Eosinophilic Esophagitis in Children and Adults

An LC-MS/MS method for the quantification of 3-bromotyrosine in plasma from patients diagnosed with eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a disease marked by a surplus of eosinophils, a type of white blood cell that causes inflammation and irritation. The current diagnostic and monitoring procedure for EoE is endoscopy with biopsy, which is invasive, expensive, and leads to tissue tearing in patients. A biomarker in plasma would offer a much less invasive form of disease monitoring for patients with EoE. Eosinophils have been shown to make eosinophil peroxidase, an enzyme that produces hypobromous acid, reacts with primary amines, and forms bromoamides. One product of this biochemical reaction is 3-bromotyrosine. We have optimized a selective, sensitive, and reproducible method to detect and quantify L-tyrosine and 3-bromotyrosine in human plasma using high-pressure liquid chromatography and tandem mass spectrometry (HPLC-MS/MS). Our sample preparation and analysis method requires fewer steps and provides a faster analysis than previous methods. Method validation yielded limits of quantification of 50 ng mL-1 for L-tyrosine and 10 ng mL-1 for 3-bromotyrosine. Calibration curves for quantification were linear from 50 to 500 ng mL-1 with an R2 value of 0.9995 for L-tyrosine and 10 to 300 ng mL-1 with an R2 value of 0.9998 for 3-bromotyrosine. Method variability was assessed resulting in relative standard deviations of 0.98-4.6% for 3-bromotyrosine (n = 18) and 0.20-0.58% for L-tyrosine (n = 18). Method applicability was tested with patients with a confirmed diagnosis of EoE, initially suggesting little to no correlation between eosinophil count and 3-bromotyrosine concentration in plasma. However, we do observe a relationship between eosinophil count and esophageal deformities. More research must be conducted to determine a more definitive correlation.

Eosinophilic Esophagitis: A Review for the Primary Care Practitioner

This chapter presents an overview of eosinophilic esophagitis (EoE) for the Primary Care Practitioner (PCP). The focus is on helping PCPs keep it in their differential diagnosis by discussing the spectrum of clinical presentations, how to screen for EoE in at-risk populations and subsequently manage the patient with this condition. The authors review epidemiology, risk factors and associated conditions, pathology, clinical presentation, diagnosis, and management options.

Untargeted, High-Resolution Metabolomics in Pediatric Eosinophilic Esophagitis

BACKGROUND/OBJECTIVES

Eosinophilic esophagitis (EoE) is an inflammatory disease of unclear etiology. The aim of this study was to use untargeted plasma metabolomics to identify metabolic pathway alterations associated with EoE to better understand the pathophysiology.

METHODS

This prospective, case-control study included 72 children, aged 1-17 years, undergoing clinically indicated upper endoscopy (14 diagnosed with EoE and 58 controls). Fasting plasma samples were analyzed for metabolomics by high-resolution dual-chromatography mass spectrometry. Analysis was performed on sex-matched groups at a 2:1 ratio. Significant differences among the plasma metabolite features between children with and without EoE were determined using multivariate regression analysis and were annotated with a network-based algorithm. Subsequent pathway enrichment analysis was performed.

RESULTS

Patients with EoE had a higher proportion of atopic disease (85.7% vs 50%, P = 0.019) and any allergies (100% vs 57.1%, P = 0.0005). Analysis of the dual chromatography features resulted in a total of 918 metabolites that differentiated EoE and controls. Glycerophospholipid metabolism was significantly enriched with the greatest number of differentiating metabolites and overall pathway enrichment ( P < 0.01). Multiple amino and fatty acid pathways including linoleic acid were also enriched, as well as pyridoxine metabolism ( P < 0.01).

CONCLUSIONS

In this pilot study, we found differences in metabolites involved in glycerophospholipid and inflammation pathways in pediatric patients with EoE using untargeted metabolomics, as well as overlap with amino acid metabolome alterations found in atopic disease.

