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HelpTest ID FXAB Xylose Absorption Test (Adult 25g dose)
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| FXAB1 | Total Volume | No | Yes |
| FXAB2 | Dosage | No | Yes |
| FXAB3 | Serum Xylose at 2 hours | No | Yes |
Method Name
Quantitative Spectrophotometry
Reporting Name
Xylose Absorption Test, AdultSpecimen Type
SerumTimed Serum
Urine
SUBMIT ALL OF THE FOLLOWING (Read ALL collection information prior to start of test and collection of specimens.)
Serum-Required: Fasting serum and Two-hour specimen Collect blood in plain, red-top tube(s), allow to clot completely at room temperature. Separate from cells ASAP and label tube with "Fasting serum" or "Two-hour serum" as appropriate. Ship specimens refrigerate.
Urine
Collect all urine for five hours. Measure and record the volume, mix well and remove a 5 mL aliquot, label sample "Five-hour urine". Ship specimen refrigerate.
REQUIRED COLLECTION INSTRUCTIONS - Read ALL collection information prior to start of test.
* 25 g Xylose dose must be obtained from a pharmacy.
* Patient should fast for eight hours prior to start of test.
* Patient should empty bladder prior to start of test. (do not collect)
* Prior to xylose administration, collect fasting serum sample, label tube
Clearly "Fasting Serum"
* Give adults 25 g D-xylose in 250 mL water. Encourage patient to drink an additional 250 mL water following 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 bed until completion of test. Mild diarrhea is common following xylose ingestion.
* Collect the second serum sample two hours after giving the xylose dose. Label tube clearly "Two-hour Serum".
* Immediately following xylose dose, COLLECT ALL URINE FOR THE NEXT FIVE HOURS. Measure and record the volume, mix well and remove a 5 mL aliquot. Label sample "Five-hour Urine", record total volume and the xylose dose given.
Specimen Minimum Volume
Serum: 0.5 mL Urine: 3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 30 days | |
| Ambient | 4 hours | |
| Timed Serum | Refrigerated (preferred) | 7 days |
| Frozen | 30 days | |
| Ambient | 4 hours | |
| Urine | Refrigerated (preferred) | 7 days |
| Frozen | 30 days | |
| Ambient | 4 hours |
Clinical Information
Several drugs can interfere with test results
-Aspirin
-Atropine
-Cochicine
-Digitalis
-Indomethacin
-MAO inhibitors
-Nalidixic acid
-Neomycin
-Opium alkaloids
-Phenelzine
Reference Values
Serum fasting specimen: No reference intervals for the fasting serum: it is used as a blank when testing the two-hour specimen.
Serum xylose at 2 hours:
17 years and older: 32-58 mg/dL
Xylose excretion, % dose 5 hr:
17-64 years: 16-40 %
65 years and older: 14-40 %
Xylose excretion, g/5 hr:
17-64 years: 4.0-10.0 g/5hrs
65 years and older: 3.5-10.0 g/5hrs