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Test Code IGGS IgG Subclasses, Serum

Reporting Name

IgG Subclasses, S

Useful For

A second-order test for evaluating patients with clinical signs and symptoms of humoral immunodeficiency or combined immunodeficiency (cellular and humoral)

 

Testing for immunoglobulin G (IgG) subclass levels may be indicated in patients with clinical evidence of a possible immunodeficiency with hypogammaglobulinemic patients or normal concentrations of total serum IgG.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Ambient  14 days
  Frozen  14 days

Reference Values

TOTAL IgG

0-<5 months: 100-334 mg/dL

5-<9 months: 164-588 mg/dL

9-<15 months: 246-904 mg/dL

15-<24 months: 313-1,170 mg/dL

2-<4 years: 295-1,156 mg/dL

4-<7 years: 386-1,470 mg/dL

7-<10 years: 462-1,682 mg/dL

10-<13 years: 503-1,719 mg/dL

13-<16 years: 509-1,580 mg/dL

16-<18 years: 487-1,327 mg/dL

≥18 years: 767-1,590 mg/dL

 

IgG1

0-<5 months: 56-215 mg/dL  

5-<9 months: 102-369 mg/dL

9-<15 months: 160-562 mg/dL

15-<24 months: 209-724 mg/dL

2-<4 years: 158-721 mg/dL

4-<7 years: 209-902 mg/dL

7-<10 years: 253-1,019 mg/dL

10-<13 years: 280-1,030 mg/dL

13-<16 years: 289-934 mg/dL

16-<18 years: 283-772 mg/dL

≥18 years: 341-894 mg/dL

 

IgG2

0-<5 months: ≤82 mg/dL

5-<9 months: ≤89 mg/dL

9-<15 months: 24-98 mg/dL

15-<24 months: 35-105 mg/dL

2-<4 years: 39-176 mg/dL

4-<7 years: 44-316 mg/dL

7-<10 years: 54-435 mg/dL

10-<13 years: 66-502 mg/dL

13-<16 years: 82-516 mg/dL

16-<18 years: 98-486 mg/dL

≥18 years: 171-632 mg/dL

 

IgG3

0-<5 months: 7.6-82.3 mg/dL

5-<9 months: 11.9-74.0 mg/dL

9-<15 months: 17.3-63.7 mg/dL

15-<24 months: 21.9-55.0 mg/dL

2-<4 years: 17.0-84.7 mg/dL

4-<7 years: 10.8-94.9 mg/dL

7-<10 years: 8.5-102.6 mg/dL

10-<13 years: 11.5-105.3 mg/dL

13-<16 years: 20.0-103.2 mg/dL

16-<18 years: 31.3-97.6 mg/dL

≥18 years: 18.4-106.0 mg/dL

 

IgG4

0-<5 months: ≤19.8 mg/dL

5-<9 months: ≤20.8 mg/dL

9-<15 months: ≤22.0 mg/dL

15-<24 months: ≤23.0 mg/dL

2-<4 years: 0.4-49.1 mg/dL

4-<7 years: 0.8-81.9 mg/dL

7-<10 years: 1.0-108.7 mg/dL

10-<13 years: 1.0-121.9 mg/dL

13-<16 years: 0.7-121.7 mg/dL

16-<18 years: 0.3-111.0 mg/dL

≥18 years: 2.4-121.0 mg/dL

Day(s) and Time(s) Performed

Monday through Saturday; Continuous

Test Classification

This test has been cleared or approved by the U.S. 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-IgG, total

82787 x 4-IgG subclasses

LOINC Code Information

Test ID Test Order Name Order LOINC Value
IGGS IgG Subclasses, S 47289-4

 

Result ID Test Result Name Result LOINC Value
T_IGG Total IgG 2465-3
IGG1 IgG 1 2466-1
IGG2 IgG 2 2467-9
IGG3 IgG 3 2468-7
IGG4 IgG 4 2469-5

Clinical Information

The most abundant immunoglobulin in human serum is immunoglobulin G (IgG) (approximately 80% of the total). IgG protein is comprised of molecules of 4 subclasses designated IgG1 through IgG4. Each subclass contains molecules with a structurally unique gamma heavy chain. Of total IgG, approximately 65% is IgG1, 25% is IgG2, 6% is IgG3, and 4% is IgG4. Molecules of different IgG subclasses have somewhat different biologic properties (eg, complement fixing ability and binding to phagocytic cells), which are determined by structural differences in gamma heavy chains. Clinical interest in IgG subclasses concerns potential immunodeficiencies (eg, subclass deficiencies) and IgG4-related diseases (eg, IgG4 elevations). The IgG subclass assay (IGGS / IgG Subclasses, Serum) is best for deficiency testing, and the IgG4 assay (IGGS4 / Immunoglobulin Subclass IgG4, Serum) is best for IgG4-related disease testing.

 

Diminished concentrations of IgG subclass proteins may occur in the context of hypogammaglobulinemia (eg, in common variable immunodeficiency where all immunoglobulin classes are generally affected) or deficiencies may be selective, usually involving IgG2. Deficiency of IgG1 usually occurs in patients with severe immunoglobulin deficiency involving other IgG subclasses. Deficiency of IgG2 is more heterogeneous and can occur as an isolated deficiency or in combination with deficiency of immunoglobulin A (IgA), or of IgA and other IgG subclasses. Most patients with IgG2 deficiency present with recurrent infections, usually sinusitis, otitis, or pulmonary infections. Children with deficiency of IgG2 often have deficient antibody responses to polysaccharide antigens including bacterial antigens associated with Haemophilus influenzae type B and Streptococcus pneumoniae. Isolated deficiencies of IgG3 or IgG4 occur rarely, and the clinical significance of these findings is not clear.

Interpretation

Diminished concentrations of all immunoglobulin G (IgG) subclasses are found in common variable immunodeficiency, combined immunodeficiency, ataxia telangiectasia, and other primary and acquired immunodeficiency diseases.  

 

A diminished concentration of IgG2 protein may be clinically significant in the context of recurrent sinopulmonary infection and may occur with or without concomitant immunoglobulin A deficiency.

 

Slightly diminished concentrations of 1 or more IgG subclass proteins are not uncommon, and usually have little clinical significance.

 

Conversely, some individuals with deficient specific antibody responses to polysaccharide antigens may have normal serum levels of IgG subclasses.

Clinical Reference

Umetsu DT, Ambrosino DM, Quinti I, et al: Recurrent sinopulmonary infection and impaired antibody response to bacterial capsular polysaccharide antigen in children with selective IgG-subclass deficiency. N Engl J Med 1985;313:1247-1251

Analytic Time

1 day

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross reject

Icterus

Mild OK; Gross OK

Other

NA

Method Name

Nephelometry

Includes total immunoglobulin G.

Forms

If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf).