Abstract
Abstract
Purpose
Intraoperative parathyroid hormone (IOPTH) monitoring supports focused parathyroidectomy by confirming biochemical response after gland excision, but standard assays may be logistically burdensome. Whole-blood point-of-care (POC) assays offer faster turnaround but may have reduced sensitivity. We compared a whole-blood POC IOPTH assay (NBCL CONNECT) with a standard laboratory assay and evaluated candidate IOPTH criteria and sampling timepoints.
Methods
We performed a single-centre retrospective cohort study of consecutive patients undergoing parathyroidectomy for primary hyperparathyroidism with IOPTH monitoring over an 18-month period. Paired samples were collected pre-incision, pre-excision, and approximately 5 and 10 min post-excision and analysed using NBCL CONNECT assay performed in theatre, and the laboratory PTH assay performed in the hospital laboratory. The reference outcome was early biochemical success defined by postoperative calcium normalisation and appropriate postoperative PTH profile during the postoperative period. Diagnostic accuracy (sensitivity, specificity, PPV, NPV) was assessed for prespecified IOPTH criteria at 5 and 10 min.
Results
Among 103 patients, early biochemical success was achieved in 98 (95.1%). Across evaluated criteria, the laboratory assay demonstrated higher overall diagnostic performance than NBCL CONNECT at both 5 and 10 min (Online Resource 1). For NBCL CONNECT, the prespecified 10-minute criterion (> 50% PTH decline from the lower pre-excision value) yielded a PPV of 96.9% (95% CI 89.3–99.6) and NPV of 51.4% (95% CI 34.0–68.6). ROC analyses showed consistently higher AUCs for the laboratory assay; differences were less marked at 10 min.
Conclusion
Whole-blood POC IOPTH using NBCL CONNECT provides a practical intraoperative adjunct but has limited negative predictive value. A 10-minute sample interpreted as a > 50% decline from the lower pre-excision value maximised diagnostic performance within this cohort, supporting a rule-in role for confirming adequacy of excision while cautioning against reliance on a negative POC result alone.