Immunoglobulin G, Subclasses (1-4)

CPT: 82784; 82787(x4)
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Test Details


  • IgG Subclasses
  • IgG1,2,3,4

Test Includes

Quantitation of IgG1, IgG2, IgG3, IgG4, total IgG


Study patients with recurrent bacterial infections or allergy


This procedure is not suitable for the measurement of samples containing rheumatoid factor, paraproteins, other circulating immune complexes (CICs), or for lipemic or hemolyzed samples due to the unpredictable degree of nonspecific light scatter these sample types may generate. The results obtained from measuring IgG subclasses should not be used in assessing atopy in allergic patients.



Additional Information

There are four subtypes, of which IgG1 and IgG2 comprise 85% of the total. IgG1 and IgG3 fix complement best; IgG3 is hyperaggregable and effects serum viscosity disproportionately.

IgG antibody responses to certain antigens occur to a greater extent in one type of IgG subclass than another. Therefore, some patients with normal total IgG levels may have problems with pyogenic infections because they do not produce IgG2 or combinations of IgG2, IgG3, and/or IgG4. Some clinically significant IgG subclass deficiencies occur in patients who have IgA deficiency.

The four subclasses of IgG differ in the constant regions of their heavy chains. A patient may have a normal total IgG yet still have a significant decrease in one subclass. IgG1 deficiencies are associated with EBV infections, IgG2 with sinorespiratory infections and infections with encapsulated bacteria, IgG3 with sinusitis and otitis media, and IgG4 with allergies, ataxia telangiectasia, and sinorespiratory infections. See tables in individual subclass listings.

Specimen Requirements




3 mL

Minimum Volume

1.8 mL


Red-top tube or gel-barrier tube


Transfer serum to a plastic transport tube.

Storage Instructions


Stability Requirements



Room temperature

3 days


7 days


13 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Gross lipemia; hemolysis

Clinical Information

Special Instructions

State patient's age on the test request form.


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
209601 IgG, Subclasses(1-4) 001776 Immunoglobulin G, Qn, Serum mg/dL 2465-3
209601 IgG, Subclasses(1-4) 160507 IgG, Subclass 1 mg/dL 2466-1
209601 IgG, Subclasses(1-4) 160515 IgG, Subclass 2 mg/dL 2467-9
209601 IgG, Subclasses(1-4) 160523 IgG, Subclass 3 mg/dL 2468-7
209601 IgG, Subclasses(1-4) 160531 IgG, Subclass 4 mg/dL 2469-5

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