Cystic fibrosis bone disease treatment: Current knowledge and future directions

Calcium, Phosphorus, and Vitamin D Levels in a Series of Cystic Fibrosis Patients: A Cross-Sectional Study

Cystic fibrosis (CF) is a monogenic disease with different types of mutations that mainly affect the respiratory-digestive system. Calcium (Ca), phosphorus (P), and vitamin D (Vit-D) are essential nutrients for maintaining adequate growth and development, as well as key components in crucial metabolic pathways. Proper diagnosis, treatment, and response are decisive components of precision medicine. Therefore, we conducted a cross-sectional study to evaluate Ca, P, and Vit-D levels along with health and nutritional indicators, regarding their non-skeletal functions, in a series of CF patients. Anthropometric and clinical evaluation, biochemical analysis, dietary survey, and respiratory and pancreatic status were performed. Even though the results showed that all patients had normal dietary and serum Ca levels, 47% of patients had deficient Vit-D intake, 53% of patients had hypovitaminosis D, 35% had insufficient Vit-D levels, 18% had hypophosphatemia, 76% had elevated alkaline phosphate levels, 29% had hypercalciuria, and 65% had hyperphosphaturia. There were no significant differences between homozygous and compound heterozygous patients. Ca, P, and Vit-D levels were associated with body mass index; body composition; physical activity; diet; growth hormones; and the immune, liver, and kidney systems. We suggest a periodically evaluation of Ca and P losses.

ESPEN-ESPGHAN-ECFS guideline on nutrition care for cystic fibrosis

BACKGROUND

Nutritional status is paramount in Cystic Fibrosis (CF) and is directly correlated with morbidity and mortality. The first ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with CF were published in 2016. An update to these guidelines is presented.

METHODS

The study was developed by an international multidisciplinary working group in accordance with officially accepted standards. Literature since 2016 was reviewed, PICO questions were discussed and the GRADE system was utilized. Statements were discussed and submitted for on-line voting by the Working Group and by all ESPEN members.

RESULTS

The Working Group updated the nutritional guidelines including assessment and management at all ages. Supplementation of vitamins and pancreatic enzymes remains largely the same. There are expanded chapters on pregnancy, CF-related liver disease, and CF-related diabetes, bone disease, nutritional and mineral supplements, and probiotics. There are new chapters on nutrition with highly effective modulator therapies and nutrition after organ transplantation.

What the future holds: cystic fibrosis and aging

Cystic fibrosis (CF) is one of the most common genetic diseases with around 70,000 affected patients worldwide. CF is a multisystem disease caused by a mutation in the CF transmembrane conductance regulator gene, which has led to a significant decrease in life expectancy and a marked impairment in the quality of life for people with CF (pwCF). In recent years, the use of highly effective CFTR modulator therapy (HEMT) has led to improved pulmonary function, fewer CF exacerbations, lower symptom burden, and increased weight. This has coincided with an increased life expectancy for pwCF, with mean age of survival being now in the 50s. This being a major breakthrough, which the CF population has hoped for, pwCF are now facing new challenges by growing old with a chronic respiratory disease. In this mini review, we are attempting to summarize the current knowledge of the aging process and its effect on CF disease and its manifestations including new developments, the current research gaps and potential future developments in the field to allow healthy aging for the CF community.

Standards for the care of people with cystic fibrosis; establishing and maintaining health

This is the second in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on establishing and maintaining health. The guidance is produced using an evidence-based framework and with wide stakeholder engagement, including people from the CF community. Authors provided a narrative description of their topic and statements, which were more directive. These statements were reviewed by a Delphi exercise, achieving good levels of agreement from a wide group for all statements. This guidance reinforces the importance of a multi-disciplinary CF team, but also describes developing models of care including virtual consultations. The framework for health is reinforced, including the need for a physically active lifestyle and the strict avoidance of all recreational inhalations, including e-cigarettes. Progress with cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy is reviewed, including emerging adverse events and advice for dose reduction and interruption. This paper contains guidance that is pertinent to all people with CF regardless of age and eligibility for and access to modulator therapy.

Metabolism and pharmacokinetics of vitamin D in patients with cystic fibrosis

Patients with cystic fibrosis (CF) commonly have lower circulating concentrations of 25-hydroxyvitamin D (25(OH)D) than healthy populations. We comprehensively compared measures of vitamin D metabolism among individuals with CF and healthy control subjects. In a cross-sectional study, serum from participants with CF (N = 83) and frequency-matched healthy control subjects by age and race (N = 82) were analyzed for: 25(OH)D2 and 25(OH)D3, 1α,25-dihydroxyvitamins D2 and D3 (1α,25(OH)2D2 and 1α,25(OH)2D3), 24,25-dihydroxyvitamin D3 (24,25(OH)2D3), 4β,25-dihydroxyvitamin D3 (4β,25(OH)2D3), 25-hydroxyvitamin D3-3-sulfate (25(OH)D3-S), and 25-hydroxyvitamin D3-3-glucuronide (25(OH)D3-G). In a 56-day prospective pharmacokinetic study, ∼25 μg deuterium-labeled 25(OH)D3 (d6-25(OH)D3) was administered intravenously to participants (N = 5 with CF, N = 5 control subjects). Serum was analyzed for d6-25(OH)D3 and d6-24,25(OH)2D3, and pharmacokinetic parameters were estimated. In the cross-sectional study, participants with CF had similar mean (SD) total 25(OH)D concentrations as control subjects (26.7 [12.3] vs. 27.7 [9.9] ng/mL) and had higher vitamin D supplement use (53% vs. 22%). However, participants with CF had lower total 1α,25(OH)2D (43.6 [12.7] vs. 50.7 [13.0] pg/mL), 4β,25(OH)2D3 (52.1 [38.9] vs. 79.9 [60.2] pg/mL), and 25(OH)D3-S (17.7 [11.6] vs. 30.1 [12.3] ng/mL) (p < 0.001 for all). The pharmacokinetics of d6-25(OH)D3 and d6-24,25(OH)D3 did not differ between groups. In summary, although 25(OH)D concentrations were comparable, participants with CF had lower 1α,25(OH)2D, 4β,25(OH)2D3, and 25(OH)D3-S concentrations than healthy controls. Neither 25(OH)D3 clearance, nor formation of 24,25(OH)2D3, appears to account for these differences and alternative mechanisms for low 25(OH)D in CF (i.e., decreased formation, altered enterohepatic recirculation) should be explored.

