title: Processing-independent analysis in the diagnosis of gastrinomas.
abstract: BACKGROUND
  This study evaluates whether a new analytic principle, processing-independent analysis (PIA), offers better specificity and sensitivity than the conventional gastrin radioimmunoassay in the diagnosis of gastrinomas.
  
  
  METHODS
  Plasma concentrations of alpha-amidated gastrins and the total progastrin product were measured with radioimmunoassay and with PIA, respectively, in 512 samples taken for gastrin measurement and in a selected group of gastrinoma patients (n=10).
  
  
  RESULTS
  Among the 512 patients were 9 with gastrinomas. In plasma from these patients the median degree of amidation (ratio of alpha-amidated gastrins to total progastrin product) was 75% (range, 25-98%), whereas in the other groups the medians varied from 41% to 86%. In the second group of gastrinoma patients all had a degree of amidation of less than 50%.
  
  
  CONCLUSIONS
  In screening for gastrinomas PIA offered no diagnostic advantages in comparison with conventional gastrin radioimmunoassay. However, in selected patients who in spite of normal or slightly increased concentrations of amidated gastrins were still suspected of having gastrinoma, additional measurement of the total progastrin product showed incomplete processing of progastrin and thus proved helpful in establishing the diagnosis.
authors.affiliation: University Dept. of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.
authors.forename: N R
authors.initials: NR
authors.lastname: Jørgensen
authors.forename: J F
authors.initials: JF
authors.lastname: Rehfeld
authors.forename: L
authors.initials: L
authors.lastname: Bardram
authors.forename: L
authors.initials: L
authors.lastname: Hilsted
mesh_terms: D000897:Anti-Ulcer Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D005260:Female; D015408:Gastrinoma / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D005755:Gastrins / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology; D010437:Peptic Ulcer / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy; D011498:Protein Precursors / Q000097:blood; D011863:Radioimmunoassay; D012680:Sensitivity and Specificity; D015043:Zollinger-Ellison Syndrome / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D000897:Anti-Ulcer Agents; D005755:Gastrins; D011498:Protein Precursors; C013706:big gastrin