Hyperammonaemia as onset of food protein-induced enterocolitis syndrome

Food protein-induced enterocolitis syndrome (FPIES) is the most severe non-IgE-mediated allergies, and has a broad clinical spectrum. Chronic FPIES usually manifests with lethargy, pallor, undernutrition, intermittent vomiting and/or chronic diarrhoea associated with multiple laboratory abnormalities (leucocytosis with left shift, eosinophilia, anaemia, thrombocytosis, hypoproteinaemia, hypoalbuminaemia, methemoglobinemia and metabolic acidosis). It resolves 3 to 10 days after exclusion of the causative allergen, and most patients develop tolerance to the protein again at approximately 3 to 5 years of age. We present the case of a 47-day-old infant who presented with vomiting and diarrhoea with severe dehydration, metabolic acidosis, methaemoglobinaemia, hypoproteinaemia, hypoalbuminaemia and hyperammonaemia, the latter being a feature that has only been described in one other case before.