Normal bone mineral density in cystic fibrosis

A Clinician’s guide to vitamin D supplementation for patients with cystic fibrosis

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Vitamin D deficiency is multifactorial in the cystic fibrosis population.

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Vitamin D deficiency can adversely affect multiple organ systems in the cystic fibrosis population.

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In the cystic fibrosis population in the United States, we aim to treat to serum 25-hydroxyvitamin D levels over 30 ng/ml.

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Cholecalciferol is used in preference to ergocalciferol.

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Daily or once weekly dosing regimens are chosen according to patient preference and compliance.

Vitamin D deficiency is common in the general population, and even more so in patients with cystic fibrosis. Deficiency is exacerbated in cystic fibrosis patients because of a myriad of causes including malabsorption, decreased fat mass, reduced 25-hydroxylation of vitamin D, reduced exposure to sunlight, decreased vitamin D binding protein, and exposure to drugs that increase catabolism. In turn, vitamin D deficiency can contribute to poor bone health. Additionally, it may contribute to pulmonary decline in the form of worsening pulmonary function, increased colonization with pathogens, and increased pulmonary exacerbation. Because vitamin D deficiency is correlated with negative clinical effects in multiple organ systems of patients with cystic fibrosis, it is important to screen for and treat deficiency in these patients. The Cystic Fibrosis Foundation has issued guidelines for the treatment of vitamin D deficiency, targeting serum levels of 25-hydroxyvitamin D of at least 30 ng/ml. The guidelines offer age-specific escalating dose regimens depending on serum vitamin D levels, with monitoring at 12- week intervals after changing therapy. They address the literature on alternative vitamin D sources, such as UV lamps, ideal formulations (cholecalciferol in preference to ergocalciferol), and optimal vehicles of administration. Despite these detailed recommendations, most centers are still unable to achieve in-target serum vitamin D levels for many of their patients. Future research examining ideal treatment regimens to achieve serum targets and maximize clinical effects are needed. Moreover, it is unknown whether vitamin D sufficiency will be easier to achieve on new triple therapy cystic fibrosis drug combinations, and how these drugs will contribute to vitamin D-related clinical outcomes.

Evaluation of bone metabolism in children with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) bone disease (CFBD) has attracted considerable recent interest from researchers, although several aspects of CFBD pathophysiology remain poorly understood. The objective of this research was to investigate CFBD in children with CF and its relation to clinical and bone metabolism markers.

METHODS

In a prospective observational study of 68 patients with CF and 63 healthy controls, we studied bone turnover biomarkers and bone mineral density (BMD). The biomarkers included osteocalcin, total-alkaline phosphatase, bone-alkaline phosphatase, N-terminal propeptide of type-1-procollagen, osteoprotegerin (OPG), interleukine-6, tumor necrosis factor alpha (TNF-α), type-1-collagen cross-linked C-telopeptide (CTX), parathormone (PTH), 25-vitamin D, 1,25-vitamin D, calcium and phosphorus. BMD was examined in lumbar spine, comparing two healthy Spanish populations. Two regression analyses were applied to any significant associations to evaluate predictors of BMD and of CF, expressed as odds ratios (OR) with 95% confidence intervals.

RESULTS

After adjusting for age, sex, and height Z-score, gains in BMD LS in children and adolescents (6-16 years) with CF were not less than in healthy reference population. Patients with CF showed significant associations with different bone turnover biomarkers. Age, gender, body mass index, PTH, CTX and OPG were significant predictors of BMD (R² = 0.866, p < 0,001). Moreover, we found that PTH (OR = 1.070; 95% CI 1.019-1.123), and TNFα (OR = 2.173; 95% CI 1.514-3.118) were significantly linked to CF, and calcium (OR = 0.115; 95% CI 0.025-0.524), 1,25-vitamin D (OR = 0.979; 95% CI 0.962 0.996) and OPG (OR = 0.189; 95% CI 0.073-0.489) were significant reduced.

