Non–IgE-mediated severe gastrointestinal food hypersensitivity, typically presents in early infancy with repeated vomiting, dehydration, lethargy, metabolic acidosis (even mimicking sepsis). Watery diarrhoea (sometimes with blood and/or mucus) can develop in some cases. The severity is really what makes it worthy of a distinct name, debatable if it is actually distinct from other non-IgE mediated food allergy.
Probably underdiagnosed.
A few unusual features cf type 1 allergy.
The most common offending foods are cow’s milk and soy in young infants; in older infants, there are a range of food triggers including some foods usually not considered allergenic eg rice, oat, chicken, sweet potato! Egg surprisingly a very unusual cause! Cases in breastfed infants have been reported.
Acute symptoms occur 1 to 5 hours after ingesting the offending food. Lasts up to 24 hours. Not always consistent, which might suggest co-factors important.
Most kids only have an issue with one or two foods.
Chronic FPIES less well characterised – Japan, Korea more? Usually young babies fed formula. Chronic vomiting, diarrhoea, faltering growth, hypoalbuminaemia. Chronic usually turns into acute on challenge!
Diagnosis is based, predictably for a non-IgE condition, on clinical history and food challenges. Leucocytosis and methaemoglobinaemia are associated but low specificity/sensitivity. Oral food challenge where FPIES suspected would be done with IV access, and divided portions of 0.15-0.3g/kg over 1 hour.
Rechallenge
No consensus on when to rechallenge. Hospital challenge, obviously. 12 months to 18 month seems reasonable. IV access recommended. Ondansetron given at start of reaction may shorten duration. 2017 International Consensus Guideline suggest using 0.3g of food protein per kilogram of body weight (max 3 g of protein or 10 g of total food or 100 ml of liquid), in 3 equal doses over 30 minutes followed by 4-6 hours of observation. But since likely to be delayed (unless IgE pos), not v logical. Lower starting dose (0.06g protein/kg body weight) +/or longer interval between doses recommended for those with history of severe reaction.
In study by Barni, 25% of the total dose (0.3 g protein/kg body weight) was given initially, followed by a full dose 4 hours later. This seemed to work well – mean latency of 136 minutes (range 60-230 minutes). Another study found this worked well for 80% of patients.
FPIES is usually outgrown by school age. Management is simply avoidance of the offending food, natural history appears to vary for different foods which makes it difficult to judge reintroduction.
Parent support at https://www.fpiesuk.org.
[Calvani update]Annals of Allergy, Asthma & Immunology, Volume 107, Issue 2, August 2011, Pages 95–101