From the Guidelines
Pancreatic enzyme insufficiency should be tested using a fecal elastase test, which is the most appropriate initial test and can be performed on a semi-solid or solid stool specimen, with a level <100 mg/g of stool providing good evidence of EPI, as recommended by the most recent guidelines 1.
Testing for Pancreatic Enzyme Insufficiency
To diagnose pancreatic enzyme insufficiency, the following tests can be considered:
- Fecal elastase test: This is the preferred initial test, as it is non-invasive and does not require special collection techniques. A level <100 mg/g of stool is indicative of severe insufficiency, while levels between 100-200 mg/g are indeterminate for EPI 1.
- Fecal fat testing: This test is rarely needed and must be performed when the patient is on a high-fat diet. However, it is not practical for routine clinical use 1.
- Breath tests and direct pancreatic function tests: These tests hold promise but are not widely available in the United States 1.
Important Considerations
When testing for pancreatic enzyme insufficiency, it is essential to consider the following:
- The fecal elastase test can be performed while the patient is on pancreatic enzyme replacement therapy 1.
- Response to a therapeutic trial of pancreatic enzymes is unreliable for EPI diagnosis 1.
- Cross-sectional imaging methods, such as computed tomography scan, magnetic resonance imaging, and endoscopic ultrasound, cannot identify EPI but play an important role in diagnosing benign and malignant pancreatic disease 1.
Clinical Features of EPI
The clinical features of exocrine pancreatic insufficiency (EPI) include:
- Steatorrhea with or without diarrhea
- Weight loss
- Bloating
- Excessive flatulence
- Fat-soluble vitamin deficiencies
- Protein-calorie malnutrition 1
Treatment and Monitoring
Once EPI is diagnosed, treatment with pancreatic enzyme replacement therapy (PERT) is required. The initial treatment should include at least 40,000 USP units of lipase during each meal in adults, with subsequent dosage adjustments based on meal size and fat content 1. Regular monitoring of fat-soluble vitamin levels and nutritional status is also essential to ensure successful treatment 1.
From the Research
Testing for Pancreatic Enzyme Insufficiency
To test for pancreatic enzyme insufficiency, several methods can be employed, including:
- Fecal elastase-1 (FE-1) test: a non-invasive, less time-consuming test that is unaffected by pancreatic enzyme replacement therapy 2, 3, 4, 5
- Endoscopic pancreatic function testing: a more accurate but cumbersome test, favored in patients suspected to have mild pancreatic exocrine insufficiency or an early stage of chronic pancreatitis 6
- 72-h fecal fat collection: a gold standard indirect test for the diagnosis of pancreatic exocrine insufficiency, but cumbersome for both patients and laboratory personnel 5
Fecal Elastase-1 Test
The fecal elastase-1 test is a reliable method for evaluating pancreatic function in many pancreatic and non-pancreatic disorders 2. The test has a pooled sensitivity value of 0.77 and specificity value of 0.88 compared to the secretin stimulation test 4. However, in patients with low pre-test probability of pancreatic exocrine insufficiency, the test has a high false-positive rate 4.
Interpretation of Test Results
The interpretation of test results varies depending on the cutoff values used. For example, a cutoff value of <100 μg/g for fecal elastase-1 has a sensitivity of 84.9% and specificity of 47.6% 5, while a cutoff value of <200 μg/g has a sensitivity of 90.9% and specificity of 9.5% 5.
Clinical Application
The fecal elastase-1 test can be used as a screening test for pancreatic exocrine insufficiency in patients with chronic pancreatitis 5. However, additional research is needed to identify a more convenient means of accurately diagnosing pancreatic exocrine insufficiency at all stages 6.