CONCLUSION

A normal bone mineral density along with altered remodeling was found in CF patients with a normal nutritional status and without acute lung disease.

Pectoralis muscle area is associated with bone mineral density and lung function in lung transplant candidates

Loss of bone mineral density and skeletal muscle area are linked in lung transplant patients. This loss is greater in patients with restrictive compared with obstructive lung diseases.

INTRODUCTION

Sarcopenia and osteoporosis are associated with aging and chronic illnesses and may be linked in patients with advanced lung disease. Pectoralis muscle index (PMI) quantitated on computed tomography (CT) of the chest can be used to measure skeletal muscle mass. This study aimed to determine the relationship of PMI to clinical parameters including bone mineral density (BMD) in candidates for lung transplantation.

METHODS

A retrospective review of transplant candidates at a single center was performed. Demographic, anthropomorphic, and clinical data were recorded. Pectoralis muscle area (PMA) was determined on an axial slice from a chest CT. PMI was calculated as the PMA divided by height squared. BMD was obtained from routine dual-energy X-ray absorptiometry (DXA) scan.

RESULTS

In 226 included patients, mean PMI was 8.2 ± 3.0 cm²/m² in males and 6.1 ± 2.1 cm²/m² in females. Osteopenia was present in 44.4%, and 23.2% of patients had osteoporosis. Patients with obstructive lung disease had lower body mass index (22.0 ± 4.9 versus 27.9 ± 4.9 kg/m², p < 0.001), PMI (6.0 ± 2.3 versus 8.2 ± 2.8 cm²/m², p < 0.001), and BMD (- 2.3 ± 1.1 versus - 1.3 ± 1.1, p < 0.001) compared with patients with restrictive lung disease. PMI was a significant predictor of BMD (β = 0.16, p < 0.001).

CONCLUSION

The association between muscle area and BMD in lung transplant candidates suggests that similar mechanisms may underlie the development of both. Differences in PMI and BMD in patients with obstructive versus restrictive lung disease may result from differences in respiratory physiology or disease processes.

Gender differences in bronchiectasis: a real issue?

Gender differences in chronic respiratory disease, including cystic fibrosis and non-cystic fibrosis bronchiectasis are clinically apparent and of increasing importance. Differences in disease prevalence, severity and outcome are all described, however, the precise cause of the gender dichotomy and their associated underlying mechanisms have been poorly characterised. A lack of dedicated clinical and epidemiological research focused in this area has led to a paucity of data and therefore a lack of understanding of its key drivers. Diagnosis, disease pathogenesis and treatment response are all complex but important aspects of bronchiectasis with an evident gender bias. Broadening our understanding of the interplay between microbiology, host physiology and the environment in the context of chronic lung diseases, such as bronchiectasis, is critical to unravelling mechanisms driving the observed gender differences. In this review, epidemiological, biological and environmental evidence related to gender in bronchiectasis is summarised. This illustrates gender differences as a “real issue” with the objective of mapping out a future framework upon which a gender-tailored medical approach may be incorporated into the diagnosis, monitoring and treatment of bronchiectasis.

CF and non-CF bronchiectasis are complex multifactorial chronic pulmonary diseases demonstrating gender differences in their prevalence, severity and infections, some of which are attributable to sex hormoneshttp://ow.ly/beDf30jseK4

Bone mineral density is related to lung function outcomes in young people with cystic fibrosis-A retrospective study

INTRODUCTION

Improvements in the medical management of cystic fibrosis (CF) in recent years have resulted in increased prevalence of long-term sequelae of the condition, such as low bone mineral density (BMD) and hence an increased risk of fractures in later life. Aim To explore the interaction between BMD and lung function, nutrition, and genotype.

METHODS

This study was a retrospective audit of 202 children with CF from August 2000 to January 2016 to investigate associations between BMD Z-scores with clinical status, nutrition, and genetics using dual-energy absorptiometry X-ray data from the Royal Children's Hospital Melbourne, Australia.

