Gut
Zonuline
A protein linked to the permeability of the bowel wall; not validated and does not demonstrate a "leaky gut".
Everything about this testWhat it measures
Zonulin is a protein that can loosen the connections between the cells of the bowel wall, making the wall more permeable. In scientific research it is used to study this permeability, including in celiac disease. The test measures a substance referred to as zonulin in a stool sample. Research has shown that widely used zonulin tests measure not only zonulin but also related proteins.
- Permeability of the bowel wall, as studied in scientific research; not a recognized diagnosis
High
A raised value is often explained as a "leaky gut", but that is not a recognized diagnosis and this measurement cannot make such a diagnosis. There is no condition for which zonulin in stool is used to make a diagnosis or choose a treatment. The value can differ greatly between tests and between laboratories. A raised value does not on its own call for a diet, supplements or treatment.
Low
A low value has no known meaning. It does not rule out any bowel condition.
If your result is abnormal
With an abnormal result without symptoms, no follow-up is usually needed. With bowel symptoms, the GP can request calprotectin in the stool and blood tests, and refer you to a gastroenterologist if there are signs of a chronic inflammation of the bowel.
Reliability
Zonulin, in blood or in stool, is a measurement from scientific research and is not validated for making a diagnosis. Research showed that widely used zonulin tests also measure other proteins, so it is not certain what the result reflects. A "leaky gut" is not a recognized diagnosis.
Limitations
- Widely used tests do not measure only zonulin; results from different tests are not comparable.
- The value differs from day to day and depends on diet and the firmness of the stool.
- There are no cut-off values established in a guideline or in independent research.
How common is this
Bowel symptoms are common: according to the guideline, irritable bowel syndrome affects about 4 in 100 adults in the Netherlands. Chronic inflammatory bowel diseases such as Crohn's disease and ulcerative colitis are much rarer; the guideline gives no Dutch figure for them. How often an abnormal result for these markers occurs in people without symptoms is not known.
Who is this useful for
In people without symptoms, an abnormal result says little, because the meaning has not been established and a passing infection or a painkiller can raise the value. With long-lasting diarrhea or abdominal symptoms, the GP uses calprotectin in the stool to rule out a chronic inflammation of the bowel, and a blood test if celiac disease is suspected. With blood in the stool, unintended weight loss, diarrhea at night or new bowel symptoms after age 50, this test is no substitute for a visit to the GP.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results