Immunoglobulin G (IgG)

Test Code

IGG

Alias/See Also

Epic: LAB71

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 3 mL

Minimum Volume

0.25 mL

Other Acceptable Specimens

Collection Container: Red top

Instructions

Centrifuge and separate cells after clot formation and within 4 hours of collection.

Transport Container

Plastic vial

Specimen Stability

Room temperature: 4 months
Refrigerated: 8 months
Frozen: 8 months

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

nlabeled, mislabeled, wrong tube type, visually lipemic, QNS, exceeds specimen stability requirements.

Methodology

Immunoturbidimetric

Setup Schedule

Daily

Report Available

Same day

Limitations

Samples containing paraproteins (abnormal monoclonal antibodies) may incorrectly fall within the reference range. Samples with elevated total protein concentrations or suspected paraproteinemia can be screened with other methods such as electrophoresis. Turbidity and particles in samples can interfere with the assay. Therefore, particulate matter should be removed by centrifugation prior to running the assay.

Reference Range

0 - 1 month: 391 - 1765 mg/dL
1 month - 1 year: 203 - 948 mg/dL
1 - 2 years: 475 - 1226 mg/dL
2 - 150 yers: 540 - 1822 mg/dL

Clinical Significance

IgG is the major immunoglobulin in the blood and is produced in copious amounts during secondary immune responses. IgG molecules bind to specific receptors on phagocytic cells, such as macrophages and polymorphonuclear leukocytes, thereby increasing the efficiency with which the phagocytic cells can ingest and destroy infecting microorganisms that have become coated with IgG antibodies in response to the infection. IgG molecules are the only antibodies that can pass from mother to fetus. The ability of IgG to cross the placenta provides a major line of defense against infection for the first weeks of an infant’s life. Quantitation of IgG can be used to evaluate humoral immunity, establish diagnosis and monitor therapy in IgG myeloma, and evaluate patients, especially children and those with lymphoma, with propensity to infections. Reduction of IgG, usually less than 300mg/dL, leads to susceptibility to infection due to encapsulated bacteria. Elevated IgG levels can be polyclonal, oligoclonal, or monoclonal.
Elevated polyclonal IgG levels are associated with autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, and Sjogren’s syndrome), chronic liver disease, some parasitic diseases, chronic or recurrent infections, and intrauterine contraceptive devices. Increased oligoclonal IgG levels are associated with malignancies, infections (especially in the elderly), some dysgammaglobulinemias, and autoimmune disorders. Increased monoclonal IgG levels are associated with multiple myeloma (IgG type), lymphomas, and leukemia.

Performing Laboratory

Inova Laboratories

2832 Juniper Street

Fairfax, VA 22031

Last Updated: April 11, 2023
Last Review: N. Wolford, April 11, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.