Eosinophilic Esophagitis

This chapter presents an overview of eosinophilic esophagitis (EoE) for the Primary Care Practitioner (PCP). The focus is on helping PCPs keep it in their differential diagnosis by discussing the spectrum of clinical presentations, how to screen for EoE in at-risk populations and subsequently manage the patient with this condition. The authors review epidemiology, risk factors and associated conditions, pathology, clinical presentation, diagnosis, and management options.

Oropharyngeal Dysphagia in Children with Eosinophilic Esophagitis

Dysphagia is the most troublesome symptom of eosinophilic esophagitis (EoE). This study aimed to investigate oropharyngeal dysphagia in children with EoE and possible related factors. Children with a definite diagnosis of EoE were included in the study. Medical and feeding histories were recorded. A disease control level was determined for each child. An oral structure examination, the Turkish version of the Mastication and Observation Evaluation (T-MOE), the Pediatric version of the Eating Assessment Tool-10 (PEDI-EAT-10) and the 3-oz water swallow test were applied in screening for oropharyngeal dysphagia. Fifty-two children participated in the study. Oropharyngeal dysphagia took the form of abnormal swallowing (PEDI-EAT-10 score ≥ 4) and increased aspiration risk (PEDI- EAT-10 score ≥ 13) in 51.9% and 25.0% of the children, respectively. Seven children failed the 3-oz water swallow test. Abnormal swallowing and aspiration risk were significantly higher in children with prolonged mealtimes, impaired chewing function, and uncontrolled disease (p < 0.05). Chewing function was the most important risk factor for abnormal swallowing and increased aspiration (R² = 0.36, R² = 0.52, p < 0.001, respectively). Oropharyngeal dysphagia is common in children with EoE and associated with increased aspiration risk in a subpopulation. Uncontrolled disease, prolonged mealtimes, and impaired chewing function may provide clues for oropharyngeal dysphagia in EoE.

Turkish Translation, Validation, and Reliability Analysis of Pediatric Eosinophilic Esophagitis Symptom Severity Module Version 2.0

The Paediatric Eosinophilic Esophagitis Symptom Severity Modules Version 2.0 (T-PEESv2.0) was developed in English as a valid, reliable questionnaire for follow up. This work aimed to develop a Turkish version of T-PEESv2.0 via translation and cultural adaptation and then to test its validation and reliability.

Methods

The PEESv2.0 was translated into Turkish by standardized procedural steps completed in cooperation with the Mapi Research Trust. The final version of the questionnaire was submitted to eosinophilic oesophagitis patients or their parents at 2 times point separated by 1 week. An age-matched control group was used to test the discriminant validity. Construct validity was tested using the Wilcoxon test, and internal consistency was tested using Cronbach's alpha. Test-retest reliability was measured with Cohen's kappa and intraclass correlation coefficient.

Results

One hundred twenty-eight participants (70 patients, 58 parents) were enrolled. Fifty-eight (39.1%) of them completed T-PEESv2.0-parent by proxy and 70 (54.7%) were T-PEESv2.0. The Cronbach's alpha coefficient and intraclass correlation coefficient for test-retest reliability were >0.70 for both questionnaires and for all domain (frequency and severity) and total scores. For discriminant validity analysis, subscale (frequency and domain) and total scores of the patient group were compared with those of the control group. The subscale and total scores were significantly different between the groups (P < 0.05).

Conclusion

T-PEESv2.0 appeared to be valid and reliable, ready to be introduced as a clinical and research tool for the assessment of patients with eosinophilic oesophagitis.

Clinical Features of Eosinophilic Esophagitis: A Single Center Experience in Ecuador

PURPOSE

Data on eosinophilic esophagitis (EoE) in South America is scarce. Moreover, no studies are available in Ecuador. We evaluated the clinical, endoscopic, and histological characteristics of Ecuadorian children with EoE.

