Specimen

Serum and Urine

Collection Medium:

Minimum:

(FASTING SERUM):  "ONE-HOUR SERUM (Absolute Minimum 0.1 mL per timed 
serum sample)" and "FIVE-HOUR URINE"

Rejection Criteria:

Hemolyzed specimens.

Delivery Instructions:

Submit specimen to laboratory as soon as possible after
collection period is completed.

Specimen
Instructions:

Indicate dose and time of sampling on requisition.

Children are defined as less than 17 years old for purposes of this 
test.

The patient should fast for eight hours (minimum four hours) prior to 
starting test.

Just prior to start of test, the patient should empty his or her 
bladder (DO NOT collect this urine).

Just prior to start of test, collect the first serum sample. (Min: 0.5 
mL serum)  Label this sample as "FASTING SERUM."

Give children 0.5 g D-xylose per kilogram of body weight, up to 25 g; 
give xylose in water (2.5 mL of water per 0.5 g of xylose, up to 250 mL 
water). Encourage the patient to drink additional water following the 
xylose dose. The patient may have water as desired, but no other food 
or fluids. The patient should rest in a chair or on a bed until 
completion of test. Mild diarrhea is common following xylose ingestion.

Collect the second serum sample one hour after giving the xylose dose. 
(Min: 0.5 mL serum) Label this sample as "ONE-HOUR SERUM."

After giving the xylose dose, collect all urine for the next five 
hours. Measure and record the volume, mix well and remove a 5 mL 
aliquot (Min: 3 mL) for transport. Label this sample as "FIVE-HOUR 
URINE."

Transport entire urine collection and blood specimens to Specimen 
Control (6240 RCP).

Analytic Time:

1 week

Reference Range:

Children are defined as 17 years or younger for this test.

Components                                 Reference Interval

Serum, fasting specimen                    0-16 yrs: none
(There are no reference intervals
for the fasting specimen; it is used
as a patient "blank" when testing the
one-hour specimen.)

Serum xylose, one hour following           0-5 months; 15-58 mg/dl
ingestion                                  6 months-16 yrs: 20-58 mg/dl

Fraction of xylose dose excreted in        0-16 yrs: 16-40% of dose
five hours in urine

Amount of xylose excreted in five          0-16 yrs: depends on
hours in urine                                       dose given

The xylose absorption test evaluates carbohydrate absorption by the 
mucosa of the proximal small intestine. In patients with renal 
deficiency, rely on the serum test only. In functionally anephric 
patients, the test is unreliable. A number of drugs can interfere with 
test results, including aspirin, atropine, colchicine, digitalis, 
indomethacin, MAO inhibitors, nalidixic acid, neomycin, opium 
alkaloids, and phenelzine. Nonfasting serum samples are often 
compromised by significant analytic interferences.

Comments:

If unable to collect pediatric urine specimens, testing will be 
completed with a disclaimer.

Record the xylose dose given and the total volume of the five-hour 
urine on the test request form.  Send and label the fasting and 
one-hour serum samples.  Record the total volume and xylose dose given 
on the urine aliquot tube.  Failure to include required information 
will result in delayed turnaround time.

CPT Code:

84620

See Additional Information:
Fasting Specimen Requirements
Urine Tests Requiring no Preservatives