The RAST test or EAST test are different names for the same test. They are blood tests.
This test (the RAST / EAST specific IgE tests) measures the level of “specific” IgE to various allergens. They give the same results as the skin tests.
To order the test you need to specify what allergens to test for – for example, egg white, cow’s milk, cat fur, rye grass pollen.
RAST / EAST specific IgE tests
- are useful to pick up QUICK onset allergy reactions (that is IgE immediate sensitivity)
- will be negative to gluten in gluten-sensitivity
- are blood tests
- are positive in anaphylaxis people
- give the same information as skin prick tests.
To order the EAST test, you have to ask for EAST tests for specific individual foods, food groups, or specific environmental allergens (such as birch pollen, or cat fur, or dog hair, or house dust mite). In my experience, my patients would rather see a skin prick test rather than see the results of an EAST test.
EAST test will be negative in slow-onset food reactions. They are not useful to detect gluten reactions.
Total IgE test
A very high level means a lot of allergic reaction.
A level between 0-100 units means that you are not very allergic (not atopic).
Some people have levels greater than 2,500.
People with high total IgE levels often benefit a lot from taking a regular antihistamine medication.
Extremely high levels of IgE warrant further investigation. This can sometimes be evidence of a chronic parasitic infestation of the gut with worms.
When to get RAST / EAST specific IgE tests?
If skin prick testing is not available.
In older children and adults when skin prick testing is not as reliable.
Especially to follow peanut and other nut allergy.