What is a RAST test?

RAST stands for Radioallergosorbent Test, and it is a type of blood test used to identify specific allergies. The test works by measuring the levels of allergy-causing antibodies in the blood, known as IgE (immunoglobulin E) antibodies. These antibodies are produced by the immune system in response to exposure to allergens such as pollen, dust mites, mold, pet dander, and certain foods.

The RAST test is often used to help diagnose allergies in people who have symptoms such as sneezing, itching, runny nose, and skin rashes, but it is not as commonly used as it used to be due to the availability of other, more sensitive tests such as ImmunoCAP. The RAST test is typically ordered by an allergist or other healthcare provider, and the results can help guide treatment decisions and recommendations for avoiding allergens in the future.

RAST test verses skin test

The RAST (Radioallergosorbent Test) and skin test are two different methods for testing for allergies.

A RAST test is a blood test that measures the levels of IgE (immunoglobulin E) antibodies in the blood that are specific to certain allergens. This test is performed in a laboratory and does not require any skin pricks. The results of the test usually take a few days to come back.

A skin test, on the other hand, involves exposing a small area of skin to a small amount of an allergen. If the person is allergic to that substance, they will develop a reaction in the form of redness, itching, or swelling at the site of the exposure. Skin tests are performed by allergists or other healthcare providers and the results are available within minutes.

Both the RAST test and skin test have their own advantages and disadvantages. The RAST test is less invasive and does not cause any discomfort, but it is not as sensitive as the skin test and may not detect all allergies. The skin test is more sensitive and can detect allergies more accurately, but it can cause minor discomfort and, in rare cases, severe reactions.

The choice between a RAST test and skin test typically depends on the person's individual needs and medical history, as well as the recommendations of their healthcare provider.

What can RAST test for?

The RAST (Radioallergosorbent Test) test can be used to test for a wide range of allergens, including:

• Food allergens, such as peanuts, tree nuts, shellfish, fish, milk, eggs, soy, and wheat.

• Environmental allergens, such as pollen from trees, grasses, and weeds, dust mites, mold, pet dander, and insect venom.

• Medications, such as penicillin and other antibiotics, aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs).

• Latex.

The RAST test measures the levels of IgE (immunoglobulin E) antibodies in the blood that are specific to each allergen. The results of the test can help diagnose allergies and guide treatment decisions, such as recommendations for avoiding allergens in the future or prescribing medications to manage symptoms.

RAST test procedure

The procedure for a RAST (Radioallergosorbent Test) test typically involves the following steps:

1. Ordering the test: The RAST test is usually ordered by an allergist or other healthcare provider based on the individual's symptoms and medical history.

2. Blood draw: A healthcare provider will draw a sample of blood from the person being tested, usually from a vein in the arm.

3. Processing the sample: The blood sample is then sent to a laboratory for processing, where it is exposed to a panel of allergens that the person is being tested for.

4. Measuring IgE levels: The laboratory measures the levels of IgE antibodies in the blood that are specific to each allergen.

5. Reading the results: The results of the test are typically available in a few days, and they are expressed as a numerical value indicating the level of IgE antibodies for each allergen.

6. Interpreting the results: An allergist or other healthcare provider will interpret the results and use them, along with the person's medical history, symptoms, and other diagnostic tests, to make a diagnosis of an allergy and provide recommendations for treatment and management.

It is important to note that the RAST test is not a diagnostic test, and a positive result does not necessarily mean that a person has an allergy. The results should be interpreted in conjunction with a thorough medical evaluation, including a physical examination and other diagnostic tests as necessary, to make a definitive diagnosis of an allergy.

When should you get an allergy test?

You may consider getting an allergy test if you have symptoms that suggest you have an allergy, such as:

• Sneezing
• Runny or stuffy nose
• Itching eyes, nose, or throat
• Skin rashes or hives
• Shortness of breath or wheezing
• Stomach cramps, diarrhea, or nausea (related to food allergies)

It is also a good idea to get an allergy test if you have a family history of allergies, or if you have been previously diagnosed with an allergy and your symptoms have changed or become more severe.

Allergy tests can be ordered by your primary care physician or by an allergist, a healthcare provider who specializes in the diagnosis and treatment of allergies. The choice of testing method will depend on your individual needs and medical history, as well as the recommendations of your healthcare provider.