Alpha-1-Antitrypsin Clearance, Feces and Serum
Use
This test is useful for diagnosing protein-losing enteropathies. Alpha-1-antitrypsin (AAT) is a glycoprotein resistant to degradation by digestive enzymes, making it a reliable marker for blood proteins in the intestinal tract. It is used to measure protein loss distal to the pylorus. The test helps identify protein enteropathy related to conditions like regional enteritis, sprue, intestinal lymphangiectasia, and others. Increased fecal excretion of AAT is indicative of small and large intestinal diseases.
Special Instructions
Both feces and serum are required for the test. Blood must be drawn during the stool collection period. Ship feces and serum together as specimens shipped separately may delay testing. If not ordering electronically, complete and send a Gastroenterology and Hepatology Test Request form with the specimen.
Limitations
The test may be less reliable in the absence of a 24-hour fecal collection or a contemporary serum specimen. Gastric loss of AAT can affect reliability, particularly in conditions like Menetrier disease where AAT is sensitive to low pH. Performing the test after starting an acid suppressive treatment is recommended if gastric loss is suspected. Turbidity, particles in the specimen, or lipemic sera may interfere with nephelometric quantitation. Urine contamination could affect results, suggesting potential use of a catheter for patients when necessary.
New York Approved
Methodology
Immunoassay (Nephelometry)
Biomarkers
LOINC Codes
- 93419-0
- 9407-8
- 18271-7
- 6771-0
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red top or serum gel; Submission in plastic vial
Collection Instructions
Within 2 hours of collection, centrifuge and aliquot into a plastic vial.
Causes for Rejection
Gross lipemia; hemolysis and icterus are acceptable.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 28 days |