Gastrointestinal Tract Permeability (Hydrostatic Pressure Gradient or Osmotic Stress Test)
This test measures how well your digestive system allows certain substances to pass through the intestinal lining. It helps assess conditions like leaky gut syndrome or intestinal inflammation.
["This test evaluates intestinal barrier function by tracking how substances move through your digestive tract."]
Key facts at a glance
- LOINC
- 2334-1
- Short code
- Hgb Gast gastro Ql
- Synonyms
- Hgb Gast gastro Ql
- Category
- hematology
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- 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, bloating, abdominal pain, or unexplained weight loss. It can also be used to diagnose conditions like celiac disease, inflammatory bowel disease, or food intolerances that affect digestion.
How the Test Works
You’ll drink a special solution containing non-digestible markers (like lactulose or mannitol). Urine samples are collected over time to measure how quickly these markers appear in your urine. This helps identify if your intestines are allowing too much substance to leak into the bloodstream.
Sample Collection Process
You’ll have a few urine samples collected over several hours. The test may require fasting before drinking the solution. Follow your doctor’s instructions carefully to ensure accurate results.
What to Expect After the Test
You may experience mild stomach discomfort or bloating after drinking the solution. Avoid strenuous activity or heavy meals for a few hours afterward. Your doctor will review the results to determine if your digestive system is functioning as expected.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Gastrointestinal Permeability Test
Frequently asked questions
This test can help identify if your intestines are overly permeable, which may be linked to chronic digestive issues, autoimmune conditions, or malnutrition. Early detection can guide treatment plans like dietary changes or medications.
How long does it take to get results? Results are typically available within a few days to a week after the test is completed, depending on your lab’s processing time.
Is this test painful or uncomfortable? No, the test involves drinking a solution and collecting urine samples, which is generally not painful. Mild stomach discomfort may occur after drinking the solution.
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