Modification of the breath hydrogen test: increased sensitivity for the detection of carbohydrate malabsorption.

The pulmonary excretion of hydrogen after a carbohydrate meal has been used to diagnose carbohydrate malabsorption in the small intestine In this study, the protocol for performing breath tests has been modified by the addition of a prolonged carbohydrate-free preparation (greater than 15 hr) and the administration of the test sugar in a defined formula containing protein and fat. The carbohydrate-free preparation significantly decreased baseline H2 excretion, implying that elevations in baseline H2 concentrations are related to carbohydrate malabsorption occurring on the night preceding the breath test. The excretion of H2 after carbohydrate meals was prolonged (greater than 8 hr), with the majority of H2 excreted more than 4 hr after the meal. The time course of H2 excretion was similar in all subjects tested and was independent of the dose and type of sugar used. When H2 excretion between 4 and 7 hr after the meal was analyzed, all subjects taking at least 3 gm of lactulose excreted significant H2 as compared to those taking carbohydrate-free meals. The addition of 10 gm of lactulose to the standard preparation on the night preceding a breath test caused a leftward shift in the time curve of H2 excretion after a subsequent 10 gm lactulose meal, indicating earlier H2 production in the colon. These results imply that breath testing can be used to determine the capacity for intestinal sugar absorption in humans and demonstrate that prior sugar malabsorption may affect the breath H2 response to a meal.