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Duodenal pH in cystic fibrosis and its relationship to fat malabsorption
P J Robinson1, A L Smith, P D Sly
1Department of Thoracic Medicine, Royal Children's Hospital, Melbourne, Australia.
Insights
Children with cystic fibrosis often have acidic duodenal pH, hindering pancreatic enzyme supplements. Acid reduction with misoprostol improved both pH and fat absorption in a small study.
Area of Science:
- Gastroenterology
- Pediatrics
- Biochemistry
Background:
- Cystic fibrosis (CF) patients exhibit altered duodenal pH.
- Pancreatic enzyme supplements are crucial for managing CF-related malabsorption.
- Optimal function of enzyme supplements depends on specific duodenal pH ranges.
Purpose of the Study:
- To examine the correlation between duodenal pH and pancreatic enzyme efficacy in pediatric CF patients.
- To assess the impact of acid-reducing medication on duodenal pH and fat absorption in CF.
Main Methods:
- Duodenal pH monitoring in 18 children with CF and age-matched controls.
- Analysis of pH levels in relation to lipase activity and enteric coating dissolution.
- Evaluation of fat malabsorption before and after misoprostol treatment in a subset of patients.
Main Results:
- CF patients showed prolonged periods below pH 4.0 and reduced time above pH 5.8 compared to controls.
- A significant link was observed between duodenal acidity and residual fat malabsorption.
- Misoprostol administration led to significant improvements in duodenal pH and fat absorption.
Conclusions:
- Duodenal pH variability in CF significantly impacts pancreatic enzyme supplement effectiveness.
- Targeting duodenal acidity with agents like misoprostol may enhance treatment outcomes for CF patients with malabsorption.
Abstract:
To investigate the relationship between duodenal pH levels and supplemental pancreatic enzyme function in cystic fibrosis, 18 children with this condition had pH recordings performed from the second and fourth part of the duodenum. Compared to age-matched controls, patients with cystic fibrosis had significantly longer periods below a pH of 4.0 in the postprandial period and significantly less time above pH 5.8. These values correspond to the pH levels at which lipase is irreversibly destroyed (pH 4.0) and enteric coating of enzyme supplements dissolves (pH 5.8). A significant relationship was found between the pH recordings from the fourth part of the duodenum and the degree of residual fat malabsorption while taking enteric-coated enzyme supplements. Four patients with an excessively acidic duodenum and residual fat malabsorption despite high-dose enzyme supplementation were treated with misoprostol (Searle), a known acid-reducing agent. There were significant improvements in both duodenal pH values and fat absorption. We conclude that there is a wide range of duodenal pH values found in patients with cystic fibrosis and that the efficiency with which enzyme supplements work is closely related to these pH levels. Administration of misoprostol to those patients with excessively acidic duodenal pH levels as well as residual malabsorption appears to be of benefit in improving both the excessively acidic pH levels and the fat malabsorption.