AbstractUp to 80 % of patients with cystic fibrosis (CF) may have increased gastroesophageal reflux (GER) and aspiration of (duodeno)-gastric contents into the lungs.Aim:To assess aspiration in CF patients, by measuring duodenogastric components in induced sputum, and to investigate whether the presence of bile acids (BA) in sputum was correlated with disease severity and markers of inflammation. METHODS:In 41 CF patients, 15 healthy volunteers, 29 asthma patients and 28 patients with chronic cough, sputum was obtained after inhalation of hypertonic saline. Sputum supernatant was tested for BA and neutrophil elastase (NSE). Spirometry and BMI were assessed on the day of sputum collection. RESULTS:2/15 healthy (13%), 8/29 (28%) asthma patients, 4/28 (14%) patients with chronic cough and 23/41 CF patients (56%) showed BA in sputum. BA concentrations were similar in BA positive patients with genotype F508del homozygote, F508del heterozygote and other CF mutations and were not related with BMI and age. CF patients with BA in sputum had a higher concentration of NSE compared to patients without BA in sputum [31.25 (20.33-54.78) vs. 14.45 (7.11-27.88) μg/ml, p<0.05]. There was a significant correlation between BA concentrations and dynamic lung volumes [FEV(1)% predicted (r=-0.53, p<0.01), FVC% (r=-0.59, p<0.01)] as well as with number of days of antibiotic IV treatment (r=0.58, p<0.01). CONCLUSION:BA are present in sputum of more than half of CF patients, suggesting aspiration of duodenogastric contents. Aspiration of BA was associated with increased airway inflammation. In patients with BA aspiration, the levels of BA were clearly associated with the degree of lung function impairment as well as the need for IV antibiotic treatment.