Total IgE
Total amount of immunoglobulin E antibodies in the blood; a building block of allergy lab testing
Also known as
Definition
Immunoglobulin E (IgE) is a class of antibodies that the immune system can also make against substances that are normally harmless, such as pollen or peanuts. Small amounts of IgE in the blood are normal. The total IgE test measures all IgE antibodies together, while a specific IgE test measures the amount against a single allergen. The total value does not show what someone reacts to.
| Parameter | Value |
|---|---|
| Unit | IU/ml (kU/l) |
| Reference Range | Adults and children aged ten and over: up to about 100 IU/ml (100 kU/l). Different, age-dependent values apply to children under ten. 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 IU/ml equals 1 kU/l; the number stays the same.
↓ What a low value means
Small amounts of IgE in the blood are normal. An unremarkable total IgE does not rule out an allergy, because the value is often, but not always, elevated in allergic conditions. Which allergen IgE is directed against is only measured by a specific IgE test. Your doctor interprets the result.
↑ What a high value means
An elevated total IgE can be linked to allergic conditions such as hay fever, house dust mite allergy, asthma, food allergies or atopic dermatitis (eczema); in atopic dermatitis the value is often strongly elevated. The total value, however, shows neither what someone reacts to nor how pronounced an allergy is. Smoking, a parasitic infection and a number of other conditions can also raise the value, and false positive results occur. Discuss deviations with your doctor.
When to test
Typical reasons are symptoms that may fit an allergy, such as a stuffy or runny nose, sneezing, itchy, watery eyes, hives, coughing, wheezing or shortness of breath. A blood test is also an option when a skin test is not possible. No special preparation is needed. Tell your practice which medications you take, such as antihistamines, and do not stop any without talking to your doctor.
Frequently asked questions
What is the difference between total IgE and specific IgE? +
Total IgE measures all IgE antibodies in the blood together. A specific IgE test measures how much IgE is made against a single allergen, such as grass pollen, cat or cow's milk; each allergen has its own test. According to MedlinePlus, the level in neither test predicts how severe an allergic reaction will be.
Can the result be a false positive? +
Yes. According to MedlinePlus, an allergy blood test can show an allergy that is not there, for example when the body reacts slightly to substances in foods eaten before the test. A positive result is therefore only meaningful together with matching symptoms.
What does RAST mean on a lab report? +
RAST (radioallergosorbent test) is a method from the 1970s that worked with radioactive substances. The name is still sometimes used for the allergy blood test, but today methods without radioactivity are used. Specific IgE is often reported in classes, such as a CAP class, which roughly ranges from negative to strongly positive.
Does the blood test replace the skin test? +
Not necessarily. The blood test is mainly an option when a skin test is not possible, for example with certain skin conditions, medications that affect the result, or a high risk of a serious reaction. For young children it is sometimes chosen because a skin test can be uncomfortable for them. Depending on the symptoms, both tests are combined.
Total IgE
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.