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Test Code IGA Immunoglobulin A (IgA)

Additional Codes

Epic: LAB73

Specimen Required

Specimen Type: Serum

Collection Container/Type

Preferred: Serum gold

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 3 mL

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

Specimen Minimum Volume

0.25 mL

Specimen Stability

Room temperature: 8 months

Refrigerated: 8 months

Frozen: 8 months

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.

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

Rejection Due To

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

Day(s) and Time(s) Performed

Daily

Report Available

Same day / 1 day

Method Name

Immunoturbidimetric

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.

LOINC

2458-8