Jejunal Permeability Test – Intestinal Barrier Diagnosis
The jejunal permeability test measures the leakiness of the small intestinal mucosa in the jejunum. It helps detect conditions such as coeliac disease or Crohn's disease at an early stage.
Things worth knowing about "Jejunal permeability test"
The jejunal permeability test measures the leakiness of the small intestinal mucosa in the jejunum. It helps detect conditions such as coeliac disease or Crohn's disease at an early stage.
What is the Jejunal Permeability Test?
The jejunal permeability test is a diagnostic procedure used to assess the permeability of the mucosal lining of the jejunum – the middle section of the small intestine. A healthy intestinal mucosa acts as a selective barrier, allowing nutrients to pass through while preventing harmful substances, bacteria, and undigested food particles from entering the bloodstream. When this barrier is compromised, the condition is referred to as increased intestinal permeability, or “leaky gut.”
How Does the Test Work?
The jejunal permeability test typically involves the oral administration of sugar probe molecules that are not normally absorbed by the body – or only absorbed in minimal amounts. The most commonly used substances include:
- Lactulose: a larger disaccharide molecule that does not readily cross an intact intestinal barrier
- Mannitol or Rhamnose: smaller monosaccharide molecules that are easily absorbed when the mucosa is healthy
- 51Cr-EDTA: a radiolabelled molecule used in specialised clinical settings
After ingestion of the test substance, urine is collected over a defined period (usually 5–6 hours) and analysed. The lactulose-to-mannitol ratio in the urine indicates the degree of intestinal permeability: an elevated ratio suggests impaired barrier function.
When is the Test Used?
The jejunal permeability test is indicated in the following clinical situations:
- Suspected coeliac disease (gluten intolerance) or other malabsorption syndromes
- Diagnosis and monitoring of Crohn's disease and other inflammatory bowel diseases (IBD)
- Investigation of chronic abdominal pain, bloating, or diarrhoea of unclear origin
- Assessment of intestinal barrier integrity following intensive care treatment or chemotherapy
- Research in patients with irritable bowel syndrome, food allergies, or autoimmune conditions
Diagnosis and Interpretation
The test results are evaluated by measuring the excreted test substances in urine using chromatographic methods (e.g. HPLC). An elevated lactulose-to-mannitol ratio indicates increased jejunal permeability. Reference values may vary depending on the laboratory and the method used. Test results should always be interpreted in conjunction with other clinical findings and investigations, such as biopsies, blood tests, and antibody panels.
Potential Limitations
- Impaired kidney function may affect the excretion of test substances
- Certain medications (e.g. non-steroidal anti-inflammatory drugs) can transiently increase intestinal permeability
- The test primarily assesses the small intestine and is less suitable for evaluating colonic permeability
Clinical Significance
Increased intestinal permeability has been associated with a wide range of conditions, including inflammatory bowel diseases, autoimmune disorders, food allergies, and metabolic disturbances. The jejunal permeability test provides valuable information about intestinal barrier function and can serve as a non-invasive complement to intestinal biopsy.
References
- Piche T. et al. - Intestinal permeability and irritable bowel syndrome. Neurogastroenterology & Motility, 2009.
- Grootjans J. et al. - Non-invasive assessment of barrier integrity and function of the human gut. World Journal of Gastrointestinal Surgery, 2010.
- Fasano A. - Leaky gut and autoimmune diseases. Clinical Reviews in Allergy & Immunology, 2012.
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