title: Evaluation of gastric acid secretion at endoscopy with a modified Congo red test.
abstract: BACKGROUND
  Markedly decreased or absent gastric acid production is associated with a number of clinically significant conditions, and identification of patients with hypo/achlorhydria may be important. However, current methods of assessing impaired acid secretion are unreliable, time-consuming, and/or complex. The aim of this prospective study was to evaluate a modified endoscopic Congo red test for the diagnosis of hypo/achlorhydria by correlation with a standard gastric acid secretory test.
  
  
  METHODS
  One hundred six consecutive outpatients with or without dyspeptic symptoms referred for endoscopy were evaluated by using a modified endoscopic Congo red test and a standard test of gastric acid secretion. The modified endoscopic Congo red test suggested hypo/achlorhydria when there was no color shift or a shift of small extent (less than one third of fundic mucosa). Hypo/achlorhydria by the standard gastric acid secretory test was defined as a maximal acid output of less than 6.9 mmol/hour in men and 5.0 mmol/hour in women.
  
  
  RESULTS
  The accuracy of the modified endoscopic Congo red test for the diagnosis of hypo/achlorhydria was 0.98 (95% CI [0.93, 0.99]). The sensitivity was 1.0 (95% CI [0.92, 1.00]) and specificity 0.96 (95% CI [0.88, 0.99]). All patients tolerated the modified endoscopic Congo red test well.
  
  
  CONCLUSIONS
  The modified endoscopic Congo red is an accurate, simple, fast, inexpensive, and well-tolerated chromoendoscopic method for identification of patients with hypo/achlorhydria during routine upper endoscopy.
authors.affiliation: Department of Radiology, University Hospitals of Malmö and Lund, Lund University, Malmö, Sweden.
authors.forename: Ervin
authors.initials: E
authors.lastname: Tóth
authors.forename: Kristina
authors.initials: K
authors.lastname: Sjölund
authors.forename: Ola
authors.initials: O
authors.lastname: Thorsson
authors.forename: Henrik
authors.initials: H
authors.lastname: Thorlacius
mesh_terms: D000126:Achlorhydria / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D003224:Congo Red; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005773:Gastroscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003224:Congo Red