Use of the one-hour blood xylose test as an indicator of small bowel mucosal disease.

The one-hour blood xylose concentration was evaluated to determine its usefulness as a screening test for small bowel mucosal disease in infants and children. Six of 13 patients with one-hour blood xylose levels of less than 20 mg/dl had normal small bowel biopsies by light microscopy. Five of 20 children with normal one-hour xylose levels had abnormal small bowel villous architecture. Because of the significant false positive (46%) and false negative results (25%), the one-hour blood xylose concentration should not be used as the sole indicator for small bowel biopsy in infants and children with chronic diarrhea.