What does low elastase level mean?

Low Fecal Elastase: Diagnosis and Implications

Low fecal elastase levels (<200 μg/g) indicate pancreatic exocrine insufficiency (PEI), with values below 100 μg/g providing good evidence of PEI and values below 50 μg/g suggesting severe PEI. 1

Understanding Fecal Elastase Testing

Fecal elastase is a pancreatic enzyme that remains stable throughout the intestinal tract, making it an excellent marker for pancreatic function. The interpretation of fecal elastase-1 (FE-1) test results follows this pattern:

• <50 μg/g: Severe exocrine pancreatic insufficiency
• <100 μg/g: Good evidence of exocrine pancreatic insufficiency
• 100-200 μg/g: Indeterminate for exocrine pancreatic insufficiency

• 200 μg/g: Normal pancreatic function 1

The fecal elastase test is considered the most appropriate initial test for suspected PEI due to its high sensitivity and specificity, particularly for moderate to severe cases 1, 2. Research has shown that the test has a sensitivity of 93% for all patients with exocrine pancreatic insufficiency and a specificity of 93% 2.

Clinical Significance of Low Elastase

Low elastase levels indicate that the pancreas is not producing sufficient digestive enzymes, which can lead to:

• Malabsorption of nutrients, especially fats
• Steatorrhea (fatty stools)
• Weight loss
• Abdominal discomfort
• Malnutrition
• Deficiencies in fat-soluble vitamins (A, D, E, K) 1

Common Causes of Low Elastase

Several conditions can cause pancreatic exocrine insufficiency resulting in low elastase levels:

• Chronic pancreatitis (most common cause)
• Relapsing acute pancreatitis
• Pancreatic ductal adenocarcinoma (particularly head tumors)
• Cystic fibrosis
• Previous pancreatic surgery (total pancreatectomy results in 100% development of PEI)
• Diabetes mellitus
• Small intestinal bacterial overgrowth (SIBO) 1

Important Considerations and Pitfalls

When interpreting low elastase results, be aware of these important factors:

• False positives: Liquid stool samples can cause falsely low FE-1 levels 1
• Enzyme stability: Unlike other pancreatic enzymes, elastase is highly stable in the intestinal tract, making it a reliable marker 3, 2
• Non-pancreatic causes: Consider conditions that mimic PEI symptoms, such as celiac disease, SIBO, and inflammatory bowel disease 1
• Day-to-day variation: Individual day-to-day variations of fecal elastase concentrations are generally low (mean CV = 15%), making it reliable for monitoring 2
• Age considerations: Some infants may have temporarily low values that normalize with age 4
• Sample handling: Proper collection, storage, and handling of stool samples are crucial for accurate results 5

Clinical Approach to Low Elastase Results

1. Confirm the diagnosis:

   • Rule out false positives by ensuring proper stool sample collection (not liquid)
   • Consider repeating the test if results are indeterminate (100-200 μg/g)

2. Identify underlying cause:

   • Evaluate for chronic pancreatitis using MRCP (preferred non-invasive method)
   • Consider ERCP if MRCP is unavailable or inconclusive
   • Screen for other conditions associated with PEI

3. Rule out mimicking conditions:

   • Test for SIBO using hydrogen/methane breath testing
   • Screen for celiac disease
   • Consider inflammatory bowel disease evaluation 1

Management of Confirmed PEI

If low elastase confirms PEI, treatment typically involves:

• Pancreatic enzyme replacement therapy (PERT) with an initial dose of 500 units of lipase/kg/meal for adults
• Taking enzymes during meals for maximum effectiveness
• Following a low to moderate fat diet (approximately 30% of total energy intake)
• Monitoring and supplementing fat-soluble vitamins (A, D, E, K) as needed
• Regular follow-up to assess treatment effectiveness through symptom improvement, weight gain, and normalization of nutritional parameters 1

Unique Characteristics of Elastase

Research has shown that elastase is often the most susceptible enzyme to pancreatic dysfunction, making it an early marker of pancreatic disease. The ratio of elastase to amylase output can provide a valuable index to assess enzyme secretory capacity in pancreatic diseases 6. Unlike fecal chymotrypsin tests, fecal elastase measurement is not affected by oral enzyme supplementation, making it useful for ongoing monitoring of pancreatic function even during treatment 3.