8%) as persistent SHPT, and 19 (3.8%) as undetermined due to the incomplete follow-up. Preoperative and postoperative serum iPTH levels had no significant differences between patients with chronic hepatitis (n=204) and those without chronic hepatitis (n=297). Receiver operating characteristic (ROC) curves showed that the decrease of iPTH level by≥88.9% after the surgery for 20 minutes could predict successful PTX, with the area under the curve (AUC) of 0.909, the sensitivity of 78.6% and the specificity of 88.5%. Serum iPTH ≥147.4 pg/mL after the surgery for 4 days could predict persistent SHPT, with the AUC of 0.998, the sensitivity of 100% and the specificity of 99.5%. Conclusion Monitoring of postoperative iPTH level can effectively predict the completeness of PTX, thereby avoiding unnecessary re-operation and its possible complications. Perioperative iPTH monitoring is useful for the prediction of persistent SHPT, for which follow-up study, medical intervention or re-operation may be necessary.

Key words: intraoperative, perioperative, parathyroid hormone, parathyroidectomy, secondary hyperparathyroidism