Alpha-1-Antitrypsin, Random, Feces
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Alpha-1-antitrypsin (A1A) is resistant to degradation by digestive enzymes and is, therefore, used as an endogenous marker for the presence of blood proteins in the intestinal tract. A1A clearance is reliable for measuring protein loss distal to the pylorus.
Gastrointestinal protein enteropathy has been associated with regional enteritis, sprue, Whipple's intestinal lipodystrophy, gastric carcinoma, allergic gastroenteropathy, intestinal lymphangiectasia, constrictive pericarditis, congenital hypogammaglobulinemia, and iron deficiency anemia associated with intolerance to cow's milk.
Diagnosing protein-losing enteropathies, especially when used in conjunction with serum alpha-1-antitrypsin (A1A) levels as a part of A1A clearance studies (see CA1A/8835 Alpha-1-Antitrypsin Clearance, Feces and Serum; preferred test)
Patients with protein-losing enteropathies generally have alpha-1-antitrypsin stool concentrations >100 mg/mL.
Borderline elevations above the normal range are equivocal for protein-losing enteropathies.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The clearance studies using 24-hour stool specimens and serum determinations are preferred in order to normalize the large range of serum alpha-1-antitrypsin (A1A) concentrations and the variability in random stool A1A concentration. In the absence of either a 24-hour stool collection or a contemporary serum specimen, the fecal concentration of A1A can be used as a surrogate marker.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
< or =54 mg/dL
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Florent C, L'Hirondel C, Desmazures C, et al: Intestinal clearance of alpha 1-antitrypsin. A sensitive method for the detection of protein losing enteropathy. Gastroenterology 1981;81:777-780
2. Crossley JR, Elliott RB: Simple method for diagnosing protein-losing enteropathy. Br Med J 1977;1:428-429
3. Perrault J, Markowitz H: Protein-losing gastroenteropathy and the intestinal clearance of serum alpha-1-antitrypsin. Mayo Clin Proc 1984;59:278-279