Changes in bone turnover after high-dose vitamin D supplementation during acute pulmonary exacerbation in cystic fibrosis

In people with cystic fibrosis (CF), chronic inflammation and infection increase the risk for low bone mineral density and CF-related bone disease. During acute pulmonary exacerbations (APE), people with CF have increases in markers of bone resorption. Vitamin D has been proposed as a potential nutrient to lower inflammation. In this ancillary analysis of the Vitamin D for the Immune System in CF study, we hypothesized that vitamin D administered at the time of APE would have favorable changes on bone turnover markers compared to placebo. Participants with CF were randomized to receive a single dose of 250,000 IU of vitamin D or placebo during an APE and followed for 1 year for the primary outcome of APE or death after randomization. Bone turnover markers: C-terminal telopeptide (CTX-1) and procollagen type 1 intact N-terminal propetide (P1NP) were assessed at randomization (during APE) and after recovery from the APE in 45 participants. Participants randomized to vitamin D had significant decreases in markers of bone turnover; participants who received placebo had non-significant increases in markers of bone turnover. Vitamin D supplementation during an APE may help reduce the risk for CF-related bone disease.

Cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic disease caused by variants in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR dysfunction results in abnormal chloride and bicarbonate transport in epithelial cells, leading to a multiorgan disease dominated by respiratory and digestive manifestations. The respiratory disease, which is characterized by airway mucus plugging, chronic bacterial infection and progressive development of bronchiectasis, may lead to chronic respiratory failure, which is the main cause of premature death in people with CF. Over the past 50 years, major progress has been obtained by implementing multidisciplinary care, including nutritional support, airway clearance techniques and antibiotics in specialized CF centers. The past 10 years have further seen the progressive development of oral medications, called CFTR modulators, that partially restore ion transport and lead to a major improvement in clinical manifestations and lung function, presumably resulting in longer survival. Although an increasing proportion of people with CF are being treated with CFTR modulators, challenges remain regarding access to CFTR modulators due to their high cost, and their lack of marketing approval and/or effectiveness in people with rare CFTR variants. The anticipated increase in the number of adults with CF and their aging also challenge the current organization of CF care. The purpose of this review article is to describe current status and future perspective of CF disease and care.

Cystic Fibrosis: A Review

Importance

Cystic fibrosis, a genetic disorder defined by variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, affects more than 30 000 individuals in the US and approximately 89 000 worldwide. Absent or decreased function of the CFTR protein is associated with multiorgan dysfunction and shortened life expectancy.

Observations

CFTR is an anion channel in the apical membrane of epithelial cells. Loss of function leads to obstructed exocrine glands. Of people with cystic fibrosis in the US, approximately 85.5% have the gene variant F508del. Manifestations of cystic fibrosis in patients with the F508del gene variant begin in infancy with steatorrhea, poor weight gain, and respiratory symptoms (coughing, wheezing). As people with cystic fibrosis age, chronic respiratory bacterial infections cause loss of lung function and bronchiectasis. With the availability of universal newborn screening in multiple countries including the US, many people with cystic fibrosis are asymptomatic at diagnosis. With multidisciplinary care teams that included dietitians, respiratory therapists, and social workers, treatment of cystic fibrosis can slow disease progression. Median survival has improved from 36.3 years (95% CI, 35.1-37.9) in 2006 to 53.1 years (95% CI, 51.6-54.7) in 2021. Pulmonary therapies for patients with cystic fibrosis consist of mucolytics (eg, dornase alfa), anti-inflammatories (eg, azithromycin), and antibiotics (such as tobramycin delivered by a nebulizer). Four small molecular therapies, termed CFTR modulators, that facilitate CFTR production and/or function have received regulatory approval. Examples are ivacaftor and elexacaftor-tezacaftor-ivacaftor. For example, in patients with 1 F508del variant, the combination of ivacaftor, tezacaftor, and elexacaftor improved lung function from -0.2% in the placebo group to 13.6% (difference, 13.8%; 95% CI, 12.1%-15.4%) and decreased the annualized estimated rate of pulmonary exacerbations from 0.98 to 0.37 (rate ratio, 0.37; 95% CI, 0.25-0.55). Improved respiratory function and symptoms have lasted up to 144 weeks in postapproval observational studies. An additional 177 variants are eligible for treatment with the elexacaftor-tezacaftor-ivacaftor combination.

Conclusion

Cystic fibrosis affects approximately 89 000 people worldwide and is associated with a spectrum of disease related to exocrine dysfunction, including chronic respiratory bacterial infections and reduced life expectancy. First-line pulmonary therapies consist of mucolytics, anti-inflammatories, and antibiotics, and approximately 90% of people with cystic fibrosis who are 2 years or older may benefit from a combination of ivacaftor, tezacaftor, and elexacaftor.

Bone health outcomes in post-lung transplant patients with cystic fibrosis

BACKGROUND

Osteoporosis is a common comorbidity in patients with cystic fibrosis (CF). Although lung transplantation (LTx) improves quality of life of CF patients, there is little research examining long-term bone health outcomes following LTx in these patients.

METHODS

Data were collected on 59 patients who underwent LTx between 2006 and 2019, including 30 with CF and 29 without CF. We compared baseline characteristics, long-term bone mineral density (BMD) trends, and fracture incidence between the two patient populations, and examined factors associated with post-LTx fractures in CF patients.

RESULTS

Compared with non-CF patients, patients with CF were younger, had lower body mass index, and lower baseline BMD Z-scores at the lumbar spine, femoral neck, and total hip (all p<0.001). BMD at all sites declined in both groups in the first year post-LTx. In subsequent years, CF patients exhibited better BMD recovery relative to pre-transplantation, but continued to have lower BMD post-LTx. Post-transplant fractures occurred in 30% and 34% of CF and non-CF patients, respectively. CF patients who developed fractures after LTx had significantly lower BMD and lower pre-transplantation percent predicted forced expiratory volume in one second (FEV1%).

CONCLUSIONS

Although CF patients exhibit better BMD recovery following LTx compared to their non-CF counterparts, CF patients start with significantly lower pre-LTx BMD and experience a similarly high rate of post-LTx fractures. These findings highlight the unique contribution of the CF disease process to bone health, as well as a clear need for better prevention and treatment of osteoporosis in CF patients before and after LTx.

