Immunoreactive trypsinogen (IRT) is produced by the pancreas and levels are elevated in cystic fibrosis.
Raised IRT also occurs in prematurity and any condition of stress e.g. difficult delivery, unwell baby. In the UK, if the IRT is high, a repeat sample is sent at 21-28 days of life, as most false positives have resolved by then.
Reference: Newborn Blood Spot Screening website
Previously published: 12/03/14, 15/01/15