Understanding the Immunoglobulin G (IgG) Test
What It Is: The Immunoglobulin G (IgG) test measures the level of IgG antibodies in your blood. IgG is the most common type of antibody found in blood circulation, representing approximately 75% of serum antibodies in humans. These antibodies play a crucial role in protecting the body against infections by "remembering" which germs you've been exposed to before.
Why It's Important: IgG is essential for long-term immunity and protection against infections. It helps the immune system recognize and respond more effectively to pathogens that the body has encountered previously. Monitoring IgG levels can provide valuable information about your immune system's health and its ability to fight off infections.
Role of IgG:
Infection Control: IgG antibodies bind to pathogens such as viruses, bacteria, and fungi, helping to neutralize and eliminate them.
Immune Memory: IgG antibodies "remember" past infections, allowing the immune system to respond more quickly and effectively if the same pathogen is encountered again.
Protection: IgG can cross the placenta, providing passive immunity to the fetus during pregnancy. It also plays a role in antibody-dependent cell-mediated cytotoxicity (ADCC) and intracellular antibody-mediated proteolysis.
How IgG Works:
Production: IgG antibodies are produced by plasma B cells in response to exposure to antigens (foreign substances).
Circulation: IgG circulates in the blood and extracellular fluid, allowing it to control infections in body tissues.
What to Expect During the Test:
Blood Sample Collection: A healthcare professional will draw a small sample of your blood, usually from a vein in your arm.
Laboratory Analysis: The sample is then sent to a lab where the level of IgG is measured.
Interpreting the Results:
Normal IgG Levels: Typically range from 700 to 1,600 milligrams per deciliter (mg/dL) in adults.
High IgG Levels: May indicate conditions such as chronic infections, autoimmune diseases, or multiple myeloma.
Low IgG Levels: May suggest conditions such as immunodeficiency disorders, chronic lymphocytic leukemia, or kidney disease.
Why Your Doctor Might Order This Test:
Diagnosing Immune Disorders: To check for conditions like immunodeficiency disorders or autoimmune diseases.
Monitoring Symptoms: If you have symptoms such as recurrent infections, chronic fatigue, or unexplained weight loss, this test can help diagnose the underlying cause.
Evaluating Immune Function: To assess your overall immune function and response to infections.
Symptoms That Might Prompt This Test:
Recurrent infections (e.g., sinusitis, bronchitis)
Chronic fatigue
Unexplained weight loss
Autoimmune symptoms (e.g., joint pain, skin rashes)