D-xylose absorption test (serum concentration, 2-hour post-oral load)
This test measures how well your intestines absorb the sugar D-xylose, which helps assess gut function and possible malabsorption disorders.
Assesses intestinal absorption and possible digestive issues after eating a sugar load.
Key facts at a glance
- LOINC
- 10454-7
- Short code
- Xylose 2h p 25 g Xyl PO SerPl-mCnc
- Synonyms
- Xylose 2h p 25 g Xyl PO SerPl-mCnc
- 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 Is This Test Done?
Your doctor may recommend this test if you have symptoms like chronic diarrhea, unexplained weight loss, or signs of nutrient deficiencies, such as fatigue or anemia. It can also help diagnose conditions like celiac disease, short bowel syndrome, or intestinal infections.
How Is the Test Performed?
You’ll drink a special solution containing D-xylose. Blood samples are taken before drinking it and 2 hours later to measure the sugar levels in your blood. This helps determine how efficiently your intestines absorbed the sugar.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for a few hours before the test to ensure accurate results. Wear comfortable clothing and plan for a few hours to rest afterward.
What to Expect During the Test
You’ll sit quietly while blood is drawn from a vein in your arm. The process is quick and usually causes only mild discomfort. You may feel a slight pinch or sting when the needle is inserted.
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 D-xylose levels after 2 hours suggest poor intestinal absorption, which may indicate conditions like celiac disease, inflammatory bowel disease, or other digestive disorders. Normal results usually mean your intestines absorb nutrients efficiently.
Short name
D-Xylose Absorption Test
Frequently asked questions
What does a low result mean?
What does a normal result mean?
Is fasting required before this 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