Confirming Your Child's Food Allergy Diagnosis: The Power of Ingestion Challenges

What is the gold standard in diagnosing an anaphylactic food allergy? It's not a skin test. It's not a blood test. It's an ingestion challenge.

In this episode,Dr. Alice Hoyt discusses the critical role of ingestion challenges when it comes to accurately diagnosing IgE-mediated food allergies. By consuming the suspected allergen under the careful supervision of a board-certified allergist, patients can achieve a precise diagnosis, which is pivotal before embarking on treatment plans like oral immunotherapy or long-term avoidance strategies. She shares valuable insights and tips on how to prepare for an ingestion challenge, ensuring a smooth and reassuring process for both patients and families.

Dr. Hoyt also explores the life-changing impact ingestion challenges can have, especially for young children and their parents. Drawing from the groundbreaking LEAP study, she stresses the importance of confidently introducing potentially allergenic foods to children, highlighting how, in some cases, ingestion challenges  provide firsthand safety assurance. Additionally, she touches on the complexities of food allergy skin and blood testing and how these tests should not be considered confirmatory for food allergies. 

Tune in to learn how ingestion challenges empower food allergy families and, in some cases, confirms that a child is no longer allergic to a food.

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Transcript

Dr. Alice Hoyt: 0:04

Hello and welcome to Food Allergy and your Kiddo. I am your host, dr Alice Hoyt, happy to be here today talking to you about ingestion challenges. I did a great episode on ingestion challenges with one of my friends and colleagues, dr Samantha Knox, a few years back reviewing data from Cleveland Clinic on the safety of ingestion challenges. So I'll definitely put a link to that episode in the show notes. But today what I wanted to talk about was the importance of an ingestion challenge and really break down what is an ingestion challenge, when do you do it, why should you do it? Should you do it and with whom should you do it? So let's get into that. So what really is an ingestion challenge? An ingestion challenge is a formal procedure performed by a board-certified allergist in which a patient who is potentially allergic to a food comes into the office and essentially eats the food. Now we don't just give the kiddo a whole tablespoon of peanut butter and say, here you go, it's definitely performs in a more incremental and sequential fashion. I'll get into some of the specifics on how we do that, but first, really, who should have an ingestion challenge? I think that's a really important question. An ingestion challenge should be performed in anyone in whom the diagnosis of an IgE-mediated food allergy or an anaphylactic food allergy is suspected but not confirmed. It should also be performed in children with food protein-induced enterocolitis syndrome when we think that that syndrome has started to resolve. Ingestion challenges for food allergies, like eosinophilic esophagitis, really have not proven to be beneficial, because you can have inflammation in your esophagus from EOE that is or is not being bothered by a specific food. So eating a specific food is not going to be helpful in diagnosing the EOE first of all, or whether or not you can really tolerate that food. Eoe is really more of a sort of eczema of the esophagus and so you can imagine that really kind of. If you have that inflammation in your throat then when you swallow kind of any food then you can have some symptoms. So that's not a food allergy in which we do an ingestion challenge, but the ones we really do ingestion challenges for are the IgE-mediated food allergies, meaning your anaphylactic food allergies and FPIES. So why are ingestion challenges important?

Dr. Alice Hoyt: 2:53

Well, before I can really give a family a good treatment plan for a food allergy, I need to be very sure about their diagnosis of food allergy. A few ways I can do that. One, of course, eliciting a really strong history, a good, detailed history from a family. And look, if a kiddo had peanut butter a few weeks ago and mom is showing me a picture of the hives and saying she vomited and all of these things and the history and the labs and or skin testing really support that, okay, this was indeed a peanut allergy reaction, then I don't need to subject that child to an ingestion challenge just so that I can see with my own eyes that, yes, they are allergic. I get enough information from the history, convincing information from the history. But let's say a patient has been a five-year-old patient, reacted to peanut when he was one and has been avoiding peanut strictly since then. And they come to see me about oral immunotherapy and the first thing I really need to do before I talk much about oral immunotherapy is really confirm their diagnosis, because this could absolutely be a case where this child had a peanut allergy but is one of the 20 to 30 percent of kids in whom it self-resolves. And so in that kiddo I might do skin testing and or blood testing to inform how are we going to try to introduce this food to this child? Is it going to be with an ingestion challenge Because if those numbers look very reassuring that he's not allergic anymore, then that's going to be my recommendation. Instead of saying, okay, you're still allergic here, let's do this long, drawn out process to teach your body to tolerate the food immunotherapy, because you might not need it.

