D-Xylose Absorption Test (2-Hour Serum Concentration)
This test measures how well your body absorbs the sugar D-xylose, which helps assess intestinal function and malabsorption issues.
["A low absorption rate may indicate problems like celiac disease or short bowel syndrome."]
Key facts at a glance
- LOINC
- 26005-9
- Short code
- Xylose 2h p Xyl PO SerPl-sCnc
- Synonyms
- Xylose 2h p Xyl PO SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82670
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have symptoms like chronic diarrhea, unexplained weight loss, or signs of malabsorption (e.g., vitamin deficiencies). It’s also used to diagnose conditions like celiac disease or intestinal disorders that affect nutrient absorption.
How the Test Works
You’ll drink a solution containing D-xylose, a sugar that your body absorbs differently than regular sugars. Blood is drawn from your arm at baseline and after 2 hours to measure xylose levels in your serum.
What to Expect Before the Test
No special preparation is needed, but avoid taking medications that may affect digestion (like antibiotics or anti-diarrheals) unless cleared by your doctor. Wear comfortable clothing for blood draws.
What to Expect During the Test
You’ll sit quietly while blood is drawn twice: once before drinking the xylose solution and again after 2 hours. The process takes about 15 minutes total.
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.
Low xylose absorption suggests impaired intestinal function, which could indicate celiac disease, short bowel syndrome, or other digestive disorders. High absorption may be normal or could indicate conditions like Crohn’s disease (though further testing is needed).
Short name
D-Xylose Absorption Test
Frequently asked questions
Will I feel any discomfort?
How long will results take?
Can I eat or drink before the second blood draw?
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