Detection of malabsorption of low doses of carbohydrate: accuracy of various breath H2 criteria

Gastroenterology. 1993 Nov;105(5):1404-10. doi: 10.1016/0016-5085(93)90145-3.


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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Anti-Bacterial Agents / pharmacology
  • Breath Tests*
  • Carbohydrate Metabolism*
  • Female
  • Humans
  • Hydrogen / analysis*
  • Intestinal Absorption
  • Malabsorption Syndromes / diagnosis*
  • Male
  • Methane / metabolism
  • Middle Aged
  • Sensitivity and Specificity


  • Anti-Bacterial Agents
  • Hydrogen
  • Methane