Dr. Alice Hoyt: 4:45

What I learned very early on in medicine is that before you can treat something, you need to diagnose it. You need to be pretty confident about your diagnosis. Does that mean that you are going to that you are going to not give someone an EpiPen because you're not sure whether or not they're allergic, but you think they're not and so you're not? No, no, you can still give them the treatment, the emergency treatment, heaven forbid. They have an accidental ingestion and they react before you can confirm or rule out their, their allergic condition. But really, you really want to confirm the diagnosis. And that brings me back to ingestion challenges.

Dr. Alice Hoyt: 5:33

An ingestion challenge is the way to confirm whether or not a person is allergic. So how do you do an ingestion challenge? In my practice, we provide families with a checklist of items they need to bring in. This is after we've had a good appointment usually two appointments and have discussed why. I think we need to do an ingestion challenge because we want to confirm that their child is indeed allergic before we move forward with a treatment plan, and that treatment plan could also be avoidant. So again, before I commit a child to a diagnosis which is the terminology that I use because it's my job to give the accurate diagnosis that is my job as a doctor is to diagnose and treat. That is my job as a doctor is to diagnose and treat. Before I can do that, I really need to be confident about my diagnosis.

Dr. Alice Hoyt: 6:23

We'll talk them through what to bring in, which, if it's a five-year-old with a possible peanut allergy, we're gonna have them bring in peanut butter, have them bring in some snacks that they really like. Also bring in their favorite bowl spoon, measuring spoons, because ultimately we're gonna want to see that kiddo ingest two tablespoons of peanut butter, which is a serving size. So in an ingestion challenge, then you really want a kiddo to ingest the serving size for their age of the food and you want them to ingest it within about an hour. And this is where allergists kind of vary in their style of doing ingestion challenges. But really for the most part we want them to eat the food in about an hour and we start with a very small amount, like maybe half a pea-sized little taste of peanut butter, make sure the kiddo has no reaction to it and then, every 15 minutes, increase the amount until, within about five doses, they have ingested all of those two tablespoons. Now, if they start having symptoms, we stop.

Dr. Alice Hoyt: 7:24

We stop the challenge and well before we've even started the challenge, we do what's called an informed consent process where we talk through the potential risks, the potential benefits and the alternatives when it comes to doing an ingestion challenge. The risks are, of course, having an IgE-mediated or an anaphylactic reaction which can cause high swelling, trouble breathing, vomiting. Ultimately could result in death. That is very unlikely, especially when done in the environment of being with a board-certified allergist very unlikely, but there is always that risk and again, I'm going to encourage you to go back and listen to that episode that I recorded with Dr Knox where we talked through that.

Dr. Alice Hoyt: 8:06

The benefits to doing the challenge is that you're going to know whether your kid's allergic and even if the challenge is positive and this happens, that a challenge is positive if an allergist is not having positive challenges, then they're not doing enough challenges and they're not doing enough challenges when a challenge is positive meaning that the child has a reaction then you're stopping the challenge and if medication is needed, you're administering it. In my practice I'll actually make sure, before we start the challenge, that the family has the child's epinephrine autoinjector and then, if we need to use epi, I talk the parent through how to use it, so that this is fortunately unfortunately an excellent time for them to get hands on training in using their child's epinephrine auto injector, so they're actually the ones administering the medication that's going to stop the allergic reaction. And so then, if the challenge is positive, then we stop. We observe for another few hours. In most cases with challenges, if epi is needed, one dose is needed. On occasion two doses would be needed and in those times you're definitely having that kiddo go to the emergency room just for further monitoring.

