Serial lung function studies in cystic fibrosis in the first 5 years of life.

Lung mechanics were studied in 8 infants with cystic fibrosis at 6 months of life and radiosotopic lung function was measured in 5 of them at 5 years of age. The children who were initially asymptomatic had normal lung mechanics in infancy but the 2 restudied later had abnormal radioisotopic lung function. The symptomatic children showed abnormalities in infancy and more marked changes later. It is concluded that the lungs in cystic fibrosis are probably normal initially and that damage occurs later even in the absence of symptoms.