Serum or plasma mass concentration of immunoglobulin G (IgG) antibodies against pneumococcal polysaccharides (pneumococcal antibody level)

What Does This Test Measure?

The test looks for the presence and amount of IgG antibodies that target common pneumococcal antigens. These antibodies are part of your immune system’s defense against pneumococcal bacteria, which can cause serious illnesses like pneumonia, meningitis, or bloodstream infections.

Why Might You Need This Test?

Your healthcare provider may order this test if you’ve had a pneumococcal vaccine, recently had a pneumococcal infection, or if you’re at higher risk of pneumococcal infections (e.g., due to weakened immune systems, chronic health conditions, or age). It can also help monitor immune function in certain medical situations.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate the serum or plasma, where the antibodies are measured using a specialized laboratory technique.

What Are Possible Results?

Results are typically reported as a mass concentration (e.g., grams per liter). Higher levels may indicate a strong immune response, while lower levels could suggest insufficient antibody production, possibly due to immune deficiency or recent vaccination.