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d-Xylose Absorption Test, Urine [941X]

Test Code


CPT Code(s)


Preferred Specimen(s)

5 mL of a 5 hour urine submitted in a fluoride oxalate (gray-top) tube

Minimum Volume

1 mL

Collection Instructions

1.) At the start of the test, have the patient empty the bladder completely and discard the urine. Some physicians recommend checking a fasting urine and/or a blood sample for non-specific interferences. If requested, retain an aliquot of the urine and collect a blood specimen at this time.
2.) Give 25 grams of D(+)-xylose (or 5 grams if so specified by the physician) dissolved in 250 mL water followed immediately by an additional 250 mL water to ensure a urine flow of at least 60 mL/hour. For children, give 0.5 g xylose/kg of body weight up to 25 g, reducing the amount of water accordingly.
3.) Collect all urine specimens voided during the next 5-hour period, including the final 5-hour void in the same container. Keep container refrigerated during collection.
4.) Mix total urine collection thoroughly, measure total volume and aliquot. Aliquot urine into an empty (gray-top) blood collection tube (the oxalate/fluoride will serve as a preservative for the urine). If (gray-top) tube is glass, please transfer urine to a plastic tube before shipping.
5.) Record the dose of Xylose given and the total 5-hour volume of the urine collection.
If additional tests are ordered, please submit a separate specimen. Adult patients and children should be kept fasting overnight and during test period (infants are fasted for 4 hours).
Ok to thaw.

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days
Refrigerated: 7 days
Frozen: 30 days


Colorimetric (C)

Performing Laboratory

Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

Setup Schedule

Set up: Mon, Thurs; Report available: Same day

Reference Range(s)

25 g dose 4.1-8.2 g in 5-hour urine
5 g dose 1.2-2.4 g in 5-hour urine

Clinical Significance

The xylose absorption test is useful in screening for carbohydrate malabsorption.

LOINC®' Code(s)

The Result and LOINC information listed below should not be used for electronic interface maintenance with Quest Diagnostics. Please contact the Quest Diagnostics Connectivity Help Desk for more information at 800-697-9302.

NOTE: The codes listed in the table below are not orderable Test Codes.

Result NameLOINC CodeComponent Name
00113Urine Total Volume12255-6Specimen volume
11613Ad-Xylose, Urine, 5 hr1646-9Xylose^post dose PO

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

LOINC assignment is based on a combination of test attributes, including the method used by the performing laboratory. For tests not performed by Quest Diagnostics, codes are assigned by the performing laboratory.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.