Screening for cystic fibrosis [letter].

Our cystic-fibrosis children usually either have severe lung disease with mild steatorrhea 
or severe maldigestion with lesser pulmonary problems. We therefore measured serum-proteases 
in cystic-fibrosis patients and controls to see if there was any 
support for the following hypothesis: since lack of antitrypsin is associated 
with lung damage, plasma-trypsin in excess of antitrypsin might be responsible 
for the lung damage in cystic fibrosis. General protease and trypsin 
levels were measured spectrophotometrically using a modification of the method of 
Erlanger, Kojowsky and Cohen. Our result showed no significant difference between 
protease and trypsin levels in cystic-fibrosis patients and controls. The difference 
between our results and those of Crossley et al. may be 
explained by the differing measuring technique used. Our trypsin levels were 
measured spectrophotometrically and theirs by radioimmunoassay. 