Letter: Serum glutathione reductase and cystic fibrosis.

We have obtained additional data which support the specificity of the reported 
serum glutathione reductase (GR) changes in cystic fibrosis (CF). As in 
previous series, mean GR in CF was 20% greater than in 
controls (P < 0.005). No difference was found between CF and 
controls for either lactate dehydrogenase (LDH) or glutamic-pyruvic transaminase (GPT). It 
appears that some underlying process or processes such as leakage into 
serum from cellular damage as reflected in raised LDH and GPT 
might lead to raised GR as demonstrated by positive correlations in 
controls. The absence of a positive correlation between these enzymes and 
GR in the CF sample as well as normal values for 
LDH and GPT in CF suggests that the raised serum GR 
in CF is not attributable to tissue leakage from damaged cells 
secondary to the disease. 