D-xylose absorption test (24-hour urine collection)
This test measures how well your body absorbs the sugar D-xylose, which helps assess intestinal function and identify malabsorption issues.
["Helps diagnose problems absorbing nutrients in your small intestine."]
Key facts at a glance
- LOINC
- 23942-6
- Short code
- Xylose 2h p 5 g Xyl PO Bld-mCnc
- Synonyms
- Xylose 2h p 5 g Xyl PO Bld-mCnc
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82670
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may recommend a D-xylose absorption test if you have symptoms like chronic diarrhea, unexplained weight loss, or signs of malabsorption, such as vitamin deficiencies. It can also be used to check for conditions like celiac disease, short bowel syndrome, or intestinal infections.
What to Expect Before the Test
You’ll collect a 24-hour urine sample after drinking a specific dose of D-xylose. Follow your doctor’s instructions carefully to ensure accurate results. Avoid certain medications (like antibiotics or laxatives) that could interfere with the test.
How the Test Works
D-xylose is a simple sugar that your body absorbs through the intestines. After drinking it, your urine is collected over 24 hours to measure how much of the sugar remains. Lower levels suggest poor absorption, which may indicate intestinal damage or disease.
What the Results Mean
Results are typically compared to a reference range for healthy individuals. A lower than expected amount of xylose in urine may indicate malabsorption, while higher levels may suggest normal absorption or other factors affecting kidney function.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: This test is critical for diagnosing conditions like celiac disease, tropical sprue, or other intestinal disorders that disrupt nutrient absorption. It helps guide treatment plans, such as dietary changes or medical interventions.
Short name
D-Xylose Test
Frequently asked questions
What causes abnormal D-xylose absorption?
How long does it take to get results?
Can I eat or drink anything before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy