RecruitingPhase 4Drug trialMarkers of Osteoporosis in Cystic FibrosisMain Study Up to 100 subjects, both non-CF volunteers and Cystic Fibrosis (CF) patients, will participate in a single study visit that will include a DEXA scan, micro CT, and blood collection. Denosumab (Prolia) Sub study Approximately 10 adult subjects with CF who participated in the main study and have results indicating bone disease will receive treatment with Denosumab for up to 5 years. They will be asked to return for repeat DEXA scans, micro CT, blood collection, and documenting of any adverse events.