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HelpTest Code A1AFS Alpha-1-Antitrypsin Clearance, Feces and Serum
Ordering Guidance
The recommended procedure for protein-losing enteropathy is A1AFS / Alpha-1-Antitrypsin Clearance, Feces and Serum.
Shipping Instructions
Feces and serum should be shipped together. Specimens shipped separately may delay testing.
Specimen Required
Both feces and serum are required. Blood must be drawn during the stool collection period.
Specimen Type: Serum
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Red top or serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial
Specimen Type: Feces
Supplies: Stool Containers - 24, 48, 72 Hour Kit (T291)
Container/Tube: Stool container
Specimen Volume: Entire collection
Collection Instructions:
1. Collect a 24-hour fecal collection.
2. If no specimen is obtained within 24 hours, extend collection time to 48 to 72 hours. Document duration.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| AATS | Alpha-1-Antitrypsin, S | No | Yes |
| A1ATF | Alpha-1-Antitrypsin, 24 Hr, F | No | Yes |
Method Name
Nephelometry
Specimen Type
FecalSerum
Specimen Minimum Volume
Homogenized feces: 1 mL; Serum: 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Fecal | Frozen (preferred) | 14 days |
| Ambient | 14 days | |
| Refrigerated | 14 days | |
| Serum | Frozen (preferred) | 28 days |
| Ambient | 28 days | |
| Refrigerated | 28 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
| Feces collected in any preservative or fixative | Reject |
Clinical Information
Alpha-1-antitrypsin (AAT) is a 54-kDa 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 adult and children.
Reference Values
CLEARANCE:
≤27 mL/24 h
FECAL ALPHA-1-ANTRYPSIN CONCENTRATION:
≤54 mg/dL
SERUM ALPHA-1-ANTRYPSIN CONCENTRATION:
100-190 mg/dL
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82103 x 2
Forms
If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Test Request (T728) with the specimen.