CFTR Modulator Effects on Bone and Muscle in Adults With Cystic Fibrosis

Inclusion Criteria: * documented, confirmed diagnosis of CF * Age ≥18 years old * \>21 days since the start of their last pulmonary exacerbation at the baseline visit * Provide signed written informed consent to participate Exclusion Criteria: * • Estimated glomerular filtration rate (eGFR) \<30 ml/min/m2 using the CKD-EPI equation, * Treatment with any osteoporosis medication within 6 months for oral agents or 1 year for intravenous or injectable agents (Subjects may participate if therapy stopped earlier than these time periods). * Current treatment with growth hormone or IGF-1 * Currently pregnant or lactating or planning plan on becoming pregnant during the duration of the study. * Life expectancy less than 12 months * History of lung transplantation * Conditions that in the opinion of the investigators would interfere with the ability to collect or interpret the data, or put the patient at higher safety risk from study procedures.