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Background and Objective: Long-term data on children with PBB has been identified as a research priority. We describe the 5-year outcomes for children with PBB to ascertain the presence of chronic respiratory disease (bronchiectasis, recurrent PBB and asthma) and identify the risk factors for these., Methods: Prospective cohort study was undertaken at the Queensland Children's Hospital, Brisbane, Australia, of 166 children with PBB and 28 controls (undergoing bronchoscopy for symptoms other than chronic wet cough). Monitoring was by monthly contact via research staff. Clinical review, spirometry and CT chest were performed as clinically indicated., Results: A total of 194 children were included in the analysis. Median duration of follow-up was 59 months (IQR: 50-71 months) post-index PBB episode, 67.5% had ongoing symptoms and 9.6% had bronchiectasis. Significant predictors of bronchiectasis were recurrent PBB in year 1 of follow-up (OR adj = 9.6, 95% CI: 1.8-50.1) and the presence of Haemophilus influenzae in the BAL (OR adj = 5.1, 95% CI: 1.4-19.1). Clinician-diagnosed asthma at final follow-up was present in 27.1% of children with PBB. A significant BDR (FEV 1 improvement >12%) was obtained in 63.5% of the children who underwent reversibility testing. Positive allergen-specific IgE (OR adj = 14.8, 95% CI: 2.2-100.8) at baseline and bronchomalacia (OR adj = 5.9, 95% CI: 1.2-29.7) were significant predictors of asthma diagnosis. Spirometry parameters were in the normal range., Conclusion: As a significant proportion of children with PBB have ongoing symptoms at 5 years, and outcomes include bronchiectasis and asthma, they should be carefully followed up clinically. Defining biomarkers, endotypes and mechanistic studies elucidating the different outcomes are now required., (© 2020 Asian Pacific Society of Respirology.)

Background: Bronchiectasis guidelines recommend antibiotics for the treatment of acute respiratory exacerbations, but randomised placebo-controlled trials in children are lacking. We hypothesised that oral amoxicillin-clavulanate and azithromycin would each be superior to placebo in achieving symptom resolution of non-severe exacerbations in children by day 14 of treatment., Methods: In this multicentre, three-arm, parallel, double-dummy, double-blind, randomised placebo-controlled trial at four paediatric centres in Australia and New Zealand, we enrolled children aged 1-18 years with CT-confirmed bronchiectasis unrelated to cystic fibrosis, who were under the care of a respiratory physician and who had had at least two respiratory exacerbations in the 18 months before study entry. Participants were allocated (1:1:1) at exacerbation onset to receive oral suspensions of amoxicillin-clavulanate (45 mg/kg per day) plus placebo azithromycin, azithromycin (5 mg/kg per day) plus placebo amoxicillin-clavulanate, or both placebos for 14 days. An independent statistician prepared a computer-generated, permuted-block (size 2-8) randomisation sequence, stratified by centre, age, and cause. Participants, caregivers, study coordinators, and investigators were masked to treatment assignment until data analysis was completed. The primary outcome was the proportion of children with exacerbation resolution by day 14 in the intention-to-treat population. Treatment groups were compared using generalised linear models. Statistical significance was set at p<0·0245 to account for multiple comparisons. This trial is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12612000011886) and is completed., Findings: Between April 17, 2012, and March 1, 2017, 604 children were screened and 252 were enrolled. Between July 31, 2012, and June 26, 2017, 197 children were allocated at the start of an exacerbation (63 to the amoxicillin-clavulanate group, 67 to the azithromycin group, and 67 to the placebo group). Respiratory viruses were identified in 82 (53%) of 154 children with available nasal swabs on day 1 of treatment. Primary outcome data were available for 196 (99%) children (one child with missing data [placebo group] was recorded as non-resolved according to criteria defined a priori). By day 14, exacerbations had resolved in 41 (65%) children in the amoxicillin-clavulanate group, 41 (61%) in the azithromycin group, and 29 (43%) in the placebo group. Compared with placebo, relative risk for resolution by day 14 was 1·50 (95% CI 1·08-2·09, p=0·015; number-needed-to-treat [NNT] 5 [95% CI 3-20]) in the amoxicillin-clavulanate group and 1·41 (1·01-1·97, p=0·042; NNT 6 [3-79]) in the azithromycin group. Adverse events were recorded in 19 (30%) children in the amoxicillin-clavulanate group, 20 (30%) in the azithromycin group, and 14 (21%) in the placebo group, but no events were severe or life-threatening., Interpretation: