Food Allergy Testing
Food allergy testing is used to help find out if you or your child has an allergy to a specific food, but it's usually only ordered if you or your child has had symptoms of an allergy.
Food allergy testing is used to help find out if you or your child has an allergy to a specific food, but it's usually only ordered if you or your child has had symptoms of an allergy. That is because when used on people who don't have any symptoms, these tests can show signs of an allergy when there isn't one (known as a false positive result). Food allergy tests can cause false positives because they are incredibly sensitive. They may, for example, find evidence of IgE in your blood and mistake that for an allergic reaction even though no allergic reaction is taking place. IgE may only be present in the blood because the food being tested is similar to a food you may actually be allergic to. Most food allergy symptoms are mild and include skin rashes and abdominal (belly) pain . But sometimes, symptoms quickly develop into a life-threatening allergic reaction called anaphylaxis , or anaphylactic shock. Anaphylaxis is a life-threatening allergic reaction that may appear within minutes to hours after exposure to certain foods. It can cause trouble breathing, a rapid heart rate, and other symptoms. If someone has symptoms of anaphylaxis, call 911 to get medical help right away. There's no way to predict when an allergic reaction may change from mild to severe. Because of this, it's important to find out if you or your child have a food allergy as soon as you or your child starts having any of the symptoms of an allergy. Testing may also be used to: See if allergies have gone away over time Tell whether your symptoms are being caused by a true food allergy or by a food intolerance or food sensitivity Food intolerances and sensitivities can cause similar symptoms to those of an allergy. The key difference is that: Allergies involve your immune system, while intolerances and/or sensitivities usually only affect your digestion . Allergies can become life-threatening, while intolerances and/or sensitivities rarely are. Allergic reactions can be caused by even a small amount of a certain food, while intolerances and/or sensitivities may only cause symptoms if you've eaten large amounts of a certain food. Symptoms of an intolerance and/or sensitivity tend to be the same every time you or your child is exposed to a certain food. Symptoms of an allergy, on the other hand, can vary. Examples of food intolerances, or food sensitivities, include: Lactose intolerance Gluten sensitivity Caffeine intolerance I rritable bowel syndrome The symptoms may include belly pain, nausea , gas , and diarrhea , which can also happen with food allergies.
Why is this test ordered? You or your child may need food allergy testing if either of you have symptoms of an allergy within minutes to hours after exposure to certain foods. Symptoms may affect your digestion, skin, and/or breathing. These can include: Nausea and vomiting Stomach pain Diarrhea Tingling in the mouth Skin reactions, such as hives or itching Red, itchy skin or a rash Coughing Stuffy, itchy, or runny nose You or your child may also need a food allergy test if either of you have had symptoms of anaphylaxis. Symptoms include: Trouble breathing Dizziness Fainting Swelling of the tongue, lips, and/or throat Rapid heart rate Cold, clammy skin that may appear grayish, bluish, or pale Lastly, you or your child may have food allergy testing if you or your child has been diagnosed with eosinophilic esophagitis (EoE) . This condition is a long-term immune system disease that causes inflammation in your esophagus (the tube connecting your mouth to your stomach). Testing is done to find out which foods may make this condition worse. Your child's provider may recommend food allergy testing if your infant or child has been diagnosed with: Moderate to severe eczema Enterocolitis, inflammation of the colon and small intestine Enteropathy, a disease of the intestine Allergic proctocolitis, a disorder that involves streaks of blood and mucus in stool (poop)
Clinical Interpretation
A food challenge test is the only food allergy test that can confirm a diagnosis of a food allergy. If you have other tests, your or your child's allergist will use your test results along with your symptoms and medical history to make a diagnosis. If you had a blood test, your results may show the amount of IgE in your blood. This amount can't confirm a food allergy or tell you how serious an allergy may be. To confirm if you have an allergy, your provider will have to use the results from other tests. If the allergist diagnoses a food allergy, the treatment is to avoid the foods that trigger your symptoms. There is no cure for food allergies. Avoiding trigger foods involves carefully reading food labels. You'll also need to explain the allergy to anyone who may prepare or serve food to you or your child, including friends, waiters, babysitters, and teachers. Your allergist will tell you how to manage a mild allergic reaction. In case you or your child has a severe allergic reaction, your allergist may prescribe an autoinjector. An autoinjector is a small device that you use to inject an emergency allergy medicine, called epinephrine. If you need to use the device, it's still very important to get medical help right away even if you feel better. Your allergist will explain when and how to use an autoinjector. If you have questions about test results and/or how to manage allergic reactions, talk with your allergist. Learn more about laboratory tests, reference ranges, and understanding results .
Clinical Protocol & Patient Advice
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If you are having any type of allergy test, you may need to stop taking certain medicines and/or supplements before the test. Your provider will let you know what to avoid and for how long. Don't stop taking any medicines unless your provider tells you to. Your test may require other preparation, so be sure to follow all your provider's instructions for getting ready.
Usage Guidance
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.