Gastroenterology Education and CPD for trainees and specialists

Pancreatic function tests

Discuss the pancreatic function tests?

Faecal elastase (FE)

FE is increasingly being used as a non-invasive first line test to diagnose exocrine pancreatic insufficiency. It is essentially the only test for exocrine pancreatic insufficiency available in most centres
It is comparable to pancreatic function tests such as the pancreolauryl test and the gold standard secretin test and has higher sensitivity and specificity for pancreatic insufficiency than other pancreatic enzymes such as Faecal Chymotrypsin.
Faecal Elastase is a proteolytic enzyme secreted by the acinar cells of the pancreas. Unlike other pancreatic enzymes such as Chymotyrpsin, Elastase-1 is not degraded during intestinal transit, and so the stool concentration reflects exocrine pancreatic function.
Digestive enzyme substitution therapy has no influence on the determination of faecal elastase. The monoclonal antibodies used in the test do not cross-react with elastases of animal origin, which are contained in enzyme substitution preparations.
Values above 200 µg elastase/g stool indicate normal exocrine pancreatic function.
Values below 200 µg elastase/g stool indicate exocrine pancreatic insufficiency.
A single spot stool sample is sufficient.
Pancreatic elastase is detected using ELISA with two monoclonal antibodies highly specific for human pancreatic elastase 1.

Secretin stimulation test (Gold standard)

The secretin stimulation test is the most sensitive and specific testing available for the diagnosis of chronic pancreatitis. However it is not available widely.
Secretin is a hormone secreted by the small intestine. Secretin stimulates the pancreas to release bicarbonate to neutralize gastric acid and aids in digestion. The secretin stimulation test measures the ability of the pancreas to respond to secretin.
A collection tube is placed in the 3rd part of duodenum under fluoroscopic guidance. After a test dose (0.2 mcg) of synthetic secretin, a full dose (0.2 mcg/kg) is administered as an intravenous bolus at time 0.
Duodenal fluid is continuously collected in 15 minute aliquots for one hour. A bicarbonate concentration less than 80 mEq/L in all of the four aliquots represents exocrine insufficiency.

Pancreolauryl test

A tablet containing fluorescein dilaurate is taken on day 1 and urine is collected for 10 hours. On day two, a tablet containing fluorescein alone is given and urine collected again for 10 hours. This allows for correction in individual variations in intestinal, hepatic and renal function.
Fluorescein dilaurate is hydrolysed by cholesterol ester hydrolase, an enzyme normally present in pancreatic juice. Fluorescein is absorbed by the intestine, conjugated in the liver, and excreted in the urine where its fluorescence can be measured.
Results are expressed as the ratio of fluorescein excreted after fluorescein dilaurate and after free fluorescein. A ratio of less than 20% is considered abnormal.
Sensitivity for detecting severe pancreatic insufficiency is at least 85%.
Pancreolauryl test is no longer available in UK. It was withdrawn by Pfizer in 2005