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Test ID FXAB Xylose Absorption Test (Adult 25g dose)

Method Name

Quantitative Spectrophotometry

Reporting Name

Xylose Absorption Test, Adult

Specimen Type

Serum
Timed Serum
Urine

Specimen Required

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

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

Day(s) and Time(s) Performed

Tuesday, Thursday

Performing Laboratory

ARUP Laboratories

CPT Code Information

84620

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FXAB Xylose Absorption Test, Adult In Process

 

Result ID Test Result Name Result LOINC Value
Z2659 Total Volume 19153-6
Z2660 Dosage 4462-8
Z2661 Serum Xylose at 2 hours 10454-7
Z2662 Xylose Excretion, g/5 hr 22626-6
Z2663 Xylose Excretion, % Dose 5 hr 22631-6

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