What is the mechanism, clinical symptoms, treatment, prognosis, and recommended follow-up for Food Protein-Induced Enterocolitis Syndrome (FPIES)?

From the Guidelines

Food Protein-Induced Enterocolitis Syndrome (FPIES) is a non-IgE-mediated food allergy primarily affecting infants and young children, characterized by a delayed T-cell mediated hypersensitivity reaction to specific food proteins, leading to increased intestinal permeability and local inflammation, with clinical symptoms typically occurring 1-4 hours after ingestion of the trigger food, including profuse vomiting, diarrhea, lethargy, pallor, and in severe cases, dehydration and hypotension resembling septic shock. The mechanism of FPIES involves a cell-mediated immune response, rather than an IgE-mediated response, which is typical of other food allergies 1. Clinical symptoms of FPIES can vary in severity, but typically include vomiting, diarrhea, and lethargy, with more severe cases presenting with dehydration, hypotension, and even septic shock-like symptoms 1. Common trigger foods for FPIES include cow's milk, soy, rice, oats, and various solid foods, with the most common triggers varying by geographic region 1. Acute treatment for FPIES focuses on fluid resuscitation with IV normal saline boluses (20 ml/kg) for dehydration, and a single dose of IV methylprednisolone (1 mg/kg) may be beneficial in severe reactions, with ondansetron helping to control persistent vomiting 1. Long-term management involves strict avoidance of trigger foods and providing nutritional guidance to ensure adequate growth and development, with the prognosis generally favorable, as most children outgrow FPIES by ages 3-5 years 1. Follow-up should include regular assessment by an allergist or gastroenterologist every 12-18 months, with consideration of oral food challenges in a supervised medical setting to determine if tolerance has developed, as these challenges should not be attempted at home due to the risk of severe reactions 1. It is also important to recognize that infants with cow's milk or soy-induced FPIES might be at increased risk of having FPIES to other foods, and supervised introduction of solids can be considered to promote implementation of normal dietary variety and prevent unnecessary avoidance 1.

Some key points to consider in the management of FPIES include:

• The importance of a careful history in diagnosing FPIES, as the clinical presentation can be similar to other conditions 1
• The need for strict avoidance of trigger foods to prevent reactions, and the importance of nutritional guidance to ensure adequate growth and development 1
• The potential for infants with FPIES to react to multiple foods, and the need for supervised introduction of new foods to prevent severe reactions 1
• The importance of regular follow-up with an allergist or gastroenterologist to monitor for the development of tolerance and to adjust the management plan as needed 1

From the Research

Mechanism

• FPIES is a non-IgE-mediated gastrointestinal food allergic disorder 2, 3, 4
• The exact mechanism is not fully understood, but it is thought to involve a complex immune response 4
• Recent studies suggest a major role of innate immune cells in acute FPIES, with the role of T cells being questioned 4

Clinical Symptoms

• Symptoms of FPIES include profuse vomiting, usually 2-6 hours after ingestion of the offending food, which may or may not be accompanied by diarrhea 2, 3
• Pallor, lethargy, and poor growth may also be present 3
• A chronic form of FPIES can occur, characterized by protracted vomiting, diarrhea, or both, accompanied by poor growth 3

Treatment

• Management of FPIES involves removing the causal food protein from the diet 2, 3
• Extensively hydrolyzed formula is recommended as a substitute for cow's milk, unless breastfeeding is continued 2
• Ondansetron has emerged as an effective treatment for acute FPIES reactions, particularly for vomiting 5, 6, 4
• Rehydration, corticosteroids, and a proactive approach with oral ondansetron may be necessary for severe reactions 6

Prognosis

• Prognosis is usually good, with most children tolerating foods before 6 years of age 3
• Early recognition and removal of the offending food are crucial for improving outcomes 2, 3

Recommended Follow-up

• Regular follow-up is necessary to monitor the child's condition and adjust the treatment plan as needed 2, 6
• Oral food challenges may be necessary to assess tolerance to the offending food 5, 6
• A better understanding of the pathophysiology of FPIES and the development of new biomarkers are needed to improve diagnosis and management 4