The Test Sample
What is being tested?
Trypsin and chymotrypsin are enzymes that digest protein in the small intestine. Their inactive precursors, trypsinogen and chymotrypsinogen, are produced in the pancreas and transported to the small intestine. In the small intestine, trypsinogen is activated and turned into trypsin. Trypsin then in turn activates chymotrypsinogen to form chymotrypsin. Together, they are responsible for breaking down the protein in food into smaller pieces called peptides. Trypsin and chymotrypsin are detectable in both the small intestine and in the stool if the pancreas is functioning normally. These tests measure the amount of trypsin and chymotrypsin in stool in order to help evaluate pancreatic function.
In people with cystic fibrosis (CF), mucous plugs can block the pancreatic ducts that lead into the small intestine, preventing trypsinogen and chymotrypsinogen from reaching the intestine.
Individuals with pancreatic dysfunction (tissue damage or blockage) may either have blocked pancreatic ducts or the cells that produce trypsinogen and chymotrypsinogen may be damaged or destroyed. Such cell damage causes pancreatic insufficiency because the amount of enzymes transported to the small intestine is inadequate for proper food digestion. This is often seen in conditions such as chronic pancreatitis and pancreatic cancer.
How is the sample collected for testing?
A fresh stool sample is collected, uncontaminated with urine. For an infant, a urine collection bag with adhesive edges that can be stuck to the baby's skin and a plastic-lined diaper are both used to keep urine out of the stool and to keep the stool from soaking into the diaper.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.