The 13C-octanoic acid breath test (13C-OABT) is the most precise breath test for the assessment of gastric emptying. The presented study concentrates on gastric emptying of a solid meal in CF patients. Method: The solid testmeal (cake) was administered with 65 microlitres of 13C-octanoic acid. Patients collected breath samples throughout a 4-hour period. The air samples were examined by mass spectrometry to obtain delta values, which were transformed to the elimination pattern of 13C. The gastric emptying half times (T1/2GE) were counted by MOMENT 4 programme, modelling elimination as incomplete gamma function. The incomplete gamma parameters estimation was done by themomentmethod. The T1/2GEs were compared with reference data obtained by Van Den Driessche (25). The 13C-OABT was performed in 20 patients, median age 13.5 years. Results: 13C-OABT were analyzed in 16 patients. In 69% of them T1/2GEs were in the reference range, in 25% below and in 6% prolonged. The difference in delta values remained in CF 13C-OABT low. Conclusion: The gastric emptying rate in CF patients does not differ in principle from the healthy population.

        Key words: gastric emptying, 13C-OABT, cystic fibrosis