METHODS

Medical records of 2,711 children who underwent upper gastrointestinal endoscopy (UGE) between 2009 and 2020 at Hospital Metropolitano de Quito, Ecuador were reviewed. Esophageal mucosal biopsies were obtained from 72 patients and the features of 35 children with EoE were described. EoE was diagnosed when there were more than 15 eosinophils in the esophagus, per high power field.

RESULTS

EoE was diagnosed in 35 children (9.4±4.5 years) with a male predominance (74%). Abdominal pain (51.4%) and vomiting (31.4%) were dominant symptoms. A history of allergic diseases was noted in 47.1% of the children, which mainly included allergic rhinitis (37.1%) and atopic dermatitis (11.4%). The most common endoscopic findings were furrowing (82.9%) and edema (74.3%). All patients were initially treated with proton-pump inhibitors (PPIs). Those who did not respond to PPIs received steroids (5.7%) and diet therapy (5.7%), and five patients were referred to an allergist. Clinical and histological resolution was observed in 65% of the patients who underwent a second UGE after 6-8 weeks of PPI.

CONCLUSION

Our study describes the clinical features of pediatric EoE in Ecuador. This is the first retrospective study in Ecuador that describes the clinical, endoscopic, and histological manifestations of EoE in a small pediatric population. Almost half of the children who underwent a biopsy had EoE.

Esophageal Eosinophilia Is Common Among Relatives of Eosinophilic Esophagitis Patients

BACKGROUND & AIMS

Familial clustering of eosinophilic esophagitis (EoE) has been described, and we report on the biopsy-assessed prevalence of esophageal eosinophilia (EE) in first-degree family members. The aim was to determine the prevalence of EE in first-degree adult relatives (FDRs) of EoE patients.

METHODS

Index EoE patients diagnosed by EE (>15 eosinophils per high-power field) and proton pump inhibitor nonresponsiveness were identified and family trees were constructed. Adult FDRs were invited to undergo upper endoscopy with esophageal biopsies and to complete reflux, dysphagia, and allergy/atopy questionnaires. Questionnaire information was gathered only for those who responded as per institutional review board purview. Records from other children and adult FDRs with prior EoE diagnoses also were obtained when permission was obtained. Simple and multivariable logistic regression models were used to evaluate the unadjusted and odds ratios of EoE for demographic and clinical variables.

RESULTS

A total of 239 FDRs from 37 index EoE patients were identified. Seventy-one of 239 adult (age, >18 y) FDRs completed endoscopy and questionnaires and 18 of 71 FDRs had EE. An additional 17 FDRs were confirmed to have EE after external medical record retrieval, resulting in a total of 35 of 239 (14.6%) FDRs with EE. Significantly more male FDRs had EE compared with female FDRs (P = .027). Proton pump inhibitors, dysphagia, gastroesophageal reflux disease, asthma, and reflux symptoms predicted EE in FDRs. FDRs who had EE reported hay fever, allergic eye symptoms, and food allergy more frequently than those without EE (P = .03, P = .001, and P = .02, respectively). Specifically, younger age, higher serum eosinophils, being male, and having food allergies all were associated with higher odds of EoE (P = .0211, P = .0031, P = .0362, and P = .0089, respectively).

CONCLUSIONS

The prevalence of esophageal eosinophilia is extremely high and male-predominant in first-degree relatives of EoE patients. Symptoms of hay fever, allergic eye symptoms, and food allergy were predictors of EE in FDRs. Dysphagia did not predict esophageal eosinophilia. Family members of EoE patients are at risk for EE, particularly those who have atopic symptoms.

Disease Burden and Treatment Patterns Associated With Eosinophilic Esophagitis in the United States: A Retrospective Claims Study

GOALS

This US-based, retrospective claims study aimed to investigate disease burden and treatment patterns in patients with eosinophilic esophagitis (EoE), and to compare health care resource use (HCRU) in patients with EoE and matched controls without EoE.

