Have you heard of FPIES?

Have you heard of FPIES?

Unfortunately it’s not a culinary delight, but rather a once rare disorder with its roots in allergy and immunology. FPIES, Food Protein Induced Enterocolitios Syndrome, presents generally in the first year of life with a delayed but violent vomiting response to a typically non-allergenic food; namely sweet potatoes, chicken and rice to name a few – foods typically introduced first to infants. Dairy and soy can also be FPIES offenders, but in the case of this type of allergic response, hives and wheezing are not present. Even more interesting, the onset of vomiting is typically several hours after ingestion, rather than within minutes. A typical allergic response is noted to be IgE (immunoglobulin) mediated – or resulting from an overwhelming number of antibodies primed against a specific food protein. FPIES is not mediated by antibodies but rather immune system protector cells, and thus cannot be screened for by skin prick testing or serum testing. There is a type of testing, referred to as “atopy” testing, that shows some promise in aiding the diagnosis of FPIES, but at this point, FPIES is essentially a clinical diagnosis.

The first case in my practice presented emergently to my office, with pallor, hypotension and protracted vomiting several hours after ingesting an innocuous food. The mom was convinced that he was suffering from an allergic reaction, but the offending agent, believed to be raspberries at the time, is not an allergenic food. Because he was hypotensive, lethargic and pale, I gave him an intramuscular epinephrine shot to help stabilize his vitals and sent them by ambulance to the ER. He was then given the presumed diagnosis of viral gastroenteritis (stomach bug) and discharged after temporary observation. See, by the time he arrived to the ER, he was no longer in shock and his hypotension had resolved. Follow-up with a reputable allergist was recommended, if symptoms happened to recur or for additional evaluation. At this visit, the patient was diagnosed as having reflux, even though this had not been an issue for the patient previously.

His symptoms just didn’t align with a diagnosis of reflux or of an acute gastroenteritis (stomach bug). He had been well, without reflux symptomology, until this acute ingestion of raspberries. Honestly, food poisoning would have made more sense. But, this is the difficulty of medicine… Either you have seen it or you haven’t, or you’ve seen it and incorrectly managed the illness but the patient self-resolves despite our medical approach.

In reality, accurate diagnoses become even more difficult for the ER physician or specialist who only sees the patient once– these doctors have no baseline reference point; no view of the evolution of a patients’ symptoms.

The highly educated parents of this 7-month-old sought a second specialist opinion and thus met with a food allergy specialist at Children’s Hospital. At this visit, their infant son was correctly diagnosed with FPIES. A food introduction plan was devised, management of any recurrent vomiting episodes discussed, and we were on our way to appropriately managing this patient’s rare diagnosis. This patient, by the way, is thriving and is tolerating a vast array of foods without incident. Like 90% of his peers with the same diagnosis, we anticipate full resolution by the age of three.

Prior to this patient, I had never diagnosed a case of FPIES. The ER docs and even a reputable pediatric allergist missed this presentation of FPIES, as the case was somewhat atypical and the diagnosis of FPIES unusual at best. Since this patient, I have diagnosed 3 additional cases and have sent all to the same Food Allergist at Childrens Medical Center for confirmation and management. One of these cases in fact, occurred in the infant son of a pediatrician, and despite both her and my belief that this was her child’s issue, the ER doctor that treated her child during an acute attack dispelled this notion, saying ‘FPIES is just too rare.” The case was later confirmed to be FPIES by a pediatric allergist. Rare doesn’t mean nonexistent, and regardless of how rare a diagnosis – if your child is the one affected, rarity loses all meaning. I really think the toughest job for any doctor is to uncover the rare diagnosis in a sea of commonality, and perhaps the toughest job for the parent is to persevere with questions until the answers really make sense.





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