Patient education: Immunoglobulin blood test (The Basics)

What is an immunoglobulin blood test? — This is a test to measure the levels of certain "immunoglobulins" in the blood. Immunoglobulins are antibodies, or proteins, that the immune system makes to fight germs.

There are different types of immunoglobulins. An immunoglobulin blood test measures:

●Immunoglobulin A ("IgA")

●Immunoglobulin G ("IgG")

●Immunoglobulin M ("IgM")

If your immune system is not working as it should, your immunoglobulin levels might be higher or lower than normal. For example:

●Low immunoglobulin levels happen if your body does not make the antibodies it should when you are exposed to a germ. The medical term for this is "immunodeficiency." Some people are born with this problem. But more commonly, it is related to certain medicines or diseases that affect how the immune system works.

Sometimes, levels can be slightly low during or just after an infection. In that case, the test should be repeated at least 1 more time.

●High immunoglobin levels can be caused by different health problems. These include "autoimmune" disease, which is when the immune system makes antibodies that attack healthy cells in the body. Liver disease, frequent infections, blood disorders, and some types of cancer can also cause high immunoglobulin levels.

Why might I need an immunoglobulin blood test? — Your doctor might order this test:

●To help figure out why you keep getting infections

●If you have other symptoms that might be related to an immune system problem, like frequent diarrhea or lung problems

●If immune system disorders run in your family

●If they think that you might have an autoimmune disease

●If you have symptoms that could be related to cancer, like anemia without a known cause

●To see how treatment is working if you have a known autoimmune disease or certain types of cancer

How do I prepare for an immunoglobulin blood test? — For this test, you need to get a "blood draw." Your doctor or nurse will tell you where to go for this.

It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.

What happens during a blood draw? — For the blood draw, a needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.

Tell the person who takes your blood:

●If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure that your bleeding is under control before you leave.

●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.

●If you have a preferred arm to use

Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.

What do my results mean? — Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.

If your immunoglobulin level is abnormal, your doctor or nurse will talk to you about what to do next. They might need to do more tests to figure out what the cause is.

If you do have a health problem, your doctor will work with you to come up with a plan for treatment.