Cystic fibrosis respiratory tract salt concentration: An Exploratory Cohort Study

In cystic fibrosis patients, electrolytic and osmolality imbalance secondary to cystic fibrosis transmembrane conductance regulator mutations may impact on mucoid secretion accumulation and secondary colonization by opportunistic pathogens such as nontuberculous mycobacteria. We performed a noninvasive exploratory prospective controlled clinical study comparing sputum salinity and acid-base characteristics of cystic fibrosis and noncystic fibrosis control patients. A total of 57 patients and 62 controls were included. Sputum salt concentrations were 10.5 g/L (95% CI: 7.7–13.3) in patients and 7.4 g/L (95% CI: 5.9–8.9) in aged-matched controls, a difference that was found to be statistically significant (P < .05). No difference in pH was observed between patients and controls. These differences in respiratory secretions salt concentrations could influence host-pathogen interactions in the context of cystic fibrosis respiratory infections. We propose to include respiratory secretion salt measurement as a routine analysis on cystic fibrosis patients’ sputum submitted for bacterial culture.