MATERIALS AND METHODS

Patients with a diagnosis of EoE and ≥12 months of prediagnosis data were identified from the Truven Health MarketScan Research databases (January 2008 to September 2016) and followed up from the diagnosis date until termination of eligibility for a health plan. Patient clinical characteristics and HCRU were recorded in the 12 months before diagnosis; HCRU and treatment patterns were recorded during follow-up. HCRU in patients with EoE and matched controls was compared during the 12-month postdiagnosis period.

RESULTS

Among the 23,003 patients with EoE (mean age: 34.3 y; 64.8% male), gastroesophageal reflux disease was the most common prediagnosis condition (34.6%). After diagnosis, the most common off-label, first-line treatments were proton pump inhibitor monotherapy (52.8%) and topical corticosteroid monotherapy (21.5%). Overall, 3336 patients (14.5%) received at least 3 lines of off-label pharmacotherapy. Outpatient visits (recorded in 99.9% of patients on and postdiagnosis) were most frequently to gastroenterologists/pediatric gastroenterologists (49.5% prediagnosis, 72.6% on and postdiagnosis). Inpatient admissions and outpatient and emergency room visits were more likely in patients with EoE than in matched controls (P<0.0001).

CONCLUSIONS

Patients with EoE in the USA experience a high disease burden both before and after diagnosis, which requires significant HCRU. Our findings highlight the unmet need for adequate control of EoE-related symptoms.

Pediatric eosinophilic esophagitis: a review for the clinician

Eosinophilic esophagitis (EoE) is a chronic clinical-pathologic disease characterized by eosinophilic infiltration of the esophageal epithelium with esophageal dysfunction symptoms.EoE can occur at any age and has different clinical manifestations depending on the age onset.To date, esophago-gastroduodenal endoscopy (EGD) with biopsy is the gold-standard for EoE diagnosis.According to the recent consensus guidelines, proton pump inhibitors, corticosteroids and elimination diets could be a first-line therapy option. The aim of the treatment is clinical and histological remission for preventing long-lasting untreatable fibrosis.A multidisciplinary approach (allergist, gastroenterology, dietitian, and pathologist) is recommended for managing patients affected by EoE, given the complexity of its treatment.This review will provide a practical guide to assist pediatricians treating children with EoE.Moreover, it highlights the unmet needs in diagnosis and treatment that require urgent attention from the scientific community in the aim of improving the management of patients with EoE.

Is There a Role for Topical Swallowed Steroids upon Emergency Room Admission for Suspected Food Bolus Obstruction in Eosinophilic Esophagitis?

Since most pharmacological treatments in case of esophageal food impaction (EFI) are unsuccessful, an endoscopy is usually required to resolve EFI. We present the first results of a budesonide orodispersible tablet (BOT) as a medical treatment option before endoscopy. We evaluated all patients with a suspected EFI to receive BOT before emergent endoscopy at a tertiary hospital between March 2019 and June 2020. A total of eight patients received BOT before endoscopy. Mean age was 50.1 years and 87.5% were male. In 38% (3/8) of patients the EFI resolved without endoscopic intervention. No adverse events occurred. After endoscopy, a diagnosis of EoE was established in 75%. This case series demonstrate the potential of BOT as medical rescue therapy in case of EFI.

Food Allergy from Infancy Through Adulthood

Food allergies are the result of immune responses that cause adverse reactions to foods. Immune responses to foods may produce a spectrum of symptoms and disorders, including acute allergic reactions and anaphylaxis, food protein-induced allergic proctocolitis, food protein-induced enterocolitis syndrome, food-dependent, exercise-induced anaphylaxis, and oral allergy syndrome (pollen-food allergy syndrome). Food-allergic responses also contribute to chronic inflammatory disorders such as eosinophilic esophagitis and atopic dermatitis. Although food allergy affects people from infancy through adulthood, there are allergic features that differ according to age (ie, presentation, triggers, and natural course) and have important implications for diagnosis, prognosis, and management. New food allergies can develop at any age, and we propose similarities in the etiology of de novo food allergy whether in infancy or adulthood. The approach to managing food allergy changes dramatically over the life course, and physicians and patients must respond accordingly to optimize care. Food allergy therapies are emerging, and the efficacy and safety of these interventions could differ by age group of those treated. In this review, we highlight interesting observations on the etiology and characteristics of food allergy presenting at different ages and discuss clinical management as it relates to life stage.

