title: Kinetic analysis of the rapid intraoperative parathyroid hormone assay in patients during operation for hyperparathyroidism.
abstract: BACKGROUND
  Rapid intraoperative parathyroid hormone (RI-PTH) assay is used to guide adequacy of resection during operation for hyperparathyroidism. We compared the RI-PTH assay (15 minutes) with a standard PTH assay, determined whether the PTH half-life varied between patients, and constructed a kinetic analysis of the RI-PTH data.
  
  
  METHODS
  Forty-five patients with hyperparathyroidism had blood sampled at baseline and at times after parathyroid resection. Intact PTH was determined using RI-PTH and a standard assay. Values were fitted to an exponential decay curve using the baseline and the follow-up time points. PTH half-life and the new postexcision baseline value were calculated from the decay curve.
  
  
  RESULTS
  The RI-PTH assay and the standard PTH assay correlated well. Average PTH half-life was 1.68 +/- 0.94 minutes (0.42 to 3.81 minutes). A kinetic analysis yielded a formula for the generation of a PTH decay curve. Using a 50% reduction in RI-PTH at 5 minutes as the criterion for adequate resection, 2 patients were incorrectly classified as not being cured. These patients were correctly classified using the kinetic analysis.
  
  
  CONCLUSIONS
  PTH half-life can vary substantially. A kinetic analysis may be more accurate in assessing adequacy of resection. This method allows the surgeon to interpret RI-PTH data independent of the timing of samples.
authors.affiliation: National Institutes of Health, Bethesda, Md. 20892, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Libutti
authors.forename: H R
authors.initials: HR
authors.lastname: Alexander
authors.forename: D L
authors.initials: DL
authors.lastname: Bartlett
authors.forename: M L
authors.initials: ML
authors.lastname: Sampson
authors.forename: M E
authors.initials: ME
authors.lastname: Ruddel
authors.forename: M
authors.initials: M
authors.lastname: Skarulis
authors.forename: S J
authors.initials: SJ
authors.lastname: Marx
authors.forename: A M
authors.initials: AM
authors.lastname: Spiegel
authors.forename: W
authors.initials: W
authors.lastname: Simmonds
authors.forename: A T
authors.initials: AT
authors.lastname: Remaley
mesh_terms: D000328:Adult; D000465:Algorithms; D002624:Chemistry, Clinical / Q000379:methods / Q000592:standards; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood* / Q000601:surgery*; D007118:Immunoassay; D007432:Intraoperative Period; D007700:Kinetics; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy; D012016:Reference Values; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone