The D-xylose tolerance tests measure the intestines' ability to absorb D-xylose, a simple sugar, as an indicator of whether nutrients are being properly absorbed.
Review Date 2/7/2022
Updated by: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.