Introduction Faecal elastase-1(FE-1) is a widely available, simple, cheap indirect pancreatic function test used in patients in whom pancreatic exocrine insufficiency (PEI) is suspected. Sensitivity is 73–100% for moderate to severe, but 0–63% for mild PEI ¹. Specificity of the test (80–100%)¹ is compromised in patients who have other causes of diarrhoea or type 1 diabetes^2,3. The aim of this observational study was to examine the causes of low faecal elastase in our hospital.

Methods A retrospective analysis of FE-1 tests performed between April 2010 and April 2012 was undertaken. The electronic medical notes of each patient with a low FE-1 (< 300 ug/l) were examined.

Results Of the 288 samples received by the laboratory, 23 patients had FE-1 of less than 100 ug/l (severe). 18 patients had FE-1 of 100–199 ug/l (moderate) and 19 patients had FE-1 of 200–299 ug/l (mild). The results were grouped as shown in Table 1. In 5 of the moderate PEI group there was insufficient information to determine the diagnosis. Non-pancreatic causes included microscopic colitis, coeliac disease, bile salt malabsorption, irritable bowel syndrome and infection.

In 2 patients the FE-1 was repeated; in 1 when treatment failed and FE-1 was still <100 ug/l (due to bile salt malabsorption), the other following treatment for coeliac disease and microscopic colitis (FE-1 147ug/l then normal). There was no difference in symptoms (steatorrhoea, diarrhoea, weight loss, abdominal pain) between the groups.

Conclusion This study shows that clinicians need to be aware that even in patients with FE-1 less than 100ug/l, the cause may be non-pancreatic in origin. FE-1 becomes a less reliable diagnostic tool in moderate to mild PEI parameters. FE-1 should be repeated if symptoms do not improve with pancreatic enzyme replacement. Symptoms may not be helpful in distinguishing pancreatic from non-pancreatic causes of low FE-1.

Disclosure of Interest None Declared

References

1. Tod J, Fine D. Fecal elastase: a useful test for pancreatic insufficiency? Dig Dis Sci. 2010 Oct; 55(10):2709–11

2. Carroccio A, Verghi F, Santini B, et al. Diagnostic accuracy of faecal elastase 1 assay in patients with pancreatic maldigestion or intestinal malabsorption: a collaborative study of the Italian Society of Pediatric Gastroenterology and Hepatology. Dig Dis Sci 2001; 46:1335

3. Hahn JU, Kerner W, Maisonneuve P, et al. Low faecal elastase 1 levels do not indicate exocrine pancreatic insufficiency in type-1 diabetes mellitus. Pancreas 2008; 36:274