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Newer tests may help you better understand your child’s food allergy

May 06, 2015

A severe food allergy is often a complex and confusing diagnosis. It’s also one of the most common medical issues, especially in children. Many parents of food-allergic kids remain somewhat perplexed about their child’s condition long after diagnosis. Will my child outgrow this allergy? What exactly is okay to feed to my child and what isn’t? Is this really a serious issue or can we relax a little? These questions often linger unanswered, and that’s not a good thing.

Unfortunately, there isn’t a one-size-fits-all cure for these unanswered questions. Even as a healthcare professional, I have been the recipient of misinformation and misunderstanding about my own child’s food allergy, and I know I am not alone. However, there is some good news that may help parents like me: food allergy component testing for peanuts, egg and milk.

Before we talk about food allergy component testing, there are some things about allergy testing that you should keep in mind. First, there is no perfect test that will give us all of the answers we desire. Food allergies are more like a puzzle than a fill-in-the-blank. Allergy tests can provide one piece of the puzzle that helps put together the whole picture, but testing alone can never give us the whole picture. Second, if we tested the blood of every person we know, many of those tests would come back positive. Does that mean that all of those people have a food allergy? It doesn’t. Many people who test positive for a food allergy aren’t actually allergic. This means that we can’t rely on tests alone to give us all of the information. The true test of whether someone is allergic or not is whether they have a reaction (such as vomiting, cramps, hives, trouble breathing) when they are exposed to a particular food.

(For more information on the symptoms associated with food allergies, click here).

Food allergy component testing

However, for those children who have had a reaction when they’ve consumed a specific food, allergy testing can be a valuable tool in figuring out the puzzle for that child. If your child has had a suspected allergic reaction, your doctor may order a blood test. This will test your child’s blood for an immune response to the things likely causing an allergy. A positive blood test along with your child’s reaction when exposed to a particular food can help your doctor say with relative certainty that your child is allergic to that food. That used to be as far as the blood test could take us.

Newer technology now allows us to take those blood tests a step further by testing which components of a food (if the allergy is to egg, milk or peanuts) your child is allergic to. As an example, think of a child who has had a reaction to milk and a positive blood test that indicates a milk allergy. We can now determine which of the proteins in the milk he is allergic to. What we know about these proteins allows us to create a profile of what your child’s allergy might look like.

Helps you determine what foods may be tolerated

Knowing which proteins your child is allergic to can help you figure out which foods he likely can or can’t tolerate. If he has a milk allergy is it necessary to avoid all products that have been made with milk (like breads and cakes) or only milk itself? The answer to this question will have a profound impact on your daily life, and component testing helps you answer that question. Some proteins are easily destroyed by heat, and if your child is allergic to one of these heat-sensitive proteins, he is likely to tolerate foods that include milk when the food has been baked. You may feel much more comfortable allowing your child to try a baked milk product knowing that there is a high likelihood he will be able to tolerate it.

Helps you understand the likelihood of a severe reaction 

Certain proteins contained in eggs, milk and peanuts are known for their ability to cause more severe reactions than others. Knowing which specific proteins your child is allergic to can help you gain a better understanding of the likelihood that your child will have a severe reaction if exposed. Because food allergies do have the potential to be severe and life-threatening this cannot offer you any guarantees, but again, may be one piece of the puzzle that helps you see the whole picture.

Helps you understand the likelihood of outgrowing the allergy

We know that children are more likely to outgrow an allergy to milk or eggs than to peanuts. Beyond that, we now know that certain proteins within each of these foods are associated with a higher chance of children outgrowing the allergy. While no test can tell you for certain that your child will outgrow their allergy, component testing allows you to gain a better understanding of your child’s individual likelihood of putting their food allergy behind them. 

Helps you pinpoint crossreactivity

Knowing which proteins within a food that your child is allergic to may also tell you something about other foods that could cause a reaction. For instance, a certain protein in milk is very similar to a protein in beef products. If you know your child is allergic to that milk protein, you might expose them to beef cautiously. Some proteins in peanuts are very similar to those of the birch tree, and a child might be sensitive to both.

Helps you determine whether eligible for oral food challenge

The true test of a person’s allergy is whether they react when exposed. There may come a time when your doctor wants to test whether your child’s reaction when given a certain food (in a safe and controlled manner, as directed by a doctor). This oral food challenge is the gold standard in answering questions about food allergies. However, it can be risky because of the potential for severe reactions. The information we gain from component testing- whether a child is likely to have severe reactions, the likelihood of a child outgrowing the allergy, potential crossreactivity- will be helpful information in deciding if and when to undergo an oral food challenge.

Allergy component testing offers us a greater ability to piece together a picture of our child’s specific allergy, and it helps us gather information that will inform our choices and next steps.

If your child has been diagnosed with a food allergy, you may want to ask your doctor if component testing would be helpful. Ask him or her what information you could gain from component testing and whether these tests might change how you understand your child’s diagnosis or how you proceed together in your child’s medical care.

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