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Frequently Asked Questions

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How often do food allergy patients need to be seen?

Once the initial evaluation is done a return visit is scheduled depending on the needs of the patient/family. We might need to see a patient back in 4-6 weeks or not for another year. Some of our patients are referred back to the referring physician for care and then seen by us in the future as needed. We will always see patients as needed after the initial evaluation.

How do I know if my child has a food allergy?

Determining if your child has a food allergy can be easy if they experience anaphylaxis (life threatening reaction to a food). Often times their symptoms are clear cut and an evaluation will help determine a food allergy. It can also be very complicated and a long process in determining an accurate diagnosis for your child. If you suspect your child has a food allergy, sensitivity and/or intolerance it is wise to see your general practitioner armed with a good history of exposure to foods and the symptoms your child gets after exposure. Once your doctor has made an assessment they might refer you to a specialist in Allergy. The Allergist will get a comprehensive history, perform a through examination and decide if they need to proceed with skin testing and/or blood tests. There is a possibility that you will need to change some things in their diet to see if that makes a difference and record a food diary for a period of time. This process can be long but it is critical to be evaluated by a board certified Allergist.

What are the different types of testing for food allergies?

Skin Prick Testing (SPT) is the preferred method for evaluating patients with food allergies. This can be done in children as young as a few months of age. Extracts containing the suspected food allergen are placed on the skin of the forearm in a prick or scratch method using a device similar to a plastic toothpick. The site is then monitored for the development of redness and swelling at the site of administration over the next 10-20 minutes. We encourage you to bring books, toys or other items to distract your child during the test. The food allergen is then removed and Benadryl liquid is applied to the site. A positive SPT indicates a possible association between the food being tested and a patient’s reaction to the suspected food. The reliability of a positive SPT is only about 50% in general; however in cases of anaphylaxis it can confirm the diagnosis. A negative SPT is about 95% predictive but may be a false negative in the very young. This is the situation when the RAST test can be utilized.

RAST Testing is a blood test whereby a patient’s IgE, the allergy antibody, is measured against a specific food. This is considered less reliable than the SPT because there is a higher false positive rate than the SPT. A negative test has the same utility as the SPT. This study is sent to a laboratory therefore the results are not immediately available as they are with the SPT. This test is generally used when there are other factors that preclude the use of the SPT such as severe atopic dermatitis (eczema) with limited clear skin for testing, patients that cannot discontinue antihistamines or the rare patient that is so sensitive that SPT may have inherent risk. RAST tests can be monitored over time. If the value decreases to an acceptable level, a food challenge can be performed under physician supervision in the office.

Food Allergy Patch Test This is an allergy test used to detect cell-mediated reactions to foods (eosinophilic esophagitis and perhaps other eosinophilic gastroenteropathies). Specific foods are placed in special chambers of the back using special tape. The foods are based upon literature review for these diagnoses and patient directed symptoms. The test is left in place for 48-72 hours after which it is removed and results obtained. This information can help direct dietary changes for these conditions.

Is there a way to prevent food allergies?

It is impossible to predict if an individual will acquire a food allergy. The highest risk time for food allergies to happen are typically the first two years of life. Breast feeding has been recommended and sometimes breastfeeding mothers are encouraged to avoid eating the high risk foods while breastfeeding. It may also be necessary to have your baby drink a hypoallergenic formula. High-risk families are also encouraged not to introduce solids to their infants prior to age 6 months. Many doctors recommend children that are born into high-risk families (history of food allergies, asthma, eczema and general allergies) avoid milk until age 1, egg until age 2 and peanuts, tree nuts, fish and shellfish until age 3. No studies have proven this avoidance is certain to prevent food allergies but there is evidence that it has helped in some cases. All decisions about what and how to feed your child should be discussed with your pediatrician.

What is food intolerance vs. a food allergy?

Often times it is very difficult to distinguish between food allergy and food intolerance. A food intolerance is when your body has a response to a food which is not caused by an immune reaction.(examples may include lactose intolerance; migraine headaches, food poisoning), but might lack a particular chemical or enzyme that is necessary to digest a certain food. A food allergy is caused by your immune system reacting to substances in foods. The body will make antibodies (IgE) to attack these substances with the result of a simple rash or as significant as a life threatening reaction. This is the reason it is critical to be evaluated by an Allergist to determine why you or your child is responding to food in such a confusing manner.

How should I introduce new foods to my child?

