[Methodological aspects of the use of the hydrogen (H2) breath test]

Normalization of the breath hydrogen (H2) concentration by simultaneous determination of breath carbon dioxide (CO2) and the addition of lactulose to a liquid meal have been recommended to improve the reproducibility of the hydrogen breath test. To assess the clinical relevance of these recommendations, we studied 64 children of 4 different age groups and 12 adults. Simultaneous determination of CO2 concentration and normalization of breath H2 resulted in a marked decrease of intestinal transit time and its variation in children; in adults, however, this correction was negligible. With lactulose alone, the mean coefficient of variation within individuals was only 11.7% and 13.2%, with and without H2 normalization, respectively. Therefore, the addition of a liquid meal does not seem to be necessary.