The possible role of breath methane measurement in detecting carbohydrate malabsorption.

To evaluate the possibility that measurement of breath methane (CH4) enhances the accuracy of breath hydrogen (H2) testing to diagnose carbohydrate malabsorption, breath CH4 concentration of healthy subjects was studied. Fasting breath CH4 concentration measured three times over a 30-minute period in 44 CH4-producing volunteers ranged from 5 to 120 ppm. Fluctuation of breath CH4 excretion exceeded 100% increase over fasting in 1 of 9 subjects who ingested a nonabsorbable, carbohydrate-free solution. Out of 13 subjects who had a false negative breath H2 response to lactulose, 11 had a CH4 percentage increase greater than 100%. In 11 of 32 lactose-intolerant patients with a negative breath H2 test, CH4 percentage increase after lactose challenge was greater than 100%. These data suggested that in methanogenic individuals, breath CH4 measurement might enhance the accuracy of H2 breath testing in detecting carbohydrate malabsorption.