title: Automated spectrophotometric bicarbonate analysis in duodenal juice compared to the back titration method.
abstract: OBJECTIVE
  We have recently evaluated a short endoscopic secretin test for exocrine pancreatic function. Bicarbonate concentration in duodenal juice is an important parameter in this test. Measurement of bicarbonate by back titration as the gold standard method is time consuming, expensive and technically difficult, thus a simplified method is warranted. We aimed to evaluate an automated spectrophotometric method in samples spanning the effective range of bicarbonate concentrations in duodenal juice. We also evaluated if freezing of samples before analyses would affect its results.
  
  
  METHODS
  Patients routinely examined with short endoscopic secretin test suspected to have decreased pancreatic function of various reasons were included. Bicarbonate in duodenal juice was quantified by back titration and automatic spectrophotometry. Both fresh and thawed samples were analysed spectrophotometrically.
  
  
  RESULTS
  177 samples from 71 patients were analysed. Correlation coefficient of all measurements was r = 0.98 (p < 0.001). Correlation coefficient of fresh versus frozen samples conducted with automatic spectrophotometry (n = 25): r = 0.96 (p < 0.001) CONCLUSIONS: The measurement of bicarbonate in fresh and thawed samples by automatic spectrophotometrical analysis correlates excellent with the back titration gold standard. This is a major simplification of direct pancreas function testing, and allows a wider distribution of bicarbonate testing in duodenal juice. Extreme values for Bicarbonate concentration achieved by the autoanalyser method have to be interpreted with caution.
authors.affiliation: Department of Medicine, Voss Hospital, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway. Electronic address: friedemann.erchinger@helse-bergen.no.
authors.forename: Friedemann
authors.initials: F
authors.lastname: Erchinger
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Engjom
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway.
authors.forename: Oddrun Anita
authors.initials: OA
authors.lastname: Gudbrandsen
authors.affiliation: Pediatric Department, Haukeland University Hospital, Bergen, Norway; Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Erling
authors.initials: E
authors.lastname: Tjora
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway; National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Odd H
authors.initials: OH
authors.lastname: Gilja
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: Georg
authors.initials: G
authors.lastname: Dimcevski
mesh_terms: D001331:Automation; D001639:Bicarbonates / Q000737:chemistry*; D006801:Humans; D010189:Pancreatic Juice / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods*; D017186:Titrimetry / Q000379:methods*
chemical_list: D001639:Bicarbonates
keywords: Bicarbonate; Pancreatic disorders; Pancreatic function test; Pancreatic juice; Secretin; Short endoscopic secretin test