Carbohydrate malabsorption in infants with diarrhea: diagnostic and evolutive aspects

Twenty three infants with acute or protracted diarrhea were investigated for carbohydrate (CHO) malabsorption during their normal feeding schedules. All infants were fed a chicken-meat formula which contained rice flour and maltodextrin. End-tidal respiratory H2 concentrations were sequentially evaluated in different clinical settings and compared to fecal pH and reducing substances. Fecal pH below 6.0 and/or breath H2 greater than 25 ppm were considered evidence of CHO malabsorption, as these values disappeared while infants were submitted to a trial of CHO withdrawal per os, reappearing after CHO reintroduction. Values of fecal pH greater than 6.0 most often (84,2%) occurred along with H2 less than 25 ppm, thus frequently reflecting a good CHO absorption. pH values below 6.0, however, although reflecting CHO malabsorption, did not predict the presence of significant H2 concentrations in expired air. In 44.4% of the well-nourished or only mildly malnourished infants some evidence of CHO malabsorption was present, whereas this occurred in all severely malnourished infants. This last group of infants had a longer history of diarrhea prior to admission and needed a longer hospitalization. The frequency of H2 values greater than 25 ppm decreased progressively during the clinical evolution, along with an increase in CHO ingestion, findings possibly related to nutritional improvement. The hydrogen breath test and fecal pH allowed the diagnosis of CHO fermentation when applied as in this study, without a conventional CHO overload and without previous fasting. It did, however, not predict clinical intolerance, as signs of CHO malabsorption still occurred in infants whose diarrhea had already subsided.