Does this test have other names?

IgA, IgE, IgG, IgM; immunology testing

What is this test?

This test measures the amount of antibodies called immunoglobulins in your blood.

Your immune system makes antibodies to fight off bacteria, viruses, and other invaders that could harm your health. Your body makes several types of immunoglobulins or antibodies. They are called IgM, IgG, IgA, and IgE.

• IgG is found in your blood and tissue.

• IgM is mostly found in your blood.

• IgA is found at high levels in fluid your mucus membranes make, such as saliva, tears, and nasal secretions.

• IgE is mostly attached to immune system cells in your blood.

Some people have deficiencies in 1 or more of these immunoglobulins, which puts them at risk for infections.

Why do I need this test?

You may need this test if your healthcare provider suspects that you have an immunoglobulin deficiency. Symptoms of a deficiency in IgG, IgA, or IgM include frequent or severe infections, such as:

• Sinusitis

• Pneumonia

• Ear infections

• Viral lung infections

In children, this deficiency can cause poor growth and failure to thrive.

What other tests might I have along with this test?

Your healthcare provider may recommend other tests, such as:

• Complete blood count, including measuring the amount of certain cells in your blood

• Measurement of different proteins in your blood

• Urinalysis to check for kidney problems

• Tests to check for other conditions that can affect your immune system, such as kidney disease and diabetes

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results may show low levels of 1 or more immunoglobulins. Depending on the specific kind, it may mean you have one of these problems:

• Common variable immunodeficiency. This is a condition that causes the immune system to work poorly. It often shows up in young adults but may be diagnosed in children. It's marked by low IgG levels.

• Ataxia telangiectasia. This is a rare genetic disorder that causes the immune system to break down. It tends to be disabling and fatal by the time people reach their 20s.

• Multiple myeloma and certain types of leukemia , which are types of cancer

• Certain autoimmune diseases, such as lupus, rheumatoid arthritis, and Hashimoto thyroiditis

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

No other factors can affect your test results.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.