Amoxicillin-clavulanate treatment is beneficial in terms of resolution of non-severe exacerbations of bronchiectasis in children, and should remain the first-line oral antibiotic in this setting., Funding: National Health and Medical Research Council (Australia), Cure Kids (New Zealand)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Although amoxicillin-clavulanate is the recommended first-line empirical oral antibiotic treatment for non-severe exacerbations in children with bronchiectasis, azithromycin is also often prescribed for its convenient once-daily dosing. No randomised controlled trials involving acute exacerbations in children with bronchiectasis have been published to our knowledge. We hypothesised that azithromycin is non-inferior to amoxicillin-clavulanate for resolving exacerbations in children with bronchiectasis., Methods: We did this parallel-group, double-dummy, double-blind, non-inferiority randomised controlled trial in three Australian and one New Zealand hospital between April, 2012, and August, 2016. We enrolled children aged 1-19 years with radiographically proven bronchiectasis unrelated to cystic fibrosis. At the start of an exacerbation, children were randomly assigned to oral suspensions of either amoxicillin-clavulanate (22·5 mg/kg, twice daily) and placebo or azithromycin (5 mg/kg per day) and placebo for 21 days. We used permuted block randomisation (stratified by age, site, and cause) with concealed allocation. The primary outcome was resolution of exacerbation (defined as a return to baseline) by 21 days in the per-protocol population, with a non-inferiority margin of -20%. We assessed several secondary outcomes including duration of exacerbation, time to next exacerbation, laboratory, respiratory, and quality-of-life measurements, and microbiology. This trial was registered with the Australian/New Zealand Registry (ACTRN12612000010897)., Findings: We screened 604 children and enrolled 236. 179 children had an exacerbation and were assigned to treatment: 97 to amoxicillin-clavulanate, 82 to azithromycin). By day 21, 61 (84%) of 73 exacerbations had resolved in the azithromycin group versus 73 (84%) of 87 in the amoxicillin-clavulanate group. The risk difference showed non-inferiority (-0·3%, 95% CI -11·8 to 11·1). Exacerbations were significantly shorter in the amoxicillin-clavulanate group than in the azithromycin group (median 10 days [IQR 6-15] vs 14 days [8-16]; p=0·014). Adverse events were attributed to the trial medication in 17 (21%) of 82 children in the azithromycin group versus 23 (24%) of 97 in the amoxicillin-clavulanate group (relative risk 0·9, 95% CI 0·5 to 1·5)., Interpretation: By 21 days of treatment, azithromycin is non-inferior to amoxicillin-clavulanate for resolving exacerbations in children with non-severe bronchiectasis. In some patients, such as those with penicillin hypersensitivity or those likely to have poor adherence, azithromycin provides another option for treating exacerbations, but must be balanced with risk of treatment failure (within a 20% margin), longer exacerbation duration, and the risk of inducing macrolide resistance., Funding: Australian National Health and Medical Research Council., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Protracted bacterial bronchitis (PBB) in young children is characterised by prolonged wet cough, prominent airway interleukin (IL)-1β expression and infection, often with nontypeable Haemophilus influenzae (NTHi). The mechanisms responsible for IL-1-driven inflammation in PBB are poorly understood. We hypothesised that the inflammation in PBB involves the NLRP3 and/or AIM2 inflammasome/IL-1β axis. Lung macrophages obtained from bronchoalveolar lavage (BAL), peripheral blood mononuclear cells (PBMCs), blood monocytes and monocyte-derived macrophages from patients with PBB and age-matched healthy controls were cultured in control medium or exposed to live NTHi. In healthy adult PBMCs, CD14 + monocytes contributed to 95% of total IL-1β-producing cells upon NTHi stimulation. Stimulation of PBB PBMCs with NTHi significantly increased IL-1β expression (p<0.001), but decreased NLRC4 expression (p<0.01). NTHi induced IL-1β secretion in PBMCs from both healthy controls and patients with recurrent PBB. This was inhibited by Z-YVAD-FMK (a caspase-1 selective inhibitor) and by MCC950 (a NLRP3 selective inhibitor). In PBB BAL macrophages inflammasome complexes were visualised as fluorescence specks of NLRP3 or AIM2 colocalised with cleaved caspase-1 and cleaved IL-1β. NTHi stimulation induced formation of specks of cleaved IL-1β, NLRP3 and AIM2 in PBMCs, blood monocytes and monocyte-derived macrophages. We conclude that both the NLRP3 and AIM2 inflammasomes probably drive the IL-1β-dominated inflammation in PBB., Competing Interests: Conflict of interest: None declared.

