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Diagnostic Tests 2023

Immunoglobulin E (IgE): what é and why can it be high

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Immunoglobulin E (IgE): what é and why can it be high
Immunoglobulin E (IgE): what é and why can it be high

Immunoglobulin E, or IgE, is a protein present in low concentrations in the blood and that is normally found on the surface of some blood cells, mainly basophils and mast cells, for example.

Because it is present on the surface of basophils and mast cells, which are cells that normally appear in higher concentrations in the blood during allergic reactions, IgE is usually related to allergies, however, its concentration can also be increased in the blood due to to diseases caused by parasites and chronic diseases, such as asthma, for example.


What is it for

The total IgE dosage is requested by the doctor according to the person's history, especially if there are complaints of constant allergic reactions. Thus, the dosage of total IgE can be indicated to verify the occurrence of allergic reactions, in addition to being indicated in the suspicion of diseases caused by parasites or bronchopulmonary aspergillosis, which is a disease caused by a fungus that affects the respiratory system. Learn more about aspergillosis.

Despite being one of the main tests in the diagnosis of allergy, the increased concentration of IgE in this test should not be the only criterion for the diagnosis of allergy, and an allergy test is recommended. In addition, this test does not provide information about the type of allergy, and it is necessary to measure IgE in specific situations in order to verify the concentration of this immunoglobulin in the face of various stimuli, which is the test called specific IgE.

How the exam is done

To perform the IgE test, it is not necessary to fast, a blood sample is collected and sent to the laboratory for analysis. The result is released in about at least 2 days and the immunoglobulin concentration in the blood is indicated, as well as the normal reference value.

It is important that the result is interpreted by the doctor together with the results of other tests. The total IgE test does not provide specific information about the type of allergy, and complementary tests are recommended.

Normal values of total IgE

The value of immunoglobulin E varies according to the age of the person and the laboratory where the test is performed, and may be:

Age Reference value
0 to 1 year Up to 15 kU/ L
Between 1 and 3 years old Up to 30 kU/ L
Between 4 and 9 years old Up to 100 kU/ L
Between 10 and 11 years old Up to 123 kU/ L
Between 11 and 14 years old Up to 240 kU/ L
From 15 years old Up to 160 kU/ L

What does high IgE mean

The main cause of increased IgE is allergy, however there are other situations in which there may be an increase in this immunoglobulin in the blood, the main ones being:

  • Allergic rhinitis;
  • Atopic eczema;
  • Parasitic diseases;
  • Inflammatory diseases such as Kawasaki disease, for example;
  • Myeloma;
  • Bronchopulmonary aspergillosis;
  • Asthma.

In addition, IgE can also be increased in the case of inflammatory bowel diseases, chronic infections and liver diseases, for example.

Hyper IgE Syndrome

Hyper IgE syndrome is a type of primary immunodeficiency in which IgE levels above normal for age can be noted, as well as increased levels of circulating eosinophils. In this type of alteration it is possible to have eczema, the appearance of abscess by bacteria in the skin, lungs and joints, in addition to a decrease in bone mass and an increase in the frequency of fractures.

It is important that the general practitioner, rheumatologist or immunoallergist be consulted so that it is possible to conclude the diagnosis and start the most appropriate treatment according to the symptoms presented by the person, which may involve the use of antibiotics, antihistamines or skin creams.

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