Immunoglobulin E, or IgE, is a protein present in low concentrations in the blood and 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 generally related to allergies, however, its concentration may also be increased in the blood due 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 measurement of total IgE can be indicated to check for 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 fungus and which affects the respiratory system. Learn more about aspergillosis.
Despite being one of the main tests in the diagnosis of allergy, the increased IgE concentration 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 on the type of allergy, and it is necessary to carry out the IgE measurement in specific situations in order to check the concentration of this immunoglobulin against various stimuli, which is the test called specific IgE.
Normal values of total IgE
The immunoglobulin E value varies according to the person's age and the laboratory in which the test is performed, which may be:
| Age | Reference value |
| 0 to 1 year | Up to 15 kU / L |
| Between 1 and 3 years | Up to 30 kU / L |
| Between 4 and 9 years | Up to 100 kU / L |
| Between 10 and 11 years | Up to 123 kU / L |
| Between 11 and 14 years | Up to 240 kU / L |
| From 15 years | 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 may also be increased in the case of inflammatory bowel diseases, chronic infections and liver diseases, for example.
How the exam is done
The total IgE test must be done with the person fasting for at least 8 hours, and a blood sample is collected and sent to the laboratory for analysis. The result is released in at least 2 days and the concentration of immunoglobulin 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 result of other tests. The total IgE test does not provide specific information on the type of allergy, and it is recommended that additional tests be performed.
