Immunoglobulin G (IgG), Serum

Casandra

Casandra Test Code MC57998Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID IGGCPT Code 82784

Immunoglobulin G (IgG), Serum

Clinical Use

Use

The Immunoglobulin G (IgG), Serum test is useful in detecting or monitoring IgG monoclonal gammopathies and immune deficiencies. Quantitative determination of immunoglobulins like IgG provides vital information on the humoral immune status, as these are produced by plasma cells during the immune response to antigens. Decreased IgG levels may signify primary immunodeficiency conditions or secondary immune insufficiencies often seen in various malignancies or diseases such as lymphatic leukemia and multiple myeloma. Monoclonal immunoglobulin proliferations detected in conditions like Waldenstrom disease and heavy-chain disease necessitate detailed diagnostic investigations beyond quantitative determination.

Special Instructions

For non-electronic orders, use the 'Gastroenterology and Hepatology Test Request' form (T728). Specimen collection must be done in a serum gel or red top container, centrifuged, and aliquoted into a plastic vial. Ensure proper handling to avoid lipemia, which can cause specimen rejection due to light scattering in nephelometry.

Limitations

Quantitative immunoglobulin analysis may not be possible in the presence of lipemia due to variable light scattering, affecting nephelometric measurements. Electrophoresis and immunofixation are typically required to classify elevated immunoglobulin as polyclonal or monoclonal. For monoclonal proteins with polyclonal backgrounds, changes in quantitation reflect changes in the background immunoglobulins, necessitating serum protein electrophoresis for accurate monitoring. Comparability of results can vary across different assay manufacturers or methods.

Test Details

FDA Approved