title: Detection of malabsorption of low doses of carbohydrate: accuracy of various breath H2 criteria.
abstract: BACKGROUND
  Although the accuracy of breath H2 testing to detect malabsorption of small (< 50 g) doses of carbohydrate has never been evaluated, studies suggest that its accuracy is limited by a high prevalence of "H2 nonproducers." The aim of this study was to determine the accuracy of H2 breath testing in the detection of malabsorption of 10 g of carbohydrate.
  
  
  METHODS
  In 55 healthy subjects, we determined the ability of breath H2 measurements to distinguish between the ingestion of 10 g of a nonabsorbable carbohydrate (lactulose) and two control meals, a nonabsorbable electrolyte solution or glucose (10 g).
  
  
  RESULTS
  The conventional criterion of a 20 ppm increase in breath H2 had 100% specificity but failed to identify lactulose malabsorption in 47% and 24% of subjects at 4 and 8 hours of testing. In contrast, a breath H2 of > 6 ppm at 5 or 6 hours had near perfect specificity and sensitivity. A sum of breath H2 at 5, 6, and 7 hours of > 15 ppm yielded perfect separation between lactulose and control solutions.
  
  
  CONCLUSIONS
  True "H2 nonproducers" are extremely rare. Using appropriate criteria, breath H2 testing provides a very accurate means of identifying malabsorption of low doses of carbohydrate.
authors.affiliation: University of Bologna, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Strocchi
authors.forename: G
authors.initials: G
authors.lastname: Corazza
authors.forename: C J
authors.initials: CJ
authors.lastname: Ellis
authors.forename: G
authors.initials: G
authors.lastname: Gasbarrini
authors.forename: M D
authors.initials: MD
authors.lastname: Levitt
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001944:Breath Tests; D050260:Carbohydrate Metabolism; D005260:Female; D006801:Humans; D006859:Hydrogen / Q000032:analysis*; D007408:Intestinal Absorption; D008286:Malabsorption Syndromes / Q000175:diagnosis*; D008297:Male; D008697:Methane / Q000378:metabolism; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: D000900:Anti-Bacterial Agents; D006859:Hydrogen; D008697:Methane