The management and course of eosinophilic oesophagitis in Israeli children

AIM

Eosinophilic oesophagitis (EoE) is a chronic inflammatory oesophageal disease, which has become more recognised in the past decade. We wanted to characterise our patients and review their course of disease and response to treatment.

METHODS

We retrospectively reviewed the medical records of EoE patients from January 2010 to May 2018 in our Gastroenterology Institute. A hundred and two children were included in this study. We investigated the characteristics of patients and the response to three treatment options: proton pump inhibitors, elimination diet and topical steroids. The response to treatment was analysed according to 3 aspects: clinical, endoscopic appearance and histological features.

RESULTS

Clinical improvement was noted in 55%, 75% and 87.5% on PPIs, diet and budesonide, respectively. Endoscopic improvement was noted in 38.4%, 51.4% and 65.4% on PPIs, diet and budesonide, respectively. Histological improvement was noted in 43.7%, 62.2% and 88.5% on PPIs, diet and budesonide, respectively.

CONCLUSION

Our findings suggest that Israeli paediatric EoE patients have characteristics that resemble previous reports. Although there is a correlation between symptoms, endoscopic and histological appearance, we cannot rely on patients reports alone, and therefore, repeated endoscopy and biopsies are mandated. Topical steroids seem to be the most effective treatment option.

Clinical and anatomopathological features of eosinophilic oesophagitis in children and adults

INTRODUCTION

Eosinophilic oesophagitis (EoE) is a chronic clinical-pathological disorder with an immunological basis characterised by symptoms of oesophageal dysfunction and, histologically, eosinophilic inflammation.

OBJECTIVE

To evaluate the clinical characteristics and differences in children and adults diagnosed with EoE in a tertiary level hospital.

METHOD

Descriptive, retrospective and cross-sectional study. We randomly selected 40 children and 40 adults diagnosed with EoE between 2009 and 2016. The patient characteristics were analysed by means of epidemiological, clinical, diagnostic and therapeutic variables.

RESULTS

The average age at diagnosis was 10 years (children) and 34 years (adults), with a higher frequency in males. The majority were sensitised to aeroallergens (77.5% children vs. 82.5% adults) and foods (75% children vs. 82.5% adults). Statistically significant differences were detected in sensitisation to fruits (p=0.007) and grains (p<0.001). Differences were observed in impaction (22.5% children vs. 82.5% adults), dysphagia (42.5% children vs. 77.5% adults) and abdominal pain (25% children vs. 7.5% adults). Endoscopy showed that children had a higher frequency of exudates (92.5%) and adults, trachealisation (50% vs. 5%) and stenosis (17.5% vs. 2.5%). Statistically significant differences were found in treatment with topical corticosteroids (30% children vs. 77.5% adults), with a variable positive response. 77.5% of the patients received elimination diets.

CONCLUSIONS

Statistically significant differences were observed between the paediatric and adult populations in the food sensitisation profiles, clinical manifestations, endoscopic findings and treatments received. This is a complex pathology that calls for a multidisciplinary team and would require new non-invasive techniques to facilitate its management.

Nationwide Multicenter Study of Eosinophilic Esophagitis in Korean Children

PURPOSE

In East Asian countries, there are only a few epidemiologic studies of eosinophilic esophagitis (EoE) and no studies in children. We investigated the incidence and compared the clinical characteristics of EoE and eosinophilic gastroenteritis involving the esophagus (EGEIE) in Korean children.

