Serum Immunoassay for Total Immunoglobulin G (IgG) Concentration

Your doctor may order this test if you have frequent or severe infections, unexplained fatigue, or other symptoms that suggest your immune system is not working as it should. It may also be used to monitor conditions that affect antibody levels, such as immune deficiencies, certain allergies, or autoimmune disorders.

Your healthcare provider may order this test if you have symptoms like frequent infections, unusual fatigue, or if you’re being evaluated for conditions like immunodeficiency, autoimmune diseases, or certain cancers. It may also be used to monitor treatment progress for conditions affecting your immune system.

Before the test, your healthcare provider will explain the procedure and answer any questions you may have. In most cases, no special preparation is needed, and you can eat and drink normally beforehand. Be sure to tell your provider about any medications or supplements you take, since some of these can affect your results.

No special preparation is usually needed. You may fast before the test if instructed, but your provider will let you know. Bring any medications you’re currently taking, as some can affect test results.

During the test, a healthcare professional will clean a small spot on your arm, wrap a band around your upper arm, and draw a blood sample from a vein using a thin needle. The procedure usually takes only a few minutes, and you may feel a quick pinch or mild discomfort when the needle goes in.

A small needle will be used to draw blood from a vein in your arm. You may feel a slight pinch, but it’s usually over quickly. The blood sample is then sent to a lab for testing.

Possible results may show IgG levels that are normal, low, or high. A normal level suggests your body is producing antibodies as expected. A low level can point to an immune deficiency or certain kidney or digestive conditions, while a high level may be linked to infections, inflammation, or autoimmune disease. Your provider will explain what your specific results mean for you.

Results are typically reported as a concentration value (e.g., grams per liter). While reference ranges can vary by lab, lower than expected levels may indicate immune deficiency, while higher levels could suggest conditions like multiple myeloma or chronic infections.