IgE (Total and Specific), Allergy Blood Test
Definition
There are two types of test:
- Total IgE measures the total immunoglobulin E antibodies in the blood
- Specific IgE measures the IgE response to a single allergen; a separate test is needed for each substance
Purpose
Ordered for patients with nasal congestion/runny nose, itchy watery eyes, hives, breathing problems or digestive complaints. It is especially valuable in people who cannot have a skin test: those with skin disease, drug interactions or a risk of serious reaction.
Results
- High total IgE may point to the presence of allergy, but does not show which allergen or how severe
- High specific IgE, possible allergy to the tested allergen; however, the IgE level does not predict the severity of the reaction
Normal Values
Laboratory specific.
Risks and Limitations
A positive result alone cannot diagnose an allergy.
- False positive: A mild reaction to food eaten before the test or smoking can raise IgE
- False negative: Rare but possible
Results must be interpreted together with the clinical picture; a positive laboratory result does not mean you actually develop a reaction when you eat or inhale that substance.