What is an immunoglobulins blood test?

This test measures the amount of immunoglobulins in your blood. Immunoglobulins are also called antibodies. Antibodies are proteins that your immune system makes to fight germs, such as viruses and bacteria. When you're exposed to germs, your body makes unique antibodies that are specifically designed to destroy only those germs.

An immunoglobulins test usually measures three main types of immunoglobulin (Ig) antibodies that do different jobs to protect your health:

• IgM antibodies are the first immunoglobulins your body makes after you're exposed to germs. They provide short-term protection while your body makes other antibodies. IgM antibodies are in your blood and lymph fluid (a watery fluid that carries the cells that fight infections and diseases to all parts of your body).
• IgG antibodies are very important for fighting infections from bacteria and viruses. Most of the immunoglobulins in your blood are IgG. You also have some IgG antibodies in all your body fluids. Your body keeps a "blueprint" of all the IgG antibodies you have made. That way, if you're exposed to the same germs again, your immune system can quickly make more antibodies.
• IgA antibodies protect your respiratory tract (the organs you use to breathe) and your digestive system (the organs you use to eat and digest food) from infections. You have IgA antibodies in your blood, saliva, and gastric "juices."

An immunoglobulins blood test measures the amounts of IgM, IgG, and IgA in your blood to help diagnose different types of health conditions that may affect your immune system.

Other names: quantitative immunoglobulins, total immunoglobulins, IgG, IgM, IgA testing

What is it used for?

An immunoglobulins blood test may be used to:

• Check the health of your immune system if you are often sick with infections or diarrhea
• Help diagnose and monitor a variety of conditions that may cause abnormal levels of IgM, IgG, and/or IgA, such as:
  • Autoimmune disorders. With these disorders your immune system attacks your own healthy cells by mistake, including cells that make immunoglobulins. Examples of autoimmune disorders include rheumatoid arthritis and lupus.
  • Certain types of cancer that affect your bone marrow, blood, or immune system
  • Chronic (long-term) infections
  • Genetic diseases you're born with (uncommon)
• Check for certain infections a baby may be born with, including syphilis or toxoplasmosis

Why do I need an immunoglobulins blood test?

You may need this test if you have symptoms that could mean your immunoglobulin levels are too low. If you have too few immunoglobulins, you have an immunodeficiency.

Symptoms of low levels of immunoglobulins usually include having many, repeated infections and other problems, such as:

• Sinus, throat, and ear infections
• Respiratory infections, such as pneumonia and bronchitis
• Diarrhea
• Serious infections from germs that don't usually cause problems in healthy people, such as:
  • Cytomegalovirus (a virus related to chickenpox)
  • A yeast infection in the mouth, eyes, or digestive tract (thrush)

You may need an immunoglobulins test if immunodeficiency runs in your family, or your health care provider thinks you may have a problem making normal levels of immunoglobulins.

You may also need this test if your provider thinks you may have high levels of immunoglobulins from an autoimmune disease or a cancer that affects your blood, bone marrow, and/or immune system. These cancers may cause a very high level of certain immunoglobulins. But those immunoglobulins don't work normally. So, even though your levels are high, you may have frequent infections and other symptoms of low immunoglobulin levels.

What happens during an immunoglobulins blood test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don't need any special preparations for an immunoglobulins blood test.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

Your provider will compare your levels of IgM, IgG, and IgA. Your results can mean different things, depending on which immunoglobulins are high or low, your symptoms, and any conditions you may have. An immunoglobulins blood test alone cannot diagnose any conditions. So if your results aren't normal, you'll probably need more testing to find out what's affecting your immune system.

Some possible causes of low levels of one or more immunoglobulins are:

• Conditions that may reduce the amount of protein in your body, including:
  • Kidney disease
  • Serious burns
  • Certain malabsorption disorders
  • Malnutrition
• Conditions that affect your ability to make immunoglobulins, including:
  • Complications from diabetes
  • Kidney failure
• A genetic disease that you were born with, such as common variable immunodeficiency disorder (CVID)

Some possible causes of high levels of one or more immunoglobulins are:

• An autoimmune disease
• Hepatitis
• Cirrhosis
• A chronic infection
• Certain cancers. These cancers often cause a very high level of one type of immunoglobulin and low levels for the other types:
  • Multiple myeloma
  • Chronic lymphocytic leukemia (CLL)
  • Lymphoma
  • Waldenstrom macroglobulinemia

If your immunoglobulin levels aren't normal, it doesn't always mean you have a condition that needs treatment. Certain medicines can affect your results. If you have questions about your results, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about an immunoglobulins blood test?

If your symptoms suggest that an immune condition may be affecting your spine or brain, your provider may order an immunoglobulin test on a sample of your cerebrospinal fluid (CSF). If your symptoms include frequent colds, sinus infections, or diarrhea, your saliva may be tested for IgA levels.