title: What is the most appropriate intraoperative baseline parathormone? A prospective cohort study.
abstract: BACKGROUND
  The time of drawing pre-incision intraoperative parathyroid hormone (ioPTH) is crucial to provide the right baseline for post-excision PTH measurement. The objective of this study was to identify the optimal time and the numbers of baseline PTH samples that best predict excision of all hypercellular parathyroid tissue when compared with 10-min post-excision PTH level.
  
  
  METHODS
  In this prospective study, two pre-incision (pre-induction and 10-min post-induction) baseline ioPTH samples along with pre- and post-excision ioPTH were collected and analyzed for 352 parathyroidectomies in 341 patients for sporadic primary hyperparathyroidism at a University hospital. Paired Wilcoxan signed rank test was used to compare the pre-incision ioPTH levels and their percent drop to 10-min post-excision levels. Sensitivity, specificity, predictive values and receiver operating characteristic (ROC) curves were used to compare the predictability of the two pre-incision levels.
  
  
  RESULTS
  The difference between pre- and post-induction baseline PTH levels was highly significant (p < 0.001). In 4% cases the criterion of post-excision PTH drop of ≥50% was achieved only with the post-induction baseline PTH and not with pre-induction PTH measurement. Using pre-induction baseline, ioPTH had an overall accuracy of 90% whereas ≥50% fall in the post-excision PTH from the post-induction baseline PTH had the accuracy of 94.85%.
  
  
  CONCLUSIONS
  There was a significant difference between pre- and post-induction PTH levels and Miami criteria was met in 95.45% cases with post-induction baseline.
  
  
  CONCLUSIONS
  The optimal time for drawing pre-incision baseline PTH sample is at 10 min post-induction of general anesthesia and positioning of patient.
authors.affiliation: Head and Neck Surgical Oncology, Cancer Care Manitoba, Winnipeg, Canada.
authors.forename: Lauren
authors.initials: L
authors.lastname: Garbutt
authors.affiliation: Head and Neck Surgical Oncology, Cancer Care Manitoba, Winnipeg, Canada.
authors.forename: Heather
authors.initials: H
authors.lastname: Sigvaldason
authors.affiliation: Head and Neck Surgical Oncology, Cancer Care Manitoba, Winnipeg, Canada.
authors.forename: Mohammed H T
authors.initials: MH
authors.lastname: Sharaf Eldin
authors.affiliation: Clinical Biochemistry, St. Boniface General Hospital, Winnipeg, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Dembinski
authors.affiliation: Head and Neck Surgical Oncology, Cancer Care Manitoba, Winnipeg, Canada.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Nason
authors.affiliation: Head and Neck Surgical Oncology, Cancer Care Manitoba, Winnipeg, Canada. Electronic address: apathak@cancercare.mb.ca.
authors.forename: Kumar Alok
authors.initials: KA
authors.lastname: Pathak
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone
keywords: Hypercalcemia; Hyperparathyroidism; Parathyrin; Parathyroid adenoma