Dr. Alice Hoyt: 10:15

Kiddo eats two tablespoons of peanut butter over the course of an hour. After two hours, no issues. A child's not allergic and you've ruled out peanut allergy. That child does not need oral immunotherapy. In that case you'll probably recommend, or I would probably recommend, keeping it in the diet at least three times per week. And that's really extrapolating information from the LEAP study, learning early about peanut and LEAP-1. So that is really why and how to do an ingestion challenge for an IgE-mediated food allergy.

Dr. Alice Hoyt: 10:43

If you're doing it for FPIES, it's a horse of a different color because FPIES reactions remember FPIES, food protein-induced enterocolitis syndrome that's going to have delayed symptoms. So maybe a two-year-old who had significant repeated vomiting and diarrhea three hours after eating scrambled eggs last year, then if you think that this child, if the allergist thinks that this child and the parent thinks that this child is now going to tolerate scrambled eggs, like maybe you've worked with your allergist and gotten baked egg into the diet. There's definitely nuance to managing kiddos with F-Pies and I had great, great conversation with Dr Anna Novak-Wegren about this. I'll link to that episode too. But when you do the F-Pies challenges then they are going to be longer, they are going to be sometimes in a hospital setting because a lot of times you'll want to have an IV available in case that child needs fluid resuscitation. Because with FPIES, fpies is not treated. An FPIES reaction is not treated with epinephrine, it's treated with fluid resuscitation and Zofran or Ondansetron, which is an anti-emetic.

Dr. Alice Hoyt: 11:56

And are there any alternatives to doing an ingestion challenge? Right, we talked about the risks, I'll talk about the benefits. But what about alternatives? An alternative to doing an ingestion challenge would be awesome, because we wouldn't have to subject somebody to an allergic reaction to confirm or rule out their allergy. Unfortunately, right now, there really are not any good alternatives to doing an ingestion challenge. And what about an alternative to an ingestion challenge? So we talked about the risks of an ingestion challenge, the benefits of an ingestion challenge, but is there a good alternative to doing an ingestion challenge? Well, let's think about why we're doing the challenge, and it's really to either confirm or rule out whether the patient is allergic. So in most cases, when you're about to perform an ingestion challenge, or when you're discussing it, planning it, it's because a patient has been avoiding food. When you perform the ingestion challenge, if the challenge is negative, then they'll no longer have to avoid food. If it's positive, then you've confirmed the diagnosis. But is there a way to confirm the diagnosis or rule out the diagnosis without actually directly exposing the kiddo to the food? And unfortunately, right now there's not a good alternative. There are some tests that are getting better at telling us whether or not it's likely less likely, more likely that a kiddo will react when they ingest the food, but we're really just not there yet.

Dr. Alice Hoyt: 13:39

Ultimately, at the end of the day, if we're doing a test and telling a family they're not allergic, I think it's very important that that family feels very confident introducing that food. This, I think, is especially important in young kiddos under the age of five, in which the LEAP study has told us how important the immune system is and how malleable the immune system is during that time. What I mean by that is if a family is concerned about an egg allergy or a peanut allergy, whatever the allergy may be, and we talk through the history, we talk through the testing and the test results and I'm pretty confident that the child is not allergic, well, it doesn't really matter how confident I am. It really needs to be the parent who's confident that the child is going to safely ingest the food. And studies have absolutely shown that if I as an allergist just say but I'm not allergic, go home and feed it to the kid, in most cases that doesn't happen right and also in most cases that doesn't generate a good relationship with the allergist because we're clearly not recognizing the importance of the family being able to see that child safely eating the food and feeling confident that they as a parent you as a parent can give your kid that food and that the food won't hurt your child, right? So the ingestion challenge is so important there's not really a good alternative right now, not in its intention of confirming or ruling out the diagnosis, but also at the end of the day, it's really important for families to feel empowered to give their child a food that use the allergist feel is very safe. And when you do that ingestion challenge it allows the family to see firsthand yes, this food is safe.

