Substrate-dependent Differences of Colonic Hydrogen Production in a Patient With Fructose Malabsorption

Hydrogen (H 2 )/methane (CH 4 ) breath testing (HMBT) is the most widely utilized diagnostic modality for the diagnosis of many common gastrointestinal conditions including small intestinal bacterial overgrowth (SIBO), intestinal methanogen overgrowth (IMO), irritable bowel syndrome-like symptoms, and carbohydrate malabsorption. [1][2]2][3] Often, in interpreting the lactulose HMBT, the term "hydrogen nonproducer" is used for a H 2 breath profile that is "flatline". 4,5Here we report on a patient with abnormal fructose HMBT results that failed to produce H 2 upon lactulose, glucose, lactose, and sorbitol HMBT.