Protracted bacterial bronchitis (PBB) in young children is a common cause of prolonged wet cough and may be a precursor to bronchiectasis in some children. Although PBB and bronchiectasis are both characterised by neutrophilic airway inflammation and a prominent interleukin (IL)-1β signature, the contribution of the IL-1β pathway to host defence is not clear. This study aimed to compare systemic immune responses against common pathogens in children with PBB, bronchiectasis and control children and to determine the importance of the IL-1β pathway. Non-typeable Haemophilus influenzae (NTHi) stimulation of peripheral blood mononuclear cells (PBMCs) from control subjects (n=20), those with recurrent PBB (n=20) and bronchiectasis (n=20) induced high concentrations of IL-1β, IL-6, interferon (IFN)-γ and IL-10. Blocking with an IL-1 receptor antagonist (IL-1Ra) modified the cellular response to pathogens, inhibiting cytokine synthesis by NTHi-stimulated PBMCs and rhinovirus-stimulated PBMCs (in a separate PBB cohort). Inhibition of IFN-γ production by IL-1Ra was observed across multiple cell types, including CD3 + T cells and CD56 + NK cells. Our findings highlight the extent to which IL-1β regulates the cellular immune response against two common respiratory pathogens. While blocking the IL-1β pathway has the potential to reduce inflammation, this may come at the cost of protective immunity against NTHi and rhinovirus., Competing Interests: Conflict of interest: Disclosures can be found alongside this article at openres.ersjournals.com

Background: Bronchiectasis unrelated to cystic fibrosis (CF) is being increasingly recognized in children and adults globally, both in resource-poor and in affluent countries. However, high-quality evidence to inform management is scarce. Oral amoxycillin-clavulanate is often the first antibiotic chosen for non-severe respiratory exacerbations, because of the antibiotic-susceptibility patterns detected in the respiratory pathogens commonly associated with bronchiectasis. Azithromycin has a prolonged half-life, and with its unique anti-bacterial, immunomodulatory, and anti-inflammatory properties, presents an attractive alternative. Our proposed study will test the hypothesis that oral azithromycin is non-inferior (within a 20% margin) to amoxycillin-clavulanate at achieving resolution of non-severe respiratory exacerbations by day 21 of treatment in children with non-CF bronchiectasis., Methods: This will be a multicenter, randomized, double-blind, double-dummy, placebo-controlled, parallel group trial involving six Australian and New Zealand centers. In total, 170 eligible children will be stratified by site and bronchiectasis etiology, and randomized (allocation concealed) to receive: 1) azithromycin (5 mg/kg daily) with placebo amoxycillin-clavulanate or 2) amoxycillin-clavulanate (22.5 mg/kg twice daily) with placebo azithromycin for 21 days as treatment for non-severe respiratory exacerbations. Clinical data and a parent-proxy cough-specific quality of life (PC-QOL) score will be obtained at baseline, at the start and resolution of exacerbations, and on day 21. In most children, blood and deep-nasal swabs will also be collected at the same time points. The primary outcome is the proportion of children whose exacerbations have resolved at day 21. The main secondary outcome is the PC-QOL score. Other outcomes are: time to next exacerbation; requirement for hospitalization; duration of exacerbation, and spirometry data. Descriptive viral and bacteriological data from nasal samples and blood inflammatory markers will be reported where available., Discussion: Currently, there are no published randomized controlled trials (RCT) to underpin effective, evidence-based management of acute respiratory exacerbations in children with non-CF bronchiectasis. To help address this information gap, we are conducting two RCTs. The first (bronchiectasis exacerbation study; BEST-1) evaluates the efficacy of azithromycin and amoxycillin-clavulanate compared with placebo, and the second RCT (BEST-2), described here, is designed to determine if azithromycin is non-inferior to amoxycillin-clavulanate in achieving symptom resolution by day 21 of treatment in children with acute respiratory exacerbations., Trial Registration: Australia and New Zealand Clinical Trials Register (ANZCTR) number http://ACTRN12612000010897. http://www.anzctr.org.au/trial&#95;view.aspx?id=347879.

