RAST test: allergy blood tests explained

By HealthEngine

Last updated: 17 January 2017

What is an allergy blood test?

An allergy blood test (radioallergosorbent or RAST test) may be requested when a specific allergy is in question.

The test gives an indication of antibodies to a specific trigger antigen, such as pollen or house-dust mite.

When would you need a RAST test?

Your doctor may request a RAST test in the event of severe allergy, asthma or hayfever, where the precipitating substance (known as an antigen) is not clear.

A subgroup of antibodies called IgE antibodies are strongly associated with the abnormal immune system response in allergic reactions.

Amongst these IgE antibodies, allergen-specific IgE antibody numbers can be measured by the RAST test.

How is a RAST test performed?

A radioallergosorbent test is a blood test and requires a blood sample from a vein.

RAST test results explained

RAST test results are given in terms of an antibody titer.

Related tests

Also known as

  • Radioallergosorbent test
  • IgE
  • Allergy screen



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This article is for informational purposes only and should not be taken as medical advice. If in doubt, HealthEngine recommends consulting with a registered health practitioner.