Cystic Fibrosis (CF) is the most common lethal genetic disease in white populations with an incidence throughout the world of 0.25- 5 per 10 000 live births. It is caused by a mutation in the cystic fibrosis transmembrane regulator (CFTR) gene and characterised by a congenital alteration of the biochemical metabolism of the epithelial cells of the exocrine glands which produces a thick and viscose mucus that obstructs the conducts. It is a multisystemic disease mostly presenting in infancy in the form of respiratory and gastrointestinal symptoms. Infants with CF have raised levels of the immunoreactive trypsinogen (IRT) at birth, a marker of pancreatic injury that remains elevated in the first weeks of life. Neonatal screening for CF often involves the combining of IRT with DNA analysis or other biochemical marker which increases test performance.