The RAST test or radioallergosorbent test is undertaken to determine if a person is allergic to a certain substance or a group of substances. RAST blood test checks for an antibody known as immunoglobulin E (IgE) to measure the immune system's reaction to specific allergens or a range of allergens.
RAST Test
Here are the basic details for RAST Test.
| Also Known As |
Radioallergosorbent Test, IgE Allergy Test, Specific IgE Test |
| Type |
Blood Test |
Purpose
|
Checks IgE in Blood |
| Sample Type |
Blood |
| Preparation |
No Special Preparation Required |
| Fasting |
No |
| Gender |
All |
| Age-Group |
Any |
| Normal Value |
0.10 kU/L to 100 kU/L |
| Reporting Time |
1 to 2 hours |
Cost
|
500 - 1000* INR |
*Price range may vary as per location, lab type, and procedure of lab test.
RAST Test Full Form
Full Form of RAST Test is Radioallergosorbent Test.
RAST Test Means
The RAST test (Radioallergosorbent Test) is a blood test used to diagnose allergies.
- It measures the level of IgE antibodies in the blood in response to specific allergens.
- IgE antibodies are produced by the immune system in response to allergens and are responsible for triggering allergic reactions.
- The RAST test can help identify which allergens a person is allergic to, which can guide treatment and prevention strategies.
- The RAST test is often used when skin testing (another method of allergy testing) is not possible or is not appropriate.
- Results of the RAST test are reported as a numerical value (usually on a scale of 0 to 5 or 6) indicating the level of IgE antibodies detected for each allergen tested.
- A higher numerical value indicates a higher level of IgE antibodies and therefore a stronger allergic response.
- The RAST test is not foolproof and can produce false positives or false negatives, so it should be interpreted by a qualified healthcare professional in the context of the patient's medical history and symptoms.
Interesting Facts About RAST
- RAST was developed as an alternative to skin prick tests for diagnosing allergies, particularly for individuals who cannot undergo skin testing due to certain medical conditions or medication use.
- Unlike skin prick tests, the RAST test does not cause immediate allergic reactions, making it a safer option for individuals with severe allergies.
RAST Test Purpose
Here are some key points about the purpose of the RAST test:
- The RAST test is a blood test used to diagnose allergies.
- It is used to identify which allergens a person is allergic to, which can guide treatment and prevention strategies.
- The RAST test measures the level of IgE antibodies in the blood in response to specific allergens.
- IgE antibodies are produced by the immune system in response to allergens and are responsible for triggering allergic reactions.
- The RAST test is often used when skin testing (another method of allergy testing) is not possible or is not appropriate.
- The RAST test can be used to diagnose allergies to a variety of substances, including foods, pollen, pet dander, and insect venom.
- The RAST test can also be used to monitor the effectiveness of allergy treatments, such as immunotherapy.
- Overall, the purpose of the RAST test is to help healthcare professionals identify and manage allergies in their patients.
RAST Test Preparation
Here are some key points about the preparation for, during, and after the RAST test:
Before Test
- Follow any instructions provided by your healthcare provider regarding fasting or discontinuing certain medications before the test.
- Wear loose, comfortable clothing that allows easy access to your arm for the blood draw.
- Bring any relevant medical records or information, such as a list of medications you are currently taking or a history of previous allergic reactions.
During Test
- A healthcare provider will draw blood from a vein in your arm using a needle and syringe.
- The process typically takes a few minutes and may be slightly uncomfortable, but should not be painful.
- After the blood is drawn, a bandage will be placed over the site to stop any bleeding.
After Test
- You can typically resume normal activities immediately after the test.
- You may experience some bruising or soreness at the site where the blood was drawn, which should go away within a few days.
- Results of the RAST test will be communicated to you by your healthcare provider, who will discuss the implications and any necessary follow-up steps.
- Depending on the results, your healthcare provider may recommend additional testing or treatment, or may advise you on strategies for avoiding the identified allergens.
Summary
Prepare for a RAST test by following instructions, wearing comfortable clothing, and discussing relevant medical information, then expect a blood draw procedure and consult with your healthcare provider about the results and any necessary actions.
RAST Test Procedure
Here are some key points about the RAST test procedure:
- The RAST test (short for radioallergosorbent test) is a blood test used to diagnose allergies.
- Before the test, a healthcare provider will clean the area where the blood will be drawn with an antiseptic solution.
- The provider will then use a needle to draw a small amount of blood from a vein in your arm.
- The blood sample will be sent to a laboratory for analysis.
- In the laboratory, the blood sample will be exposed to specific allergens to measure the level of IgE antibodies in the blood in response to each allergen.
- The results of the test are reported as a numerical value (usually on a scale of 0 to 5 or 6) indicating the level of IgE antibodies detected for each allergen tested.
- The healthcare provider will review the results with you and discuss any necessary follow-up steps, such as additional testing or treatment.
- The entire procedure typically takes about 10-15 minutes, though you may need to wait a few days for the results to be available.
RAST Test Result
RAST test results are reported as a numerical value (usually on a scale of 0 to 5 or 6) indicating the level of IgE antibodies detected for each allergen tested.
- A higher numerical value indicates a higher level of IgE antibodies and therefore a stronger allergic response.
- The results should be interpreted by a qualified healthcare professional in the context of the patient's medical history and symptoms, as well as any other allergy test results.
- The healthcare professional will use the results to help identify which allergens are triggering the patient's symptoms and develop an appropriate treatment plan.
