What is the cellobiose-mannitol test and how does it related to the diagnosis of celiac disease?
The test measures the permeability of the small intestine mucosa to different size molecules (cellobiose, large; mannitol, small). In untreated celiac disease, the mocosa is more permeable to large polar molecules and less permeable to small polar molecules. The two molecules are given simultaneously. They are absorbed intact, not metabolized and excreted in the urine (5-hour collections). The relation of cellobiose-mannitol to urine excretion is increased in celiac disease (as well as in regional enteritus) relative to patients with normal small bowel. The test is considered to be more sensitive and more specific than the D-xylose absorption test. Q: What is the D-xylose test and what contribution does it make to the diagnostic evaluation for celiac disease when it is used? A: D-xylose is an aidopentose (5-carbon sugar) which is not normally present in the diet. Approximately 50% are absorbed intact from the upper small intestine. It is poorly metabolized and approximately 50% of the