Background: Despite bronchiectasis being increasingly recognised as an important cause of chronic respiratory morbidity in both indigenous and non-indigenous settings globally, high quality evidence to inform management is scarce. It is assumed that antibiotics are efficacious for all bronchiectasis exacerbations, but not all practitioners agree. Inadequately treated exacerbations may risk lung function deterioration. Our study tests the hypothesis that both oral azithromycin and amoxicillin-clavulanic acid are superior to placebo at improving resolution rates of respiratory exacerbations by day 14 in children with bronchiectasis unrelated to cystic fibrosis., Methods: We are conducting a bronchiectasis exacerbation study (BEST), which is a multicentre, randomised, double-blind, double-dummy, placebo-controlled, parallel group trial, in five centres (Brisbane, Perth, Darwin, Melbourne, Auckland). In the component of BEST presented here, 189 children fulfilling inclusion criteria are randomised (allocation-concealed) to receive amoxicillin-clavulanic acid (22.5 mg/kg twice daily) with placebo-azithromycin; azithromycin (5 mg/kg daily) with placebo-amoxicillin-clavulanic acid; or placebo-azithromycin with placebo-amoxicillin-clavulanic acid for 14 days. Clinical data and a paediatric cough-specific quality of life score are obtained at baseline, at the start and resolution of exacerbations, and at day 14. In most children, blood and deep nasal swabs are also collected at the same time points. The primary outcome is the proportion of children whose exacerbations have resolved at day 14. The main secondary outcome is the paediatric cough-specific quality of life score. Other outcomes are time to next exacerbation; requirement for hospitalisation; duration of exacerbation; and spirometry data. Descriptive viral and bacteriological data from nasal samples and blood markers will also be reported., Discussion: Effective, evidence-based management of exacerbations in people with bronchiectasis is clinically important. Yet, there are few randomised controlled trials (RCTs) in the neglected area of non-cystic fibrosis bronchiectasis. Indeed, no published RCTs addressing the treatment of bronchiectasis exacerbations in children exist. Our multicentre, double-blind RCT is designed to determine if azithromycin and amoxicillin-clavulanic acid, compared with placebo, improve symptom resolution on day 14 in children with acute respiratory exacerbations. Our planned assessment of the predictors of antibiotic response, the role of antibiotic-resistant respiratory pathogens, and whether early treatment with antibiotics affects duration and time to the next exacerbation, are also all novel., Trial Registration: Australia and New Zealand Clinical Trials Register (ANZCTR) number ACTRN12612000011886.

Background: A study was undertaken to observe the gains in bone mass in children and adolescents with cystic fibrosis (CF) over 24 months and to examine the relationship between areal bone mineral density (aBMD) and associated clinical parameters including physical activity, nutrition, and 25-hydroxyvitamin D (25OHD)., Methods: Areal BMD of the total body (TB), lumbar spine (LS), and total femoral neck (FNt) were repeatedly measured in 85 subjects aged 5-18 years with CF and 100 age and sex matched controls over 2 years. At each visit anthropometric variables, nutritional parameters, pubertal status, disease severity, physical activity, dietary calcium, caloric intake, and serum 25OHD were assessed and related to aBMD., Results: After adjusting for age, sex, and height Z-score, gains in LS aBMD in children (5-10 years) and TB and FNt aBMD in adolescents (11-18 years) with CF were significantly less than in controls. Lean tissue mass was significantly associated with TB and LS aBMD gains in children and adolescents and explained a significant proportion of the aBMD deficit observed. Lung function parameters were significantly associated with aBMD gains in adolescents with CF., Conclusions: Inadequate bone mass accrual during childhood and adolescence contributes to the low bone mass observed in adults with CF. Accounting for the height discrepancy which is frequently observed in those with CF, in addition to age and sex, is important when assessing low bone mass in children and adolescents with CF. To optimise an individual's potential to acquire maximal bone mass, it is necessary to maximise nutritional status and limit the progression of chronic suppurative lung disease.

