Comparison of methemoglobin levels in food protein-induced enterocolitis syndrome and other gastrointestinal diseases in neonates

Heterogeneity of food protein-induced enterocolitis syndrome (FPIES)

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy with gastrointestinal symptoms such as vomiting and diarrhea. The development of international consensus guidelines for the diagnosis and management of FPIES in 2017 enabled us to compare patients worldwide, regardless of geographic variation in disease features. As a result, it has become clear that there is heterogeneity among patients with FPIES or that there are cases that partly fit the diagnostic criteria for FPIES but have different characteristics. This review highlights the heterogeneity in FPIES characteristics in terms of trigger foods, the age of onset, differences in geographic regions, and symptoms; it further proposes four disease entities, including acute FPIES in children, acute FPIES in adults, chronic FPIES, and early-onset neonatal FPIES, depending on the age of onset and presumed pathophysiology. The major symptoms at onset and trigger foods differ in acute FPIES in children, acute FPIES in adults, and chronic FPIES, whereas the disease entities may share a similar pathophysiology. Early-onset neonatal FPIES may have a different pathophysiology than acute or chronic FPIES, and may not necessarily fulfil the full diagnostic criteria for acute or chronic FPIES described in the international consensus guidelines. Due to the similarity in symptoms, early-onset neonatal FPIES may sometimes be misdiagnosed as necrotizing enterocolitis. We aim to increase awareness of FPIES among medical staff in pediatrics, neonatology, and internal medicine and promote research, to gain a better understanding of the heterogeneity and pathophysiology of FPIES.

Update on Food Protein-Induced Enterocolitis Syndrome (FPIES)

PURPOSE OF REVIEW

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated food allergy characterized by delayed, and potentially severe, gastrointestinal symptoms. Since the advent of a specific diagnostic code and establishment of diagnostic guidelines, our understanding of this condition has grown.

RECENT FINDINGS

FPIES affects patients from early infancy into adulthood. Any food can be a trigger, and common culprit foods vary geographically and by age. An understanding of the complex underlying immune mechanisms remains elusive, although studies show pan-leukocyte activation, cytokine release, and increased gastrointestinal permeability. Management involves trigger avoidance, and patients may benefit from the support of a dietitian to ensure adequate nutrient intake. Tolerance develops over time for most children, but due to the risk of severe symptoms, re-introduction of a suspected FPIES trigger is recommended only under supervision at an oral food challenge. Studies continue to evaluate the optimal challenge protocol. Caregivers of children with FPIES report high levels of anxiety and stress, which is attributed to the dramatic symptomatology, dietary restrictions, nutritional concerns, lack of confirmatory diagnostic tests, and limited tools for management of reactions. Our understanding of the FPIES diagnosis has improved over the last few decades, but there remain opportunities, particularly regarding discerning the pathophysiology and best management practices.

A Cyanotic Infant: Infrequent Presentation of Cow’s Milk Protein Allergy

We report the case of a three-month-old boy who presented with poor weight gain, loose stools, and poor oral intake for three weeks. Physical examination revealed a pale infant with abdominal distension and cyanosis. Oxygen saturation was normal, but the laboratory showed important methemoglobinemia. The diagnosis of FPIES (food protein-induced enterocolitis syndrome) in the context of cow’s milk protein allergy (CMPA) was suspected. Although CMPA is a common condition encountered in small children, chronic forms of FPIES can be difficult to diagnose. Maintaining clinical suspicion about the potential association between methemoglobinemia and gastrointestinal symptoms can lead to prompt recognition and intervention.

Evaluation of the Diagnostic Accuracy of Thymus and Activation-Regulated Chemokine to Discriminate Food Protein-Induced Enterocolitis Syndrome from Infectious Gastroenteritis

BACKGROUND

Post-emetic elevation in thymus and activation-regulated chemokine (TARC) levels has been reported in patients with food protein-induced enterocolitis syndrome (FPIES); however, no studies have investigated differences in TARC levels between FPIES and other diseases.

OBJECTIVES

We evaluated the clinical usefulness of TARC measurement in differentiating between FPIES and infectious gastroenteritis.

METHODS

This study included 8 patients with solid-food FPIES (FPIES group; hen's egg [n = 6], rice [n = 1], and short-neck clam [n = 1]; a total of 11 episodes necessitating emergency department visit or positive result of oral food challenge test) and 17 patients with infectious gastroenteritis (control group), and all patients had no eczema. Post-emetic serum TARC levels and modified TARC levels (serum TARC value - normal mean for each age) were compared between the 2 groups.

RESULTS

The median (range) ages for the FPIES and control groups were 0.7 (0.5-6.2) and 1.8 (0.1-4.4) years, respectively (p > 0.05). In the FPIES and control groups, median (range) TARC levels were 2,911 (1,062-7,816) and 600 (277-2,034) pg/mL, and median (range) modified TARC levels were 2,204 (355-7,109) and 129 (0-1,314), respectively. The TARC and modified TARC levels were significantly higher in the FPIES group than in the control group (p < 0.001 for both).

CONCLUSION

In the absence of eczema, post-emetic serum TARC levels might be a potential diagnostic biomarker for distinguishing FPIES from infectious gastroenteritis.