Diagnosis and Testing

Be prepared to be asked many questions from your specialist. Your answers to those questions are essential because the diagnosis of FPIES is what is called a ‘clinical diagnosis’. This term, ‘a clinical diagnosis’, refers to conditions where there is no definitive laboratory tests to confirm or make a diagnosis. In these instances, the doctor depends on the child’s medical history to decide what is going on. Determining a diagnosis is essential for developing the appropriate immediate and long-term management plans.

Symptoms that occur as a result of FPIES can be similar to those caused by other medical problems. In the young child exhibiting these symptoms it is important to consider these other illnesses. They can be as devastating and need to be excluded. FPIES shares symptoms with viral gastroenteritis, bacterial sepsis, and food allergy. Other considerations include metabolic disorders and abdominal surgical emergencies. Tests are often performed to rule in or out these other diagnoses.

1. What happened?
2. What were the symptoms experienced by the child?
3. What was the time course of the child’ symptoms?
4. How old was the child at the time of the event(s)?
5. How many times has this happened?
6. Was it the same every time?
7. What was the timing from the exposure to a suspected food to the onset of the child’ symptoms?
8. What foods were involved?
9. What was done to take care of the child?
10. How long did it take for the child to recover?
11. What advice were you given about handling future events?
12. What tests have been done? Specifically, if your child had any blood tests done at the time of the symptoms, can you get me those results**?

Other questions will be asked to help rule out those other medical conditions especially infection or food allergy. The selection of tests may depend on whether or not the child is currently having an acute episode or is currently well and has recovered from the event.

** During an FPIES reaction, the white blood cell count and sometimes the platelet count changes in way that can suggest FPIES– this can further assist in determining a diagnosis.

(A note from the Foundation families: It is helpful to have as much of this written down prior to your appointment as possible. Bring this with you to the specialist. Sometimes it is difficult to recall all the information during an appointment, and a information sheet they can keep allows for less time the physician spends writing- meaning more time to consult with you.)

If your child presents to the emergency department, they may evaluate your child to be sure that an overwhelming infection is not at work. Young children with a severe infection may present with the signs and symptoms shared by FPIES. Since infection is more common than FPIES, and depending on the condition of the infant or child and circumstances at the time, a physician may wish to perform tests to exclude the possibility of an infection. Additional tests may be performed once the acute reaction has passed, typically at a follow-up appointment with an allergist.

CBC (complete blood count, may be performed during the ER visit):

Results may appear to reflect an infection
White blood cell counts and/or platelet counts in the test results may be suggestive of an FPIES diagnosis

Oral Food Challenge

The obvious ‘test’ that could be performed to confirm the diagnosis of FPIES would be an oral food challenge; in a controlled clinical environment, the suspected food is reintroduced and the child is observed for symptoms of FPIES. It is important that the challenges be done only if necessary since FPIES reactions could be severe and life-threatening.
A food challenge in a young infant who has had a significant life-threatening reaction may not be immediately necessary to make the diagnosis of FPIES, but it may be of value in the future to show that this reactivity has gone away. A food challenge for this condition would be performed in a hospital or doctor’s office.

Atopy Food Patch Test

APT may be used to aid in diagnosis. However, it has not been universally accepted at this time and should be considered for use as a research tool rather than a standard test.

Unfortunately, there are no other blood tests or biopsies that can be done to confirm the diagnosis. If the reaction is suggestive of a IgE immediate food reaction (classic allergy), then an allergy test(s) may be performed to confirm that suspicion.

In a young child, viral gastroenteritis with dehydration, sepsis (a severe infection) and anaphylaxis are conditions that may mimic FPIES during an acute symptomatic episode; abdominal surgical emergencies, such as intussusception or necrotizing enterocolitis (in infants), may also present similarly. These other diagnostic possibilities are important considerations and may lead to other diagnostic tests.

Certainly, conditions can co-exist! A child with FPIES can have other issues with food such as other intolerances and food allergy.

Most of the time, a child with FPIES to a specific food has negative IgE tests (skin test/blood IgE test) to that food. Up to 10% of the time, a child with FPIES might have positive (IgE) tests to the food that also triggered the FPIES reaction. This may indicate that additional symptoms (hives, anaphylaxis) could occur. Additionally, children with FPIES could also have “typical” allergies to foods (i.e., hives, anaphylaxis).Your allergist may use IgE tests to evaluate those types of allergies.

Negative allergy test results should not be interpreted that the problem (FPIES) was not due to a suspected food. In FPIES, the food is affecting the child in a way that conventional allergy (IgE) tests do not predict.

In Summary, the diagnosis of FPIES is confirmed when:
1. No other reason can be found for the reaction(s)
2. The child improves when the offending food(s) is avoided
3. An oral food challenge results in the return of symptoms (often reserved to demonstrate resolution of the condition)

Answers provided collaboratively by Medical Advisory Board members:

Sakina S. Bajowala, MD; J. Andrew Bird, MD; April Clark, RD/LD; John J. Lee, MD; Fred Leickly, MD, MPH; David R. Naimi, DO; Harumi Jyonouchi, MD; Scott H. Sicherer, MD; Anna Nowak-Wegrzyn, MD.

Copyright © 2011, The FPIES Foundation

Page published: June 18, 2012. Last update: Feb.6, 2018. Copyright © 2011,The FPIES Foundation