Beyond the Lungs-Emerging Challenges in Adult Cystic Fibrosis Care

Cystic fibrosis (CF) is a multisystem disease. This article provides an up-to-date review of many of the nonrespiratory complications of CF, including mental health issues, nutritional and gastrointestinal problems, fertility issues, diabetes mellitus, bone health and musculoskeletal problems, liver disease, renal problems, and risk of malignancy. It highlights the recent impact of new therapies, including CF transmembrane conductance regulator modulators, on the nonrespiratory complications of CF and provides insights into the potential challenges faced by an aging population of adults with CF and their caregivers, including the potential future risk for cardiovascular disease.

The use of DXA for early detection of pediatric cystic fibrosis-related bone disease

BACKGROUND

Cystic fibrosis (CF)-related bone disease (CFBD) is seen in adults and can be associated with respiratory illness and malnutrition. There is limited and conflicting data regarding CFBD in pediatric CF. With longer life expectancy and promotion of disease prevention, pediatric CFBD demands further investigation.

METHODS

Our center initiated a quality improvement (QI) project from April 2016 to December 2018 to improve CFBD screening in patients 8 years or older, per current CF Foundation (CFF) guidelines. Our team formulated a dual-energy X-ray absorptiometry (DXA) scan algorithm based upon degree of bone mineral density (BMD); shared CFBD guideline recommendations in our quarterly newsletter; and ordered scans for eligible patients at weekly review meetings. We reviewed DXA results from 141 patients after institutional review board approval and gathered data including comorbidities, genetics, anthropometric measures, medication exposure, and relevant serum studies.

RESULTS

Fifty-three percent of our patients had normal BMD (n = 75). Seventeen patients (12%) had a Z score ≤ -2. Patients with lower BMD also had lower mean forced expiratory volume (FEV₁ ) percent predicted (FEV₁ %) (p < 0.001) as well as lower body mass index % (p = 0.001). Patients with lower BMD were overall older at time of DXA (p = 0.016). During study duration, 13 patients who had abnormal DXA results underwent repeat DXAs after physical therapy; 11 of the 13 showed improvement in DXA results.

CONCLUSIONS

A DXA scan is a useful screening tool and can be used to identify pediatric patients who could benefit from further therapy and interventions to preserve adequate bone health and avoid further loss. QI initiatives can lead to improved screening and diagnosis and earlier intervention such as physical therapy. Further studies are needed to better understand the utility of physical therapy in children with CF.

Cystic Fibrosis Bone Disease: The Interplay between CFTR Dysfunction and Chronic Inflammation

Cystic fibrosis is a monogenic disease with a multisystemic phenotype, ranging from predisposition to chronic lung infection and inflammation to reduced bone mass. The exact mechanisms unbalancing the maintenance of an optimal bone mass in cystic fibrosis patients remain unknown. Multiple factors may contribute to severe bone mass reduction that, in turn, have devastating consequences in the patients' quality of life and longevity. Here, we will review the existing evidence linking the CFTR dysfunction and cell-intrinsic bone defects. Additionally, we will also address how the proinflammatory environment due to CFTR dysfunction in immune cells and chronic infection impairs the maintenance of an adequate bone mass in CF patients.

Future therapies for cystic fibrosis

We are currently witnessing transformative change for people with cystic fibrosis with the introduction of small molecule, mutation-specific drugs capable of restoring function of the defective protein, cystic fibrosis transmembrane conductance regulator (CFTR). However, despite being a single gene disorder, there are multiple cystic fibrosis-causing genetic variants; mutation-specific drugs are not suitable for all genetic variants and also do not correct all the multisystem clinical manifestations of the disease. For many, there will remain a need for improved treatments. Those patients with gene variants responsive to CFTR modulators may have found these therapies to be transformational; research is now focusing on safely reducing the burden of symptom-directed treatment. However, modulators are not available in all parts of the globe, an issue which is further widening existing health inequalities. For patients who are not suitable for- or do not have access to- modulator drugs, alternative approaches are progressing through the trials pipeline. There will be challenges encountered in design and implementation of these trials, for which the established global CF infrastructure is a major advantage. Here, the Cystic Fibrosis National Research Strategy Group of the UK NIHR Respiratory Translational Research Collaboration looks to the future of cystic fibrosis therapies and consider priorities for future research and development.

Bisphosphonates for osteoporosis in people with cystic fibrosis

BACKGROUND

Osteoporosis is a disorder of bone mineralisation occurring in about one third of adults with cystic fibrosis. Bisphosphonates can increase bone mineral density and decrease the risk of new fractures in post-menopausal women and people receiving long-term oral corticosteroids. This is an updated version of a previous review.

OBJECTIVES

To assess the effects of bisphosphonates on the frequency of fractures, bone mineral density, quality of life, adverse events, trial withdrawals, and survival in people with cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Trials Register of references (identified from electronic database searches and hand searches of journals and abstract books) on 5 May 2022. We performed additional searches of PubMed, clinicaltrials.gov and the WHO ICTRP (International Clinical Trials Registry Platform) on 5 May 2022.

SELECTION CRITERIA

Randomised controlled trials of at least six months duration studying bisphosphonates in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Authors independently selected trials, extracted data and assessed risk of bias in included studies. Trial investigators were contacted to obtain missing data. We judged the certainty of the evidence using GRADE.

