title: Characterizing the operative findings and utility of intraoperative parathyroid hormone (IOPTH) monitoring in patients with normal baseline IOPTH and normohormonal primary hyperparathyroidism.
abstract: During parathyroidectomy with intraoperative parathyroid hormone monitoring, the successful removal of a hypersecreting gland(s) resulting in normocalcemia is indicated by a >50% decrease in intraoperative parathyroid hormone level, typically into the normal range. Some patients, however, will have baseline parathyroid hormone levels within the normal range. We sought to determine the utility of intraoperative parathyroid hormone testing in these patients.
  
  
  
  We retrospectively studied all patients who underwent parathyroidectomy for primary hyperparathyroidism at our institution over a 10-year period.
  
  
  
  Overall, 317 (17%) patients had parathyroid hormone within the normal range at the onset of operation (baseline intraoperative parathyroid hormone), and 1,544 (83%) had classic primary hyperparathyroidism. The intraoperative parathyroid hormone degradation was slower in normal baseline intraoperative parathyroid hormone patients than classic primary hyperparathyroidism patients, though this did not reach statistical significance (P < .254). A >50% intraoperative parathyroid hormone decrease predicted cure in 98.7% of normal baseline patients and 98.8% of classic primary hyperparathyroidism patients (P = .810). Normal baseline patients had a lesser cure rate the longer it took to achieve a 50% decrease intraoperatively; however, the cure rate was constant at any time point the 50% decrease occurred in patients with classic primary hyperparathyroidism (P < .05).
  
  
  
  The 50% rule delineating operative cure can be applied with equal confidence to patients with normal range, baseline intraoperative parathyroid hormone. Moreover, the time at which the 50% drop is achieved impacts operative success rates in these patients.
authors.affiliation: Queen's University School of Medicine, Kingston, Ontario, Canada.
authors.forename: Gina
authors.initials: G
authors.lastname: Trinh
authors.affiliation: Department of Surgery, The George Washington University School of Medicine and Health Sciences, Washington, DC.
authors.forename: Salem I
authors.initials: SI
authors.lastname: Noureldine
authors.affiliation: Division of Head and Neck Endocrine Surgery, Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Jonathon O
authors.initials: JO
authors.lastname: Russell
authors.affiliation: Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Chicago, Chicago, IL.
authors.forename: Nishant
authors.initials: N
authors.lastname: Agrawal
authors.affiliation: Department of Surgery, The George Washington University School of Medicine and Health Sciences, Washington, DC.
authors.forename: Michael
authors.initials: M
authors.lastname: Lopez
authors.affiliation: Endocrine Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Prescott
authors.affiliation: Endocrine Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Martha A
authors.initials: MA
authors.lastname: Zeiger
authors.affiliation: Department of Surgery, The George Washington University School of Medicine and Health Sciences, Washington, DC. Electronic address: rtufano1@jhmi.edu.
authors.forename: Ralph P
authors.initials: RP
authors.lastname: Tufano
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000706:statistics & numerical data*; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy / Q000379:methods; D012008:Recurrence; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D010281:Parathyroid Hormone