Immunoreactive Trypsinogen (Neonatal Screening)

Trypsinogen is a proenzyme, an inactive precursor to the proteolytic enzyme trypsin. Normally, trypsinogen is produced in the pancreas and transported tothe small intestine. Infants (1 to 2 weeks of age) with cystic
fibrosis, show increased levels of immunoreactive trypsinogen in the neonatal heal-prick test. It is currently the best screening test for cystic fibrosis but cannot be done after the first few weeks
of life since it falls as pancreatic insufficiency develops.