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Faecal immunoreactive lipase: a simple diagnostic test for cystic fibrosis
R Münch1, C P Brägger, J Altorfer
1Division of Gastroenterology, University Children's Hospital Zurich, Switzerland. Muench@bluewin.ch
Insights
Faecal immunoreactive lipase (IRL) testing in stool samples is a reliable indicator of exocrine pancreatic function. This test effectively identifies cystic fibrosis (CF) by detecting significantly lower IRL levels in patients.
Area of Science:
- Gastroenterology
- Pediatrics
- Biochemistry
Background:
- Exocrine pancreatic insufficiency is a common complication in cystic fibrosis (CF).
- Accurate assessment of pancreatic function is crucial for CF management.
- Current diagnostic methods may have limitations.
Purpose of the Study:
- To evaluate the utility of faecal immunoreactive lipase (IRL) measurement in spot stool samples as an index of exocrine pancreatic function.
- To establish reference ranges for faecal IRL in healthy children.
- To assess the diagnostic performance of faecal IRL testing in patients with CF.
Main Methods:
- Faecal IRL was measured in spot stool samples from 183 healthy volunteers (aged 2 days to 14.2 years) and 58 patients with proven CF.
- IRL values were analyzed for distribution, age-related differences, and response to milk feeding.
- Diagnostic sensitivity, specificity, and predictive values were calculated for CF detection.
Main Results:
- Healthy controls showed a log-normal distribution of IRL values, with higher levels in neonates and a significant increase after milk feeding.
- Patients with CF exhibited significantly lower median faecal IRL concentrations compared to healthy controls (P < 0.001).
- Faecal IRL levels in meconium were very low, similar to those in CF patients.
Conclusions:
- Faecal IRL determination demonstrates high diagnostic sensitivity (87%) and excellent specificity (97%) for identifying CF.
- A negative faecal IRL test result (PVneg. 99%) effectively excludes CF in screening settings.
- Faecal IRL measurement is a valuable, non-invasive tool for assessing exocrine pancreatic function and diagnosing CF.
Unlabelled:
The study evaluates faecal immunoreactive lipase (IRL) measurement in spot stool samples as an index of exocrine pancreatic function in patients with cystic fibrosis (CF). Stool samples (211) from 183 healthy volunteers (age range: 2 days-14.2 years) showed a normal log distribution of IRL values with a median concentration of 71.4 micrograms/g (range: 0.53-4160 micrograms/g). In 156 stool samples from 58 patients with proven CF, the median IRL concentration of 0.4 microgram/g (range: 0.003-107 micrograms/g) was significantly lower (P < 0.001) than that of normal controls. In healthy controls, IRL levels were age related with significantly higher levels (P < 0.001) shortly after birth compared to older children. Stimulation of the exocrine pancreas by oral milk feeding resulted in a significant (P < 0.001) increase in a faecal IRL concentration. Faecal IRL concentrations in meconium were very low and of the same magnitude as in patients with CF.
Conclusion:
Faecal IRL determination had a high diagnostic sensitivity (87%) and excellent diagnostic specificity (97%) in patients with CF. A negative test result (PVneg. 99%) virtually excluded CF under screening conditions.
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