D-Xylose Absorption

Patient Instructions:

1. First thing in the morning; empty your bladder and discard the urine.

2. You should not eat breakfast or consume any other food before or during the five hour test period.

3. Dissolve the 5g D-Xylose in a glass of water and drink it.

4. Note the time.

5. After one hour drink a further glass of water.

6. You can now drink normally (but please do not eat anything).

7. Collect all urine for the five hours following ingestion of the D-Xylose. (Make sure your bladder is emptied at the five hour stage and the urine is included in the collection).

8. If you can accurately measure the total volume of urine collected (use a measuring jug), you can return a small well-mixed sample of the urine collection in the empty container supplied. Please ensure that the total volume of the collection is written on the label with your name and Biolab reference number (if applicable).

If you are not able to measure the total volume, return the complete urine collection to Biolab.

Clinical Indications:

In a normal subject at least 1.2 gm (25%) of an oral 5 gm dose of xylose should be recovered in a 5 hour urine collection; most normal results are in the range of 1.3 to 2.4g (26% to 50%).

Sample Report:

dxylrep.pdf (Click to Download)

Sample Requirements:

Kit required; 5 hr urine collection

Postal Samples Acceptable:



1. Roe JH and Rice EW (1948). A photometric method for the determination of free pentoses in animal tissues. J Biol Chem 1948;173;507-512.
2. Goodhart JM and Kingston GR. Modification of the method for the estimation of xylose in urine. J Clin Pathol 1969;22;621-622.
3. Gowenlock AH (ed). Gastrointestinal tract function tests. In:Varley’s Practical Clinical Biochemistry, pub Heinemann, Oxford, 6th edition 1988;pp 706-707.

For further details please contact the laboratory at: lab@xxxxbiolab.co.uk