RESULTS

Severity of both lung disease (P < 0.0001) and nutritional status (P < 0.05) was found to be strongly associated with BMD Z-scores.

CONCLUSIONS

This is the biggest study to date to provide further evidence that the severity of pulmonary disease is related to BMD in CF patients and therefore screening guidelines for bone health in children with CF should target individuals with the poorest clinical status.

Bone Mineral Density of Indian Children and Adolescents with Cystic Fibrosis

OBJECTIVE

To document bone mineral density of children and adolescents with cystic fibrosis.

DESIGN

Cross-sectional study.

SETTING

Tertiary-care center of Northern India, July 2012 to August 2015.

PARTICIPANTS

52 children aged 6-18 years with cystic fibrosis and 62 healthy controls of similar age and sex.

METHODS

Both patients and controls were stratified into two groups, as pre-pubertal and peri-/post-pubertal, and compared for whole body bone mineral density, measured using dual energy X-ray absorptiometry. Serum levels of calcium, phosphate, alkaline phosphatase, 25-hydroxyvitamin D and parathyroid hormone were measured in children with cystic fibrosis.

RESULTS

Compared with controls, the mean (SD) bone mineral density of children with cystic fibrosis was significantly lower in both the pre-pubertal (0.7 (0.1) g/cm2 vs 0.9 (0.1) g/cm2; P<0.001)) and peri-/post-pubertal groups (0.9 (0.1) g/cm2 vs 1.1 (0.1) g/cm2; P<0.001). Also, the mean (SD) bone mineral apparent density of pre-pubertal and peri-/post-pubertal cystic fibrosis patients was lower than the controls (P <0.001 and P= 0.01, respectively). Thirty-seven (71.2%) cystic fibrosis patients had serum 25-hydroxyvitamin D level below 15 ng/mL.

CONCLUSION

Bone mineral density of children with cystic fibrosis was significantly lower than controls; majority of them were vitamin-D deficient. Intervening at an early stage of the disease and providing optimal therapy involving simultaneous management of the several factors affecting bone mineral accretion may be beneficial in improving bone health of these patients.

Physiotherapy management of cystic fibrosis

For many years physiotherapy for cystic fibrosis (CF) was synonymous with a daily routine of postural drainage and percussion. Improved longevity and a desire for independence, together with a clearer understanding of the pathophysiology of the disease, has led to the development of many airway clearance techniques. The contribution of ‘chest’ physiotherapy remained unchallenged until recent times when lack of robust evidence and the presentation of asymptomic infants and adults led some physiotherapists to question this traditional approach. As survival increases into the fourth and fifth decade unique complications have evolved and physiotherapy management is challenged with nonrespiratory aspects of treatment. This review will consider the evidence for, and current practice of airway clearance, the value of exercise and the emerging problems of musculoskeletal complications and incontinence.

Cystic fibrosis-related bone disease in children: Examination of peripheral quantitative computed tomography (pQCT) data

BACKGROUND

The investigation of skeletal health data beyond dual X-ray absorptiometry (DXA) is limited in young individuals with CF. We assessed volumetric bone mineral densities (BMD), and bone and muscle parameters using peripheral quantitative computed tomography (pQCT) in individuals with CF and controls, 7.00-17.99 years.

METHODS

Peripheral QCT (XCT 3000, Stratec) measurements were made in 53 individuals with CF and 53 controls. Bone mineral content (BMC), total volumetric BMD (vBMD) and cross sectional area (CSA) of the bone were measured at the 4% and 66% sites of the non-dominant tibia and radius. Additionally, trabecular vBMD and bone strength index (BSIc) were measured at the 4% sites, and cortical vBMD, muscle CSA (mCSA) and strength strain index (SSI) were measured at the 66% sites.

