IgG Immunoglobulins (Plasma / Serum)

Test Identifier Information

As a stand alone IgG test

End-point Nephelometry: - Latex particles are coated with protein specific anti-human antibodies (e.g. anti-IgG) forming antigen:antibody complexes, when exposed to serum containing that specific protein. The latex particles improve sensitivity by increasing the turbidity of the antigen:antibody complex in solution. Quantitative nephelomtric measurement of the turbidity is proportional to the concentration of the protein in the serum. Serum protein concentrations can then be calculated by comparing the turbidity to that of a known standard. 

As part of the Serum Protein Profile (SPE)

Immunoelectrophoresis: - Electrophoretic separation of proteins in an anti-sera impregnated gel resulting in quantitative identification of specific proteins. 

Quantitative analysis of IgG is useful for:

• Detection and monitoring of immunodeficiency
• Monitoring of monoclonal gammopathies*

Note:* If light chain multiple myeloma (LCMM), primary systemic amyloidosis (AL), or light chain deposition disease (LCDD) is suspected, Serum Free Light Chains(SFLC) should also be considered.

Note: Quantitative analysis may be unreliable if a cryoglobulin is suspected.

Specimen Collection

Instructions for Referral to CHLabs

CHLabs Laboratory

Type and age dependant

Quantitative analysis does not distinguish between monoclonal, oligoclonal, or polyclonal elevation. Serum Protein Profile (SPE) and Immunofixation should be used to determine if any increase is due to a monoclonal band.

Note:

• Quantitative analysis may be unreliable if a cryoglobulin is suspected.
• Acute infections may elevate IgG levels to levels within the normal range in patients who  may have hypogammaglobulinaemia.

A monoclonal elevation of IgG is indicative of gammopathies such as:

• Multiple myeloma
• Monoclonal gammopathy of uncertain significance (MGUS)
• Other related disorders.

Oligoclonal or polyclonal elevation of IgG may arise from:

• Proliferative liver diseases (e.g. Hepatitis, cirrhosis)
• Connective tissue diseases
• Infections, acute and chronic.
• Immunoglobulin levels may also be elevated if blood is extracted from the umbilical cord of neonates where there has been an intrauterine or perinatal infection.

IgG deficiencies may be due to:

• Primary or secondary immunodeficiency.
• Immunosuppression due to the presence of a plasma cell dyscrasia.

Refer to Protein Chemistry Lab Ext 80334.