Do you want FPIES with that?

aka Pediatric Perplexity 015

A 7-month-old infant is brought into the ED.  The infant was well until 1 hour ago when she became pale, floppy and developed profuse non-bilious vomiting.

The vomiting started 2 hours after eating rice bran mixed with breast milk.  Her mother reports two similar but less dramatic episodes over the past 2 months after ingesting rice bran mixed with cow’s milk. These episodes had been discussed with the local GP and diagnosed as “gastro”.

On examination you note the child is pale with a CRT of 3 seconds and no signs of dehydration.  Her temp is 35.2 while the other vital signs are normal.  The child has mild decreased tone and a soft non tender abdomen.  Other examinations are unremarkable.

Q1. What is your differential diagnosis?

The differential diagnosis for a flat vomiting infant is broad but includes;

  • Infection
    • Gastroenteritis/Food poisoning
    • Sepsis
    • UTI
    • Meningitis
  • Surgical causes
    • Intussusception
    • Malrotation with volvulus
    • Appendicitis
  • Neurological
    • Space occupying lesion
    • Head injury/non accidental injury
  • Metabolic
    • Congenital adrenal hyperplasia
    • Hyper/hyponatraemia
    • Hypoglycaemia
  • Allergic
    • IgE mediated allergy eg to Cow’s Milk
    • FPIES

Q2 What does FPIES mean?

FPIES stands for Food protein-induced enterocolitis syndrome

is a non-IgE mediated food allergy resulting in the acute onset of gastrointestinal symptoms +/- collapse 1 to 4 hours post ingestion of the causative agent.

  • It’s onset is before 6 months of age and has an incidence of 3.4 per 1000 infants.
  • It is the most severe of the non-IgE mediated gastrointestinal food hypersensitivities, the others being food protein-induced enteropathy and proctocolitis.

Q3 What is the proposed underlying pathophysiological mechanism?

  • The mechanism is unclear but is though secondary to a T cell mediated process resulting in intestinal inflammation driven by tumor necrosis factor with decreased expression of transforming growth factor-beta receptors.  This leads to increased intestinal permeability and third space fluid loss resulting in the gastrointestinal symptoms +/- hypotension.
  • Food specific IgE antibodies are not typically detected but atopy is more common in these patients.

Q4 What are the most common triggers?

  • In contrast to IgE mediated reactions, rice is one of the most common precipitants resulting in up to half of all reactions requiring hospitalization.
  • Other common food triggers are cow’s milk, soy, grains, meat (both white and red), legumes, potato and fruit.
  • 80% react to more than one food.
  • A few case reports have described reactions to cow’s milk protein transmitted in breast milk.

Q5 How do these patients most commonly present?

Acutely these infants present with profuse vomiting (all) within hours of ingestion +/- diarrhoea (25%) on average 5 hours post ingestion of the trigger.  Other common features are;

  • Lethargy                                                                     85%
  • Pallor                                                                          67%
  • Hypothermia                                                             24%
  • Hypotension
  • Bloody diarrhea

Acute episodes tend to last from a few hours to 2 days and are commonly misdiagnosed as gastroenteritis or sepsis.  There may be a background of less dramatic chronic symptoms such as failure to thrive and persistent diarrhea.

Q6 What investigations are most useful?

  • The diagnosis is clinical but lab investigations can be supportive.  A thrombocytosis, neutrophilia or eosinophilia is common during the acute phase but all of these findings are non-specific.  One case series found a large proportion of infants exhibited severe acidosis (mean pH 7.03) and one third had methemaglobinemia, some requiring methylene blue!
  • Some pediatricians are prepared to make the diagnosis on history alone, confirmed by the cessation of symptoms with removal of the offending trigger from the diet.  Otherwise a medically supervised oral challenge resulting in typical symptoms, raised stool WCC or hemaglobin, or peripheral neutrophilia or eosinophilia confirms the diagnosis.
  • Skin prick testing and RAST tests for IgE mediated allergies are typically negative in isolated FPIES but up to 10% have or develop IgE mediated allergy to cow’s milk or soy on testing and clinical grounds.

Q7 What is the management and natural history of the illness?

  • The management of acute episodes involves good supportive care with rehydration and symptomatic management.  An allergist should be involved early in their care.
  • The cornerstone of ongoing management is avoidance of the trigger.  This may involve maternal exclusion diet in breastfed babies however FPIES is rare in exclusively breastfed infants.  If the reaction is thought secondary to cow’s milk protein an extensively hydrolyzed formula can be trialed under medical supervision.
  • The overall prognosis is good.  The majority of children are able to tolerate the trigger 1 to 3 years after diagnosis.  Re-introduction is performed under medical guidance in a controlled manner with increasing doses of the offending protein.

References

  • Leonard SA, Nowak-Wegrzyn. Food protein-induced enterocolitis syndrome: an update on natural history and review of management. Ann Allergy Asthma Immunol. 2011 Aug;107(2):95-101. [PMID 21802016]
  • Sicherer SH. Food protein-induced enterocolitis syndrome: clinical perspectives. J Pediatr Gastroenterol Nutr. 2000;30 Suppl:S45-9. [PMID 10634298]
  • Allergic enterocolitis – work in progress. In DynaMed [database online]. EBSCO Publishing.  Updated May 28, 2010. Accessed Aug 27, 2012.
  • Lake AM. Food protein-induced proctitis/colitis, enteropathy and enterocolitis of infancy. In: UpToDate, Klish WJ, Sicherer SH (Ed), UpToDate, Waltham, MA, updated Feb 3 2012.
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