Background: Pubertal delay is thought to contribute to suboptimal peak bone mass acquisition in young people with cystic fibrosis (CF), leading to an increased fracture incidence. This study aims to compare pubertal development in young people with CF with that of a local healthy population and assess the influence it has on areal bone mineral density (aBMD)., Methods: Tanner stage, age of menarche, bone age (BA), sex hormone levels and aBMD were examined in 85 individuals with CF (aged 5.3-18.1 years, 39 females) and 100 local controls (5.6-17.9 years, 54 females)., Results: Tanner stage and age of menarche were not significantly different between controls and CF. Tanner stage-adjusted mean values for follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T) were lower in males with CF (FSH: P = 0.004, LH: P = 0.01 and T: P = 0.002). Bone age was delayed in adolescents with CF compared to controls (chronological age-BA: controls = 0.13 years (SE = 0.16), CF = 0.95 years (SE = 0.22), P = 0.003). Areal bone mineral density (adjusted for age, sex, height and lean tissue mass) was not significantly different between CF and controls. Moderate negative correlations were found between delayed BA and weight (r = -0.41, P < 0.001) and height (r = -0.41, P < 0.001)., Conclusions: There was no evidence of clinical pubertal delay or low aBMD (adjusted for short stature and lean tissue mass) in young people with CF when compared with a local population, despite lower nutritional markers, height and weight and delayed skeletal maturation.

Background: Serum vitamin A, normally depressed in inflammatory conditions, is frequently low in people with CF. Vitamin A is important in respiratory epithelial regeneration and repair. We hypothesised that serum vitamin A would be associated with inflammation and disease severity., Methods: Serum vitamin A (as retinol), C-reactive protein (CRP), vitamin E, 25-hydroxy vitamin D (25OHD), 1,25-dihydroxy vitamin D (1,25(OH)(2)D), weight, and lumbar spine bone mineral density (LSBMD) were measured in 138 subjects with CF (5-56 years) and 138 control subjects (5-48 years). FEV(1), presence of CF liver disease (CFLD) and hospital admissions were recorded in those with CF., Results: Serum vitamin A level was lower in CF subjects than in controls (mean, 95% CI: 1.29, 1.0-1.37 vs. 1.80, 1.7-1.87 micromol/l, p < 0.0001), and inversely correlated with CRP (r(s) = -0.37, p < 0.0001). CF subjects with low vitamin A (45%) level had poorer FEV(1), weight z-score, LSBMD z-score, and higher CRP compared with those with normal levels. In the CF group CRP, vitamin E, 1,25(OH)(2)D, presence of CFLD, admissions, and age were associated with vitamin A level., Conclusions: Serum vitamin A is negatively associated with CRP in subjects with CF, consistent with normal population studies. It is important to distinguish between low serum vitamin A associated with the inflammatory response and that due to poor nutritional stores. The role of vitamin A in CF warrants further study, in the contexts both of chronic recurrent inflammatory disease and acute pulmonary exacerbation.

Background: Body cell mass (BCM) may be estimated in clinical practice to assess functional nutritional status, eg, in patients with anorexia nervosa. Interpretation of the data, especially in younger patients who are still growing, requires appropriate adjustment for size. Previous investigations of this general issue have addressed chemical rather than functional components of body composition and have not considered patients at the extremes of nutritional status, in whom the ability to make longitudinal comparisons is of particular importance., Objective: Our objective was to determine the power by which height should be raised to adjust BCM for height in women of differing nutritional status., Design: BCM was estimated by (40)K counting in 58 healthy women, 33 healthy female adolescents, and 75 female adolescents with anorexia nervosa. The relation between BCM and height was explored in each group by using log-log regression analysis., Results: The powers by which height should be raised to adjust BCM were 1.73, 1.73, and 2.07 in the women, healthy female adolescents, and anorexic female adolescents, respectively. A simplified version of the index, BCM/height(2), was appropriate for all 3 categories and was negligibly correlated with height., Conclusions: In normal-weight women, the relation between height and BCM is consistent with that reported previously between height and fat-free mass. Although the consistency of the relation between BCM and fat-free mass decreases with increasing weight loss, the relation between height and BCM is not significantly different between normal-weight and underweight women. The index BCM/height(2) is easy to calculate and applicable to both healthy and underweight women. This information may be helpful in interpreting body-composition data in clinical practice.

