what does total IgE test for?

What is Total IgE?

Total IgE measures the level of antibodies in the blood made by the immune system in response to an allergen.

Immunoglobulin E (IgE) is an antibody that causes an allergic reaction. When exposed to an allergen (typically a harmless substance that the immune system considers dangerous, such as peanuts), the body produces specific IgE antibodies designed to recognize that allergen in the future. Then, with repeated exposure to the same allergen, the immune system quickly produces large numbers of allergen-specific IgE particles to identify and eliminate the allergen.

What is Total IgE?

The total IgE test detects the presence of IgE antibodies in the blood, indicating an increased chance of an allergic reaction. The test for allergen-specific IgE particles is then used to obtain information about the specific substance causing the allergic reaction.

How do I know if I have allergies?

Allergic reactions range from localized red spots, itchy skin, to anaphylaxis, which includes a sudden drop in blood pressure and difficulty breathing.

Allergic reactions can vary greatly in type and severity depending on the individual and allergy. The following symptoms are strong indications that IgE needs to be measured:

• Itchy eyes or watery eyes

• Sneezing and/or coughing

• Intermittent or persistent itching, hives

• Stuffy nose

• Persistent diarrhea

• Difficulty breathing

• Nausea or vomiting 44

What is a normal IgE level?

IgE test results are expressed in Fluorescent Assay Standard Units (FSU). A number less than 0.01 FSU indicates no detectable IgE.

Generally, the higher the IgE level, the higher the risk of allergic symptoms. Each potential allergen is assigned a class according to this level as shown below.

Class 0/1

0.01–0.34 BSS

Clinical significance not established

Class 1

0.35-0.70

Low sensitivity

Class 2

0.71-3.50

Moderate sensitivity

Class 3

3.51-17.50

High Sensitivity

Class 4 or higher

17.51-50.00

Ultra High Sensitivity

Class 5

50.01-100.00

Ultra High Sensitivity

>100

Highly sensitive

What does high IgE mean?

Higher IgE levels are more likely to cause symptoms of allergy to a specific allergen, but lower classes of allergens also need to be controlled. They can contribute to the buildup of allergy burden during allergy season, for example.

What if IgE is elevated?

If your IgE levels are elevated due to indoor, outdoor or food allergies, a board-certified allergist can work with you to develop a program to help relieve your symptoms.

This may include the use of antihistamines and other drugs, allergen avoidance, and immunotherapy.