From the Research
Stool alpha-1 antitrypsin (A1AT) testing is primarily diagnostic of protein-losing enteropathy, a condition characterized by excessive loss of serum proteins through the gastrointestinal tract. This test is particularly useful because A1AT is a protein that resists degradation by digestive enzymes, making it an excellent marker for protein leakage into the intestinal lumen. Elevated levels of A1AT in stool indicate increased intestinal permeability or mucosal damage. Common conditions diagnosed using this test include:
- Inflammatory bowel disease (particularly Crohn's disease) 1, 2, 3, 4
- Intestinal lymphangiectasia
- Certain food allergies
- Protein-losing gastropathy The test works because A1AT is normally present in blood but not in stool in significant amounts; when the intestinal barrier is compromised, this protein leaks into the intestinal lumen and appears in the stool. For accurate results, patients should avoid NSAIDs before testing as these medications can increase intestinal permeability, as noted in various studies 1, 2, 3, 4, 5. The test is particularly valuable in pediatric patients where other diagnostic procedures might be more invasive or difficult to perform. It is also useful in monitoring disease activity and response to treatment in patients with inflammatory bowel disease, as shown by studies such as 4. Overall, stool A1AT testing is a sensitive and non-invasive method for diagnosing and managing protein-losing enteropathy and related conditions.