Serum IgG Immunoglobulin Level

What Is Immunoglobulin G (IgG)?

IgG, or Immunoglobulin G, is the primary antibody in your blood that plays a key role in defending against bacteria and viruses. It’s produced by your immune system in response to infections and helps remember past illnesses to prevent future ones. IgG is found in high levels in serum (the liquid part of blood after clotting) and is crucial for protecting tissues and organs from infections.

Why Might You Need This Test?

Your doctor may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow healing wounds, or unexplained fatigue. It can also be used to monitor conditions like HIV, lupus, or certain autoimmune diseases where IgG levels might be abnormal.

What Could Abnormal Results Mean?

Low IgG levels may indicate an immune deficiency, where your body struggles to fight infections effectively. High IgG levels could suggest an overactive immune response, chronic infections, or certain medical conditions like multiple myeloma or severe allergies.

How Is This Test Done?

A blood sample is drawn from a vein in your arm, usually in a clinic or lab. The blood is then processed to separate serum (the liquid part) for testing. The test measures the concentration of IgG antibodies in this serum using an immunoassay method, which detects the presence and amount of antibodies.