title: Utility of intraoperative parathyroid hormone monitoring in patients with multiple endocrine neoplasia type 1-associated primary hyperparathyroidism undergoing initial parathyroidectomy.
abstract: BACKGROUND
  Intraoperative parathyroid hormone monitoring (IOPTH) is a widely used adjunct for primary hyperparathyroidism (pHPT). However, the benefit of IOPTH in familial pHPT, such as in multiple endocrine neoplasia type I (MEN1), remains unclear.
  
  
  METHODS
  We performed a retrospective analysis of 52 patients with MEN1-associated pHPT undergoing initial parathyroidectomy with IOPTH monitoring at our institution. Parathyroid hormone (PTH) levels were measured before skin incision and 10 min after resection of the last parathyroid gland. Variables analyzed included percent drop of PTH from baseline and the final PTH level compared to the normal reference range (RR).
  
  
  RESULTS
  A total of 52 patients underwent initial subtotal parathyroidectomy with IOPTH. An IOPTH decrease cutoff of ≥75 % from baseline had the highest biochemical cure rate (87 %). In the remaining 13 % who met this cutoff, all had persistent pHPT, with ≥90 % drop of PTH from baseline. The remaining patients, who did not meet the ≥75 % cutoff, were cured. Follow-up was available for three of four patients with final IOPTH levels above the RR: one had persistent pHPT, two had hypoparathyroidism (50 %). When a postresection PTH level was within the RR, 88 % of patients were cured. While considered cured from pHPT, 7 % of patients in this group developed permanent hypoparathyroidism. When the final PTH level dropped below the RR, 28 % developed permanent hypoparathyroidism.
  
  
  CONCLUSIONS
  A cutoff in IOPTH decrease of ≥75 % from baseline has the highest biochemically cure rate in patients with pHPT associated with MEN1. However, a 75 % cutoff in IOPTH decrease does not exclude persistent pHPT. The absolute IOPTH value does not accurately predict postoperative hypoparathyroidism.
authors.affiliation: Endocrine Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 10 Center Drive, MSC1201 Room 3-3940, Bethesda, MD 20892-1201, USA. niluboln@mail.nih.gov
authors.forename: Naris
authors.initials: N
authors.lastname: Nilubol
authors.forename: Allison B
authors.initials: AB
authors.lastname: Weisbrod
authors.forename: Lee S
authors.initials: LS
authors.lastname: Weinstein
authors.forename: William F
authors.initials: WF
authors.lastname: Simonds
authors.forename: Robert T
authors.initials: RT
authors.lastname: Jensen
authors.forename: Giao Q
authors.initials: GQ
authors.lastname: Phan
authors.forename: Marybeth S
authors.initials: MS
authors.lastname: Hughes
authors.forename: Steven K
authors.initials: SK
authors.lastname: Libutti
authors.forename: Stephen
authors.initials: S
authors.lastname: Marx
authors.forename: Electron
authors.initials: E
authors.lastname: Kebebew
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D049950:Hyperparathyroidism, Primary / Q000097:blood* / Q000209:etiology*; D007011:Hypoparathyroidism / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D018761:Multiple Endocrine Neoplasia Type 1 / Q000150:complications*; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy; D011183:Postoperative Complications / Q000175:diagnosis; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone