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23239 Alpha-1-Antitrypsin, Random, Feces

Alpha-1-Antitrypsin, Random, Feces
Test Code: AATFSO
Synonyms/Keywords
a-1-Antitrypsin, Feces; Alpha 1 Antitrypsin; Alpha-1-Antitrypsin, Feces Only; Antitrypsin, Feces; A1AT; A1A; Alpha-1-Antitrypsin Feces (A1AF), ST AATFSO.  
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.
 
Ordering Guidance:  The preferred test for diagnosing protein-losing enteropathies is A1AFS/Alpha-1-Antitrypsin Clearance, Feces and Serum​.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
Fecal​ ​Stool container ​ ​5g ​Homogenized Stool: 1 mL ​
Collection Processing Instructions
Collect a random fecal specimen.
Specimen Stability Information
Specimen Type Temperature Time
​Fecal ​ ​ ​Frozen (preferred) ​14 days
​Ambient ​14 days
​Refrigerated ​14 days
Rejection Criteria

​Feces collected in any preservative or fixative.

Interference

The clearance studies using 24-hour fecal specimens and serum determinations are preferred as it normalizes the large range of serum alpha-1-antitrypsin (AAT) concentrations and the variability in random fecal AAT concentrations. In the absence of either a 24-hour fecal collection or a contemporary serum specimen, the fecal concentration of AAT can be used as a surrogate marker.

When gastric loss of AAT is suspected (eg, Menetrier disease), AAT clearance is not a reliable indicator of protein loss as AAT is sensitive to pH <3 and is rapidly destroyed. When gastric protein loss is suspected and the AAT clearance is normal, the recommendation is to repeat testing after starting an acid suppressive medication regime.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Friday ​1 to 2 days
Nephelometry​
Reference Lab
Mayo Clinic Laboratories
Test 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.

Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​< or =54 mg/dL
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.

Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​82103 ​ ​1 ​ ​
Synonyms/Keywords
a-1-Antitrypsin, Feces; Alpha 1 Antitrypsin; Alpha-1-Antitrypsin, Feces Only; Antitrypsin, Feces; A1AT; A1A; Alpha-1-Antitrypsin Feces (A1AF), ST AATFSO.  
Ordering Applications
Ordering Application Description
​COM Alpha-1-Antitrypsin Feces (A1AF)
Cerner​ Alpha-1-Antitrypsin Feces (A1AF)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
Fecal​ ​Stool container ​ ​5g ​Homogenized Stool: 1 mL ​
Collection Processing
Collect a random fecal specimen.
Specimen Stability Information
Specimen Type Temperature Time
​Fecal ​ ​ ​Frozen (preferred) ​14 days
​Ambient ​14 days
​Refrigerated ​14 days
Rejection Criteria

​Feces collected in any preservative or fixative.

Interference

The clearance studies using 24-hour fecal specimens and serum determinations are preferred as it normalizes the large range of serum alpha-1-antitrypsin (AAT) concentrations and the variability in random fecal AAT concentrations. In the absence of either a 24-hour fecal collection or a contemporary serum specimen, the fecal concentration of AAT can be used as a surrogate marker.

When gastric loss of AAT is suspected (eg, Menetrier disease), AAT clearance is not a reliable indicator of protein loss as AAT is sensitive to pH <3 and is rapidly destroyed. When gastric protein loss is suspected and the AAT clearance is normal, the recommendation is to repeat testing after starting an acid suppressive medication regime.

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.
 
Ordering Guidance:  The preferred test for diagnosing protein-losing enteropathies is A1AFS/Alpha-1-Antitrypsin Clearance, Feces and Serum​.
Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​< or =54 mg/dL
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.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Friday ​1 to 2 days
Nephelometry​
Reference Lab
Mayo Clinic Laboratories
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​82103 ​ ​1 ​ ​
For most current information refer to the Marshfield Laboratory online reference manual.