RESULTS

Pre-pubertal males with CF had greater trabecular vBMD (p=0.01) and total vBMD (p=0.00) at 4% tibia, and greater total vBMD (p=0.02) at 4% radius. Pre-pubertal females with CF had greater total vBMD at 66% tibia (p=0.02) and radius (p=0.04), and cortical vBMD (p=0.04) at the radius. At puberty, the CF cohort had less BMC at 4% tibia (males, p=0.02; females, p=0.01), and smaller mCSA at 66% tibia (males, p=0.02; females, p=0.01). Pubertal CF females had a smaller bone CSA (p=0.01) at 4% tibia, and lower bone strength (SSI) at the tibia (p=0.00) and radius (p=0.05) sites.

CONCLUSIONS

Bone strength parameters were not compromised prior to puberty in this CF cohort. At puberty, the bone phenotype changed for this CF cohort, showing several deficits compared to the controls. However, bone strength was adapting to the mechanical demands of the muscle. Altered bone parameters and their implications for lowered bone strength with increased age may be greatly influenced by: the CF cohort remaining smaller for age and/or a reduced bone strain, secondary to reduced muscle force.

Osteoporoza w mukowiscydozie/ Osteoporosis in cystic fibrosis

Mukowiscydoza jest chorobą uwarunkowaną genetycznie spowodowaną nieprawidłowym działaniem transbłonowego regulatora mukowiscydozy. Choroba ta manifestuje się przede wszystkim w układzie oddechowym oraz pokarmowym. W przebiegu mukowiscydozy obserwuje się także zmiany w układzie kostno- stawowym, takie jak występowanie obniżonej gęstości kości, a w konsekwencji osteopenii i osteoporozy. Najczęściej wykorzystywanym badaniem diagnostycznym osteoporozy jest densytometria wykonywana średnio co 2 do 5 lat. Inne badania to oznaczenie poziomu witamin D i K, wapnia oraz markerow obrotu kostnego. W leczeniu osteoporozy wykorzystuje się farmakoterapię i fizjoterapię. Leczenie farmakologiczne to przede wszystkim suplementacja witaminami D i K oraz wapniem jak rownież stosowanie bifosfonianow, parathormonu lub terapia hormonem wzrostu. Farmakoterapia osteoporozy jest trudna ze względu na wzajemną interakcję lekow oraz niekorzystny wpływ niektorych lekow stosowanych w leczeniu mukowiscydozy np. steroidow na gęstość kości. Stosując leczenie farmakologiczne nie możemy zaniedbywać istotnego terapeutycznego działania jakim jest fizjoterapia. Terapia drog oddechowych, ćwiczenia ogolnousprawniające i zwiększona aktywność fizyczna w codziennym życiu są zasadniczymi elementami kompleksowego postępowania leczniczego. Wpływają na długotrwałą poprawę wynikow leczenia oraz na wydłużenie i jakość życia pacjentow. Konsekwencje mukowiscydozy, takie jak bole mięśniowo-szkieletowe, wady postawy czy cukrzyca wymagają wdrożenia odpowiedniej strategii postępowania fizjoterapeutycznego.

Cystic fibrosis-related bone disease explored using a four step algorithm

BACKGROUND

A suboptimal bone accrual in young individuals with cystic fibrosis (CF) may be related to the development of a premature CF-related bone disease. Dual energy X-ray absorptiometry (DXA) is the mainstream measure of bone health; however, the influence of body size and lean tissue mass (LTM) on bone data is poorly interpreted.

METHODS

Total body dual-energy X-ray absorptiometry (DXA) measurements of bone mineral content (BMC) and LTM in 53 individuals with CF (7.00-17.99years) were compared to 53 sex-matched controls. BMC, height, and LTM in relation to height and BMC Z-scores were calculated and used in a 4-step algorithm.

RESULTS

Pubertal females with CF had less total body BMC for age (p=0.02); pre-pubertal males (p=0.05) and pubertal females with CF (p=0.03) were shorter; and pubertal females with CF showed less total body BMC for LTM (p=0.01).

