Skip to content

2-Hour Oral D-Xylose Absorption Test

Published: August 9, 2026Updated: August 16, 2026

This test measures how well your body absorbs and processes a simple sugar called D-xylose, which helps assess intestinal function and nutrient absorption.

Quick summary

["Evaluates gut health and absorption issues with a simple sugar challenge."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
41173-6
Short code
Xylose 2h p Xyl PO SerPl-mCnc
Synonyms
Xylose 2h p 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 This Test Is Done

Your doctor may recommend this test if you have symptoms like chronic diarrhea, weight loss, malnutrition, or unexplained nutrient deficiencies. It can also help diagnose conditions like celiac disease, short bowel syndrome, or malabsorption disorders.

What to Expect Before the Test

You’ll drink a sweet liquid containing D-xylose and then provide a urine sample 2 hours later. No special preparation is needed beyond fasting for 8–12 hours before drinking the solution.

How the Test Works

After drinking the D-xylose solution, your body absorbs it through the intestines. The test measures how much xylose appears in your urine over 2 hours, indicating how well your intestines are functioning.

What the Results Mean

Lower than expected xylose levels in urine suggest poor absorption, which may point to intestinal issues. Results alone don’t diagnose a specific condition but guide further testing if needed.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A

Specimen: serum

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.

This test is primarily used to identify malabsorption syndromes, such as celiac disease, tropical sprue, or other gastrointestinal disorders that impair nutrient uptake. It’s not a diagnostic test for infections or metabolic disorders but helps rule out intestinal absorption problems.

Short name

D-Xylose Test

Frequently asked questions

What does a low or high xylose result mean?
A lower-than-expected amount of xylose in your urine suggests your intestines may not be absorbing nutrients properly. This could indicate conditions like celiac disease, short bowel syndrome, or other malabsorption issues. A higher-than-expected result is less common but may indicate overabsorption due to certain intestinal conditions or medications.
Is fasting required before this test?
Yes, you’ll need to fast for 8–12 hours before drinking the D-xylose solution. This helps ensure accurate results by reducing interference from food in your digestive system.
Can I take medications before this test?
Ask your doctor about any medications you’re taking, especially those for digestive issues or diabetes. Some medications may affect how your body absorbs xylose, so it’s best to discuss this with your healthcare provider before the test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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