Xylose Absorption Test (Adult

Marshfield Lab Public WebSite

Marshfield Clinic Public WebSite

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

Test Code: MISC

Overview
Ordering
Specimen
Performing
Clinical/Interpretive
Contacts
Coding

Synonyms/Keywords

Ref Lab Code: 57321, D-Xylose, Dxylose

Specimen Requirements

Fasting Required	Specimen Type	Preferred Container/Tube	Specimen Volume	Specimen Minimum Volume (allows for 1 repeat)
Yes	Serum	Red Top Tube (RTT)	5.0 mL	0.5 mL
Yes (2 hour)	Serum(timed)	Red Top Tube (RTT)	5.0 mL	0.5 mL
	Urine	Container	5.0 mL	3.0 mL
SUBMIT ALL OF THE FOLLOWING (Read ALL collectioninformation prior to start of test and collection of specimens.)

Collection Processing Instructions

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 Stability Information

Specimen Type	Temperature	Time
Serum Timed Serum Urine	Refrigerated (preferred)	7 days
	Frozen	30 days
	Ambient	4 hours

Specimen Type

Temperature

Time

Serum

Timed Serum

Urine

Refrigerated (preferred)

7 days

Frozen

30 days

Ambient

4 hours

Rejection Criteria

Hemolysis	mild OK; Gross reject
Thawing	Warm reject; Cold OK

Performing Laboratory Information

Performing Location	Day(s) Test Performed	Analytical Time	Methodology/Instrumentation
Mayo Medical Laboratories forwards to ARUP Laboratories	Tuesday, Thursday	1-5 days	Quantitative Spectrophotometry

Reference Lab

Mayo Clinic Laboratories

Test Information

Several drugs can interfere with test results: Aspirin, Atropine, Cochicine, Digitalis, Indomethacin, MAO Inhibitors, Nalidixic acid, Neomycin, Opium alkaloids, Phenelzine.
Test is forwarded from Mayo Medical Labs to ARUP Laboratories.

Reference Range Information

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

Outreach CPTs

CPT	Modifier (if needed)	Quantity	Description	Comments
84620