Frequently Asked Questions About Allergy Testing
This is a blood test that is quick and simple. It measures the amount of allergen specific antibodies in the blood , which is an indicator of allergic sensitization. As a powerful diagnostic tool, it can test for hundreds of allergic triggers, such as pollen, mold, food, and animal dander and can be performed at any age. This blood test can help your healthcare professional determine if you are allergic, and to what.
You can be tested for just about anything you encounter that could cause allergy symptoms. A blood test is commonly used to identify sensitizations to pollens, molds, animal dander, foods, dust mites, insect venoms, and some medications.
There are many benefits to getting this blood test, also called a specific IgE blood test. Unlike a skin-prick test, an allergic sensitization test can be performed on anyone no matter the condition of their skinâeven during an eczema flare-up. It can also be performed on someone while currently on medication, including antihistamines. This blood test is also safe to perform on someone who is pregnant.
Anyone experiencing allergy-like symptoms can receive specific IgE blood testing. For babies and very young children, one blood sample collection is often less traumatic than the several scratches of a skin-prick test .
Typically, it takes a few days to get blood test results back because the blood sample has to be sent to a lab for processing.
How To Prepare For Allergy Testing
Before your allergy test, your doctor will ask you about your lifestyle, family history, and more.
Theyll most likely tell you to stop taking the following medications before your allergy test because they can affect the test results:
- prescription and over-the-counter antihistamines
An allergy test may involve either a skin test or a blood test.
Why Do I Need Food Allergy Testing
You or your child may need food allergy testing if you have certain risk factors and/or symptoms.
Risk factors for food allergies include having:
- A family history of food allergies
- Other food allergies
- Other types of allergies, such as hay fever or eczema
- Asthma
Symptoms of food allergies usually affect one or more of the following parts of the body:
- Skin. Skin symptoms include hives, tingling, itching, and redness. In babies with food allergies, the first symptom is often a rash.
- Digestive system. Symptoms include abdominal pain, metallic taste in the mouth, and swelling and/or itching of the tongue.
- Respiratory system . Symptoms include coughing, wheezing, nasal congestion, trouble breathing, and tightness in the chest.
Anaphylactic shock is a severe allergic reaction that affects the entire body. Symptoms may include those listed above, as well as:
- Rapid swelling of the tongue, lips, and/or throat
- Tightening of the airways and trouble breathing
- Fast pulse
- Pale skin
- Feeling faint
Symptoms can happen just seconds after someone is exposed to the allergic substance. Without quick medical treatment, anaphylactic shock can be fatal. If anaphylactic shock is suspected, you should call 911 immediately.
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How Is An Allergy Test Performed In A Blood Test
Radioallergosorbent testing is an outdated form of allergy testing that involves measuring specific allergy antibodies in a blood sample. While RAST is still available, newer forms of allergy blood testing involve the use of an enzyme-linked immunosorbent assay , which involves binding allergy antibodies in a blood sample to an allergen, causing a color change to be added when developers use it. The darkness of this color change can be measured and translated into the concentration or amount of allergic antibodies in a blood sample. Although the quality of allergy blood tests has improved in recent years, the number of tests available is still limited, as well as the presence of small numbers of mild allergens in specific tests.
However, allergy blood tests have recently become more useful in the diagnosis and management of food allergies. While a skin test for food can provide a sense, based on the size of the reaction, whether a person is actually allergic to the food, the allergy blood test actually measures the amount of allergic antibodies to the food. For example, this value can help determine whether a child may no longer have a food allergy.
The high cost of allergy blood tests and delayed results of days to weeks also make them less desirable than skin tests compared to less expensive skin tests. Skin tests also continue to be the better tests, with fewer false positives and false negatives.
Diagnosis Of Dairy Allergy
A little drop of liquid containing the dairy allergen is inserted under your skin on your forearm or back as a skin prick test. A dairy allergy is likely if you notice a raised bump surrounded by itchy red skin.
Your doctor may also order a blood test to determine the number of certain antibodies in your blood. “False positives” can occur in both tests. Even if you don’t have an allergy, you can test positive for it. Your allergist will go over the results with you.
Your doctor may ask you to do an oral challenge if an allergy is still suspected but not verified. You’ll be served a variety of foods, some of which may or may not contain milk, in increasing amounts to see how you react to milk-containing items.
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Symptoms Associated With Allergies
Symptoms associated with allergies can include:
- skin rashes such as eczema or hives
- swelling of lips, face, eyes
- swelling of tongue
- sneezing and running nose
- teary, red, itchy eyes
- wheeze, cough
- anaphylaxis a severe allergic reaction that causes serious breathing problems. Anaphylaxis can be fatal.
