Overview: Immunoglobulin G (IgG) TestIntroduction: The Immunoglobulin G (IgG) Test measures IgG levels to diagnose immune deficiencies or infections, causing fatigue or infections. Following 2023 AAAAI guidelines, it uses immunoassays for high accuracy, supporting immune screening. This test is critical for guiding diagnosis, treatment planning, and improving outcomes in immunology for patients with suspected immune deficiencies or infections.
Other Names: IgG Serum Assay, Total IgG Test.
FDA Status: Laboratory-developed test (LDT), meeting immunology standards for diagnostic accuracy.
Historical Milestone: IgG testing began in the 1960s with immune research. Immunoassay-based methods improved in the 1990s, enhancing diagnostic precision.
Purpose: Measures IgG levels to diagnose immune deficiencies or infections, guides treatment, and evaluates patients with fatigue or infections.
Test Parameters: 1. Immunoglobulin IgG
Pretest Condition: No fasting required. Collect serum, plasma, or saliva at any time. Report history of infections, fatigue, or immune deficiencies.
Specimen: 2-5 mL serum (SST), 2-4 mL plasma (EDTA), or 1-2 mL saliva (sterile container). Transport in a biohazard bag.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 7 days
Sample Stability at Frozen: 6 months
Medical History: Document infections, fatigue, or family history of immune deficiencies. Include current medications, especially immunoglobulins.
Consent: Written consent required, detailing the tests purpose, immune deficiency implications, and potential need for immunoglobulin therapy.
Procedural Considerations: Uses immunoassays to measure IgG levels. Results are available in 1-2 days, supporting rapid clinical decisions. Performed in laboratories, often for immune assessment.
Factors Affecting Result Accuracy: Improper sample handling or contamination can affect results. Recent infections or immunoglobulin therapy may influence levels.
Clinical Significance: Low IgG suggests immune deficiency, guiding immunoglobulin therapy. Elevated IgG may indicate chronic infections, requiring further testing.
Specialist Consultation: Consult an immunologist for result interpretation and treatment planning.
Additional Supporting Tests: IgA, IgM, or lymphocyte subset analysis to assess immune function.
Test Limitations: Not specific to one condition; clinical correlation is needed. IgG levels vary with age or infections.
References: AAAAI Immune Deficiency Guidelines, 2023; Journal of Allergy and Clinical Immunology, Bonilla FA, 2022.