MAIN RESULTS

We included nine trials with a total of 385 participants (272 adults and 113 children (aged five to 18 years)). Trial durations ranged from six months to two years. Only two of the studies were considered to have a low risk of bias for all the domains.  Bisphosphonates compared to control in people with cystic fibrosis who have not had a lung transplant Seven trials included only adult participants without lung transplants, one trial included both adults and children without lung transplantation (total of 238 adults and 113 children). We analysed adults (n = 238) and children (n = 113) separately. Adults Three trials assessed intravenous bisphosphonates (one assessed pamidronate and two assessed zoledronate) and five trials assessed oral bisphosphonates (one assessed risedronate and four assessed alendronate). Bisphosphonates were compared to either placebo or calcium (with or without additional vitamin D). Data showed no difference between treatment or control groups in new vertebral fractures at 12 months (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.02 to 2.09; 5 trials, 142 participants; very low-certainty evidence) and two trials (44 participants) reported no vertebral fractures at 24 months. There was no difference in non-vertebral fractures at 12 months (OR 2.11, 95% CI 0.18 to 25.35; 4 trials, 95 participants; very low-certainty evidence) and again two trials (44 participants) reported no non-vertebral fractures at 24 months. There was no difference in total fractures between groups at 12 months (OR 0.57, 95% CI 0.13 to 2.50; 5 trials, 142 participants) and no fractures were reported in two trials (44 participants) at 24 months. At 12 months, bisphosphonates may increase bone mineral density at the lumbar spine (mean difference (MD) 6.31, 95% CI 5.39 to 7.22; 6 trials, 171 participants; low-certainty evidence) and at the hip or femur (MD 4.41, 95% 3.44 to 5.37; 5 trials, 155 participants; low-certainty evidence). There was no clear difference in quality of life scores at 12 months (1 trial, 47 participants; low-certainty evidence), but bisphosphonates probably led to more adverse events (bone pain) at 12 months (OR 8.49, 95% CI 3.20 to 22.56; 7 trials, 206 participants; moderate-certainty evidence). Children The single trial in 113 children compared oral alendronate to placebo. We graded all evidence as low certainty. At 12 months we found no difference between treatment and placebo in new vertebral fractures (OR 0.32, 95% CI 0.03 to 3.13; 1 trial, 113 participants) and non-vertebral fractures (OR 0.19, 95% CI 0.01 to 4.04; 1 trial, 113 participants). There was also no difference in total fractures (OR 0.18, 95% CI 0.02 to 1.61; 1 trial, 113 participants). Bisphosphonates may increase bone mineral density at the lumbar spine at 12 months (MD 14.50, 95% CI 12.91 to 16.09). There was no difference in bone or muscle pain (MD 3.00, 95% CI 0.12 to 75.22), fever (MD 3.00, 95% CI 0.12 to 75.22) or gastrointestinal adverse events (OR 0.67, 95% CI 0.20 to 2.26). The trial did not measure bone mineral density at the hip/femur or report on quality of life.  Bisphosphonates compared to control in people with cystic fibrosis who have had a lung transplant One trial of 34 adults who had undergone lung transplantation compared intravenous pamidronate to no bisphosphonate treatment. It did not report at 12 months and we report the 24-month data (not assessed by GRADE). There was no difference in the number of fractures, either vertebral or non-vertebral. However, bone mineral density increased with treatment at the lumbar spine (MD 6.20, 95% CI 4.28 to 8.12) and femur (MD 7.90, 95% CI 5.78 to 10.02). No participants in either group reported either bone pain or fever. The trial did not measure quality of life.

AUTHORS' CONCLUSIONS

Oral and intravenous bisphosphonates may increase bone mineral density in people with cystic fibrosis, but there are insufficient data to determine whether treatment reduces fractures. Severe bone pain and flu-like symptoms may occur with intravenous bisphosphonates. Before any firm conclusions can be drawn, trials in larger populations, including children, and of longer duration are needed to determine effects on fracture rate and survival. Additional trials are needed to determine if bone pain is more common or severe (or both) with the more potent zoledronate and if corticosteroids can ameliorate or prevent these adverse events. Future trials should also assess gastrointestinal adverse effects associated with oral bisphosphonates.

Clinical relevance of low bone density in cystic fibrosis adult patients: A pilot study

Survival improvement in cystic fibrosis (CF) is associated with more frequent long-term complications, including CF related bone disease (CFBD). Impact of CFBD on global health outcome remains poorly described. We aimed to assess the relationship between low bone mineral density (BMD) and spinal pain, disability, and quality of life in CF adult patients. This monocentric cross-sectional study with prospective data collection was conducted from November 2016 to December 2019 in the Department of Respiratory Diseases at the University Hospital of Reims (NCT02924818). BMD was assessed by X-ray absorptiometry (DXA). Disability was assessed by the Health Assessment Questionnaire (HAQ). Quality of life was assessed by both the St George's Respiratory Questionnaire and the Cystic Fibrosis Questionnaire for teenagers and adults (CFQ 14+). Forty patients were analyzed, 68% of men, with a median age of 25 years, a median body mass index of 21 kg/m² and a median FEV1% of 54%. Nine patients (23%) had spinal pain. Ten patients (25%) had a low BMD. Compared with patients with normal BMD, patients with low BMD had a significantly lower BMI (22 vs 19 kg/m²; P = .006) and less vitamin D supplementation (33% vs 0%; P = .035). Low BMD was not associated with spinal pain, disability and quality of life. Low BMD is frequent in CF, affecting 1-quarter of adult patients. No significant association was found between low BMD and spinal pain, disability or quality of life.

Evaluation of an association between RANKL and OPG with bone disease in people with cystic fibrosis

BACKGROUND

As people with Cystic Fibrosis (CF) live longer, extra-pulmonary complications such as CF-related bone disease (CFBD) are becoming increasingly important. The etiology of CFBD is poorly understood but is likely multifactorial. Bones undergo continuous remodeling via pathways including RANK (receptor activator of NF-κB)/sRANKL (soluble ligand)/OPG (osteoprotegerin). We sought to examine the association between sRANKL (stimulant of osteoclastogenesis) and OPG levels (inhibitor of osteoclast formation) and CFBD to investigate their potential utility as biomarkers of bone turnover in people with CF.

METHODS

We evaluated sRANKL and OPG in plasma from people with CF and healthy controls (HC) and compared levels in those with CF to bone mineral density results. We used univariable and multivariable analysis to account for factors that may impact sRANKL and OPG.

RESULTS

We found a higher median [IQR] sRANKL 10,896pg/mL [5,781-24,243] CF; 2,406pg.mL [659.50-5,042] HC; p= 0.0009), lower OPG 56.68pg/mL [36.28-124.70] CF; 583.20pg/mL [421.30-675.10] HC; p < 0.0001), and higher RANKL/OPG in people with CF no BD than in HC (p < 0.0001). Furthermore, we found a higher RANKL/OPG ratio 407.50pg/mL [214.40-602.60] CFBD; 177.70pg/mL [131.50-239.70] CF no BD; p = 0.007) in people with CFBD versus CF without bone disease. This difference persisted after adjusting for variables thought to impact bone health.

