Assessment of small bowel function in the elderly using a modified xylose tolerance test.

Using the combined results of oral and intravenous xylose tests, it is demonstrated that 26 percent of a group of geriatric patients absorb from the small bowel less efficiently than younger subjects. The method used excludes poor renal function and incomplete bladder emptying as possible causes for the differences found between the two age groups. Altered gastric emptying is also excluded as a possible factor.