Xylose Absorption Test (Child)
Ordering Recommendation

Nonstandard test for determining cause of malabsorption. Test evaluates carbohydrate absorption of the proximal small intestine.

Quantitative Spectrophotometry
Tue, Thu
1-5 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Children are defined as less than 17 years old for purposes of this test. Patient should fast for 8 hours (Min: 4 hours) prior to administration of xylose. 
Fasting serum, five-hour urine, and one-hour serum according to the following instructions. 
Specimen Preparation
1. Just prior xylose administration, patient should empty his or her bladder (DO NOT collect this urine).
2. Just prior to xylose administration, collect first serum specimen (Min: 0.5 mL). Allow serum to clot completely at room temperature. Separate serum from cells ASAP or within 2 hours of collection. Label this specimen as "FASTING SERUM" and prepare for transport.
3. Give children 0.5 g D-xylose per kilogram of body weight, up to 25 g; give xylose in water (5 mL of water per 0.5 g of xylose, up to 250 mL water). Encourage the patient to drink additional water following the xylose dose. The patient may have water as desired, but no other food or fluids. The patient should rest in a chair or on a bed until completion of test. Mild diarrhea is common following xylose ingestion.
4. Immediately following the xylose dose, collect all urine for the next five hours. Measure and record the volume, mix well, and remove a 5 mL aliquot (Min: 3 mL) and prepare for transport. Label this specimen as "FIVE-HOUR URINE." Record the total volume and the xylose dose given on the urine aliquot tube.
5. One hour after administration of xylose dose, collect the second serum specimen (Min: 0.5 mL). Allow serum to clot completely at room temperature. Separate serum from cells ASAP or within 2 hours of collection. Label this specimen as "ONE-HOUR SERUM" and prepare for transport.
6. Record the xylose dose given and the total volume of the five-hour urine on the test request form.
-If unable to collect pediatric urine samples, testing will be completed with a disclaimer, provided both serum specimens are received.
-Failure to include all required information will result in delay of turnaround time.
Storage/Transport Temperature
Unacceptable Conditions
Non-fasting specimens. Whole blood or unspun clot tubes. Grossly hemolyzed serum. 
The fasting serum specimen does not have a reference interval since it is used as a blank for the two-hour serum sample. 
Ambient: 4 hours; Refrigerated: 1 week; Frozen: 1 month 
Reference Interval
Reference Interval
Serum, fasting specimen
(There are no reference intervals for the fasting specimen; it is used as a patient "blank" when testing the one-hour specimen.)
0-16 years: None
Serum xylose, one hour following ingestion0-5 months: 15-58 mg/dL
6 months-16 years: 20-58 mg/dL
Fraction of xylose dose excreted in five hours in urine0-16 years: 16-40% of dose
Amount of xylose excreted in five hours in urine0-16 years: depends on dose given

Interpretive Data

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.
CPT Code(s)
Component Test Code*Component Chart NameLOINC
0020085Serum Xylose 60 Minutes10453-9
0020088Xylose Excretion % Dose 5 hr22630-8
0020600Xylose Excretion, g/5hr22626-6
0097110Total Volume19153-6
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • D-xylose
  • Dxylose
  • Xylose
  • Xylose Child
  • Xylose Tolerance Test