Fecal elastase-1 determination: 'gold standard' of indirect pancreatic function tests?

Area of Science:

• Gastroenterology
• Biochemistry
• Diagnostic Medicine

Background:

• Tubeless pancreatic function tests, including fecal elastase-1 and chymotrypsin, are utilized for diagnosing pancreatic exocrine insufficiency.
• These tests employ varying cut-off levels, leading to inconsistent diagnostic success.

Purpose of the Study:

• To re-evaluate the diagnostic sensitivity and specificity of fecal elastase-1 and chymotrypsin in assessing exocrine pancreatic insufficiency.

Main Methods:

• 127 patients with malassimilation signs underwent the secretin-caerulein test (gold standard), fecal fat analysis, fecal chymotrypsin activity, and fecal elastase-1 concentration.
• Exocrine pancreatic insufficiency was graded (mild, moderate, severe) based on secretin-caerulein test results.
• Fecal elastase-1 and chymotrypsin were measured using commercial kits with defined cut-off levels.

Main Results:

• Fecal elastase-1 demonstrated 100% sensitivity for severe and 89% for moderate exocrine pancreatic insufficiency (cut-off 200 microg/g), significantly higher than fecal chymotrypsin (76% and 47%, respectively).
• Specificities for both tests were low (elastase-1: 55%, chymotrypsin: 47%).
• Correlation between fecal enzyme levels and duodenal enzyme outputs was moderate (33-55% for elastase-1, 25-38% for chymotrypsin).

Conclusions:

• Fecal elastase-1 is a highly sensitive marker for moderate and severe exocrine pancreatic insufficiency, surpassing fecal chymotrypsin.
• Both tests exhibit low specificity, limiting their utility for general screening due to false positives in non-pancreatic patients.
• While useful for diagnosing insufficiency, neither test is a standalone screening tool.