Screening for cystic fibrosis: a four year regional experience.

A four year regional screening programme to detect cystic fibrosis using measurement of immunoreactive trypsinogen is described. During this period 60 infants were diagnosed; 34 by screening, 12 born with meconium ileus, and 14 not identified by the screening assay but who presented with clinical symptoms at a later age, giving an incidence of cyst fibrosis in the region during this time of 1/1807. Screening has resulted in earlier detection of cystic fibrosis in many infants, thus allowing treatment to be instituted at an early age, and genetic counseling offered to the parents. There were a number of false positives and false negatives with the immunoreactive trypsinogen screening assay. In addition, eight infants who were sweat tested at an early age had a sweat sodium concentration of less than 70 mmol/l, although they were subsequently shown to have cystic fibrosis. These results confirm other published data showing that sweat sodium results may be low in very young infants with cystic fibrosis. At the time of diagnosis seven (20%) of the infants identified by screening were totally asymptomatic and several additional children had symptoms of such a type that the diagnosis of cystic fibrosis had not been considered at the time of screening. Despite the problems experienced it has been decided to continue screening.