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Fecal chymotrypsin and elastase-1 determination on one single stool collected at random: diagnostic value for
Isabelle Molinari1, Karamo Souare, Thierry Lamireau
1Biochemistry Laboratory, Hôpital Pellegrin, Bordeaux, France.
Insights
Measuring fecal proteases from a single stool sample is sufficient for evaluating pancreatic exocrine function. This simplifies testing for pancreatic insufficiency in children, avoiding the need for multiple sample collections.
Area of Science:
- Pediatric Gastroenterology
- Diagnostic Testing
- Pancreatic Function Assessment
Background:
- The secretin-cholecystokinin test is the gold standard for exocrine pancreatic function but is invasive and costly.
- Noninvasive tests like fecal chymotrypsin (FChT) and fecal elastase-1 (FEL-1) are alternatives.
- No established consensus exists for optimal stool collection protocols for these tests.
Purpose of the Study:
- To determine if collecting stool samples over multiple consecutive days offers a diagnostic advantage compared to a single random sample.
- To evaluate the diagnostic utility of measuring fecal proteases (chymotrypsin and elastase-1) for pancreatic insufficiency.
Main Methods:
- 69 children were divided into groups collecting stool for 2 or 3 consecutive days.
- Fecal chymotrypsin activity and fecal elastase-1 concentration were measured in each stool sample.
- Patients were categorized as pancreatic-sufficient (PS) or severe pancreatic-insufficient (PI).
Main Results:
- Significant intraindividual variability was observed for both fecal chymotrypsin and elastase-1.
- No significant diagnostic discordance was found when comparing 1, 2, or 3 days of stool collection.
- Variability (CVs) for chymotrypsin was 36% vs. 40.2%, and for elastase-1 was 22.2% vs. 26.8%.
Conclusions:
- Determining fecal proteases from a single, randomly collected stool sample is adequate for assessing pancreatic exocrine status.
- This finding simplifies the diagnostic process for pancreatic insufficiency in pediatric patients.
- A single stool sample is sufficient for evaluating both pancreatic sufficiency and severe insufficiency.
Objective:
The secretin-cholecystokinin test is the "gold standard" to evaluate exocrine pancreatic function. But this direct duodenal intubation test is invasive, particularly in children, time-consuming, and expensive. For several years, indirect noninvasive tests of pancreatic insufficiency have been developed, such as fecal chymotrypsin (FChT) and fecal elastase-1 (FEL-1) measurements. Generally, elastase-1 is truly admitted to be the most relevant test of exocrine pancreatic status. However, so far, no consensus for stool collection protocol exists. The aim of our study was to investigate the diagnostic advantage from measuring fecal proteases in stool samples collected for two or three consecutive days in comparison to one single stool sample collected at random.
Design:
A total of 69 children were divided into group A (stool samples collected for three consecutive days) and group B (stool samples collected for two consecutive days). These two groups included pancreatic-sufficient patients (PS) and severe pancreatic-insufficient patients (PI). One single determination of fecal chymotrypsin activity and of fecal elastase-1 concentration was realized on each stool.
Results:
The same relatively important intraindividual variability of fecal proteases was observed in group A and B (mean coefficients of variation (CVs) 36% vs. 40.2% for chymotrypsin, 22.2% vs. 26.8% for elastase-1). No significant PS or severe PI diagnostic discordance was observed between 1, 2, or 3 days of stool collections.
Conclusion:
Our study clearly shows that the determination of fecal proteases on one single stool collected at random is sufficient to evaluate pancreatic exocrine status for PS and severe PI.
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