CONCLUSIONS

The current screening recommendations of imaging for CFBD may miss important markers of bone turnover such as the RANKL/OPG ratio. These findings support the investigation of therapies that modulate the RANK/RANKL/OPG pathway as potential therapeutic targets for bone disease in CF.

Updates in Nutrition Management of Cystic Fibrosis in the Highly Effective Modulator Era

Attainment and maintenance of good nutrition has been an important aspect of management in cystic fibrosis (CF) for decades. In the era of highly effective modulator therapy for CF, the quality of the nutrients we recommend is increasingly important. Our therapy must support our patients' health for many years beyond what we previously thought. Preventing cardiovascular disease, reducing hyperlipidemia, and optimizing lean body mass for active, longer lives now join the long-standing goal of promoting lung function through nutrition. This chapter summarizes recent developments in nutrition in people with CF, with an eye to the evolution of our practice.

Endocrine Complications of Cystic Fibrosis

Endocrine comorbidities have become increasingly important medical considerations as improving cystic fibrosis (CF) care increases life expectancy. Although the underlying pathophysiology of CF-related diabetes remains elusive, the use of novel technologies and therapeutics seeks to improve both CF-related outcomes and quality of life. Improvements in the overall health of those with CF have tempered concerns about pubertal delay and short stature; however, other comorbidities such as hypogonadism and bone disease are increasingly recognized. Following the introduction of highly effective modulator therapies there are many lessons to be learned about their long-term impact on endocrine comorbidities.

Romosozumab used to treat a patient with cystic fibrosis-related osteoporosis

Bone disease is a known complication of cystic fibrosis (CF). To date, there have been no reports on the effectiveness of romosozumab, monoclonal antibody to sclerostin, to treat CF-related bone disease. We report a case of a 46-year-old premenopausal female with CF-related bone disease and multiple fractures who was treated with romosozumab. After one year of therapy with romosozumab, the patient tolerated therapy and bone mineral density (BMD) significantly improved. Of the currently available anti-resorptive or anabolic osteoporosis medications, only bisphosphonates have been studied in individuals with CF. This report highlights that romosozumab may be an effective alternative treatment modality in selected patients with CF at high risk for fractures. Further studies are warranted to evaluate the efficacy and safety profile of romosozumab in people with CF.

Auxological and Endocrinological Features in Children and Adolescents with Cystic Fibrosis

Cystic fibrosis (CF) is a multisystem autosomal recessive disease caused by mutations that lead to deficient or dysfunctional CF transmembrane conductance regulator (CFTR) proteins. Patients typically present malnutrition resulting from the malabsorption of fundamental nutrients and recurring lung infections, with a progressive worsening of the respiratory function. For these reasons, the clinical management of CF requires a multidisciplinary team. From an endocrinological point of view, patients often present major complications, such as diabetes, bone disease, thyroid disorders, delayed growth and puberty, hypogonadism and infertility, which negatively affect their quality of life and, in some cases, significantly reduce life expectancy. These complications can arise as a direct result of CFTR dysfunction and/or as a consequence of a deterioration in the function of the organs affected. The objective of this review is to analyze all the possible endocrinological complications that can occur in patients with CF by evaluating the most recent papers in the literature.

Treatment of cystic fibrosis related bone disease

The advent of highly effective CFTR modulator therapies has slowed the progression of pulmonary complications in people with cystic fibrosis. There is increased interest in cystic fibrosis bone disease (CFBD) due to the increasing longevity of people with cystic fibrosis. CFBD is a complex and multifactorial disease. CFBD is a result of hypomineralized bone leading to poor strength, structure and quality leading to susceptibility to fractures. The development of CFBD spans different age groups. The management must be tailored to each group with nuance and based on available guidelines while balancing therapeutic benefits to risks of long-term use of bone-active medication. For now, the mainstay of treatment includes bisphosphonates. However, the long-term effects of bisphosphonate treatment in people with CF are not fully understood. We describe newer agents available for osteoporosis treatment. Still, the lack of data behooves trials of monoclonal antibodies treatments such as Denosumab and Romozosumab and anabolic bone therapy such as teriparatide and Abaloparatide. In this review, we also summarize screening and non-pharmacologic treatment of CFBD and describe the various options available for the pharmacotherapy of CFBD. We address the prospect of CFTR modulators on bone health while awaiting long-term trials to describe the effects of these medications on bone health.

Prevalence and Impact of Rheumatologic Pain in Cystic Fibrosis Adult Patients

Background

With the improvement of cystic fibrosis (CF) patient survival, the prevalence of long-term complications increased, among them rheumatologic disorders.

Methods

The aim of this prospective study was to evaluate the prevalence of spinal and joint pain, and their impact on disability, anxiety, depression, and quality of life in CF adult patients.

Results

Forty-seven patients were analyzed, 72% of men, mean aged 28 years, with a mean body mass index of 22 kg/m² and a mean FEV₁% of 63%. Twenty-two patients (47%) described rheumatologic pain either spinal (n = 15, 32%) and/or joint pain (n = 14, 30%). Patients with spinal and/or joint pain were shorter (p = 0.023), more frequently colonized with Staphylococcus aureus (p < 0.008), had more frequent ΔF508 homozygous mutations (p = 0.014), and a trend for more impairment of the 6-min walking distance (p = 0.050). The presence of rheumatologic pain tended to be associated with disability according to the Health Assessment Questionnaire (HAQ) and anxiety. Compared with patients with no pain patients with both spinal and joint pain exhibited a more pronounced impact on the St George's Respiratory Questionnaire (SGRQ).

Conclusion

Rheumatologic pain is frequent in CF adult patients, and may affect daily living, anxiety and quality of life. Systematic assessment of rheumatologic pain should be included in the management of CF patients.

