Immunoglobulin A (IgA)

Test Code

IGA

Alias/See Also

Epic: LAB73

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 3 mL

Minimum Volume

0.25 mL

Other Acceptable Specimens

Collection Container: Red top

Instructions

Centrifuge and separate cells after clot formation and within 4 hours of collection.

Transport Container

Plastic vial

Specimen Stability

Room temperature: 8 months
Refrigerated: 8 months
Frozen: 8 months

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unlabeled, mislabeled, wrong tube type, hemolyzed, visually lipemic, QNS, exceeds specimen/stability requirements.

Methodology

Immunoturbidimetric

Setup Schedule

Daily

Report Available

Same day

Limitations

Samples containing paraproteins (abnormal monoclonal antibodies) may incorrectly fall within the reference range. Samples with elevated total protein concentrations or suspected paraproteinemia can be screened with other methods such as electrophoresis. Turbidity and particles in samples can interfere with the assay. Therefore, particulate matter should be removed by centrifugation prior to running the assay.

Reference Range

Males
0 - 3 months: 1 - 34 mg/dL
>3 months: 8 - 91 mg/dL
1 - 12 years: 21 - 291 mg/dL
12 - 60 years: 63 - 484 mg/dL
>60 years: 101 - 645 mg/dL

Female
0 - 3 months: 1 - 34 mg/dL
>3 months: 8 - 91 mg/dL
1 - 12 years: 21 - 282 mg/dL
12 - 60 years: 65 - 421 mg/dL
>60 years: 69 - 517 mg/dL

Clinical Significance

Approximately 10-15% of serum immunoglobulin is IgA. Serum IgA is predominantly found in monomeric form with 10-15% as a dimer. Secretory IgA, found in tears, sweat, saliva, milk, colostrum and gastrointestinal and bronchial secretions, is synthesized mainly by plasma cells in mucous membranes and breast ductules. IgA can initiate complement activation by alternative pathway. Secretory IgA plays a major role in the protection of the respiratory, genitourinary, and gastrointestinal tracts against infection. The specific role of serum IgA is unclear, but may be important in virus neutralization. Indications for serum IgA quantification include recurrent infections, anaphylactic transfusion reactions, differentiation of M-components in myeloma, and evaluation of progression of IgA myeloma.
IgA does not cross the placenta, and as a result, IgA levels in infants’ sera are very low. Serum IgA levels do not reach adult concentrations until 12 years of age. Approximately one in every 700 caucasians is genetically IgA deficient. Individuals with absent IgA have a higher than expected incidence of rheumatic disorders and lymphoma. Secondary IgA deficiency is seen in non-IgA or multiple myeloma or macroglobulinemia, and with nephrotic syndrome.
Elevated IgA levels are associated with both polyclonal as well as monoclonal increases. Polyclonal increases include chronic liver disease, chronic infections, and neoplasia of the lower GI tract, inflammatory bowel disease, and autoimmune disease such as rheumatoid arthritis. Monoclonal increases include IgA multiple myeloma and occasionally other lymphomas.

Performing Laboratory

Inova Laboratories

2832 Juniper Street

Fairfax, VA 22031

Last Updated: April 11, 2023
Last Review: April 11, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.