Evaluate mucosal absorption efficiency in a variety of malabsorptive diseases. May be used for diagnosing cause of malabsorption.
Age and dose specific reference ranges provided with report.
The xylose absorption test evaluates carbohydrate absorption by the mucosa of the proximal small intestine. In patients with renal deficiency, rely on the serum test only. In functionally anephric patients, the test is unreliable. A number of drugs can interfere with test results, including aspirin, atropine, colchicine, digitalis, indomethacin, MAO inhibitors, nalidixic acid, neomycin, opium alkaloids, and phenelzine. Nonfasting serum samples are often compromised by significant analytic interferences.
Days Test Performed
3 - 10 days
Soft Order Code
d-Xylose Absorption Test
Xylose Tolerance Test
Mayo FXAB (91713) (ARUP 0020609 Adult 25 g dose), Mayo 91712 (ARUP 0020615 Adult 5 g dose), or Mayo FXAT (91711) (ARUP 0020612 Child)
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Offsite Collection Instructions
MLabs does not provide d-xylose; client or physician will need to obtain d-xylose from a local pharmacy. 1) Patient should fast for 8 hours (minimum 4 hours) prior to administration of d-xylose. 2) Prior to administration of d-xylose, have patient empty bladder and discard urine. Collect a blood specimen in a red top tube from the fasting patient. 3) Dissolve 25 grams of d-xylose in 250 mL of water and administer, and follow immediately with an additional 250 mL of water. For patients who do not tolerate the 25 g dose, a 5 g dose can be used. For children aged
0.5 mL serum (pre- and post-dose) and 5 mL aliquot of 5 hour urine collection
0.5 mL serum (pre- and post-dose) and 3 mL aliquot of 5 hour urine collection
Test sent to Mayo Medical Laboratories; performed by ARUP Laboratories.