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Bile acid malabsorption in cystic fibrosis with and without pancreatic insufficiency
Insights
Children with cystic fibrosis (CF) show impaired bile acid (BA) absorption, particularly cholic acid, regardless of pancreatic insufficiency. Postprandial serum BA measurements effectively detect this malabsorption in CF patients.
Area of Science:
- Gastroenterology and Hepatology
- Pediatric Medicine
- Biochemistry
Background:
- Cystic Fibrosis (CF) is a genetic disorder affecting multiple organs, including the digestive system.
- Bile acids (BAs) are crucial for fat digestion and absorption, and their metabolism can be altered in CF.
- Previous studies suggest potential BA malabsorption in CF, but its characteristics remain unclear.
Purpose of the Study:
- To investigate serum and fecal bile acid (BA) levels in children with cystic fibrosis (CF) without liver involvement.
- To determine if pancreatic insufficiency affects bile acid (BA) absorption in CF patients.
- To evaluate the utility of postprandial serum bile acid (BA) measurements for assessing malabsorption in CF.
Main Methods:
- Measured fasting serum conjugated cholic acid (CCA) and conjugated chenodeoxycholic acid (CCDCA) in 30 children with CF and controls.
- Administered a standard liquid meal to seven CF children and measured postprandial serum BA levels.
- Assessed total and fractional fecal bile acid (BA) excretion in these children.
Main Results:
- Fasting serum BA levels were similar between CF patients and controls.
- Postprandial serum CCA increase was reduced in CF patients with and without pancreatic insufficiency compared to controls.
- Postprandial serum CCDCA increase was reduced only in CF patients with pancreatic insufficiency.
- Fecal analysis revealed increased cholic and deoxycholic acid excretion in CF patients without pancreatic insufficiency.
- CF patients with pancreatic insufficiency showed markedly increased total fecal BA levels and a higher fecal percentage of chenodeoxycholic and lithocholic acids.
Conclusions:
- Results indicate selective malabsorption of cholic acid in cystic fibrosis (CF), independent of pancreatic insufficiency.
- Postprandial serum bile acid (BA) measurements are a valuable tool for detecting BA malabsorption in CF.
- These findings highlight the complex impact of CF on bile acid homeostasis.
Abstract:
Serum conjugated cholic acid (CCA) and conjugated chenodeoxycholic acid (CCDCA) fasting levels were measured in 30 children with cystic fibrosis (CF) without liver involvement, and mean levels were not significantly different from control values. In seven children (four with partially corrected pancreatic insufficiency and three without pancreatic insufficiency) serum levels of both primary bile acids (BAs) were also measured after the ingestion of a standard liquid meal; the values were then compared with those for total and fractional fecal BA excretion. The CCA mean peak increase was significantly reduced in patients with pancreatic insufficiency (p less than 0.01), as well as in those without pancreatic insufficiency (p less than 0.05), as compared to controls. The CCDCA mean peak increase was reduced only in patients with pancreatic insufficiency (p less than 0.01). Fecal results confirmed serum data, showing a significantly increased excretion of cholic and deoxycholic acids in patients without pancreatic insufficiency as compared to controls (p less than 0.02), despite a similar total BA excretion. In patients with pancreatic insufficiency, total fecal BA levels were markedly increased compared to control values (p less than 0.001); the fecal percentage of chenodeoxycholic and lithocholic acids was greater than that recorded in patients without pancreatic insufficiency (p less than 0.05), in agreement with the different behaviour of serum CCDCA postprandial curves for the two groups of patients. The results are consistent with selective malabsorption of cholic acid in CF, independent of the presence of pancreatic insufficiency; they confirm the usefulness of serum BA postprandial determinations in measuring BA malabsorption.