Always consult with your child’s pediatrician or your allergy doctor to discuss the plan for introduction of foods to your child

Where are you located?

The central clinic to assess patients/families with food allergies is at the Domino’s Farms Clinic in Ann Arbor. We have three other Allergy Clinics that see patients/families for a variety of Allergy/Immunology concerns and occasionally can be evaluated for food allergies at these sites.

Are your specialists board certified?

Our Allergy doctors are board certified in Internal Medicine or Pediatrics and Allergy/Immunology and have done fellowship programs in Allergy/Immunology.

Will my child grow out of his/her food allergy(s)?

It is impossible to predict who might outgrow a food allergy, when they might outgrow a food allergy or what food allergies do people grow out of. There are people that do outgrow food allergies to all of the various food allergens. We don’t know for sure how or when this might happen. With the increase in the prevalence of food allergies we have also seen an increase in the time it takes for some to outgrow their food allergies. An individual might outgrow one food allergy while they continue to be allergic to a different food. There is always hope that over time your child might outgrow one or more food allergies. This is the reason your child needs to be evaluated annually so that we can do tests that help us predict and determine the possibility of a food challenge. We continue to study food allergies so that we can continue to treat children with food allergies with research based strategies.

Why are some food allergies in children often outgrown but not peanut?

This is a good question and one that is not easily answered. It is not well understood why children and adults for that matter often outgrow sensitivity to foods such as milk, wheat, and soy but retain reactivity to peanuts and tree nuts. There are now reports that as many as 20% of children may “outgrow” peanut allergy. Most of these children had very mild reactions at a very early age and then successfully avoided peanuts for a prolonged period of time. Children should periodically be reevaluated to determine if they have lost their sensitivity. If appropriate, an oral challenge could be performed in the office under physician supervision. Patients who have “outgrown” their peanut allergy must be monitored carefully for the redevelopment of sensitivity and must continue to carry their injectable epinephrine. There are reports in the literature of patients who have “outgrown” their peanut allergy becoming sensitive to peanut once again.

Why are severe food allergies on the rise in children?

There is no clear answer as to why food allergies seem to be on the rise in children. We know that allergies as a whole are rising in our population and therefore one would expect food allergies to rise as well. In the U.S.A. the current prevalence indicates more than 12 million Americans or 4% of the population, have food allergies. Three million of these are children.

What is protracted anaphylaxis?

Anaphylaxis may present in a variety of ways. The most common is the immediate form where one has symptoms within 5 to 30 minutes of exposure to the offending substance. One may also experience a bi-phasic response whereby one develops symptoms of anaphylaxis approximately 6 to 12 hours after the initial episode. Symptoms may mimic or be worse than the initial reaction. Protracted anaphylaxis is a term that describes a persistent episode, which may last hours to days. There may be asymptomatic periods during a period of protracted anaphylaxis. Given that anaphylaxis is unpredictable it is essential that all patients be treated promptly and observed in an emergency room where they can be monitored for the development of biphasic or protracted symptoms.

What is a late phase or bi-phasic anaphylactic reaction?

A late phase reaction is a second reaction that occurs between approximately 4 to 8 hours after the initial reaction. Late phase reactions can be in the form of rhinitis, asthma, hives, and even anaphylaxis. Generally, one must have an immediate reaction to set up a late phase reaction but this is not always the case. The immediate reaction releases chemical mediators in the body that then recruit more cells that release more chemicals that causes a continuation of the reaction. In patients who have anaphylaxis, there is about a 60% chance of a late phase reaction, which is why observation in an emergency room is essential. A late phase reaction may even be more severe than the immediate response.

Why does having the combination of asthma and food allergies put someone at a greater risk of having anaphylaxis?

Several factors are associated with an increased risk for anaphylaxis. Patients with asthma are at higher risk because they can develop significant acute spasm of the airways along with the other symptoms of anaphylaxis. This was obvious in the articles published on fatal/near-fatal food anaphylaxis. Patients taking beta-blockers for other medical conditions such as high blood pressure and migraine headaches may be resistant to standard therapeutic agents used to treat anaphylaxis and may be at increased risk for severe protracted anaphylaxis. These risk factors have also been demonstrated in studies pertaining to insect sting allergy and patients experiencing anaphylaxis while receiving allergy immunotherapy.

 

These questions were answered by:
Marc S. McMorris M.D.
Associate Professor
University of Michigan
Division of Allergy & Clinical Immunology
Director, University of Michigan Food Allergy Program