Estrogen Patches for Adolescent and Young Adult Women With Cystic Fibrosis

The goal of this clinical trial is to learn about the role of estrogen in bone development in adolescent and young adult women with cystic fibrosis (CF) and low estrogen levels. The main questions it aims to answer are:Is a study of transdermal estradiol (estrogen skin patches) feasible in this group?How does transdermal estradiol impact bone health and quality of life?Participants will apply transdermal estradiol patches (or placebo patches -- patches that look like the estradiol patches but do not contain any estradiol) once weekly for 12 months, fill out brief quality-of-life surveys twice per month, and complete blood draws and questionnaires at four study visits (baseline, 3 months, 6 months, and 12 months). The participants will also have x-rays and DXAs (bone density assessment) performed at the baseline and 12 month visits. Researchers will compare changes in various measurements between the treatment and placebo groups to determine the impact of transdermal estradiol.

Inclusion Criteria:CF diagnosis16-30 years oldAt least 2 years after first menstrual cycleLow serum estradiol levels (< 50 pg/mL)Exclusion Criteria:Contraindications to transdermal estradiolCurrent use of systemic estrogen (such as estrogen-containing oral contraceptive pill)Previous lung or liver transplantUse of chronic systemic glucocorticoidsSevere vitamin D deficiency (serum 25(OH)D < 6 ng/mL)Use of anti-osteoporosis therapy including anti-resorptives such as bisphosphonates or anabolic agents such as teriparatide or denosumabConditions increasing risk of clot: history of previous deep vein thrombus or pulmonary embolism, current immobility, current peripherally inserted central catheter or mediport, known hypercoagulable conditionBaseline study visit falls between 1 and 8 weeks after initiation of CF transmembrane receptor (CFTR) modulatorCurrently in pulmonary exacerbationRecent antibiotic use within the past 4 weeks for an acute pulmonary exacerbationPregnant, lactating, or planning to become pregnant during studyUnwilling or unable to use a non-estrogen containing method of contraception such as barrier, abstinence, or progesterone-only methodIn the opinion of the CF care team or study investigators participant should not participate in the studyInability to provide informed consent/assent