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HelpTest Code IGA Immunoglobulin A (IgA), Serum
Reporting Name
Immunoglobulin A (IgA), SUseful For
Detection or monitoring of IgA monoclonal gammopathies and IgA-related immune deficiencies
Testing Algorithm
The following algorithms are available:
-Celiac Disease Comprehensive Cascade Test Algorithm
-Celiac Disease Diagnostic Testing Algorithm
-Celiac Disease Gluten-Free Cascade Test Algorithm
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
Cascade testing is recommended for celiac disease. Cascade testing ensures that testing proceeds in an algorithmic fashion. The following cascades are available; select the appropriate one for your specific patient situation.
-CDCOM / Celiac Disease Comprehensive Cascade, Serum and Whole Blood: Complete testing including HLA DQ
-CDSP / Celiac Disease Serology Cascade, Serum: Complete serology testing excluding HLA DQ
-CDGF / Celiac Disease Gluten-Free Cascade, Serum and Whole Blood: For patients already adhering to a gluten-free diet
To order individual tests, see Celiac Disease Diagnostic Testing Algorithm.
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 14 days |
Special Instructions
Reference Values
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
≥18 years: 61-356 mg/dL
Day(s) Performed
Monday through Friday
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82784
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| IGA | Immunoglobulin A (IgA), S | 2458-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| IGA | Immunoglobulin A (IgA), S | 2458-8 |
Clinical Information
The gamma globulin band as seen in conventional serum protein electrophoresis consists of 5 immunoglobulins. In normal serum, about 15% is IgA.
Monoclonal gammopathies of all types may lead to a spike in the gamma globulin zone seen on serum protein electrophoresis.
Monoclonal elevations of IgA characterize multiple myeloma.
Decreased immunoglobulin levels are found in patients with congenital deficiencies.
Interpretation
Increased serum immunoglobulin concentrations occur due to polyclonal or oligoclonal immunoglobulin proliferation in hepatic disease (hepatitis, liver cirrhosis), connective tissue diseases, acute and chronic infections, as well as in the cord blood of neonates with intrauterine and perinatal infections.
Elevation of IgA may occur in monoclonal gammopathies such as multiple myeloma, primary systemic amyloidosis, monoclonal gammopathy of undetermined significance, and related disorders.
Decreased levels are found in patients with primary or secondary immune deficiencies.
Cautions
Electrophoresis is usually required to interpret an elevated immunoglobulin class as polyclonal versus monoclonal. Immunofixation is usually required to characterize a monoclonal protein.
If there is a discrete M-peak, the monoclonal protein can be monitored with quantitative immunoglobulins.
If immunoglobulin quantitation is used to monitor the size of a monoclonal protein that is contained in a background of polyclonal immunoglobulins, changes in the immunoglobulin quantitation may reflect changes in the background immunoglobulins, and serum protein electrophoresis should therefore be used to monitor the monoclonal protein.
Results determined by assays using different manufacturers or methods may not be comparable.
Clinical Reference
1. Webster ADB: Laboratory investigation of primary deficiency of the lymphoid system. In: Clinics in Immunology and Allergy. Vol 5. 3rd ed. WB Saunders Company; 1985:447-468
2. Pinching AJ: Laboratory investigation of secondary immunodeficiency. In: Clinics in Immunology and Allergy. Vol 5. 3rd ed. WB Saunders Company; 1985:469-490
3. Dispenzieri A, Gertz MA, Kyle RA: Distribution of diseases associated with moderate polyclonal gammopathy in patients seen at Mayo Clinic during 1991. Blood. 1997;90:353A
4. Kyle RA, Greipp PR: The laboratory investigation of monoclonal gammopathies. Mayo Clin Proc. 1978 Nov;53(11):719-739
5. Ballow M, O'Neil KM: Approach to the patient with recurrent infections. In: Middleton Jr E, Reed CE, Ellis, et al. Allergy: Principles and Practice. Vol 2. 4th ed. Mosby-Year Book, Inc; 1993:1027-1058
6. Kyle RA: Detection of quantitation of monoclonal proteins. Clin Immunol Newsletter. 1990 June;10(6):84-86
7. Dietzen DJ, Willrich MAV: Amino acids, peptides, and proteins. In: Rifai N, Chiu RWK, Young I, Burnham CAD, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:chap 31
Method Description
In this Siemens Nephelometer II method, the light scattered onto the antigen-antibody complexes is measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions. If the antibody volume is kept constant, the signal behaves proportionally to the antigen volume.
A reference curve is generated by a standard with a known antigen content on which the scattered light signals of the samples can be evaluated and calculated as an antigen concentration. Antigen-antibody complexes are formed when a sample containing antigen and the corresponding antiserum are put into a cuvette. A light beam is generated with a light emitting diode, which is transmitted through the cuvette. The light is scattered onto the immuno-complexes that are present. Antigen and antibody are mixed in the initial measurement, but no complex is formed yet. An antigen-antibody complex is formed in the final measurement.
The result is calculated by subtracting the value of the final measurement from the initial measurement. The distribution of intensity of the scattered light depends on the ratio of the particle size of the antigen-antibody complexes to the radiated wavelength.(Instruction manual: Siemens Nephelometer II, Siemens, Inc.; Version 3, 2008; Addendum to the Instruction Manual 2.3, 08/2017)
Report Available
1 to 3 daysSpecimen Retention Time
14 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Method Name
Nephelometry
Forms
If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Test Request (T728) with the specimen.