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Test ID: IGA    
Immunoglobulin A (IgA), Serum

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Useful For Suggests clinical disorders or settings where the test may be helpful

Detection or monitoring of monoclonal gammopathies and immune deficiencies

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The gamma globulin band as seen in conventional serum protein electrophoresis consists of 5 immunoglobulins. In normal serum, about 15% is immunoglobulin A (IgA).

 

Monoclonal gammopathies of all types may lead to a spike in the gamma globulin zone seen on serum protein electrophoresis.

 

Monoclonal elevation of IgA characterize multiple myeloma.

 

Decreased immunoglobulin levels are found in patients with congenital deficiencies.

 

For your convenience, we recommend utilizing cascade testing 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. Algorithms for the cascade tests are available in Special Instructions.

-CDCOM / Celiac Disease Comprehensive Cascade: complete testing including HLA DQ

-CDSP / Celiac Disease Serology Cascade: complete testing excluding HLA DQ

-CDGF / Celiac Disease Gluten-Free Cascade: for patients already adhering to a gluten-free diet

To order individual tests, see Celiac Disease Diagnostic Testing Algorithm in Special Instructions.

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.

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

Interpretation Provides information to assist in interpretation of the test results

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 immunoglobulin A 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 Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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 which is contained in a background of polyclonal immunoglobulins, however, 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.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Webster ADB: Laboratory investigation of primary deficiency of the lymphoid system. In Clinics in Immunology and Allergy. Vol. 5. Third edition. Philadelphia, WB Saunders Company, 1985, pp 447-468

2. Pinching AJ: Laboratory investigation of secondary immunodeficiency. In Clinics in Immunology and Allergy. Vol. 5. Third edition. Philadelphia, WB Saunders Company, 1985, pp 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;90:353

4. Kyle RA, Greipp PR: The laboratory investigation of monoclonal gammopathies. Mayo Clin Proc 1978;53:719-739

5. Ballow M, O'Neil KM: Approach to the patient with recurrent infections. In Allergy: Principles and Practice. Vol. 2. Fourth edition. Edited by E Middleton Jr, CE Reed, EF Ellis, et al. St. Louis, MO, Mosby-Year Book, Inc., 1993, pp 1027-1058

6. Kyle RA: Detection of quantitation of monoclonal proteins. Clin Immunol Newsletter 1990;10:84-86

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test