Utilization of the Healthy Eating Index in Cystic Fibrosis

(1) Background: Malnutrition has been a hallmark of cystic fibrosis (CF) for some time, and improved nutritional status is associated with improved outcomes. While individuals with CF historically required higher caloric intake than the general population, new CF therapies and improved health in this population suggest decreased metabolic demand and prevalence of overweight and obesity have increased. This study aimed to (a) examine diet quality in a population of young adults with CF using the Healthy Eating Index, a measure of diet quality in accordance with the U.S. Dietary Guidelines for Americans and (b) evaluate and describe how subcomponents of the HEI might apply to individuals with CF (2) Methods: 3-day dietary recalls from healthy adolescents and young adults with CF were obtained and scored based on the Healthy Eating Index (3) Results: Dietary recalls from 26 (14M/12F) adolescents and young adults with CF (ages 16–23), were obtained. Individuals with CF had significantly lower HEI scores than the general population and lower individual component scores for total vegetables, greens and beans, total fruits, whole fruits, total protein, seafood and plant protein and sodium (p values < 0.01 for all). (4) Conclusion: Dietary quality was poor in these healthy adolescents and young adults with CF. Given the increased prevalence of overweight and obesity in CF, updated dietary guidance is urgently needed for this population. The Healthy Eating Index may be a valuable tool for evaluating dietary quality in CF.

It starts from the womb: maximizing bone health

The foundation of bone health is established in utero. Bone accrual starts from the developing fetus and continues throughout childhood and adolescence. This process is crucial to achieve peak bone mass. Understanding factors that influence bone accrual before attainment of peak bone mass is thus critical to improve bone health and prevent osteoporosis, thereby reducing the burden of osteoporotic fractures in older women. In this review, we broadly outline factors influencing peak bone mass from pregnancy to infancy, childhood and adolescence with potential diseases and medications that may affect the optimum trajectory to maximizing bone health. It is estimated that a 10% increase in peak bone mass will delay the onset of osteoporosis by 13 years in a woman.

Emerging non-pulmonary complications for adults with cystic fibrosis

Improved treatments of cystic fibrosis (CF) related lung disease have resulted in increased longevity, but also increasing prevalence and severity of extrapulmonary manifestations of CF, treatment related complications, age-related conditions and psychosocial effects of longstanding chronic disease. Likewise, the recognition of mild CF phenotypes has changed the landscape of CF disease. This review outlines our current understanding of the common extrapulmonary complications of CF, as well as the changing landscape and future directions of the extrapulmonary complications experienced by patients with CF.

Findings from a feasibility study of estradiol for hypogonadal women with cystic fibrosis-related bone disease

Background

Advancements in therapies for patients with cystic fibrosis (CF) have decreased mortality, leading to increased prevalence of chronic complications including bone disease. CF-related bone disease (CFBD) is characterized by low bone mineral density (BMD) and fragility fractures. Estrogen deficiency increases bone resorption, resulting in decreased BMD that can be restored with estrogen replacement. Current CF guidelines recommend treating female hypogonadal patients with CFBD with estrogen replacement, but no prospective study has investigated the effects of estrogen supplementation on CFBD. Estrogen is known to modulate inflammatory markers and autoimmune diseases.

We proposed to test the hypothesis that estrogen status plays a critical role in optimizing bone health, modulating inflammation, preserving lung function, and maximizing quality of life in premenopausal women with CF.

Methods

We planned a randomized, placebo-controlled, investigator- and patient-blinded, pilot trial with two parallel arms. Eligible subjects were women with CF 18–50 years old with hypogonadism and low BMD who were not taking systemic glucocorticoids, had not had a prior transplant, and did not have contraindications to oral estradiol. Subjects would be block randomized to receive oral estradiol or placebo for 6 months. The primary outcome was feasibility metrics. Secondary outcomes included relative changes in estradiol, bone turnover markers, lung function, inflammatory markers, and quality of life metrics. The study was funded through departmental funds.

Results

Of 233 subjects screened, 86 subjects were women with CF 18–50 years old and none were eligible for participation. Most subjects were excluded due to absent DXA report (24%), normal BMD (22%), or use of systemic estrogen (16%). Due to difficulty recruiting the planned 52 subjects, the trial was closed for recruitment and no subjects were randomized.

Conclusion

This study was designed to investigate the feasibility of a safety and efficacy trial of estrogen therapy for women with CF. Unfortunately, due to eligibility criteria, the study was unable to recruit subjects. This feasibility study highlights the need for improved BMD screening in young women with CF. Future study designs may require the incorporation of a screening DXA as part of subject recruitment.

Trial registration

The study was registered on ClinicalTrials.gov (NCT03724955).

[Osteoporosis in pneumological diseases : Joint guideline of the Austrian Society for Bone and Mineral Research (ÖGKM) and the Austrian Society for Pneumology (ÖGP)]

Chronic inflammation induces proinflammatory cytokine cascades. In addition to systemic inflammation, hypoxemia, hypercapnia, a catabolic metabolism, gonadal or thyroid dysfunction, musculoskeletal dysfunction and inactivity as well as vitamin D deficiency contribute to an increased risk of fragility fractures. Iatrogenic causes of osteoporosis are long-term use of inhaled or systemic glucocorticoids (GC). Inhalative GC application in asthma is often indicated in childhood and adolescence, but interstitial lung diseases such as chronic organizing pneumonia, COPD, sarcoid or rheumatic diseases with lung involvement are also treated with inhalative or oral GC. In patients with cystic fibrosis, malabsorption in the context of pancreatic insufficiency, hypogonadism and chronic inflammation with increased bone resorption lead to a decrease in bone structure. After lung transplantation, immunosuppression with GC is a risk factor.The underlying pneumological diseases lead to a change in the trabecular and cortical bone microarchitecture and to a reduction in osteological formation and resorption markers. Hypercapnia, acidosis and vitamin D deficiency can accelerate this process and thus increase the individual risk of osteoporotic fragility fractures.A bone mineral density measurement with a T‑Score < -2.5 is a threshold value for the diagnosis of osteoporosis; in contrast the vast majority of all osteoporotic fractures occur with a T‑Score > -2.5. A history of low-trauma fracture indicates osteological therapy.All antiresorptive or anabolic drugs approved in Austria for the treatment of osteoporosis are also indicated for pneumological patients with an increased fragility fracture risk of bone fractures in accordance with the national reimbursement criteria.

