Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

Immunoreactive Trypsinogen

Print this article
Share this page:
Also known as: Trypsin-like Immunoreactivity; Immunoreactive Trypsin; Serum Trypsinogen; IRT
Formal name: Immunoreactive Trypsinogen

Board approvedAll content on Lab Tests Online has been reviewed and approved by the Editorial Review Board.

The Test Sample

What is being tested?

Trypsinogen is an inactive precursor produced by the pancreas that is converted to the enzyme trypsin. This test measures the amount of trypsinogen in the blood.

Normally, trypsinogen is produced in the pancreas and transported to the small intestine. In the small intestine, it is activated and converted to trypsin. Trypsin is one of the enzymes responsible for breaking down the protein in food into smaller pieces called peptides. Without sufficient trypsinogen and trypsin, a person will not be able to properly digest and use proteins. Any condition that prevents trypsinogen from reaching the small intestine may cause an increase in trypsinogen in the blood. 

In people with cystic fibrosis (CF), mucus plugs can block the pancreatic ducts that lead into the small intestine, preventing trypsinogen from reaching the intestine and preventing the breakdown of food proteins.

As part of a group of newborn screening tests, infants may be screened for CF using a test called immunoreactive trypsinogen (IRT). Newborns with CF may have elevated levels of IRT.

Damage to the pancreas caused by other diseases, such as chronic pancreatitis and pancreatic cancer, may cause blockages that prevent trypsinogen from reaching the small intestine. The cells that produce trypsinogen can also become damaged or be destroyed, decreasing the body's supply.

How is the sample collected for testing?

A blood sample is drawn from a newborn's or very young infant's heel, a spot of blood is put onto filter paper, or a blood sample is drawn from a vein in the arm.

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.