IgG Immunoglobulin (Serum) - Mass Concentration

What Is IgG Used For?

IgG is the primary antibody produced by your immune system to protect against bacteria and viruses. It plays a critical role in long-term immunity, helping your body remember past infections to fight them more effectively if exposed again. This test is often used to evaluate immune function, diagnose immune system disorders, or monitor conditions like chronic infections or autoimmune diseases.

When Might You Need This Test?

Your healthcare provider may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or signs of an autoimmune condition. It may also be used in newborns to check for congenital immune deficiencies or in patients receiving immune-modulating treatments.

What Does a Low or High IgG Level Mean?

Low IgG levels may indicate an immune deficiency, where your body struggles to produce enough antibodies to fight infections. High IgG levels can sometimes suggest chronic infections, autoimmune diseases, or certain types of cancer, though this is less common and requires further evaluation.

How Is the Test Done?

A blood sample is drawn from a vein in your arm. The blood is then processed to separate the serum (the liquid part without clots), and the IgG level is measured using a specialized immunoassay technique. The test typically takes a few hours to complete, and results are reported as a mass concentration value.