How Much Does An Allergy Profile Test Cost
Allergy Profile test cost varies across the world. It also depends upon the kind of allergy test recommended for a person. It is advisable to opt for a reliable name such as Dr. Lal PathLabs. Established in 1949, Dr. Lal PathLabs is a renowned diagnostic centre trusted by millions of people and doctors for its accurate results. For allergy profile test price, visit their website or walk into a centre near you.
Types of Allergy testing done at Dr Lal PathLabs
There are over 100 types of allergy tests that one can get done at Dr Lal PathLabs. Some of them are mentioned below:
- Allergy, Milk
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How Is It Used
The allergen-specific IgE antibody test is a blood test used to help diagnose an allergy to a specific substance or substances for a person who presents with acute or chronic allergy-like symptoms. This is especially true if symptoms are recurrent and appear to be tied to triggers, such as exposures to particular foods or environments, and if other family members are known to have allergies.
Other types of allergy tests may be performed by exposing a person to different substances under careful medical supervision. The usefulness of these tests, however, can be affected by skin conditions, such as significant dermatitis or eczema, and by medications, such as antihistamines and some antidepressants. With some tests there is also the potential for severe reactions, including, for example, anaphylaxis, which can be life-threatening. In these cases, the allergen-specific IgE antibody test may be ordered as an alternative, as it is performed on a blood sample.
The allergen-specific IgE antibody test may also be performed to monitor immunotherapy or to see if a child has outgrown an allergy. Typically, the healthcare practitioner will interpret the results of the test in comparison with a person’s symptoms and any other allergy tests being performed.
What Is A Skin Test
Skin testing is the oldest and most reliable form of allergy testing. This form of testing has been available for 100 years and remains the test of choice for diagnosing allergic diseases. The test begins with a prick, puncture, or scrape method, which involves placing a drop of the allergen in question on the skin and rubbing it with a needle skin.
After the skin is scratched, the test takes about 15 minutes to perform. Depending on a persons age, symptoms, and other factors, many skin tests may be performed. A positive skin test appears as a raised, red, itchy bump that resembles a mosquito bite. This test is compared to positive and negative controls, which are 2 additional skin tests placed with the allergen to be tested.
The positive control is usually histamine, which causes raised, itchy bumps in anyone not taking antihistamines such as benadrine. It is impossible to be allergic to histamine because this chemical is present in the body. A positive histamine skin test means that any concurrent negative skin test results are actually negative .
Negative controls are usually saline or saline substances. The purpose of this test is to ensure that a person does not experience the irritating effects of acupuncture. Negative skin test results for negative controls ensure that positive skin test results are not due to irritation in people with very sensitive skin.
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What Is Being Tested
Immunoglobulin E is a class of antibody associated with allergic reactions. It is normally found in very small amounts in the blood. This test measures the amount of allergen-specific IgE in the blood in order to detect an allergy to a particular substance.
IgE is an antibody that functions as part of the body’s immune system, its defense against “intruders.” When someone with a predisposition to allergies is exposed to a potential allergen such as food, grass, or animal dander for the first time, that person becomes sensitized. The person’s body perceives the potential allergen as a foreign substance and produces a specific IgE antibody that binds to specialized mast cells in the skin, respiratory system, and gastrointestinal tract, as well as to basophils in the bloodstream. With the next exposure, these attached IgE antibodies recognize the allergen and cause the mast and basophil cells to release histamine and other chemicals, resulting in an allergic reaction that begins at the exposure site.
While the traditional method for blood testing was the RAST , it has been largely replaced with newer IgE-specific immunoassay methods. Some healthcare practitioners continue to refer to all IgE allergy blood tests as RAST even though it is not the exact assay that the testing laboratory uses.
So When Should You Have Allergy Tests
If you have allergy symptoms, you may get relief from self-help steps and over-the-counter drugs. If these steps do not help your symptoms, then it is time to see your doctor.
The doctor should ask you about your medical history and make sure you get the right tests. If your medical history suggests that you have an allergy, your doctor might refer you to an allergist or immunologist for testing.
- A skin test is the most common kind of allergy test. Your skin is pricked with a needle that has a tiny amount of something you might be allergic to.
- If you have a rash or take a medicine that could affect the results of a skin test, you may need a blood test.
- For chronic hives, you usually do not need an allergy test. However, your doctor might order tests to make sure that the hives are not caused by other conditions, such as a thyroid disorder.
This report is for you to use when talking with your healthcare provider. It is not a substitute for medical advice and treatment. Use of this report is at your own risk.
07/2012
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How Is Allergy Testing Performed On A Blood Test
Radioallergosorbent testing is an outdated form of allergy testing that involves measuring specific allergic antibodies from a blood sample. While RAST is still available, newer forms of blood testing for allergies involves the use of enzyme-linked immunosorbent assays , which involves the binding of allergic antibodies in a blood sample to an allergen, which results in a color change when a developer is added. The darkness of this color change can be measured and translated into a concentration or amount of allergic antibody in the blood sample. While the quality of allergy blood testing has improved in recent years, it is still limited in the number of tests available, as well as the smaller amount of minor allergens present in a particular test .
