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Faecal chymotrypsin: a reliable index of exocrine pancreatic function
G A Brown1, D Sule, J Williams
1Institute of Child Health, University of Birmingham.
Insights
Measuring fecal chymotrypsin is a simple, non-invasive test for pancreatic function in children. It accurately reflects duodenal chymotrypsin levels, aiding in diagnosing conditions like cystic fibrosis.
Area of Science:
- Pediatric Gastroenterology
- Diagnostic Testing
- Pancreatic Function
Background:
- Assessing pancreatic exocrine function in children is crucial for diagnosing malabsorption disorders.
- Intraduodenal tests, while accurate, are invasive and complex.
- Faecal chymotrypsin concentration is a potential non-invasive biomarker for pancreatic exocrine function.
Purpose of the Study:
- To evaluate the correlation between duodenal chymotrypsin secretion and faecal chymotrypsin concentration in children.
- To determine the diagnostic utility of faecal chymotrypsin measurement in pediatric pancreatic insufficiency, including cystic fibrosis.
Main Methods:
- Simultaneous measurement of duodenal and faecal chymotrypsin in 30 children (3 weeks to 14 years) post-pancreozymin stimulation.
- Comparison of apparent chymotrypsin secretion rates with mean faecal chymotrypsin concentration from three stool specimens.
- Analysis of faecal chymotrypsin in a separate cohort of 46 children with cystic fibrosis.
Main Results:
- A significant positive correlation was observed between duodenal chymotrypsin secretion and mean faecal chymotrypsin concentration in responsive children.
- Single stool specimen correlation was poorer than using mean values from multiple specimens.
- Children with undetectable duodenal chymotrypsin showed very low faecal levels.
- All 46 children with cystic fibrosis exhibited subnormal faecal chymotrypsin concentrations.
Conclusions:
- Faecal chymotrypsin concentration is a reliable indicator of pancreatic exocrine function in children.
- This non-invasive test demonstrates high specificity and sensitivity.
- Faecal chymotrypsin measurement should precede more invasive intraduodenal pancreatic function tests.
Abstract:
Simultaneous measurements of duodenal and faecal chymotrypsin were made in 30 children aged 3 weeks to 14 years. Apparent chymotrypsin secretion rates measured after stimulation with pancreozymin were compared with the mean faecal chymotrypsin concentration derived from three stool specimens collected at random within 72 hours of the intraduodenal test. In the 25 children who responded to pancreozymin stimulation the mean faecal chymotrypsin concentration was significantly positively correlated with the apparent chymotrypsin secretion rate. Correlation using single specimen stools collected at random was appreciably poorer. In the five children with undetectable or only traces of chymotrypsin in the duodenum after stimulation, the mean faecal chymotrypsin concentrations were only 3-10% of the lower limit of the reference interval. In a second group of 46 children with cystic fibrosis proved by sweat tests and clinical evidence of malabsorption, the chymotrypsin concentration measured in a single stool specimen collected at random was unequivocally subnormal in each case. Faecal chymotrypsin measurement is a rapid, simple, cheap, readily repeated, non-invasive test of high specificity and sensitivity. Faecal chymotrypsin should be measured before contemplating intraduodenal tests of pancreatic function.