Background: Low bone mineral density (BMD) is recognised in individuals with cystic fibrosis (CF) although the pathogenesis remains unclear. The aims of this study were to compare BMD over a broad continuum of Australian individuals with CF with healthy controls and to examine the relationship between BMD and clinical parameters including physical activity, nutrition, and vitamin D levels., Methods: BMD of the lumbar spine (LS), total body (TB), femoral neck (FN), cortical wrist (R33%), and distal wrist (RUD) was examined in 153 individuals with CF aged 5.3-55.8 years (84 males) and in 149 local controls aged 5.6-48.3 years (66 males) using dual energy x ray absorptiometry. Anthropometric variables, body cell mass, markers of disease severity, corticosteroid usage, measures of physical activity, dietary calcium and caloric intake and serum vitamin D were assessed and related to BMD., Results: Compared with controls, mean BMD was not significantly different in children aged 5-10 years with CF. Adolescents (females 11-18 years, males 11-20 years) had reduced TB and R33% BMD when adjusted for age, sex, and height (difference in BMD (g/cm2) adjusted means between control and CF: TB=0.04 (95% CI 0.01 to 0.07); R33%=0.03 (95% CI 0.01 to 0.06)). BMD was reduced at all sites except R33% in adults (difference in BMD (g/cm2) adjusted means between control and CF: TB=0.05 (95% CI 0.02 to 0.09); LS=0.08 (95% CI 0.03 to 0.14); FN=0.09 (95% CI 0.03 to 0.15); RUD=0.03 (95% CI 0.01 to 0.05)). In children/adolescents BMD was weakly associated with nutritional status and disease severity., Conclusions: BMD was normal in a well nourished group of prepubertal children with CF. A BMD deficit appears to evolve during adolescence and becomes more marked in adults. Individuals with CF should optimise nutrition, partake in physical activity, and maximise lung health in order to optimise BMD. Further longitudinal studies are required to understand the evolution of reduced BMD in young people and adults with CF.

Abnormalities of calcium and vitamin D metabolism in cystic fibrosis (CF) are well documented. We tested the hypothesis that alterations in calcium metabolism are related to vitamin D deficiency, and that bone resorption is increased relative to accretion in patients with CF. Calcitropic hormones, electrolytes, osteocalcin (OC) and bone alkaline phosphatase (BAP), (markers of bone mineralisation), urinary deoxypyridinoline [total (t) Dpd, a marker of bone resorption] and lumbar spine bone mineral density (LS BMD), expressed as a z-score, were measured in 149 (81 M) CF and 141 (61 M) control children aged 5.3-10.99 years, adolescents aged 11-17.99 years and adults aged 18-55.9 years. Data were analysed by multiple regression to adjust for age. In patients, FEV(1)% predicted and CRP (as disease severity markers), genotype and pancreatic status (PS) were recorded. The distribution of PTH differed between groups ( P<0.0001), with CF levels both below and above the control range. 25OH vitamin D (25OHD) was not different in control and CF subjects ( P=0.06). Active hormonal vitamin D (1,25(OH)(2)D) was lower in the CF group ( P<0.0001), not explained by 25OHD or disease severity, as was serum magnesium ( P<0.0001). OC was decreased in CF adults ( P=0.004), and tDpd increased in CF adolescents ( P=0.003) and adults ( P=0.03). The ratio of OC to tDpd (a measure of bone coupling) was similar in CF and control children, but decreased in CF adolescents ( P=0.04) and adults ( P=0.02), suggesting decreased overall bone accrual in CF adolescents and uncoupling of bone balance in adults. 1,25(OH)2D was weakly correlated with OC in CF children ( r=0.43, P=0.01), and with tDpd in CF and control adolescents ( r=0.33, P=0.05 and r=0.36, P=0.02, respectively); thus there was limited evidence of association of calcitropic hormones, which had an abnormal pattern in all age groups, with bone turnover. There was no association between calcitropic hormones or bone turnover markers and LS BMD z-score. Despite vitamin D sufficiency, abnormalities of calcium metabolism and bone turnover markers were still apparent and bone accretion was decreased relative to resorption in the CF adolescent and adult groups. These changes were not fully explained by disease severity or genotype, but are consistent with reports of decreased BMD and unique bone histomorphometry in older subjects with CF.