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Irritable Bowel Syndrome (IBS) Health Center

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D-Xylose Absorption Test

How It Feels

Drinking the D-xylose solution can make you feel sick to your stomach (nauseated).

Blood test

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Urine test

There is no pain while collecting a 5-hour urine sample.


Blood test

There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the risk of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.

Urine test

This test can cause dehydration. Make sure that you drink enough fluids to replace lost liquids after you have completed the test.

Drinking the D-xylose preparation may cause vomiting and diarrhea. Tell your doctor if you have problems after drinking the D-xylose solution.


The D-xylose test measures the level of D-xylose, a type of sugar, in a blood or urine sample.

Blood levels of D-xylose are highest about 2 hours after drinking the D-xylose solution. Almost all of the D-xylose is eliminated from the body in the urine within 5 hours. If the intestines camera.gif can't absorb the D-xylose properly, the amount of D-xylose in the blood and urine will be very low.

Many conditions can change D-xylose levels. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.


The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

D-xylose in blood 1

Infants (5-gram dose):

More than 15 milligrams per deciliter (mg/dL) or more than 1.0 millimole per liter (mmol/L)

Children (5-gram dose):

More than 20 mg/dL or more than 1.3 mmol/L

Adults (5-gram dose):

More than 20 mg/dL in 2 hours or more than 1.3 mmol/L

Adults (25-gram dose):

More than 25 mg/dL in 2 hours or more than 1.6 mmol/L

WebMD Medical Reference from Healthwise

Last Updated: September 09, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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