Quick answer: Leaky gut is hard to identify because its symptoms are nonspecific and overlap with many conditions, and there is no single validated test. Tests sometimes used include the lactulose-mannitol test, comprehensive stool analysis, calprotectin, zonulin, LPS antibodies, CRP and breath tests for SIBO. Your provider chooses tests based on your symptoms.
Key takeaways
Testing for leaky gut is challenging because symptoms are nonspecific and no single test confirms it.
The lactulose-mannitol test is mostly used in research, while stool and blood markers can give clues about inflammation and permeability.
Functional labs are optional and can help in more complex cases, so choosing tests is best done with your doctor.
Why evaluation is challenging
Symptoms like fatigue, headaches and joint pain are nonspecific. Related conditions are complex, and no single test confirms leaky gut. Background: introduction to leaky gut.
Testing options
Lactulose-mannitol test
You drink two sugars and urine levels show how much passed through the gut lining. It is mostly used in research.
Comprehensive stool analysis
Assesses the microbiome, digestion, pancreatic function and gut inflammation.
Calprotectin
A stool marker of intestinal inflammation, commonly used to help distinguish IBD from IBS.
Zonulin
A tight junction regulator; available tests vary in reliability.
LPS antibodies
May indicate exposure to bacterial toxins.
CRP
A blood marker of body-wide inflammation. See hs-CRP.
Breath tests
Can identify small intestinal bacterial overgrowth (SIBO).
Food sensitivity tests
IgG food tests are controversial and should be interpreted cautiously.
Choosing the right tests
Please work with your doctor to decide which option is best for you. Functional labs are optional. They can be helpful in more complex cases.
Testing and healthy aging
Tracking inflammation over time helps you and your provider see whether changes are working.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have ongoing bloating, gas, diarrhea or constipation, or food reactions that seem to be multiplying. The same is true if you have fatigue, skin flares or joint aches alongside gut symptoms, or if you want a personalized gut plan instead of guessing.
See a medical provider promptly for blood in your stool, black stools, unexplained weight loss, persistent vomiting, severe abdominal pain, fever, or trouble swallowing.
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Which test, if any, would be worth running for my gut symptoms?
How should I read gut permeability testing alongside the rest of my labs and my symptoms?
How often would it make sense to recheck gut permeability testing in my situation?
Which daily habits or medications could be influencing gut permeability testing before we retest?
Frequently asked questions
Is there a test for leaky gut?
Several tests are used, but none is a single validated routine screening test.
What is calprotectin?
A stool marker of intestinal inflammation.
Are food sensitivity tests accurate?
IgG food tests are controversial; an elimination diet is often more informative.
Do I need testing to start a gut plan?
Not always. Many people start with food and lifestyle changes.
Sources
- Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in humans. Gut 2019. PMID: 31076401. https://pmc.ncbi.nlm.nih.gov/articles/PMC6790068/
- van Rheenen PF, Van de Vijver E, Fidler V. Faecal calprotectin for screening of patients with suspected inflammatory bowel disease: diagnostic meta-analysis. BMJ 2010. PMID: 20634346. https://pmc.ncbi.nlm.nih.gov/articles/PMC2904879/
- Ajamian M, et al. Serum zonulin as a marker of intestinal mucosal barrier function: May not be what it seems. PLoS One 2019. PMID: 30640940. https://pmc.ncbi.nlm.nih.gov/articles/PMC6331146/
- Rezaie A, et al. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol 2017. PMID: 28323273. https://pmc.ncbi.nlm.nih.gov/articles/PMC5418558/
- Stapel SO, et al. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy 2008. PMID: 18489614. https://pubmed.ncbi.nlm.nih.gov/18489614/
- MedlinePlus: Calprotectin Stool Test
- MedlinePlus: Digestive Diseases
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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