title: Intraoperative parathyroid hormone analysis: A study of 200 consecutive cases.
abstract: BACKGROUND
  Immunoassays for parathyroid hormone (PTH), with short incubation times and results available in <15 min, have allowed intraoperative monitoring of the success of parathyroid surgery. The purpose of this study was to evaluate the analytical performance of a rapid PTH assay and its clinical performance in a series of 200 patients.
  
  
  METHODS
  PTH was measured with a modified immunochemiluminometric assay with a 7-min incubation time (QuiCk-IntraOperative(TM) Intact PTH assay). The rapid assay was compared with results in a central laboratory (immunoradiometric assay) in 44 EDTA-plasma specimens. The rapid assay was used intraoperatively in 200 consecutive cases with specimens analyzed before and 5-10 min after resection of the hypersecreting parathyroid gland(s).
  
  
  RESULTS
  Intraassay imprecision was 12% at 28 ng/L and 11% at 278 ng/L. Regression analysis of results of the rapid PTH assay and the IRMA PTH assay in 44 parathyroidectomy patients yielded y = 1.26x - 12 ng/L, S:(y|x) = 26.3 ng/L, r = 0.984, and in 40 of 44 patients with values <200 ng/L, y = 1.02x + 1.9, S:(y|x) = 13.9, r = 0.947. In the 195 cases using intraoperative PTH testing with complete results and defined clinical outcomes, the overall accuracy of the assay in predicting surgical success was 88% using the criterion of a 50% decrease at 5-10 min and 97% including the subset of patients with delayed decreases of PTH.
  
  
  CONCLUSIONS
  The rapid PTH assay had excellent analytical performance and excellent agreement with the PTH immunoradiometric assay and predicted the success of parathyroid surgery in this large series of consecutive patients.
authors.affiliation: Departments of Pathology and Surgery, Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA. lsokoll@jhmi.edu
authors.forename: L J
authors.initials: LJ
authors.lastname: Sokoll
authors.forename: H
authors.initials: H
authors.lastname: Drew
authors.forename: R
authors.initials: R
authors.lastname: Udelsman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D007118:Immunoassay; D007432:Intraoperative Period; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy; D012044:Regression Analysis
chemical_list: D010281:Parathyroid Hormone