From the Guidelines
The fecal elastase test is the most appropriate initial test for diagnosing exocrine pancreatic insufficiency, and it should be performed on a semi-solid or solid stool specimen, with a level <100 mg/g of stool providing good evidence of EPI, and levels of 100–200 mg/g being indeterminate for EPI. This test is preferred over older pancreatic function tests because it's non-invasive, requires only a single stool sample, and the enzyme remains stable during intestinal transit 1. The test can be performed while the patient is on pancreatic enzyme replacement therapy, and it is particularly useful for diagnosing chronic pancreatitis, cystic fibrosis, pancreatic cancer, and monitoring pancreatic function in diabetes 2. However, false low results can occur with watery diarrhea due to dilution effects, so clinical correlation is important when interpreting results.
Some key points to consider when interpreting the results of the fecal elastase test include:
- Normal elastase levels are typically above 200 μg/g of stool
- Values between 100-200 μg/g suggest mild to moderate pancreatic insufficiency
- Values below 100 μg/g indicate severe insufficiency
- The test is unaffected by simultaneous enzyme therapy or diet
- The test requires only a single 100 mg stool sample
- Faecal elastase-1 has been well characterised as a sensitive biomarker for moderate to severe pancreatic insufficiency, with sensitivities of 73–100% and specificities of 80–100% 3.
It's also important to note that the fecal elastase test is not useful in cases of mild pancreatic insufficiency, with sensitivities of <60%, and it is not able to reliably distinguish pancreatic from non-pancreatic malabsorption 3. Therefore, clinical correlation and further testing may be necessary to confirm the diagnosis.
In terms of the clinical application of the fecal elastase test, it is recommended as the test of first choice in patients who present with diarrhoea of putative pancreatic origin, due to its ease of use and acceptable reliability 4. However, it's also important to consider other potential causes of chronic diarrhoea, such as small bowel bacterial overgrowth, bile acid malabsorption, and factitious diarrhoea, and to use a combination of diagnostic tests and clinical evaluation to determine the underlying cause of the patient's symptoms 5.
From the Research
Tool Elastase Test
- The tool elastase test, also known as the fecal elastase-1 (FE-1) test, is a non-invasive test used to evaluate pancreatic function 6, 7.
- The test measures the level of elastase in stool, which is an enzyme produced by the pancreas, and is used to diagnose pancreatic exocrine insufficiency (PEI) 8, 9.
- The FE-1 test is reliable, less time-consuming, and unaffected by pancreatic enzyme replacement therapy, making it a suitable test for screening patients at risk of PEI 6.
- The test results are correlated with other pancreatic enzymes, such as amylase, lipase, and trypsin, and can be used to determine the presence of PEI in patients with symptoms suggestive of pancreatic disease 7.
Diagnostic Value
- The diagnostic value of the fecal elastase test has been evaluated in comparison with the secretin-pancreozymin test, and it has been shown to be a useful non-invasive test of pancreatic function 7.
- The test has been used to diagnose PEI in patients with chronic pancreatitis, cystic fibrosis, and other pancreatic disorders 6, 8.
- The FE-1 test has also been used to stage exocrine pancreatic dysfunction, with different stages corresponding to different levels of pancreatic enzyme output and digestive capacity 9.
Clinical Utility
- The clinical utility of the FE-1 test has been demonstrated in several studies, including its use in diagnosing PEI and monitoring response to pancreatic enzyme replacement therapy 8, 10.
- The test has also been used to detect unsuspected pancreatic neoplasia in patients with low FE-1 levels 10.
- However, the test is not perfect, and its results should be interpreted in conjunction with other clinical and laboratory findings 9.