Promising tool could make food allergy tests safer

Food allergies affect nearly 10 percent of children in the United States and seem to be growing more common.

Now a researcher at the University of Michigan is testing a novel way to detect whether children might develop anaphylaxis during the oral food challenges conducted to diagnose food allergies.

Dr. Charles Schuler, an expert in food allergy at the university’s health center, believes this monitoring technique, which measures water lost through the skin during the food challenge, can accurately detect evolving anaphylaxis.

Anaphylaxis causes the immune system to release a flood of chemicals that can lead to shock – when blood pressure drops suddenly and the airways narrow, blocking breathing. Food anaphylaxis, a potentially fatal, whole-body allergic reaction, causes more than 200,000 emergency room visits yearly in the United States.

If Dr Schuler is right, and oral food challenge can be stopped early, such procedures can be made “safer and better tolerated,” he said.

Eggs, milk, and peanuts are the most common causes of food allergies in children. Wheat, soy, and tree nuts also are frequent offenders.

An important point, Dr. Schuler said: A food allergy is an abnormal response of the body to a certain food. This is different than a food intolerance, which does not affect the immune system, although some of the same symptoms may be present.

But before having a food allergy reaction, a sensitive child must have been exposed to the food at least once before. It is the second time the child eats the food that the allergic symptoms happen.
That’s when antibodies react to the food, releasing histamines that can cause hives, asthma, itching in the mouth, trouble breathing, and other symptoms.

Oral food challenges, during which the child eats a potential food allergen and results are observed in the allergy office, can be tricky to conduct in very young children, Dr. Schuler said.

“Very young children often haven’t developed the necessary language skills to describe any symptoms, if they are having any. That can lead to the full onset of anaphylaxis, and that can be pretty scary,” he said.

Some parents simply have their children avoid certain foods, which Dr. Schuler says may be unnecessary, impeding growth and nutrition and causing intense anxiety for them and their children.”

Still, oral food challenges are the diagnostic standard for food allergies. Skin and blood food allergy testing have false positive rates over 30 percent, Dr. Schuler noted.

During the food challenge, patients eat increasing doses of the food every 15-20 minutes up to a full serving, as defined for each food. Patients either react during the challenge or do not, and are observed for 1-2 hours after the final food dose or to the end of the reaction.

In his Gerber Foundation-funded study, Dr. Schuler proposes to use transepidermal (across-the-skin) water loss as a real-time, dynamic monitoring technique to detect evolving anaphylaxis. Higher value water loss is associated with food allergy, he said.

“Transepidermal (TEWL) water loss is a well-established, non-invasive tool that could provide earlier detection of allergic reactions,” he said. The technique is now used to evaluate topical medications and cosmetics, and in diagnosing skin conditions.

In this study, 100 children will be enrolled in an oral food challenge monitoring group, followed by 40 children in a pilot clinical trial, divided between a control and intervention group. Children will be 6 months to 3 years of age.

“Statistically, young children are less likely to have severe anaphylaxis, so maybe they are a little safer group, less likely to have a drop in blood pressure, which is the big problem,” Dr. Schuler said.

His team will monitor water loss during the oral food challenges. Measurements will be taken using a small adhesive to attach the TEWL probe to the skin on the upper back and the forearm. Single measurements can be taken in 20-30 seconds. Thresholds for transepidermal water loss will be identified and compared to symptom reports, and test stopping rules will be established.

In the second phase, a pilot, double-blind, randomized clinical trial will be used to determine whether the stopping rules reduce the incidence and severity of anaphylactic reactions.

A control group will have TEWL monitoring done but will not implement any stopping rules. An intervention group will have the TEWL monitoring and will undergo stopping rules based on TEWL.

The researchers will measure reaction rate, anaphylaxis rate, anaphylaxis severity, symptoms, time to treatment, time to symptoms, epinephrine use rate, and any other treatments used.

The study results are likely to have a significant impact on the field of food allergy and anaphylaxis. Dr. Schuler said. He hopes to provide a rationale to adopt transepidermal water loss as the viable monitoring tool during food challenges.

“No widely employed device, tool, or measurement currently detects anaphylaxis in real time, much less predict it,” he said. “We hope this project will increase safety for oral food challenges and will allow more patients to be tested at younger ages.”

When the pilot clinical trial is completed, Dr. Schuler said he will pursue a National Institute of Health-funded multi-site clinical trial to broadly assess TEWL in anaphylaxis monitoring and the stopping rules his team develops.

Project Information:


Charles Schuler, MD


University of Michigan Health

Funded Research:

Developing transepidermal water loss as a novel food anaphylaxis monitoring tool