Immunoglobulin A, Subclasses (1-2)

CPT: 82784; 82787(x2)
Print Share


  • IgA Subclasses
  • IgA1,2

Test Includes

Quantitation of IgA1, IgA2, total IgA

Expected Turnaround Time

3 - 6 days

Related Documents

Specimen Requirements




2 mL

Minimum Volume

1 mL


Red-top tube or gel-barrier tube


Transfer specimen to a plastic transport tube.

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gross lipemia; hemolysis

Test Details


Study IgA deficiencies in patients in association with recurrent sinopulmonary infections or repeated transfusions; study IgA elevations associated with IgA myeloma



Additional Information

Two classes of IgA have been identified in humans: IgA1, which accounts for 80% to 90% of total serum IgA, and IgA2 which is the major subclass in secretions such as milk. The two subclasses appear to be regulated independently. Antigenic sites on the IgA subclasses are responsible for the anaphylactic transfusion reactions experienced by some patients totally deficient in either IgA1 or IgA2. After repeated transfusions, such patients may produce antibodies to these antigens. IgA subclasses are of further importance in that certain pathogenic microörganisms, including Haemophilus influenzae, are capable of enzymic cleavage of IgA1, leading to partial inactivation of this subclass. Recurrent sinopulmonary infections may, therefore, be related to deficiency of IgA2, which is resistant to these organisms. Grossly elevated levels of either subclass can occur in patients with IgA myeloma.


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
123049 IgA, Subclasses (1-2) 001784 Immunoglobulin A, Qn, Serum mg/dL 2458-8
123049 IgA, Subclasses (1-2) 123050 IgA, Subclass 1 mg/dL 6886-6
123049 IgA, Subclasses (1-2) 123051 IgA, Subclass 2 mg/dL 6939-3

For Providers

Please login to order a test

Order a Test

© 2021 Laboratory Corporation of America® Holdings and Lexi-Comp Inc. All Rights Reserved.

CPT Statement/Profile Statement

The LOINC® codes are copyright © 1994-2021, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at Additional information regarding LOINC® codes can be found at, including the LOINC Manual, which can be downloaded at