Laboratory tests used to detect pancreatic insufficiency
- Elastase is a protein-cleaving enzyme produced and secreted by the pancreas. It is resistant to degradation by other enzymes and so is excreted and can be measured in the stool. The amount of this enzyme is reduced in pancreatic insufficiency. This test, also known as the fecal elastase-1 test, is often chosen to aid in the diagnosis of pancreatic insufficiency in children and adults; however, it is more effective at detecting severe exocrine pancreatic insufficiency and not as effective for mild to moderate forms.
- Chymotrypsin is a pancreatic enzyme that cleaves proteins. Unlike elastase, chymotrypsin is digested while passing through the intestine; however, there remains sufficient residual activity for measurement.
- Fecal fat (fat in the stool) is often the first sign of insufficiency. The simplest test for fecal fat is to place a suspension of stool onto a glass slide, add a fat stain, and observe the number and size of fat globules that are present. A more accurate assessment of fecal fat requires a timed stool collection, typically spanning 72 hours, and a dietary sheet to help calculate the total fat intake during the collection period. This test is generally thought of as unreliable because it is difficult to achieve proper control of the diet, challenging to ensure complete sample collection, and there is significant assay variation.
- 13C-mixed triglyceride breath test is a novel test that is a noninvasive, reliable method of diagnosing moderate pancreatic insufficiency, but it is not widely used and not commonly available. The test may also be used to evaluate the efficacy of enzyme therapy on fat digestion in people with insufficiency.
Non-laboratory tests used in diagnosing pancreatic insufficiency
- Endoscopic retrograde cholangiopancreatography (ERCP): a test that uses a flexible scope inserted through the mouth and threaded through the esophagus to see and document damage to the pancreas and/or bile ducts.
- Magnetic resonance cholangiopancreatography (MRCP): a type of magnetic resonance imaging (MRI) used to examine the pancreas and bile ducts.
- Secretin test (not widely available): a tube is positioned in the duodenum to collect pancreatic secretions stimulated by intravenous (IV) secretin. Secretin is a hormone that causes the pancreas to release fluid containing digestive enzymes. The amount of certain enzymes and bicarbonate in this fluid is measured and compared to normal values.
For more on imaging studies, see RadiologyInfo.org.