Allergy blood testing has recently become more useful in the diagnosis and management of food allergies, however. While skin testing to foods can give a sense, based on the size of the reaction, whether a person is truly allergic to the food, allergy blood testing actually measures the amount of allergic antibody to the food. This value can help determine is a child has possibly outgrown the food allergy, for example.
The high cost of allergy blood testing, as opposed to the less expensive skin test, as well as the delay in results of days to weeks, also makes it less desirable than skin testing. Skin testing also continues to be the better test, with less false-positive and false-negative results.
Allergy Patch Test Or Epicutaneous Test
To diagnose allergies using an Allergy Patch Test, a doctor or nurse places some patches with different substances on the skin of the back. The test determines what allergen may be causing contact dermatitis. The doctor or nurse removes the patches after 48 hours, but the final reading is performed after 72-96 hours. If you are sensitized to the substance, you should develop a local rash. The number of patches depends on the suspected substances your doctor wants to investigate. Inform your doctor about all the medication you are receiving. Systemic corticosteroids or immunomodulators can change the results of the test. Baths and sweating can move the patches, so be careful.
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Types Of Allergy Tests
The most common forms of allergy tests are the skin prick tests and the blood tests.
If you have skin prick testing, you will be pricked on the arm or back a number of times, with a tiny amount of allergen dropped onto the pinprick. If you are allergic, where you were pricked will become swollen and itchy. This generally subsides within 2 hours. Although skin prick testing can be uncomfortable, most people find it tolerable. The results are available within 20 minutes.
Blood tests can be also used to test for allergies. They may be used when skin testing is not suitable, such as for people who have severe eczema or who are taking medications that may interfere with the test.
Other, less common allergy tests include:
- intradermal skin testing
- and oral allergen testing
Unreliable Test Results Can Lead To Unnecessary Changes In Your Lifestyle
If the test says you are allergic to some foods, such as wheat, soy, eggs, or milk, you may stop eating those foods. You may end up with a poor diet, unnecessary worries and frustration, or extra food costs. If the test says you are allergic to cats or dogs, you may give up a loved pet.
And tests for chronic hivesred, itchy, raised areas of the skin that last for more than six weekscan show something that may not look normal but is not a problem. However, this can lead to anxiety, more tests, and referrals to specialists.
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How Do I Know If I Need An Allergy Test
If youre allergic to allergens in the air like dust, pollen or pet dander, you may develop allergic rhinitis. Also known as hay fever, this allergic reaction causes:
Food allergy symptoms typically occur within 30 minutes of food ingestion but may occur up to two hours after ingestion. People with food allergies may experience:
- Skin symptoms such as hives, swelling of the face, lips or tongue, generalized itching.
- Respiratory symptoms such as coughing, wheezing, shortness of breath, chest or throat tightness.
- GI symptoms such as nausea and vomiting, abdominal pain and cramps, vomiting and diarrhea.
- Cardiovascular symptoms such as pale skin, weak pulse, dizziness or lightheadedness.
People who are allergic to latex, fragrances or metals like nickel may develop contact dermatitis. This allergic reaction affects your skin. You may have:
- Burning sensation on skin or blisters.
- Skin rash or itchy skin.
A patch test, performed by a dermatologist, is used to diagnose these types of reactions.
Why Do Healthcare Providers Perform Allergy Tests
Your healthcare provider may perform an allergy test if you have allergy symptoms that bother you. Providers also perform allergy tests on people who have asthma. The test can identify allergy triggers that can worsen asthma symptoms or bring on an asthma attack.
You may also need a test if youve had a severe allergic reaction called anaphylaxis. This potentially life-threatening problem can cause hives or swelling, breathing difficulty and/or a sharp drop in blood pressure that brings on anaphylactic shock. Your health history along with allergy testing is used to determine the cause of severe reaction. If you have had an anaphylactic reaction or may be at risk for one, then you may need to carry an epinephrine auto-injector to treat the symptoms.
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What Do The Results Mean
If the results show that you or your child has a food allergy, the treatment is to avoid the food.
There is no cure for food allergies, but eliminating the food from your diet should prevent allergic reactions.
Avoiding allergy-causing foods can involve carefully reading labels on packaged goods. It also means you need to explain the allergy to anyone who prepares or serves food for you or your child. This includes people like waiters, babysitters, teachers, and cafeteria workers. But even if you are careful, you or your child may be exposed to the food by accident.
If you or your child is at risk for a severe allergic reaction, your allergist will prescribe an epinephrine device you can use if accidentally exposed to the food. You’ll be taught how to inject the device in your or your child’s thigh.
If you have questions about your results and/or how to manage allergic complications, talk to your allergist.
