Immunoglobulins (IgA, IgG, IgM)
Antibodies of the immune system; the blood test usually measures the three main classes IgG, IgA and IgM
Also known as
Definition
Immunoglobulins are antibodies: proteins the immune system makes against germs such as viruses and bacteria. The test usually measures the three main classes. IgM is made first after contact with a germ, IgG is the most common class and helps fight off known germs quickly again, and IgA mainly protects the airways and the digestive tract. The test alone does not make a diagnosis.
| Parameter | Value |
|---|---|
| Unit | g/l (mg/dl) |
| Reference Range | Typical ranges for adults: IgG 7.0–16.0 g/l (700–1,600 mg/dl), IgA about 1.0–5.0 g/l (103–501 mg/dl), IgM 0.4–2.3 g/l (40–230 mg/dl). Labs differ; the reference range on your own report is what counts. Discuss deviations with your doctor. |
Agree on your personal target range with your doctor.
1 g/l equals 100 mg/dl.
↓ What a low value means
Low values of one or more classes can be linked to protein loss or reduced production, for example in kidney disease, severe burns, malabsorption disorders, malnutrition, complications of diabetes or an inherited immunodeficiency such as common variable immunodeficiency (CVID). Low IgA can also be due to hereditary IgA deficiency. Certain blood cancers and some chemotherapy medicines can lower values as well. A main sign of low levels can be frequent infections. Discuss deviations with your doctor.
↑ What a high value means
Elevated values can be linked to chronic infections or inflammation, autoimmune diseases such as rheumatoid arthritis, hepatitis or cirrhosis of the liver. Elevated IgM can occur in mononucleosis, for example, and elevated IgA in inflammatory bowel disease. If one class is very strongly elevated and the others are low, this can be linked to certain cancers of the blood or immune system, such as multiple myeloma. Your doctor interprets the result.
When to test
The typical reason is frequent or recurring infections, for example of the sinuses, throat, ears or airways, diarrhea, or infections with germs that rarely cause problems in healthy people. Immunodeficiency in the family can also be a reason. Usually no special preparation is needed; some labs ask you not to eat or drink for four hours beforehand. Tell your practice which medications you take, and do not stop any without talking to your doctor.
Frequently asked questions
Can the test alone identify a disease? +
No. According to MedlinePlus, an immunoglobulins test alone cannot diagnose any condition. The values of the three classes are compared with each other and with the symptoms. A deviation does not always mean that treatment is needed; medications can also affect the values.
Can frequent infections occur despite high values? +
Yes. In some autoimmune diseases and cancers, many immunoglobulins are made, but they do not work normally. Frequent infections can then occur despite high values.
Is IgE part of this test? +
The usual test measures IgG, IgA and IgM. IgE, the antibody class involved in allergic reactions, is usually measured separately, as total IgE or as specific IgE against individual allergens.
Which tests can follow? +
Depending on the result, your doctor may order further tests, such as protein electrophoresis of blood or urine, a measurement of IgA in saliva for frequent colds, sinus infections or diarrhea, or, if the brain or spinal cord could be affected, an analysis of cerebrospinal fluid.
Immunoglobulins (IgA, IgG, IgM)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.