Dr. Alice Hoyt: 15:36

Now I'm not going to go super into detail about FPI's challenges and you should definitely listen back to that FPI's episode that I did. But FPI's challenges you definitely want to do a challenge when you think that FPI's has resolved, because FPI's is a disease process where sometimes a kiddo might react, sometimes not. That is very different than IgE-mediated food allergies or anaphylactic food allergies where if you're giving a child a very reasonable amount of the allergen, like a full serving size, if they don't react in that challenge, it is highly unlikely that that child is allergic, even with a fluctuating what's called threshold, meaning there's a threshold at which a patient is going to have a reaction and people can have pretty high thresholds, meaning like they could eat one or two peanuts and not react. But if they eat three, then like they're having a reaction. But that's why when you do a challenge, but if they ate three, then like they're having a reaction. But that's why when you do a challenge, the allergen is just really wanting to see you eat a very generous amount of the allergen.

Dr. Alice Hoyt: 16:41

We talked about the risks, we talked about the benefits and I just so. We talked about the risks, we talked about the benefits and I just went through. Is there an alternative? Not really. So what do you do? Continue to avoid the food, right? So that's why it is important to have a discussion about ingestion challenges. So that's really what an ingestion challenge is and why you do an ingestion challenge. I really want to underscore the importance of the ingestion challenge because so many families their kiddo presents with an allergic reaction and maybe is presenting to the emergency room and then following up with a pediatrician or even an allergist, and they get testing done, skin testing, and then multiple things might be positive on skin tests.

Dr. Alice Hoyt: 17:34

Testing done, skin testing, and then multiple things might be positive on skin tests. Let's say, somebody does a panel. Even though the kiddo reacted to cashew, they're doing a panel of all these things which you can do a test. Right, you can have a test done, but the goal of any sort of food allergy testing should be to help you safely introduce and incorporate that food into a kiddo's diet. So what do I mean by that?

Dr. Alice Hoyt: 17:58

If a family comes to see me because they're 18-month-old, had peanut butter for the first time and had an allergic reaction, they say she's never had tree nuts before and we're not going to give her any until we know she's not allergic. So then yeah, absolutely, I'm going to work with the family, do either skin testing or blood testing. I do a lot more blood testing than I do skin testing, just because I feel that it gives me more information. And then if we do immunotherapy, then I'm able to track those numbers. Yes, you can track skin testing too. I've talked about skin testing and blood testing before and I won't go into that on this episode, but if you want to know more about that, then send me a message or leave a note in the comments.

Dr. Alice Hoyt: 18:40

So when you have had skin testing done, it's not okay. Skin testing is positive. Here's your EpiPen. See you later. It should be okay. Skin testing is positive. Blood testing is positive. How positive especially does this blood testing look?

Dr. Alice Hoyt: 18:56

Because not all blood testing is created equal. Some of the peanut testing, specifically peanut component testing, can be very helpful in me sort of restratifying the likelihood of a kiddo having the allergy as opposed to other blood tests are just not really as helpful, for whatever reason. Or like some foods like a very low cashew IgE number can be very relevant, as opposed to a very low soy number might not be, might not indicate as strongly that this child is very likely to be allergic. So not all tests are created equal. Not all results should be interpreted equal to each other. But once you're doing a test you have to have a game plan for how you're going to help that family. Or I, as an allergist, have to have a game plan for how I'm going to help that family get the food into the diet, because what I don't want to do is testing and say, okay, well, all this testing is positive, you're allergic, see you later. If the testing's positive, then we say we really dive into the history really and say have they ever had any of this food? Let's do some ingestion challenges here, unless the numbers are crazy high, and even then we're having discussions right, because before I'm committing someone to a diagnosis, we're having a discussion. So, doing the ingestion challenge to say, okay, pecans are safe for you, and walnuts and pecans, they cross-re react. Walnuts are safe for you, cashew, pistachio they cross react. Doing a challenge to cashew, it's positive. Ok, cashew is not safe for you, pistachio is not safe for you. So you can see that I'm not just doing a test and saying, ok, you're allergic.

Dr. Alice Hoyt: 20:41

The testing does not say whether or not someone is allergic. I'll repeat that Testing does not confirm that someone is allergic. Testing positive tests help us risk stratify whether or not we think someone is allergic. They help us inform whether or not we think someone is allergic. But it's really that next step of the ingestion challenge that's going to tell us whether or not this person is indeed allergic.