METHODS

A total of 910 children, who had symptoms of esophageal dysfunction, from 10 hospitals in Korea were included. EoE was diagnosed according to diagnostic guidelines and EGEIE was diagnosed when there were >15 eosinophils in the esophagus per high power field (HPF) and >20 eosinophils per HPF deposited in the stomach and duodenum with abnormal endoscopic findings.

RESULTS

Of the 910 subjects, 14 (1.5%) were diagnosed with EoE and 12 (1.3%) were diagnosed with EGEIE. Vomiting was the most common symptom in 57.1% and 66.7% of patients with EoE and EGEIE, respectively. Only diarrhea was significantly different between EoE and EGEIE (p=0.033). In total, 61.5% of patients had allergic diseases. Exudates were the most common endoscopic findings in EoE and there were no esophageal strictures in both groups. The median age of patients with normal endoscopic findings was significantly younger at 3.2 years, compared to the median age of 11.1 years in those with abnormal endoscopic findings (p=0.004).

CONCLUSION

The incidence of EoE in Korean children was lower than that of Western countries, while the incidence of EGEIE was similar to EoE. There were no clinical differences except for diarrhea and no differences in endoscopic findings between EoE and EGEIE.

Eosinophilic esophagitis in esophageal atresia: Tertiary care experience of a "selective" approach for biopsy sampling

BACKGROUND

A high prevalence (9.5-30%) of eosinophilic esophagitis (EoE) in patients with esophageal atresia (EA) has been reported. The application of the EoE criteria to EA patients might be problematic. To date, only studies using a "routine" biopsy approach, even in asymptomatic patients, have been performed. The aim of the study was to establish the prevalence of EoE among symptomatic EA patients (EA/EoE group) without anastomotic stricture (AS) and to compare their characteristics with those of EoE patients from general population (EoE group).

METHODS

From 2005 to 2018, we reviewed charts of children with EA and EoE. "Selective" biopsy approach only in EA children without AS and/or endoscopic feature of EoE was performed. Characteristics of EA/EoE and EoE groups were compared.

RESULTS

Among 370 EA and 118 EoE, 15 EA/EoE patients were detected (4.0% of EA patients). Male predominance and a high prevalence of allergy without differences between EA/EoE and EoE groups was observed. EA/EoE children were significantly younger (p < 0.0001). PPI-responder patients were significantly more prevalent in EA/EoE group (p = 0.045).

CONCLUSION

Our data confirm that EA patients are at high risk for developing EoE. High incidence, early onset, and high prevalence of PPI-responders might suggest that esophageal motility disorders interact to increase propensity to EoE in EA patients. However, our study also suggests that overdiagnosis of EoE may occur in EA and that adapted criteria for EoE diagnosis should be developed for EA patients.

TRIAL REGISTRATION

Not applicable for this retrospective study.

siRNA Targeting and Treatment of Gastrointestinal Diseases

RNA interference via small interfering RNA (siRNA) offers opportunities to precisely target genes that contribute to gastrointestinal (GI) pathologies, such as inflammatory bowel disease, celiac, and esophageal scarring. Delivering the siRNA to the GI tract proves challenging as the harsh environment of the intestines degrades the siRNA before it can reach its target or blocks its entry into its site of action in the cytoplasm. Additionally, the GI tract is large and disease is often localized to a specific site. This review discusses polymer and lipid‐based delivery systems for protection and targeting of siRNA therapies to the GI tract to treat local disease.

