Screening for cystic fibrosis by analysis of serum protein in faeces.

Faecal specimens from 51 infants free of cystic fibrosis (CF) and from 9 infants with the disease were analysed for albumin and alpha1-antitrypsin content. Faeces from infants with no CF had a mean albumin content of less than 0-1 mg/g dry weight and a mean albumin: alpha1-antitrypsin ratio value of less than 0-1. Faeces from infants with CF had, with one exception, an albumin content of more than 2-0 mg/g dry weight and a ratio value greater than 3-0. It was subsequently found that the duodenal aspirate from the child with CF but whose faeces had a low albumin content and ratio value, had tryptic activity though at a much reduced level compared to the activity in aspirates from healthy infants.