Xylose Tolerance Test Research Articles

Xylose disposition in humans as a function of age.

D-xylose disposition was examined in 24 healthy men between 32 and 85 years of age. Xylose was administered as a 5 gm iv infusion and as a 25 gm po solution. Serum xylose concentrations and urinary excretion of intact xylose were determined. There were statistically significant inverse relationships with age for each of the following parameters after intravenous infusion: elimination rate constant (r2 = 0.71); systemic clearance (r2 = 0.66); renal clearance (r2 = 0.66); and nonrenal clearance (r2 = 0.35). Similar inverse relationships were found after oral dosing for the elimination rate constant (r2 = 0.69) and renal clearance (r2 = 0.54). There was no significant age relationship for the apparent volume of distribution or the steady-state volume of distribution. The percentage of the oral and intravenous dose recovered in urine up to 5 hours after dosing was significantly and inversely correlated with age. The implications of the latter finding are discussed with regard to the interpretation of the xylose tolerance test used to assess gastrointestinal absorptive capacity.

Mechanism of D‐Xylose Transport in Human Small Intestine

Summary: The transport mechanism of D‐xylose across the mucosal border of small intestine was investigated in humans both in vitro and in vivo. A comparative study was also made between infants and adults. We investigated the Na+ dependence of D‐xylose influx from the mucosal solution into the epithelial cells, the phlorizin sensitivity of the influx, transport kinetics and electro‐genie property of the D‐xylose transport. The results of kinetic study indicated that the transport of D‐xylose was completely diffusional. The influx of D‐xylose across the mucosal border of human small intestine was Na+ independent and phlorizin insensitive. The electrical property of D‐xylose transport could not be observed. There was no difference in the characteristics of D‐xylose transport between small intestines of infants or adults. These results in the present study suggest that D‐xylose does not share a common transport mechanism of D‐glucose, and xylose tolerance test does not give any information about the absorptive capacity of D‐glucose.

Effect of Gluten-free diet on recurrent aphthous ulceration

Ferguson et al. (1976) found that eight out of thirty-three patients presenting with recurrent aphthous ulceration (R.A.U.) had jejunal mucosal features of coeliac disease; their oral ulceration remitted on a gluten-free diet. We have studied eighteen consecutive R.A.U. patients using standard haematological and biochemical parameters of malabsorption, including a xylose tolerance test. Twelve of the patients consented to a jejunal biopsy, following which they were placed on a gluten-free diet for 3 months. They maintained a daily record of the number of oral ulcers and a daily entry for the pain experienced on a visual analogue chart.

How to approach the child suspected of malabsorption. Experience from a prospective investigation of suspected malabsorption in children 1968-1976 in Malmö.

ABSTRACT. 180 children (mean age 20 months) suspected of malabsorption because of failure to thrive, abnormal stools more than 3 weeks, vomiting, an/or abdominal distension were investigated with peroral small intestinal biopsy at duodeno‐jejunal flexure (172 children) and/or duodenal intubation for analysis of trypsin and amylase activity in duodenal juice before and after a test meal of water (76 children). Results of xylose tolerance test, lactose tolerance test, faecal fat, B‐folate, S‐iron, and S‐albumin were related to morphology of mucosa. A normal finding of one of these tests means in 15–26% a normal mucosa (diagnostic sensitivity). An abnormal finding means in 40–85% a severely damaged mucosa and in 85–100% a slightly, moderately, or severely damaged mucosa (diagnostic specificity). Combinations of these tests increase the diagnostic sensitivity 10–15%. Faecal chymotrypsin seems to be a reliable screening test for exocrine pancreatic function. Border values or low values indicate a direct evaluation of exocrine pancreatic function. The simple test meal (water) method with determination of trypsin in duodenal juice gives, from a practical point of view, good information of the exocrine pancreatic function.The following plan of investigation is proposed: Step 1. careful clinical history and examination; Step 2. analysis of faeces for Giardia lamblia, entero‐pathogenic microorganisms, and chymotrypsin, sweat test; Step 3. peroral small intestinal biopsy and/or duodenal juice analysis, and finally—if steps 2 and 3 give normal results; Step 4. re‐evaluation of dietary history and tests to detect any food intolerance (e.g. carbohydrate).

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.

Limitations of xylose tolerance test as a screening procedure in childhood coeliac disease.

The usefulness of the xylose tolerance test as a screening procedure for coeliac disease has been reassessed in 54 children with suspected coeliac disease. 5- and 24-hour urinary excretion rates of xylose were of no value in discriminating between patients with and without coeliac disease; similarly, the 3-hour blood xylose concentration was nondiscriminatory. Three (15-8%) patients with subtotal villous atrophy and 8 (61-5%) with partial villous atrophy due to coeliac disease had one-hour blood xylose values which fell within the normal range. The effect of withdrawal or reintroduction of dietary gluten on sequential one-hour blood xylose levels was variable and generally unhelpful in predicting those patients who developed gluten-induced mucosal changes. The results of the present study emphasize the serious limitations of the xylose tolerance test as a screening procedure in childhood coeliac disease. It is recommended that the use of the urinary xylose test should be abandoned in the paediatric population. A normal one-hour blood xylose value does not exclude a diagnosis of coeliac disease even in young children who have never received a gluten-free diet. A clinical suspicion of coeliac disease remains the most important single factor in deciding whether to preform a jejunal biopsy.

Proceedings: Limitations of xylose tolerance test as screening procedure for coeliac disease.

Proceedings: Limitations of xylose tolerance test as screening procedure for coeliac disease.

