The use of breath tests in the study of malabsorption.

Breath analysis has evolved into a technique that can support nicely the evaluation of patients with diarrhoea and/or weight loss and in whom nutrient malabsorption is a possibility. The lactose and sucrose breath hydrogen tests offer direct (and probably the most sensitive) documentation of the malabsorption of carbohydrate and are currently widely used for clinical analysis. The 14C-xylose breath test is the most sensitive and specific breath test for detecting bacterial overgrowth; it may be used in combination with the labelled bile acid breath test to make the latter a sensitive and specific test for ileal malabsorption of bile salts. The labelled fat breath test has promise in aiding the detection and/or cause of fat malabsorption, but requires modification for optimum sensitivity and utility in quantifying the level of fat absorption.