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).