RAST Test Report
RAST Test Report PDF
RAST Test Normal Report
RAST Normal Test Report PDF Format
RAST Test Normal Result Report PDF
RAST Test Abnormal Report
RAST Abnormal Test Report PDF Format
RAST Test Abnormal Result Report PDF
RAST Test Normal Range
Here is the normal range for RAST Test IgE Level.
| Grade |
IgE Level |
Comment |
| Grade 0 |
<0.35 KUA/L |
Negative or Undetectable Level |
| Grade 1 |
0.35-0.7 KUA/L |
Weak Positive Level |
| Grade 2 |
0.7-3.5 KUA/L |
Moderate Positive Level |
| Grade 3 |
3.5-17.5 KUA/L |
High Positive Level |
| Grade 4 |
17.5-52.5 KUA/L |
Strong Positive Level |
| Grade 5 |
52.5-100 KUA/L |
Very Strong Positive Level |
| Grade 6 |
>100 KUA/L |
Extremely Strong Positive Level |
RAST Test Interpretation
Here is an example table that could be used for interpreting RAST test results for various allergens:
| Allergen Tested |
RAST Test Result |
Interpretation |
| Dust mites |
4.5 KUA/L |
Strongly positive for dust mite allergy |
| Pollen (grass) |
1.2 KUA/L |
Weakly positive for grass pollen allergy |
| Cat dander |
0.8 KUA/L |
Negative for cat allergy |
| Peanut |
5.6 KUA/L |
Strongly positive for peanut allergy |
| Mold |
2.9 KUA/L |
Moderately positive for mold allergy |
Summary
- The interpretation column provides an explanation of what each result may indicate in terms of the patient's likelihood of having an allergy to the tested allergen.
- It's important to note that the interpretation of RAST test results should always be done by a qualified healthcare provider, who will take into account the patient's medical history, symptoms, and other factors when making a diagnosis and developing a treatment plan.
Who should get a RAST test?
Here are some suggestion about who may be recommended to undergo RAST testing:
- Individuals who have a history of allergy symptoms such as hives, itching, swelling, nasal congestion, coughing, or wheezing after exposure to a potential allergen.
- Individuals with a suspected food allergy, especially if they have experienced anaphylaxis or other severe allergic reactions in the past.
- Individuals with a suspected medication allergy, especially if they cannot tolerate alternative medications or if there is concern about a potentially life-threatening reaction.
- Individuals with a suspected allergy to insect venom, especially if they have experienced anaphylaxis or other severe allergic reactions in response to insect stings.
- Individuals who have a family history of allergies or asthma.
- Individuals who have unexplained symptoms that could be related to allergies, such as chronic hives or eczema.
- Individuals who have been exposed to a potential allergen through their occupation, such as healthcare workers or laboratory personnel who work with certain medications or chemicals.
It's important to note that the decision to undergo RAST testing should be made in consultation with a healthcare provider, who can help determine whether the test is appropriate and interpret the results in the context of the patient's overall health and medical history.
Specimen Requirments For RAST Test
Here are the specimen requirements for the RAST Test.
| Specimen |
Blood Serum |
| Volume |
3-5 ml |
| Container |
EDTA or heparin tube |
RAST Test is Safe?
RAST testing is generally considered safe and carries minimal risk. The most common side effect is mild pain or bruising at the site where blood is drawn.
- The risks of RAST testing are similar to those of any blood test, which can include bleeding, infection, or a fainting episode.
- Although rare, some people may experience a severe allergic reaction to the needle stick or to the allergens being tested. However, healthcare providers are trained to manage and treat any potential adverse reactions that may occur during the testing process.
When Do You Get RAST Test Results?
- The time it takes to receive RAST test results can vary depending on the laboratory conducting the test and the specific allergens being tested.
- In general, results are typically available within 1 to 2 hours after the blood sample is collected.
- It's important to follow up with a healthcare provider to review the results and discuss any next steps or treatment options, as well as any potential lifestyle changes that may be necessary based on the results.
RAST Test Limitation
Here are some possible limitations of the RAST Test.
- Limited ability to identify specific allergens.
- False-positive or false-negative results are possible.
- Cannot distinguish between current and past allergies.
- Results may be affected by certain medications.
- May not detect allergies to certain substances or foods.
RAST Test Risk Factors
Here is the potential risk factor of the RAST Test.
- Limited sensitivity and specificity for diagnosing allergies.
- False-positive and false-negative results are possible.
- Can be influenced by medications that suppress immune response.
- Not suitable for diagnosing all types of allergies (e.g., food allergies).
Doctor Recommendations After RAST Test Result
Here are Doctor recommendations or consult a specialist after RAST Test.
| RAST Test Result |
Doctor to Visit |
Reason to Visit |
| High |
Allergist |
Determine specific allergens and treatment options. |
| Normal |
Primary Care Physician |
Monitor general health and discuss symptoms. |
| Low |
Primary Care Physician |
Rule out allergies as the cause of symptoms. |
RAST Test Price
Here are the estimated RAST Test Price in India with different top cities:
*Prices are approximate and vary depending on a specific laboratory or healthcare facility.
Summary
Overall, The RAST test is a safe and effective blood test that measures the level of specific IgE antibodies in the blood to identify allergies to specific substance. Also check Drlogy Test for detailed information about all medical tests for patients, doctors, scholers and medical students.
Reference
- Radioallergosorbent test - Wikipedia [1].
- IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper [2].
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