Reliability of the xylose tolerance test as an index of intestinal absorption

Reliability of the xylose tolerance test as an index of intestinal absorption

Reliability of the xylose tolerance test as an index of intestinal absorption.

Reliability of the xylose tolerance test as an index of intestinal absorption.

The correction of defective vit. B.12 absorption due to anti-convulsant drugs by folic acid.

Defective Vit. B.12 absorption was found in six out of a total of fifteen epileptics on anti-convulsant drugs. The defect in absorption was corrected by folic acid in five patients, and by intrinsic factor in one. The defect in absorption was associated with an abnormal xylose tolerance test in only one patient, and all other investigations for gastrointestinal function were within normal limits. This suggested that the defect in absorption of B.12 was due to interference with folic acid metabolism at intestinal level, and that folic acid is probably essential in Vit. B.12 absorption.

The interpretation and significance of the xylose tolerance test in the tropics.

Abstract Xylose tolerance tests were performed in 158 Thai and 60 American subjects in Thailand. Urinary xylose excretion was normally distributed in the 2 nationalities. Five hour total urine xylose was significantly higher in the American subjects. After 8 months in Thailand, however, the American subjects excreted the same amount of xylose as the Thai subjects. The serum xylose concentration 2 hours following oral administration of the pentose sugar was significantly lower in the Americans and did not change when the test was repeated after 8 months of residence in the tropics. Studies of the reproducibility of the test showed a low coefficient of variation for the chemical determination of xylose. There was marked day-to-day variation in individuals which could not be accounted for by laboratory error. Because of this, considerable caution must be exercised in the interpretation of intermediate values for xylose excretion (3 to 5 Gm. per 5 hours) in subjects in the tropics.

Neomycin-Induced Malabsorption in a Tropical Population

Intestinal function and morphology were studied sequentially in 50 normal Thai subjects given oral neomycin. Within 6 hr of a single small dose of neomycin there was diminished absorption of d-xylose and sucrose, as determined by tolerance tests. Histological evidence of damage to intestinal epithelial cells was present as well. Macrophages accumulated in the lamina propria of the jejunum and contained inclusions which were consistent with the appearance of bacteria. All changes reverted to normal after the drug was discontinued. A similar degree of change in the xylose tolerance test was induced by a small dose of neomycin over 24 hr in both Thais and Americans. The response of the two nationalities to the antibiotic appears to be similar quantitatively as well as qualitatively. There is no evidence that the nonspecific jejunal abnormality present in tropical populations such as the Thais confers unusual sensitivity to noxious stimuli such as neomycin.

54 Congenital Pernicious Anemia with Coexistent Transitory Intestinal Malabsorption of Vitamin B12

Pernicious anemia (PA) with coexistent transitory intestinal malabsorption of vitamin B12 has been documented in adults. This report is the first description of proven transitory selective intestinal malabsorption of vitamin B12 in congenital PA. A vitamin B12 responsive anemia was demonstrated in the patient, a 2 ½-year-old girl, by change in the bone marrow from megaloblastic hyperplasia to normoblastic hyperplasia 48 h after 5 μg of vitamin B12. No intrinsic factor (IF) was found in gastric fluid by in vitro assay before and again 4 and 6 weeks after therapy. Congenital PA was established by the age of the patient, absence of IF in gastric fluid, lack of antibodies to IF and parietal cells, presence of HCl in gastric fluid, and normal gastric biopsy. The xylose tolerance test, 72 h fecal fat determination, upper GI series, and biopsy of the jejunum were normal, but the Schilling test was abnormal with hog IF of known potency on two occasions, indicating selective malabsorption of vitamin B12. Six months after therapy the Schilling test was still abnormal without IF, but was normal with both human and hog IF. This normal absorption with IF after therapy is indicative that selective malabsorption was originally present, probably as a consequence of the vitamin B12 deficiency resulting from IF lack. In patients with abnormal radioactive vitamin B12 absorption tests with administration of IF, coexistent PA must be excluded by demonstration of IF in gastric fluid. (SPR)

A CLINICAL EVALUATION OF THE D-XYLOSE TOLERANCE TEST.

Excerpt The xylose tolerance test has been the subject of much investigative work and interest. Its application to the study of the malabsorption syndrome has been described in previous publication...

Oral D-Xylose Test in Healthy Infants and Children

THE purpose of this paper is to report values for the so-called xylose tolerance test in a group of healthy infants and children at different ages. We have chosen to designate this test the oral D-xylose test, for reasons discussed below.Xylose is absorbed chiefly in the duodenum and proximal jejunum, and since it is a simple sugar, digestion is unnecessary and absorption is independent of bile, intestinal or pancreatic secretions. The primary use of this test, therefore, is in the demonstration of malabsorption states arising from lesions involving the upper small-bowel wall, such as gluteninduced enteropathy. This procedure, first . . .

Xylose tolerance test in old age

Xylose tolerance test in old age

The Xylose Tolerance Test with a Five-Gram Dose

Summary A modification of the xylose tolerance test employing a 5-gm. dose has been proposed. This dosage gives results comparable to the original test in malabsorption states but eliminates the side effects encountered with the original procedure.

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

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.

A Study of Carbohydrate and Fat Absorption from the Normal and Diseased Intestine in Man

Summary 1.Normal blood and urine xylose concentrations in man following the ingestion of 25 grams of d-xylose have been described. 2.The xylose, glucose and fructose tolerance tests have been compared by their coefficient of variation and of the three the xylose tolerance test has been shown to be the most reproducible test of absorption. 3.The urinary excretion of d-xylose and its application as a test of kidney function should be considered further. 4.The possible phosphorylation of d-xylose during absorption and its subsequent metabolism in the body has been suggested and discussed.