D-xylose Absorption Test

Xylose Tolerance Test

Results

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 the 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 cannot 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.

Normal

Normal values may vary from lab to lab.

D-xylose in blood

Babies younger than 6 months:	More than 15 milligrams per deciliter (mg/dL) or more than 1.0 millimole per liter (mmol/L) (SI units)
Children age 12 and younger:	More than 20 mg/dL or more than 1.3 mmol/L
Adults:	More than 20 mg/dL in 2 hours or more than 1.3 mmol/L

 

D-xylose in urine (5-hour urine sample)

Children:	16%–33% of the D-xylose dose is found in the sample.
Adults:	16%–40% of the D-xylose dose or more than 4 grams (g) is found in the sample.
Adults over age 65:	More than 14% of the D-xylose dose or more than 3.5 g is found in the sample.

High values

High values may be caused by:

• A disease, such as Hodgkin's disease or scleroderma.
• Radiation treatment.

Low values

Low values may be caused by:

• A disease that interferes with the intestine's ability to absorb nutrients (malabsorption syndrome), such as Crohn's disease, celiac disease, or Whipple's disease.
• Inflammation of the lining of the intestine.
• An infection with a parasite, such as giardiasis or hookworm.

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Author:	Bets Davis, MFA	Last Updated: April 29, 2009
Medical Review:	Kathleen Romito, MD - Family Medicine Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology
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