A Distinct Esophageal mRNA Pattern Identifies Eosinophilic Esophagitis Patients With Food Impactions

Eosinophilic esophagitis (EoE), a Th2-type allergic immune disorder characterized by an eosinophil-rich esophageal immune infiltrate, is often associated with food impaction (FI) in pediatric patients but the molecular mechanisms underlying the development of this complication are not well understood. We aim to identify molecular pathways involved in the development of FI. Due to large variations in disease presentation, our analysis was further geared to find markers capable of distinguishing EoE patients that are prone to develop food impactions and thus expand an established medical algorithm for EoE by developing a secondary analysis that allows for the identification of patients with food impactions as a distinct patient population. To this end, mRNA patterns from esophageal biopsies of pediatric EoE patients presenting with and without food impactions were compared and machine learning techniques were employed to establish a diagnostic probability score to identify patients with food impactions (EoE+FI). Our analysis showed that EoE patients with food impaction were indistinguishable from other EoE patients based on their tissue eosinophil count, serum IgE levels, or the mRNA transcriptome-based p(EoE). Irrespectively, an additional analysis loop of the medical algorithm was able to separate EoE+FI patients and a composite FI-score was established that identified such patients with a sensitivity of 93% and a specificity of 100%. The esophageal mRNA pattern of EoE+FI patients was typified by lower expression levels of mast cell markers and Th2 associated transcripts, such as FCERIB, CPA3, CCL2, IL4, and IL5. Furthermore, lower expression levels of regulators of esophageal motility (NOS2 and HIF1A) were detected in EoE+FI. The EoE+FI -specific mRNA pattern indicates that impaired motility may be one underlying factor for the development of food impactions in pediatric patients. The availability of improved diagnostic tools such as a medical algorithm for EoE subpopulations will have a direct impact on clinical practice because such strategies can identify molecular inflammatory characteristics of individual EoE patients, which, in turn, will facilitate the development of individualized therapeutic approaches that target the relevant pathways affected in each patient.

Plasma Urea Cycle Metabolites May Be Useful Biomarkers in Children With Eosinophilic Esophagitis

Background: Eosinophilic esophagitis (EoE) is a disorder of the esophagus that has become increasingly recognized in children. Because these children undergo multiple endoscopies, discovering a non-invasive biomarker of disease activity is highly desirable. The aim of this study was to use targeted plasma metabolomics to identify potential biomarker candidates for EoE in a discovery phase. Methods: A prospective, single-center clinical trial was performed on 24 children ages 2-18 years with and without EoE undergoing upper endoscopy for any indication. Blood samples were collected for metabolomics profiling using the subclasses: amino acids, tricarboxylic acid cycle, acetylation, and methylation. Using mass spectrometry and systematic bioinformatics analysis, 48 metabolites were measured and compared between children with active EoE (+EoE) and controls (-EoE). To investigate the effect of proton pump inhibitor (PPI) use on metabolites, patients were also stratified based on PPI use (+PPI, -PPI). Results: Seven children had active EoE at the time of endoscopy. Eleven children were on PPI (4 with EoE). Of the 48 metabolites measured, 8 plasma metabolites showed statistically significant differences (p < 0.05) comparing +EoE -PPI to -EoE -PPI, a few of which were upregulated metabolites involved in the urea cycle. There were 14 significant differences comparing +EoE +PPI to +EoE -PPI. This demonstrated that in EoE patients, PPI use upregulated metabolites involved in the urea cycle, while it downregulated metabolites involved in methylation. Comparison among all four groups, +EoE +PPI, +EoE -PPI, -EoE +PPI, and -EoE -PPI, revealed 27 significantly different metabolites. +EoE +PPI had downregulated methionine and N-acetyl methionine, while both +EoE groups and -EoE +PPI had upregulated homocysteine, N-acetylputrescine, N-acetylornithine, arginine, and ornithine. Conclusion: The present study revealed key plasma metabolite differences in children with EoE compared to unaffected controls. Notable candidate biomarkers include dimethylarginine, putrescine, and N-acetylputrescine. PPI use was shown to influence these urea cycle metabolites, regardless of EoE presence. Therefore, future studies should distinguish patients based on PPI use or determine metabolites while not on treatment. These findings will be confirmed in a larger validation phase, as this may represent a significant discovery in the search for a non-invasive biomarker for EoE. Clinical Trial Registration: This clinical trial was registered with ClinicalTrials.gov, identifier: NCT 03107819.