Allergy tests
What is analysed?
Allergy tests are used to identify specific allergens that may be triggering allergic reactions.
Common types of allergy tests include:
- Blood tests, including the total IgE test
- Skin tests, including the skin prick test, the patch test, and the intradermal test
- Food challenges, including the elimination diet
Specifically, the total IgE test measures the total amount of specific IgE (immunoglobulin E) to an allergen in the blood in order to identify an allergen to a particular substance. IgE is an allergen-specific antibody in the blood.
What does the result mean?
The result of the total IgE test indicates the concentration of IgE antibodies in the blood, suggesting whether a patient has developed an immune response to a specific allergen.
Why conduct the analysis?
The total IgE test is conducted to help diagnose allergies. In some cases, the analysis may also be performed to monitor the effectiveness of allergy treatments like immunotherapy.
When to conduct the analysis?
The total IgE test is conducted when symptoms of an allergic reaction, such as sneezing, itchy skin or difficulty breathing, are observed.
What sample is required?
A blood sample is used for the analysis of total IgE levels. The blood is drawn from a vein, usually in the arm.
Is any prior preparation necessary?
Patients should fast for 8-12 hours before the blood sample is taken. In addition, patients should also inform a healthcare professional about any medications being taken, as they could affect results.
How is it performed?
The collected blood sample is sent to a laboratory, where it is analysed using techniques such as enzyme-linked immunosorbent assay (ELISA) or radioallergosorbent test (RAST) to quantify IgE levels.
What are the normal values?
| Total IgE level | Normal range (Approximate) |
|---|---|
| Children (0-15 years) | Up to 100 IU/mL |
| Adults (16 years and above) | Up to 100 IU/mL |
Normal values indicate the absence of an IgE antibody response against a specific allergen, suggesting the absence of an allergy. However, the possibility of an allergy shouldn’t be ruled out completely.
What does having altered values mean?
- Elevated total IgE levels: Elevated total IgE levels indicate hypersensitivity or an allergic response to specific allergens. However, this doesn’t necessarily mean that the patient will develop an allergy when exposed to the specific allergens.