Trypsin and Chymotrypsin

Trypsin and chymotrypsin are proteolytic enzymes. Their job is to digest protein in the small intestine. Normally, their precursors (their inactive forms: trypsinogen and chymotrypsinogen) are produced in the pancreas and transported to the small intestine. In the small intestine, trypsinogen is activated, turned into trypsin, by an enzyme in the intestinal mucosa and then trypsin in turn activates chymotrypsinogen to chymotrypsin. Together, they form powerful chemicals responsible for breaking down the protein in food into smaller pieces called peptides. Trypsin and chymotrypsin will be detectable in the small intestine and in the stool if the pancreas is functioning normally.

In people with cystic fibrosis, mucous plugs can block the pancreatic ducts that lead into the small intestine, preventing trypsinogen and chymotrypsinogen from reaching the intestine. Similarly, mucous plugs can block small airway passages in the lungs, making one susceptible to respiratory infections and chronic pulmonary disease. It is usually the respiratory complications of cystic fibrosis that eventually prove fatal for patients with this disease.

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, in which enzyme transport to the small intestine is inadequate for proper food digestion. This is often seen in conditions such as chronic pancreatitis and pancreatic cancer.

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.

No test preparation is needed.