Objective: Determine the normal FA1-AT level in random wet stool of Thai children using RID and NPL, and to study the correlation between RID and NPL methods for measurement of FA1-AT.
Material and Method: Random stool samples were collected from healthy children and intestinal-disorders patients. Alpha1-antitrypsin (FA1-AT) in wet stool samples was measured by nephelometry (NPL) and radialimmunodiffusion (RID) methods.
Results: Newborn infants had the highest FA1-AT level during the first day of life and declined to the same level as older children on day 3-4. Median and geometric mean of FA1-AT levels by NPL from healthy children aged 1 month - 15 years was 1.23 and 1.11 mg/dL respectively. FA1-AT levels by NPL from children with severe intestinal disorders, displaying median and geometric mean at 6.77 and 12.39 mg/dL respectively, were much higher than healthy children. The RID and NPL methods showed a correlation of r = 0.87 (p < 0.01) and R2 = 0.75.
Conclusion: Random FA1-AT assay in wet stool is a non–invasive and simple test for supporting diagnosis of protein-losing enteropathy.

Keywords: Protein-losing enteropathy, Fecal alpha1-antitrypsin, Radial-immunodiffusion, Nephelometry, Gastrointestinal disorders