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Immunoglobulins Blood Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Immunoglobulins Blood Test

An immunoglobulins blood test measures the levels of antibodies in your blood to help diagnose immune system disorders, infections, and certain types of cancer.

What is an immunoglobulins blood test?

An immunoglobulins blood test measures the amount of immunoglobulins, also known as antibodies, in your blood. Antibodies are proteins produced by your immune system to fight germs like viruses and bacteria. The test typically measures the three main types of antibodies:

  • IgM: The first antibodies produced after exposure to a germ, providing short-term protection.
  • IgG: Specialized antibodies produced in response to specific germs; the body "remembers" these to provide quick protection upon future exposure.
  • IgA: Antibodies that protect the respiratory tract and digestive system from infections.

What is it used for?

This test helps providers diagnose conditions affecting the immune system, including:

  • Autoimmune disorders, such as rheumatoid arthritis and lupus, where the immune system attacks healthy cells.
  • Certain cancers affecting the bone marrow, blood, or immune system.
  • Chronic infections.
  • Genetic diseases or infections present at birth.

Why do I need an immunoglobulins blood test?

You may need this test if you have symptoms of low immunoglobulin production, such as frequent or repeated infections. These may include:

  • Frequent sinus, throat, and ear infections.
  • Respiratory infections like pneumonia or bronchitis.
  • Gastrointestinal infections or diarrhea.
  • Serious infections from germs that typically do not affect healthy people, such as cytomegalovirus or thrush.

Your provider may also order this test if you have a family history of immunodeficiency or if they suspect your immunoglobulin levels are too high, which can occur with certain autoimmune diseases or cancers.

What happens during the test?

A health care professional will collect a blood sample from a vein in your arm using a small needle. The process typically takes less than five minutes. There is very little risk, though you may experience slight pain or bruising at the puncture site.

What do the results mean?

An immunoglobulins blood test alone cannot diagnose a condition; abnormal results usually require further testing. Low levels may be caused by kidney disease, serious burns, malnutrition, or genetic conditions like common variable immunodeficiency disorder (CVID). High levels may indicate an autoimmune disease, hepatitis, cirrhosis, chronic infection, or certain cancers, such as multiple myeloma, lymphoma, or chronic lymphocytic leukemia (CLL).

Depending on your results, your provider may order additional tests, such as a lumbar puncture to check cerebrospinal fluid, a saliva test for IgA levels, or a protein electrophoresis test.

Frequently Asked Questions

Common signs of low immunoglobulin production include frequent, severe, or recurrent infections that do not respond well to standard antibiotics. This often manifests as repeated sinusitis, ear infections, or pneumonia. Patients may also experience chronic gastrointestinal issues, such as persistent diarrhea or malabsorption, due to low IgA levels affecting the gut lining. If you find yourself hospitalized for infections more than twice a year or have infections caused by opportunistic pathogens like thrush or cytomegalovirus, your provider will likely order this test to evaluate for immunodeficiency.
Generally, no special preparation, fasting, or dietary changes are required before an immunoglobulins blood test. The test measures protein levels in the blood, which are not significantly affected by recent food intake. However, you should inform your healthcare provider about any medications you are taking, as certain drugs can influence immune function or interfere with the accuracy of the assay. If you are currently undergoing treatment for an infection or autoimmune condition, let your provider know, as active inflammation can temporarily alter antibody levels.
The pattern of these antibodies helps determine the timing and nature of an infection. IgM is the first antibody to appear, typically rising within days of exposure and indicating a recent or acute infection. IgG appears later, often weeks after exposure, and persists for a long time, providing long-term immunity and indicating past infection or vaccination. IgA is primarily found in mucosal areas and protects against respiratory and gastrointestinal infections. A high IgM with low IgG suggests a new infection, while high IgG with normal IgM suggests a past infection or resolved state. This timeline helps clinicians decide if you need immediate treatment or if your body has already developed immunity.
Yes, elevated immunoglobulin levels can indicate that the immune system is overactive or that there is an abnormal proliferation of plasma cells. High levels are often associated with autoimmune diseases like rheumatoid arthritis or lupus, chronic liver diseases such as cirrhosis, and certain blood cancers like multiple myeloma or Waldenström macroglobulinemia. Unlike low levels, which suggest a lack of defense against infection, high levels can sometimes lead to hyperviscosity syndrome, where the blood becomes too thick to flow easily, causing symptoms like blurred vision, headaches, or nosebleeds.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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