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Test ID: A1AF Alpha-1-Antitrypsin, Random, Feces

Reporting Name

Alpha-1-Antitrypsin, Random, F

Useful For

Diagnosing protein-losing enteropathies, especially when used in conjunction with serum alpha-1-antitrypsin (AAT) levels as a part of AAT clearance studies

Specimen Type

Fecal


Advisory Information


The preferred test for diagnosing protein-losing enteropathies is A1AFS / Alpha-1-Antitrypsin Clearance, Feces and Serum.



Specimen Required


Supplies:

-Stool container, Small (Random), 4 oz (T288)

-Stool Collection Kit, Random (T635)

Container/Tube: Stool container

Specimen Volume: 5 g

Collection Instructions: Collect a random fecal specimen.


Specimen Minimum Volume

Homogenized Stool: 1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Fecal Frozen (preferred) 14 days
  Ambient  14 days
  Refrigerated  14 days

Reference Values

≤54 mg/dL

Day(s) and Time(s) Performed

Monday through Friday; Continuously until 2 p.m.

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82103

LOINC Code Information

Test ID Test Order Name Order LOINC Value
A1AF Alpha-1-Antitrypsin, Random, F 9407-8

 

Result ID Test Result Name Result LOINC Value
AAT_F Alpha-1-Antitrypsin, Random, F 9407-8

Clinical Information

Alpha-1-antitrypsin (AAT) is a 54kDa glycoprotein that 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. AAT clearance is reliable for measuring protein loss distal to the pylorus. A serum sample is required to interpret results as a serum deficiency of AAT) would make the AAT fecal excretion lower and could invalidate the test utility.

 

Gastrointestinal protein enteropathy has been associated with regional enteritis, sprue, Whipple intestinal lipodystrophy, gastric carcinoma, allergic gastroenteropathy, intestinal lymphangiectasia, constrictive pericarditis, congenital hypogammaglobulinemia, and iron deficiency anemia associated with intolerance to cow's milk. Increased fecal excretion of AAT can be found in small and large intestine disease and is applicable to adults and children.

Interpretation

Patients with protein-losing enteropathies generally have alpha-1-antitrypsin fecal concentrations over 100 mg/dL.

 

Borderline elevations above the normal range are equivocal for protein-losing enteropathies.

Clinical Reference

1. Florent C, L'Hirondel C, Desmazures C, Aymes C, Bernier JJ: Intestinal clearance of alpha 1-antitrypsin. A sensitive method for the detection of protein losing enteropathy. Gastroenterology. 1981 Oct;81(4):777-780

2. Crossley JR, Elliott RB: Simple method for diagnosing protein-losing enteropathies. Br Med J. 1977 Feb 12;1(6058):428-429

3. Perrault J, Markowitz H: Protein-losing gastroenteropathy and the intestinal clearance of serum alpha-1-antitrypsin. Mayo Clin Proc. 1984 Apr;59(4):278-279

4. Levitt DG, Levitt MD: Protein losing enteropathy: comprehensive review of the mechanistic association with clinical and subclinical disease states. Clin Exp Gastroenterol. 2017 Jul;10:147-168

5. Murray FR, Morell B, Biedermann L, Schreiner P: Protein-losing enteropathy as precursor of inflammatory bowel disease: A review of the literature. BMJ Case Rep. 2021 Jan 11;14(1):e238802

Analytic Time

1 day

Method Name

Nephelometry

Mayo Clinic Laboratories | Gastroenterology Catalog Additional Information:

mml-gi-genetics