The Clinical Usefulness of Fecal Elastase-1 Test as an Exocrine Pancreatic Function Test for the Diagnosis of Chronic Pancreatitis

Lee, Sung Hee; Choi, Ho Soon

Abstract

BACKGROUND/AIMS
The quantitative analysis of fecal elastase-1 has been proposed as a noninvasive test for the examination of pancreatic exocrine function. Therefore, we evaluated the diagnostic value of fecal elastase-1 by comparing with endoscopic intraductal secretin test (IDST) which is used as a direct exocrine function test for the diagnosis of chronic pancreatitis.
METHODS
Fecal elastase-1 concentrations were measured by ELISA in spot stool samples of 40 healthy control subjects, 21 patients with liver disease, and 12 patients with chronic pancreatitis diagnosed with endoscopic retrograde cholangiopancreatography (ERCP) and IDST. Chronic pancreatitis were then sub-classified into mild (I), moderate (II) and severe form (III), using the Cambridge classification according to ERCP finding. The linear regression analysis to evaluate the correlation between the concentration of fecal elastase-1 and IDST was performed during ERCP. The cut-off value of fecal elastase-1 to discriminate chronic pancreatitis was calculated based on receiver operating characteristic curve, and the clinical usefulness of fecal elastase-1 in the diagnosis of chronic pancreatitis was evaluated.
RESULTS
There were several significant correlations between fecal elastase-1 and various parameters of IDST: pancreatic juice secretory volume (r=0.797, p<0.002), bicarbonate concentration (r=0.846, p<0.001), elastase-1 concentration in pancreatic juice (r=0.671, p<0.017), and amylase output (r=0.783, p<0.003). The mean value of fecal elastase-1 concentration in the patients with chronic pancreatitis (197+/-77microgram/g stool) was significantly lower than those in the healthy control subjects (815+/-133microgram/g stool) and patients with liver disease (594+/-206microgram/g stool) (p<0.05). The cutoff value of fecal elastase-1 to discriminate between the healthy control and chronic pancreatitis patients was 201microgram/g stool. With this cutoff value, the accuracy, sensitivity, and specificity of fecal elastase-1 to diagnose chronic pancreatitis were 78.8%, 67.7%, and 82.5%, respectively, compared to the morphological severity (the sensitivity of mild, moderate, and severe chronic pancreatitis was 33.3%, 66.7%, 83.3%, respectively).
CONCLUSIONS
Measurement of fecal elastase-1 is a reliable and sensitive non-invasive test for the diagnosis of moderate to severe forms of chronic pancreatitis.