CONCLUSIONS

The algorithm showed the following: (1) prior to puberty lowered total body BMC was primarily due to short stature, (2) LTM was appropriate for body size, and (3) pubertal females with CF had significantly less total body BMC for their LTM. Longer controlled trials are needed to clinically interpret CF-related bone disease using DXA derived data that considers patient size and body composition.

Bone mineral density, pulmonary function, chronological age, and age at diagnosis in children and adolescents with cystic fibrosis

OBJECTIVE

To assess bone mineral density in patients with cystic fibrosis (CF), and to correlate it with possible intervening variables.

METHODS

Children and adolescents diagnosed with CF, aged 6 to 18 years, followed at the outpatient clinic were included in the study. First, demographic data were collected and, subsequently, patients underwent a spirometric test. All patients answered the Cystic Fibrosis Quality of Life Questionnaire (CFQ) and underwent the six-minute walk test (6MWT) and bone densitometry (DXA).

RESULTS

A total of 25 CF patients were included, of which 56% were males. The mean age was 12.3±3.4 years; mean height was 149.2±14.4 cm; and mean weight was 44.4±13.9 kg. Most results on pulmonary function and bone mineral density (BMD) were within normal limits. The mean forced expiratory volume in one second (FEV) was 92.5±23.6 (% of predicted), mean forced vital capacity (FVC) was 104.4±21.3 (% of predicted), and1 mean BMD z-score was 0.1±1.0. BMD was moderately correlated with FEV (r = 0.43, p = 0.03) and FVC (r = 0.57, p = 0.003). Regarding chronological age and age at diagnosis, a moderate and inverse correlation was also found (r = -0.55, p = 0.004; r = -0.57, p = 0.003, respectively). However, no significant correlations were found with the data from CFQ, 6MWT, and body mass index.

CONCLUSION

Most patients had BMD within normal limits and presented a positive correlation with pulmonary function, as well as a negative correlation with chronological age and age at diagnosis.

A roadmap to the brittle bones of cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive disorder which despite advances in medical care continues to be a life-limiting and often fatal disease. With increase in life expectancy of the CF population, bone disease has emerged as a common complication. Unlike the osteoporosis seen in postmenopausal population, bone disease in CF begins at a young age and is associated with significant morbidity due to fractures, kyphosis, increased pain, and decreased lung function. The maintenance of bone health is essential for the CF population during their lives to prevent pain and fractures but also as they approach lung transplantation since severe bone disease can lead to exclusion from lung transplantation. Early recognition, prevention, and treatment are key to maintaining optimal bone health in CF patients and often require a multidisciplinary approach. This article will review the pathophysiology, current clinical practice guidelines, and potential future therapies for treating CF-related bone disease.

Bone mineral and body composition alterations in paediatric cystic fibrosis patients

BACKGROUND

With the increased life span of cystic fibrosis (CF) patients, CF-related bone diseases could have an increased prevalence and morbidity in this group. In children, previous retrospective and prospective studies have yielded conflicting results on bone mineralization.

OBJECTIVE

To monitor body composition and bone mineral status of children with CF.

MATERIALS AND METHODS

We reviewed the dual-energy X-ray absorptiometry (DXA) data of 161 children with CF (age 10 +/- 4.8 years). Total body bone mineral content (BMCt), total lean tissue mass (LTMt) and total fat mass (FMt) were measured and compared to expected data calculated from ideal weight for height (Wi; e.g. BMCti, LTMti, FMti). The bt (BMCt/BMCti), lt (LTMt/LTMti) and ft (FMt/FMti) ratios were used as quantitative variables.

RESULTS

Low bt ratio was found at all ages (mean bt ratio 0.94 +/- 0.10; P < 0.001), even in children <6 years of age. However, the children's BMCt was satisfactorily adapted to their weight. lt and ft ratios were not constant across age groups. Children <10 years had 8% reduction of their lt ratio, maintaining normal levels thereafter. The opposite trend was found for ft ratio. Poor clinical, nutritional status and vitamin A levels were correlated with bt and lt ratios.