Dr. Alice Hoyt: 21:13

And there are plenty of kids who, for multiple reasons one of the biggest reasons they have eczema. They have positive tests to lots of things. That doesn't mean they're allergic to all those things. So you can see, it's very important when you, as a parent, are told that X, y and Z allergy tests are positive, it doesn't mean that they're positive for the allergy. It doesn't mean your kiddo is positive for the allergy, it means that there's an increased likelihood that your kiddo is positive for the allergy. It means that there's an increased likelihood that your kiddo has an allergy because your kiddo is sensitized. They have positive tests, they are sensitized, but they should not be deemed clinically allergic until there is clinical suspicion, meaning they have ingested the food and have had symptoms that suggest that they are clinically allergic. And again I will say look, if you have an ERA H2, which is a peanut component test that is greater than 100, then chances are, yes, you are allergic to peanuts, but not all testing is that slam dunk and I'll tell you, I guarantee you, there's someone out there who has that number and they're tolerant of peanuts, for whatever reason.

Dr. Alice Hoyt: 22:28

So all of this to come back to the importance of the ingestion challenge being a part of the discussion when you and your allergist are talking about what is it that your kiddo is allergic to? And really the thought of, okay, going back and seeing your allergist every year to repeat testing. Like yeah, that's totally fine, good, like, stay engaged with your allergist. I like to see my patients at least twice per year, especially now. School forums, new treatments for food allergies, new tests, just there's so much more in the world of food allergy now compared to even like five years ago, right? So I like to see my patients every six months and I also like to stay engaged in what's going on with them have they had accidental ingestions? Just all the things so that I can provide them with the most advanced care.

Dr. Alice Hoyt: 23:20

But when you're doing that sort of annual skin testing and or blood testing, you want it to be with a reason, and the reason is how is it going to change our plan? Meaning okay, if the testing is looking like things are, numbers are going down and maybe you've had an accidental ingestion and there's been no reaction, then absolutely, maybe we should be doing an ingestion challenge and those numbers are helping to inform the likelihood of okay. Do we think that it's going to be a positive challenge? There are numbers that give sort of a positive predictive value of when a challenge is going to be positive, but I'll tell you, nothing is 100%. So I don't, I absolutely don't think allergists should be doing ingestion challenges just willy-nilly and being cavalier about anything.

Dr. Alice Hoyt: 24:10

But I know that sometimes children are committed to diagnoses that they don't have, all because an ingestion challenge has not been performed. Wrapping up here ingestion challenges are super important. They should be done by board-certified allergists who are well-versed in performing these procedures because, again, there is risk to these procedures. But they're definitely important in helping families navigate life with food allergies because, first and foremost, they're confirming or ruling out whether or not they even need to avoid a food. Also, even with positive challenges, when kiddos have reactions, there's still evidence that support that it improves the family's quality of life. I've had families tell me okay, well, now you know, I've seen this now and I've treated it now and that will help them moving forward. It empowers them to be more confident that should their child have an axon ingestion, they know how to manage it because they did manage it.

Dr. Alice Hoyt: 25:14

So if your kiddo has a food allergy and or has been diagnosed with a food allergy but has never had an ingestion challenge, then I would definitely encourage you to talk with your allergist about when should you guys do an ingestion challenge and also, of course, talk about the latest therapies available for food allergies. Whether it's oral immunotherapy or sublingual immunotherapy. You always want to do an evidence-based type of treatment for food allergy and remember avoidance is still absolutely a management strategy for food allergies. So don't ever feel like you're not being proactive for your child if you're not doing immunotherapy. That is not an accurate statement. So that's the show on ingestion. Challenges, questions, comments, reach out, comments, reach out. That's the episode. Thanks so much for tuning in. Of course I'm an allergist, but I'm not your allergist. So talk with your allergist about what you learned on this episode and visit us at foodallergyandyourkiddocom where you can submit your family's questions. God bless you and God bless your family.