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HelpMayo Test ID AAT Alpha-1-Antitrypsin, Serum
Specimen Required
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Useful For
Workup of individuals with suspected disorders such as familial chronic obstructive lung disease
Diagnosing alpha-1-antitrypsin deficiency
Testing Algorithm
For more information see Alpha-1-Antitrypsin-A Comprehensive Testing Algorithm.
Special Instructions
Method Name
Nephelometry
Reporting Name
Alpha-1-Antitrypsin, SSpecimen Type
SerumSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Clinical Information
Alpha-1-antitrypsin (A1A) is the most abundant serum protease inhibitor, and it inhibits trypsin and elastin as well as several other proteases. The release of proteolytic enzymes from plasma onto organ surfaces and into tissue spaces results in tissue damage unless inhibitors are present. Congenital deficiency of A1A is associated with the development of emphysema at an unusually early age and with an increased incidence of neonatal hepatitis, usually progressing to cirrhosis.
For more information see Alpha-1-Antitrypsin-A Comprehensive Testing Algorithm.
Reference Values
100-190 mg/dL
Interpretation
Patients with serum levels less than 70 mg/dL may have a homozygous deficiency and are at risk for early lung disease. Alpha-1-antitrypsin proteotype testing should be done to confirm the presence of homozygous deficiency alleles.
If clinically indicated, patients with serum levels less than 125 mg/dL should have proteotype testing in order to identify heterozygous individuals. Heterozygotes do not appear to be at increased risk for early emphysema.
Cautions
Low alpha-1-antitrypsin (A1A) levels may result from liver disease, and A1A proteotype testing should be done to confirm A1A deficiency disease.
A1A is an acute-phase reactant, and any inflammatory process will elevate serum A1A levels.
Quantitation of specific proteins by nephelometric means may not be possible in lipemic sera due to the extreme light scattering properties of the specimen. Turbidity and particles in the specimen may result in extraneous light scattering signals, resulting in variable specimen analysis.
Clinical Reference
1. Tejwani V, Stoller JK: The spectrum of clinical sequelae associated with alpha-1 antitrypsin deficiency. Ther Adv Chronic Dis. 2021 Jul;12_suppl. doi: 10.1177/2040622321995691
2. Patel D, McAllister SL, Teckman JH: Alpha-1 antitrypsin deficiency liver disease. Transl Gastroenterol Hepatol. 2021 Apr 5;6:23. doi: 10.21037/tgh.2020.02.23
3. Donato LJ, Snyder MR, Greene DN: Measuring and interpreting serum AAT concentration. Methods Mol Biol. 2017;1639:21-32. doi: 10.1007/978-1-4939-7163-3_3
Method Description
In this Siemens Nephelometer II method, the light scattered onto the antigen-antibody complexes is measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions. If the antibody volume is kept constant, the signal behaves proportionally to the antigen volume.
A reference curve is generated by a standard with a known antigen content on which the scattered light signals of the samples can be evaluated and calculated as an antigen concentration. Antigen-antibody complexes are formed when a sample containing antigen and the corresponding antiserum are put into a cuvette. A light beam is generated with an LED, which is transmitted through the cuvette. The light is scattered onto the immuno-complexes that are present. Antigen and antibody are mixed in the initial measurement, but no complex is yet formed. An antigen-antibody complex is formed in the final measurement.
The result is calculated by subtracting value of the final measurement from the initial measurement. The distribution of intensity of the scattered light depends on the ratio of the particle size of the antigen-antibody complexes to the radiated wavelength.(Unpublished Mayo method; instruction manual: Siemens Nephelometer II. Siemens, Inc; Version 2.3, 2008; Addendum to the Instruction Manual 2.3, 08/2017)
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysSpecimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82103
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| AAT | Alpha-1-Antitrypsin, S | 6771-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| AAT | Alpha-1-Antitrypsin, S | 6771-0 |