The pathophysiology of functional dyspepsia remains unknown. 

Duodenal eosinophil infiltration has been reported.

Dr Walters and colleagues from Australia assessed the association between dyspeptic symptoms and duodenal eosinophilia in children undergoing upper gastrointestinal endoscopy.

In this retrospective cohort study, children with normal upper endoscopy and routine histology at a single tertiary pediatric centre between 2010 and 2014 were included. 

The research team defined functional dyspepsia as epigastric pain or discomfort >2 months without response to acid suppression. 

Controls presented with nonerosive reflux disease, dysphagia or rumination syndrome. 

Intramucosal eosinophil counts were compared between the groups using uni- and multivariate regression analyses.

The team identified 36 cases, and 36 nonmatched controls. 

Atopic history, and psychological comorbidity were frequent in cases and controls.

The researchers found that self-reported nausea, lethargy, and family functional gastrointestinal disorder were more common in cases than controls. 

Duodenal eosinophil counts were significantly higher in cases than controls with >112 eosinophils per mm² predictive for functional dyspepsia. 

The team observed that duodenal eosinophilia was associated with weight loss.

Dr Walters' team concludes, "Functional dyspepsia in children is strongly associated with duodenal eosinophilia, in the absence of endoscopic or routine histological findings."

"Frequent atopic and psychological comorbidity illustrate likely multifactorial mechanisms."