RAST test (radioallergosorbent test)

a small sample of the patient's blood along with extracts of the different foods or substances that are under suspicion will be tested for the possible allergen. The main advantages of this test are that it cannot be influenced by drugs or by specific skin diseases that are present but not diagnosed at the time of the test. In addition, a greater number of allergens can be assessed with a single extraction. This would include an infinite number of allergens, among the most common: milk protein, anisakis, Dermatophagoides farinae (D2), Dermatophagoides pteronyssinus (D1), olive tree, alternaria (A. tenuis), grasses, etc. Consult the laboratory for allergens.

There are no requirements for this test, no need to fast. Neither is an appointment necessary, blood draws are performed from 8:00h – 10:30h from Monday to Friday.

The results are delivered after 4-6 days.

The radioallergosorbent test, or RAST, is a laboratory test that is performed on the blood. This test checks the amount of specific lgE antibodies in the blood, which are present if there is a “true” allergic reaction.

Allergies are a common chronic problem affecting the immune system. Normally, the immune system fights viruses, bacteria, and other infectious agents. With an allergy, the immune system treats a harmless substance such as dust or pollen as a threat. To fight it, it produces antibodies called immunoglobulin E (IgE).

The substances that cause an allergic reaction are called allergens. There are common food allergies and allergens in addition to pollen and dust such as animal dander, foods such as nuts and shellfish, and certain medications such as penicillin. Allergy symptoms can range from sneezing and stuffy nose to a potentially life-threatening complication called anaphylactic shock. Blood allergy tests measure the amount of IgE antibodies in the blood. A small amount of IgE antibodies is normal. But high IgE levels may indicate an allergy.

When talking about food allergies, it is important to understand the difference between allergies and food intolerances.

  • IgE food allergy: an evident pathology in which a component of the food triggers an immediate reaction, such as diarrhoea, oedema, hives, etc.
  • IgG-type food intolerance: It is more difficult to detect and its symptoms are usually moderate, so it is common for us not to notice this intolerance and to go back to eating foods that are harmful to us and make us sick. That is why it is so important to perform such tests.

If you have doubts about which test to take, do not hesitate to consult us.