Cystic fibrosis

Cystic fibrosis is a monogenic disease considered to affect at least 100 000 people worldwide. Mutations in CFTR, the gene encoding the epithelial ion channel that normally transports chloride and bicarbonate, lead to impaired mucus hydration and clearance. Classical cystic fibrosis is thus characterised by chronic pulmonary infection and inflammation, pancreatic exocrine insufficiency, male infertility, and might include several comorbidities such as cystic fibrosis-related diabetes or cystic fibrosis liver disease. This autosomal recessive disease is diagnosed in many regions following newborn screening, whereas in other regions, diagnosis is based on a group of recognised multiorgan clinical manifestations, raised sweat chloride concentrations, or CFTR mutations. Disease that is less easily diagnosed, and in some cases affecting only one organ, can be seen in the context of gene variants leading to residual protein function. Management strategies, including augmenting mucociliary clearance and aggressively treating infections, have gradually improved life expectancy for people with cystic fibrosis. However, restoration of CFTR function via new small molecule modulator drugs is transforming the disease for many patients. Clinical trial pipelines are actively exploring many other approaches, which will be increasingly needed as survival improves and as the population of adults with cystic fibrosis increases. Here, we present the current understanding of CFTR mutations, protein function, and disease pathophysiology, consider strengths and limitations of current management strategies, and look to the future of multidisciplinary care for those with cystic fibrosis.

Bone Cells Differentiation: How CFTR Mutations May Rule the Game of Stem Cells Commitment?

Cystic fibrosis (CF)-related bone disease has emerged as a significant comorbidity of CF and is characterized by decreased bone formation and increased bone resorption. Both osteoblast and osteoclast differentiations are impacted by cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The defect of CFTR chloride channel or the loss of CFTRs ability to interact with other proteins affect several signaling pathways involved in stem cell differentiation and the commitment of these cells toward bone lineages. Specifically, TGF-, nuclear factor-kappa B (NF-B), PI3K/AKT, and MAPK/ERK signaling are disturbed by CFTR mutations, thus perturbing stem cell differentiation. High inflammation in patients changes myeloid lineage secretion, affecting both myeloid and mesenchymal differentiation. In osteoblast, Wnt signaling is impacted, resulting in consequences for both bone formation and resorption. Finally, CFTR could also have a direct role in osteoclasts resorptive function. In this review, we summarize the existing literature on the role of CFTR mutations on the commitment of induced pluripotent stem cells to bone cells.

[Cystic fibrosis being a polyendocrine disease (Review)]

The cystic fibrosis transmembrane regulator (CFTR) gene encodes the synthesis of a protein of the same name, which functions as a direct activator of anionic transport. Chloride is the most abundant anion; as an antagonist of Na+ and K+, it provides electroneutrality of cell membranes at rest; together with cations, it serves as an important osmolyte and forms water flow across cell membranes for transepithelial secretion.Glandular cells in CF trap Cl- and Na+, and the prodused secretion is excessively viscous. Subnormal CFTR activity leads to stagnation of mucociliary clearance, inhibition of intestinal transport.In addition to exocrine disorders, CFTR mutations are associated with a decrease in volume, mass, increased apoptosis of β-cells of the pancreas, a significant suppression of insulin exocytosis in response to stimulation with glucose and glucagon-like peptide-1, hyperglucagonemia against the background of a defect in the suppression of α-cell function by insulin, but a decrease in maximum capacity α-cells.Deficiency and progressive decline in bone mineral density is an expected secondary manifestation of CF due to pancreatic exocrine insufficiency with malabsorption of nutrients and fat-soluble vitamins. However, in patients with the F508del mutation, a significant decrease in the synthesis of OPG, COX-2, PGE2 in the osteoblastic formation, and an increase in the activity of the antianabolic NF-kB were found. We are talking about a defect in the canonical signaling pathway (Wnt/β-catenin), which regulates the expression of genes-activators of osteoblastogenesis, dissociation of the stages of physiological bone remodeling.In addition to congenital bilateral or unilateral aplasia of the vas deferens, an increase in the frequency of CFTR mutations is also found in non-obstructive azoospermia, oligo-, astheno- and teratospermia. CFTR is involved in the entry of HCO3- into Sertoli cells to trigger cAMP-dependent transcription and its defects lead to suppression of FSH-dependent gene expression of spermatogenesis, loss of sequence in the Wnt cascade, destruction of the PGE2-dependent transepithelial interaction and, as a consequence, the blood-testicular barrier.CF is characterized, along with classical signs, by endocrine dysfunction of the pancreas, osteoporosis with suppression of osteoblastogenesis, and a defect in spermatogenesis.

Changes in handgrip strength in children with cystic fibrosis compared to children without cystic fibrosis

BACKGROUND & AIMS

Cystic Fibrosis (CF) may impact nutritional status. Handgrip strength (HGS) may be used for nutrition assessment. The objective of the study was to evaluate changes in HGS over time in children with CF compared to children without CF. A secondary purpose was to analyze the relationship of clinical characteristics of CF with HGS.

METHODS

A prospective, longitudinal study was conducted. The non-CF group (n = 76) was recruited from a school and the CF group (n = 75) from an accredited CF center. Height, weight, mid-upper arm circumference, triceps skinfold, and HGS were measured at baseline and approximately three and six months in both groups. Data for pulmonary function, nutrition risk, enteral supplementation, CF transmembrane conductance regulator modulator, steroids, antibiotics, vitamin levels, CF related diabetes (CFRD), and recent hospitalization were collected for the CF group. A mixed model determined the difference in the change in HGS between the CF group and the non-CF group. For all analyses, p=<0.05 was significant.

RESULTS

The rate of change in HGS z-score in the CF-group (0.18 ± 0.05) versus the non-CF group (0.06 ± 0.06) was not significant (p = 0.15). Initial mean dominant HGS z-score was significantly lower (p = 0.02) in those with vitamin D deficiency (-1.35 ± 0.09) versus those without (-1.02 ± 0.11). HGS z-score significantly (p = 0.02) decreased over time in children with CFRD (-0.19 ± 0.22) versus children without CFRD (0.32 ± 0.14), p = 0.02.

CONCLUSION

Serial measurements of HGS may help detect changes in muscle function related to CFRD and vitamin D deficiency. Further investigation is warranted to elucidate HGS's role in nutrition assessment of children with CF.

