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d-Xylose Absorption Test, Urine
Test Code2437
Quest Code
941
Alias/See Also
Quest 941; Sunquest: XYLU
CPT Codes
84620
Preferred Specimen
5 mL fasting urine collected in a flouride oxalate tube (gray-top)
Patient Preparation
Adult patients and children should be kept fasting overnight and during test period (infants are fasted for 4 hours)
Minimum Volume
1 mL
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 g of D(+) -xylose (or 5 g, 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 a 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. Note and record starting time of the test and the amount of xylose given.
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.
NOTE: This test cannot be performed at a Patient Service Center because of the preparation step required for the d-Xylose solution.
2. Give 25 g of D(+) -xylose (or 5 g, 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 a 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. Note and record starting time of the test and the amount of xylose given.
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.
NOTE: This test cannot be performed at a Patient Service Center because of the preparation step required for the d-Xylose solution.
Transport Container
Transport tube
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 30 days
Refrigerated: 7 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Urine with no preservative
Methodology
Colorimetric (C)
Setup Schedule
Mon, Thurs
Report Available
2-6 days
Reference Range
| 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.
Performing Laboratory
| Quest Diagnostics Nichols Institute-Chantilly VA |
| 14225 Newbrook Drive |
| Chantilly, VA 20151-2228 |
