Xylose Absorption Test (Adult - 5g dose)
0020615
 
Ordering Recommendation
Mnemonic
XYL-5G
Methodology
Quantitative Spectrophotometry
Performed
Tue, Thu
Reported
1-5 days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Patient should fast for 8 hours (Min: 4 hours) prior to administration of xylose.  
Collect
Fasting serum, five-hour urine, and two-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 adults 5 g D-xylose in 250 mL water. Encourage the patient to drink an additional 250 mL water following the xylose dose. The patient may have water as desired, but no other food or fluids. Smoking should be prohibited. 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. Two hours 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 "TWO-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.
Failure to include all required information will result in delay of turnaround time.
 
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
Non-fasting specimens. Whole blood or unspun clot tubes. Grossly hemolyzed serum.  
Remarks
The fasting serum specimen does not have a reference interval since it is used as a blank for the two-hour serum sample.
For children, refer to Xylose Absorption Test (Child) (ARUP test code 0020612).  
Stability
Ambient: 4 hours; Refrigerated: 1 week; Frozen: 1 month  
Reference Interval
Components Reference Interval
Serum, fasting specimen
(There are no reference intervals for the fasting serum specimen; it is used as a patient "blank" when testing the two-​hour specimen.)
17 years and older: None
Serum xylose, two hours following ingestion 17 years and older: 5-​17 mg/dL
Fraction of xylose dose excreted in five hours in urine 17 years and older: 20-​40% of dose
Amount of xylose dose excreted in five hours in urine 17 years and older: 1.2-​2.0 g/5 hours
Interpretive Data
Note
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.

The xylose absorption test can be performed using a 25 g dose of xylose. Refer to Xylose Absortion Test (Adult-25 g dose) (0020609) or a 5 g dose, refer to Xylose Absortion Test (Adult -5 g) (0020615) as described here. The 5 g dose is generally preferred in patients who do not tolerate the 25 g dose.
CPT Code(s)
84620
Components
Component Test Code*Component Chart Name
0020616Serum Xylose at 2 Hours
0020617Xylose Excretion, g/5 hrs
0020618Xylose Excretion, % Dose 5 hr
0097109Dosage
0097110Total Volume
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, contact interface support at interface.support@aruplab.com.
Cross References
  • D-xylose
  • Xylos
  • Xylose Tolerance Test