The Xylose Tolerance Test as a Measure of the Intestinal Absorption of Carbohydrate in Sprue

Abstract

The studies reported in this paper concern adults with the sprue syndrome, but the technique should be considered for application in the study of children with the celiac syndrome. The glucose tolerance test has well-known limitations for the study of absorption of carbohydrate from the intestine. Xylose, a pentose sugar, has been proposed as an alternative substance for use in a test of intestinal absorption of carbohydrate. Xylose is not normally found in the blood or in the urine and is thought not to undergo transformation or metabolism during passage through the liver. In the experimental animal it is absorbed from the gut at a rate equal to that of glucose. The test is performed by the administration of an oral dose of xylose and estimation of the concentration of xylose in the blood at intervals subsequently. At the same time the amount of xylose excreted in the urine is measured. Reproducible results are obtained in normal subjects and those suffering from steatorrhea and other gastrointestinal disorders. Individuals with untreated idiopathic sprue reveal low levels of xylose in the blood after the oral dose and a decreased excretion of xylose in the urine as compared to normal individuals. These values are restored to normal during successful treatment of the malabsorption. The present study reports data on 25 normal individuals and 33 patients having steatorrhea of various types. Observations were made during therapy of patients with steatorrhea with cortisone and with a gluten-free diet. Interesting observations concerning discrepancies between the results in the xylose tolerance test and evidence of steatorrhea are presented.