Test Code IGG Immunoglobulin G (IgG), Serum
Additional Codes
Mayo Test ID |
---|
IGG |
Reporting Name
Immunoglobulin G (IgG), SUseful For
Detecting or monitoring of IgG monoclonal gammopathies and immune deficiencies
Performing Laboratory

Specimen Type
SerumSpecimen Required
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
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 |
---|---|---|
Serum | Refrigerated (preferred) | 28 days |
Frozen | 28 days | |
Ambient | 14 days |
Reference Values
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
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 |
---|---|---|
IGG | Immunoglobulin G (IgG), S | 2465-3 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
IGG | Immunoglobulin G (IgG), S | 2465-3 |
Clinical Information
Immunoglobulins are produced by plasma cells as a humoral immune response to contact of the immune system by antigens. The primary reaction after the initial contact is the formation of antibodies of the IgM class, followed later by IgG and IgA antibodies. Quantitative determination of the immunoglobulins can provide important information on the humoral immune status. Decreased serum immunoglobulin concentrations occur in primary immunodeficiency conditions as well as in secondary immune insufficiencies (eg, in advanced malignant tumors, lymphatic leukemia, multiple myeloma, and Waldenstrom disease).
Monoclonal immunoglobulin proliferations in the serum are found in plasmacytomas, Waldenstrom disease, and heavy-chain disease. Monoclonal immunoglobulinemia requires detailed differential diagnostic investigations in addition to the quantitative determination. Local immune reactions result in elevated immunoglobulin levels, particularly IgG, in the cerebrospinal fluid. IgA increases with asparaginase treatment, during pregnancy, with exercise, and in people with alcohol use disorder. It falls with prolonged exposure to benzene and after 1 year's abstinence from drinking alcohol. Diphenylhydantoin, dextran, methyl prednisolone, toluene, xylol, and oral contraceptives may also lower IgA levels. IgM may rise in people with narcotic addiction and after various drug use, as with IgA and IgG.
The gamma globulin band as seen in conventional serum protein electrophoresis consists of 5 immunoglobulins. In normal serum, about 80% is IgG.
Elevations of IgG may be due to polyclonal immunoglobulin production. Monoclonal elevations of IgG characterize multiple myeloma.
Monoclonal gammopathies of all types may lead to a spike in the gamma globulin zone seen on serum protein electrophoresis.
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 IgG 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; therefore, serum protein electrophoresis should be used to monitor the monoclonal protein.
Results determined by assays using different manufacturers or methods may not be comparable.
Quantitation of specific proteins by nephelometric means may not be possible in lipemic sera due to the extreme light scattering properties of the specimen. Turbidity and particles in the specimen may result in extraneous light scattering signals, resulting in variable specimen analysis.
Reject 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.
Day(s) Performed
Monday through Friday