Test ID: IGAS
IgA Subclasses, 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
Investigation of immune deficiency due to IgA2 deficiency
Evaluating patients with anaphylactic transfusion reactions
Method Name A short description of the method used to perform the test
Nephelometry for Total IgA, IgA1, and IgA2
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Specimen Type Describes the specimen type needed for testing
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.
Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 1 mL
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 | Mild OK; Gross OK |
| Lipemia | Mild OK; Gross reject |
| Icterus | 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 |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Ambient | 7 days | |
| Frozen | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
IgA, the predominant immunoglobulin secreted at mucosal surfaces, consists of 2 subclasses, IgA1 and IgA2. IgA1 is the major (approximately 80%) subclass in serum. IgA2 is the major subclass in secretions such as milk. Although IgA deficiency is a common defect (1 in 700), it is usually asymptomatic. IgA deficiency with or without IgG subclass deficiency, however, can lead to recurrent pulmonary and gastrointestinal infections. Some infections (eg, recurrent sinopulmonary infections with Haemophilus influenzae) may be related to a deficiency of IgA2 in the presence of normal total IgA concentrations.
Paradoxically, bacterial infections may also cause IgA deficiency. For example, IgA1 (but not IgA2) can be cleaved and inactivated by certain bacteria, thus depleting the majority of the IgA. In the presence of a concurrent IgA2 deficiency, infection by these organisms results in an apparent IgA deficiency.
IgA deficiency is 1 cause of anaphylactic transfusion reactions. In these situations, IgA-deficient patients produce anti-IgA antibodies that react with IgA present in the transfusion product. While transfusion reactions typically occur in patients who have no detectable levels of IgA, they can occur in patients with measurable IgA. In these situations, the complete deficiency of 1 of the IgA subclasses may be the cause of the transfusion reactions.
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.
IgA
0-<5 months: 7-37 mg/dL
5-<9 months: 16-50 mg/dL
9-<15 months: 27-66 mg/dL
15-<24 months: 36-79 mg/dL
2-<4 years: 27-246 mg/dL
4-<7 years: 29-256 mg/dL
7-<10 years: 34-274 mg/dL
10-<13 years: 42-295 mg/dL
13-<16 years: 52-319 mg/dL
16-<18 years: 60-337 mg/dL
> or =18 years: 61-356 mg/dL
IgA1
0-<5 months: 10-34 mg/dL
5-<9 months: 14-41 mg/dL
9-<15 months: 20-50 mg/dL
15-<24 months: 24-58 mg/dL
2-<4 years: 16-162 mg/dL
4-<7 years: 17-187 mg/dL
7-<10 years: 21-221 mg/dL
10-<13 years: 27-250 mg/dL
13-<16 years: 36-275 mg/dL
16-<18 years: 44-289 mg/dL
> or =18 years: 50-314 mg/dL
IgA2
0-<5 months: 0.4-5.5 mg/dL
5-<9 months: 1.5-6.2 mg/dL
9-<15 months: 2.8-7.0 mg/dL
15-<24 months: 3.9-7.7 mg/dL
2-<4 years: 1.3-31.1 mg/dL
4-<7 years: 1.1-39.1 mg/dL
7-<10 years: 1.4-48.0 mg/dL
10-<13 years: 2.6-53.4 mg/dL
13-<16 years: 4.7-55.1 mg/dL
16-<18 years: 6.6-54.3 mg/dL
> or =18 years: 9.7-156.0 mg/dL
Interpretation Provides information to assist in interpretation of the test results
Low concentrations of IgA2 with normal IgA1 levels suggest an IgA2 deficiency.
Elevated concentrations of IgA2 with normal or low amounts of IgA1 suggest a clonal plasma cell proliferative disorder secreting a monoclonal IgA2.
Increased total IgA levels also may be seen in benign disorders (eg, infection, inflammation, allergy), hyper IgD syndrome with periodic fever and monoclonal gammopathies (eg, myeloma, monoclonal gammopathies of undetermined significance [MGUS]).
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Schauer U, Stemberg F, Rieger CHL, et al: Establishment of age-dependent reference values for IgA subclasses. Clin Chim Acta 2003;328:129-133
2. Saulsbury FT: Hyperimmunoglobulinemia D and periodic fever syndrome (HIDS) in a child with normal serum IgD, but increased serum IgA concentration. J Pediatrics 2003:127-129
3. Popovsky MA: Transfusion Reactions. American Association of Blood Banks, 3rd edition, 2007
Method Description Describes how the test is performed and provides a method-specific reference
The assay is performed on a Siemens NII nephelometer. Nephelometry is based on the increase in light scatter that occurs when antibody binds to antigen. The increase in light scatter is proportional to the amount of antigen present in the sample. The assay uses immune reagent sets from The Binding Site. (Package insert: Human IgA Subclass Liquid Latex Reagent Kits. The Binding Site)
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; Continuously
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.
82784-IgA
82787 x 2-Immunoglobin subclasses
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 |
|---|---|---|
| IGA_ | IgA | 2458-8 |
| IGA1_ | IgA1 | 6886-6 |
| IGA2_ | IgA2 | 6939-3 |
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