Test ID: CA1A
Alpha-1-Antitrypsin Clearance, Feces and Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosing protein-losing enteropathies
Profile Information A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CA1A_ | Clearance | No | Yes |
| A1A24 | Alpha-1-Antitrypsin, 24 Hr, F | No | Yes |
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Nephelometry
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Alpha 1 Antitrypsin
Alpha 1 Antitrypsin (A1A) Clearance, Feces and Serum
Antitrypsin Fecal Clearance
Intestinal Clearance of Alpha-1-Antitrypsin
A1A
Anti-Alpha-1-Trypsin
AAT (Alpha-1-Antitrypsin)
Specimen Type Describes the specimen type needed for testing
Serum
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Feces and serum are required.
Blood must be drawn during the stool collection period.
Specimen Type: Serum
Collection Container/Tube: Red top or serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Specimen Type: Stool
Container/Tube: Stool container (Supply T291)
Specimen Volume: Entire collection
Collection Instructions:
1. Collect a 24-hour stool collection.
2. If no specimen is obtained in 24 hours, extend collection to 48 to 72 hours. Note time frame.
3. See Stool Collection Information Sheet in Special Instructions.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Feces: NA Serum: Mild OK; Gross OK |
| Lipemia | Feces: NA Serum: Mild OK; Gross OK |
| Icterus | Feces: NA Serum: Mild OK; Gross OK |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Fecal | Frozen (preferred) | 14 days |
| Ambient | 14 days | |
| Refrigerated | 14 days | |
| Serum | Frozen (preferred) | 14 days |
| Ambient | 14 days | |
| Refrigerated | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Alpha-1-antitrypsin (A1A) 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. A1A clearance is reliable for measuring protein loss distal to the pylorus.
Gastrointestinal protein enteropathy has been associated with regional enteritis, sprue, Whipple's intestinal lipodystrophy, gastric carcinoma, allergic gastroenteropathy, intestinal lymphangiectasia, constrictive pericarditis, congenital hypogammaglobulinemia, and iron deficiency anemia associated with intolerance to cow's milk.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Clearance: < or =27 mL/24 hours
Fecal alpha-1-antitrypsin concentration: < or =54 mg/dL
Serum alpha-1-antitrypsin concentration: 100-190 mg/dL
Interpretation Provides information to assist in interpretation of the test results
Elevated alpha-1-antitrypsin (A1A) clearance suggests excessive gastrointestinal protein loss. (The positive predictive value of the test has been found to be 97.7% and the negative predictive value is 75%.)
Patients with protein-losing enteropathies generally have A1A clearance values >50 mL/24 hours and A1A stool concentrations >100 mg/mL.
Borderline elevations above the normal range are equivocal for protein-losing enteropathies.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
In the absence of either a 24-hour stool collection or a contemporary serum specimen, the fecal concentration of alpha-1-antitrypsin (A1A) can be used as a surrogate marker. The clearance is preferred in order to normalize the large range of serum A1A concentrations and the variability in random stool A1A concentration.
Supportive Data
Protein-losing enteropathy has been studied by intravenous injection of radioactive chromium chloride or labeled human serum albumin. The correlation between radiochromium and stool alpha-1-antitrypsin clearance has been measured with excellent correlation coefficients.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Florent C, L'Hirondel C, Desmazures C, et al: Intestinal Clearance of alpha 1-antitrypsin. A sensitive method for the detection of protein losing enteropathy. Gastroenterology 1981;81:777-780
2. Crossley JR, Elliott RB: Simple method for diagnosing protein-losing enteropathy. Br Med J 1977;1:428-429
3. Perrault J, Markowitz H: Protein-losing gastroenteropathy and the intestinal clearance of serum alpha-1-antitrypsin. Mayo Clin Proc 1984;59:278-279
Method Description Describes how the test is performed and provides a method-specific reference
Nephelometry. Immunonephelometry quantitates the alpha-1-antitrypsin (A1A) contained in a 24-hour stool collection. From the concentration of stool A1A and serum A1A, a 24-hour clearance is calculated. In the absence of a serum specimen and/or a timed stool collection, an A1A stool concentration will be reported. (Instruction manual: Siemens Nephelometer II Siemens, Inc., Newark, DE)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Saturday; 2 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82103
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| AAT24 | Alpha-1-Antitrypsin, 24 Hr, F | 46429-7 |
| CRCLR | Clearance | In Process |
| AATS | Alpha-1-Antitrypsin, S | 6771-0 |
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