D -xylose absorption test
D-xylose absorption test,
a blood or urine test whose results reflect intestinal absorption, of the monosaccharide D-xylose, which is not metabolized by the body. In patients with malabsorption, intestinal D-xylose absorption is diminished, and as a result, blood levels and urine excretion are reduced. The test is used to separate patients with diarrhea caused by maldigestion (pancreatic/biliary dysfunction) from those with diarrhea caused by malabsorption (sprue, Whipple's disease, Crohn's disease).