The IgG blood test is used to detect either a deficiency or an extra amount of immunoglobulins that are in the blood. This information gives medical providers an idea of a patient’s overall health in regards to their immune system. This test can also be used to help diagnose certain health conditions or diseases that affect IgG levels.
Immunoglobulins are often better known as “antibodies.” They are proteins that are produced by a body’s plasma cells. They target specific invasion threats so that viruses, bacteria, and other micro-organisms cannot cause harm. The IgG blood test is often ordered in conjunction with urine protein tests and other serum tests to help determine a specific diagnosis.
When Will Doctors Order the IgG Blood Test?
This blood test is generally ordered when an immunoglobulin deficiency is suspected. The symptoms of such a deficiency may include recurrent infections, especially in the sinuses and lungs. Chronic diarrhea and other gastro-intestinal symptoms may also be caused by a problem with IgG levels in the blood. Chronic inflammation of an unknown cause may also have a medical provider order this test.
The IgG blood test can also be used as a tracking mechanism to determine the effectiveness of a treatment plan.
If there is a family history of immunodeficiency, then a medical provider may order the test on a routine basis to track health development. The most common reason why this test is ordered is because of a medical history that includes several opportunistic infections that do not seem to generate a proper response from the body.
What Do the Test Results Mean?
Most medical providers will evaluate three immunoglobulin blood tests at the same time: IgG, IgA, and IgM levels are will usually be tested together. If the results come back as abnormal, then this is an indication that there is something within the body that is currently affecting the immune system. Abnormal results generally result in additional testing to determine a specific need because it can provide strong indications of disease or a specific condition, but not a definitive result.
If your IgG blood test has high results:
High results are seen with a number of different conditions. When an increase in just IgG is seen, then this is typically due to leukemia, multiple myeloma, or lymphoma. If all three immunoglobulins have high results, then this can be because of an infection, an autoimmune disorder, or inflammatory disorders. A hyperimmunization reaction may also cause this type of result. Extra cells may even be monoclonal, which means they are clones of just one plasma cell.
If your IgG blood test has low results:
Most low results on this blood test are because of an acquired condition. Medications and other conditions that artificially lower immunoglobin levels are the most common cause of this result. It may also be because of diabetes, kidney failure, or a transient delay in production if the test was conducted on a newborn. Burns, digestive disorders, and nephrotic syndrome which causes proteins to be removed through the urine may also cause low results.
Certain inherited immune disorders have also been known to cause low results on the IgG blood test, but these disorders are rather rare. They may affect levels of all immunoglobulin classes or just affect the IgG class. CVID, X-linked agammaglobulinemia, Wiskott-Aldrich syndrome, and SCID are all possible diagnostic options for a medical provider.
What You Need to Know About the IgG Blood Test
When IgG levels are low, a person’s exposure to infection development is higher. In newborns, it may just be an indication that the child’s immune system has yet to kick in and begin working. For adults, then the deficiency must have a specific cause and specific testing to determine those causes will be ordered as a follow-up.
IgG levels do not normally change because of lifestyle activities. No test preparation is needed to have the blood draw completed either. Some patients may be able to give a saliva sample in lieu of a blood sample. In severe immunoglobulin deficiencies, a cerebrospinal fluid sample may be requested by a medical provider instead. Most people will never need to have this test done over the course of their life.
The IgG blood test is ordered to evaluate a person’s immune system status. It is only ordered when a problem is suspected. Use this guide to discuss with your doctor what your results may mean and if future testing may be required so that a specific diagnosis can be achieved.