Immunoglobulin G (IgG) in Serum, Mass Concentration

What Does This Test Measure?

IgG is one of the most common types of antibodies in your blood. It plays a key role in defending your body against bacteria and viruses. This test helps doctors assess your immune system’s ability to produce antibodies, which is important for fighting infections and maintaining immunity over time.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, unusual fatigue, or if you’re being treated for conditions like autoimmune diseases, certain cancers, or after receiving certain medical treatments (e.g., chemotherapy). It can also be part of monitoring for conditions like HIV or other immune-related disorders.

What to Expect Before the Test

No special preparation is usually needed for this blood test. You may be asked to fast before the test if it’s part of a larger panel, but this is not always required for IgG alone. Bring any medications or supplements you’re taking to your appointment.

What to Expect During the Test

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch or discomfort, but it usually only takes a few minutes. The blood sample will be sent to a lab for analysis.