How is leaky gut syndrome diagnosed?

Carmen Patrick Mohan, MD
Internal Medicine
Although people diagnosed with "leaky gut syndrome" have very real symptoms, it is not a recognized diagnosis within the scientific community.  Providers of complementary and alternative medicine use the catch phrase "leaky gut" to describe a hypothetical malfunction in the complex relationship between the intestinal wall's function as a barrier and its ability to allow substances such as fluid and substances dissolved within the fluid to move through the intestinal lining ‹-- what scientists call "intestinal permeability."  Though intestinal permeability can be measured, it is unclear whether that measurement is clinically useful or predictive, and therefore only special laboratories will conduct the test and a physician order is required. Also, the test may not be covered by insurance.  If you are having symptoms such as depression, decreased energy, fatigue, frequent loose or watery stools, change in stool diameter or bloody stools, prompt evaluation with a health care provider is strongly recommended. A test for intestinal permeability is unlikely to be necessary for appropriate diagnosis and treatment.
Robynne K. Chutkan, MD
Leaky gut is a clinical diagnosis, and while there's no specific test that can tell you with 100% certainty that you have it, a positive Intestinal Permeability Test is strongly associated with the condition. This test measures the ability of two non-metabolized sugar molecules -- mannitol and lactulose -- to get through the digestive lining.

Mannitol is a small molecule that normally passes through easily and serves as a marker of how well nutrients are being absorbed. Lactulose is a larger molecule that doesn't normally pass through very well and serves as a marker for whether there are large holes in the lining. To perform the test, the patient mixes pre-measured amounts of lactulose and mannitol and drinks it. The test measures the amount of lactulose and mannitol recovered in a 6-hour urine sample.

Low levels of both mannitol and lactulose indicate malabsorption. Elevated levels of both lactulose and mannitol suggest general increased intestinal permeability, consistent with leaky gut. Permeability to lactulose may be increased, suggesting leaky gut, while permeability to mannitol may be decreased, suggesting malabsorption of small molecules.

The lactulose/mannitol ratio is a useful value; an elevated ratio indicates that the effective pore size of the gut lining has increased, allowing larger, possibly harmful molecules to gain access to the body.
Leopold D. Galland, MD
Internal Medicine
There are only a few laboratories that test for Leaky Gut Syndrome and all require a doctor's order. Talk to your doctor about what test might be appropriate. High levels of antibodies to common food proteins or to normal intestinal bacteria may indicate increased intestinal permeability. Many research studies have used a challenge test involving a special solution consisting of two sugars, and seeing how much of each appears in urine. A blood test for celiac disease is essential.

Continue Learning about Digestive Diseases

Digestive Diseases

Digestive diseases, also known as gastrointestinal diseases, are disorders that affect your esophagus, stomach and small and large intestines. The symptoms of digestive diseases vary widely depending on which part of your digestiv...

e system is affected. Generally symptoms can be blood in your stool, a change in bowel habits, pain, weight loss or heartburn that is not relieved by antacids. See you doctor if you have any of these signs of digestive disease.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.