Also Known As
Trypsin-like Immunoreactivity
Immunoreactive Trypsin
Serum Trypsinogen
IRT
Formal Name
Immunoreactive Trypsinogen
This article was last reviewed on
This article waslast modified on November 5, 2017.
At a Glance
Why Get Tested?

To screen for cystic fibrosis (CF); sometimes to detect pancreatitis

When To Get Tested?

As part of a newborn screening test; sometimes when you have symptoms of pancreatitis, such as severe abdominal pain that may be persistent or intermittent, nausea, vomiting, weakness, and jaundice

Sample Required?

A blood sample drawn from an infant's heel, a spot of blood that is put onto filter paper, or a blood sample drawn from a vein in your arm

Test Preparation Needed?

None

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

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.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Accordion Title
Common Questions
View Sources

Sources Used in Current Review

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