Triage for Malnutrition Risk among Pediatric and Adolescent Outpatients with Cystic Fibrosis, Using a Disease-Specific Tool

Malnutrition prevails in considerable proportions of children with Cystic Fibrosis (CF), and is often associated with adverse outcomes. For this, routine screening for malnutrition is pivotal. In the present cross-sectional study, we aimed to assess the risk for malnutrition in pediatric outpatients with CF. A total of 76 outpatients (44 girls, 11.9 ± 3.9 years old, 39.5% adolescents) were recruited and anthropometric, clinical, dietary and respiratory measures were collected. All outpatients were screened for malnutrition risk with a validated disease-specific instrument. Most children exhibited a low risk for malnutrition (78.9%), whereas none of the participants were characterized as having a high malnutrition risk. In the total sample, malnutrition risk was positively associated with age (r = 0.369, p = 0.001), and inversely related to the body mass index (r = −0.684, p < 0.001), height z-score (r = −0.264, p = 0.021), and forced expiratory volume (FEV₁%, r = −0.616, p < 0.001). Those classified as having a low malnutrition risk were younger (p = 0.004), heavier (p < 0.001) and taller (p = 0.009) than their counterparts with a moderate risk. On the other hand, patients in the moderate risk group were more likely pubertal (p = 0.034), with a reduced mid-upper arm fat area (p = 0.011), and worse pulmonary function (p < 0.001). Interestingly, none of the children attaining ideal body weight were classified as having a moderate malnutrition. risk, whereas 37.5% of the patients allocated at the moderate risk group exhibited physiological lung function. In this cohort of outpatients with CF that were predominantly well-nourished and attained physiological lung function, malnutrition risk was identified only in small proportions of the sample. Our data support that patients that are older, pubertal, or have diminished fat mass are at greater risk for malnutrition.

Understanding the interplay between factors that influence bone mineral density in CF

BACKGROUND AND OBJECTIVES

Multiple factors affect bone mineral density (BMD) in cystic fibrosis (CF). Our aim was to perform comprehensive analyses of parameters potentially contributing to BMD.

METHODS

A prospective single-center study assessing BMD, and correlations with multiple parameters including pancreatic status, lung functions, 6-minute walk test (6MWT), clinical score (modified Shwachman-Kulczycki [SK] score), vitamin D, nutritional intake, hand grip strength (HGS), habitual physical activity (smart watches), and quality of life (SF-36 questionnaire).

RESULTS

Forty CF patients, mean age 18.3 ± 8.1 years, forced expiratory volume in 1 second 74.7% ± 17.9% predicted. Fifteen (37.5%) and 11 (27.5%) had osteopenia and osteoporosis, respectively. BMD was similar in pancreatic sufficient (pancreatic sufficient [PS], n = 15) and insufficient (pancreatic insufficient [PI], n = 25); median hip z score -1.5 ((-2.7)-(+0.2)) vs -1.5 ((-3.5)-(+0.7)), P = .79; spine -0.8 ((-2.2)-(+2)) vs -1.2 ((-4.4)-(+1.5)), P = .39 in PS vs PI, respectively. BMD correlated with HGS (r = .72, P < .001 hip; r = .52, P = .001 spine) and fat-free mass index (r = .81, P < .001 hip; r = .63, P < .001 spine). BMD z score correlated weakly with SK score and moderately with SF-36 general health. Data from smart watches, nutrition questionnaires, and 6MWT did not correlate with BMD. In a multivariate model, age and SK score predicted spine z score BMD.

CONCLUSIONS

A substantial number of CF patients have low BMD. Similar rates in PS and PI suggest that other factors, such as disease severity, may contribute to low BMD. SK and age, which can easily be obtained even with limited resources, were the best predictors of low BMD. Further larger multicenter studies are warranted to evaluate the contribution of multifactorial etiologies to low BMD in CF.

Relationship Between Estrogen Treatment and Skeletal Health in Women With Cystic Fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) are at risk for CF-related bone disease. Women with CF may use estrogen supplementation for reasons other than skeletal health. It is unknown whether estrogen therapy has a beneficial impact on skeletal health in women with CF.

METHODS

In this retrospective cohort study of women with CF followed at a single CF center, the lumbar spine bone mineral density (BMD) of women with CF exposed to supplemental and not exposed to supplemental estrogen were compared. Spline function models included the main effect of estrogen exposure and the interaction between age and estrogen supplementation.

RESULTS

Of the 145 subjects analyzed, 44 subjects were exposed to supplemental estrogen. The baseline characteristics of estrogen exposed and unexposed subjects were similar except for use of CF transmembrane conductance regulator modulators and anti-osteoporosis medications. Women exposed to estrogen reached peak BMD around 21 years of age, but women not exposed to estrogen reached peak BMD around 25 years of age. A significant interaction of age and estrogen supplementation indicated that the lumbar spine BMD trajectories differed by exposure group.

CONCLUSIONS

Our study demonstrates that few women with CF of reproductive age are prescribed estrogen therapy. Furthermore, estrogen exposure up to age 21 is associated with improved BMD, but estrogen exposure after age 21 does not appear to be associated with improved BMD. Further studies are needed to understand the reasons for the low rates of estrogen use in young women with CF and the optimal timing, dose and formulation of estrogen prescription.

Oral ethinyl estradiol treatment in women with cystic fibrosis is associated with lower bone mineral density

Objective

The purpose of this study was to determine whether estrogen supplementation primarily from oral contraceptive pills compared to no estrogen supplementation is associated with differences in mean bone mineral density (BMD) measured by DXA in a cross-sectional study of women with cystic fibrosis (CF).

Methods

In this cross-sectional study of women with CF followed at a single center, we analyzed 49 women with CF ages 18–50 years with a documented DXA. BMD of women with CF taking estrogen supplementation was compared to BMD of women with CF not taking estrogen supplementation.

Results

Twelve women with CF were taking estrogen supplementation with mean dose of 23.3 mcg/day (SD 6.9 mcg/day) of ethinyl estradiol. There were no statistically significant differences between demographics of the 12 women with CF taking estrogen supplementation compared to the 37 women with CF not taking estrogen supplementation. Women taking estrogen had lower mean lumbar spine Z-score: −0.7 ± 0.7, compared to women not taking estrogen, Z-score: −0.04 ± 1.0 (p-value 0.046). Women taking estrogen had lower mean BMD at the lumbar spine: 0.952 ± 0.086 g/cm², compared to women not taking estrogen: 1.023 ± 0.105 g/cm² (p-value 0.038). Similar trends were seen at the total hip and femoral neck.

Conclusion

Low-dose estrogen supplementation in premenopausal women with CF was associated with lower BMD compared to no estrogen supplementation in a similar group of premenopausal young women with CF. Future studies are needed to investigate the optimal formulation, route of administration, and dose to accrue and preserve bone mass in premenopausal women with CF.