CONCLUSION

Our results indicate that children with CF could have early alterations in their bone status and that lt and ft ratios did not have constant values across ages. Interpreting DXA data using this approach is suitable in children with CF.

'Old' bones in young bodies: the tale of cystic fibrosis

PURPOSE OF REVIEW

Cystic fibrosis (CF) is the most common genetic disease within the white population and leads to premature respiratory failure. Approximately, 60 000 individuals are currently living with CF in North America and Europe, almost half of whom are adults.

RECENT FINDINGS

Dozens of studies across the globe indicate that CF adults have low bone density and increased rates of fractures. This genesis of the problem appears to be in late childhood to adolescence.

SUMMARY

Prevention and treatment of CF-related bone disease must address the myriad risk factors (decreased absorption of fat-soluble vitamins due to pancreatic insufficiency, altered sex hormone production, chronic lung infection with increased serum levels of proinflammatory, bone-active cytokines, malnutrition and low body weight, physical inactivity and glucocorticoid therapy) for poor bone health. This review will address the pathogenesis, diagnosis and treatment of bone disease in CF. It will also discuss best practice guidelines for optimizing bone health in patients with CF.

Bone and body composition analyzed by Dual-energy X-ray Absorptiometry (DXA) in clinical and nutritional evaluation of young patients with Cystic Fibrosis: a cross-sectional study

Background

the improved general therapy has led to reduced morbidity and mortality from Cystic Fibrosis (CF), and bone status may have a potentially greater clinical impact.

We investigated the correlation between the severity of the clinical condition, bone status and body composition parameters, in a group of children and young adults with CF.

Methods

we measured lumbar spine bone density and total body composition by dual energy x-ray absorptiometry (DXA) in 82 consecutive CF patients (42 males; median age: 13 years - range: 5-30). Eighty-two healthy subjects, matched for age, gender, height and pubertal stage were recruited as a control group.

Results

37 patients (45.1%) had a normal bone mineral density (BMD). A BMD reduction were observed in 45 (54.8%) patients. Lumbar spine Z score was positively related to Body Mass Index (BMI) and a higher Shwachman-Kulczycki score, and negatively related to Crispin-Norman score. A positive and significant correlation was also observed between lumbar spine Z score and total body composition.

Conclusion

a significant BMD reduction can be present early in CF children and adolescents. A careful follow up of bone status is required starting in childhood.

Update on cystic fibrosis-related bone disease: a special focus on children

A high prevalence of low bone mineralization is documented in adult patients with cystic fibrosis (CF). Osteopenia is present in up to 85% of adult patients and osteoporosis in 10% to 34%. In children, study results are discordant probably because of comparisons to different control populations and corrections for bone size in growing children. Malnutrition, inflammation, vitamin D and vitamin K deficiency, altered sex hormone production, glucocorticoid therapy, and physical inactivity are well known risk factors for poor bone health. Puberty is a critical period for bone mineralization and requires a careful follow-up to achieve optimal bone peak mass. Strategies for optimizing bone health, such as monitoring bone mineral density (BMD) and providing preventive care are necessary from childhood through adolescence to minimize CF-related bone disease in adult CF patients.

Well-nourished cystic fibrosis patients have normal mineral density, but reduced cortical thickness at the forearm

Our goal was to assess mineral density and geometry of the cortex at the level of the forearm in adolescents and young adults with cystic fibrosis, using peripheral quantitative computed tomography. We found that density was normal, but cortical thickness significantly reduced, as well in males as in females.

INTRODUCTION

Our goal was to measure bone mineral density as a volumetric density, as well as total cross-sectional area, cortical area and cortical thickness, using peripheral quantitative computed tomography (pQCT) at the forearm in adolescents and young adults with cystic fibrosis. We evaluated relationships between forearm bone measurements and body composition assessed using dual energy X-ray absorptiometry (DXA).

METHODS

An XCT 2000 pQCT (Stratec, Pforzheim, Germany) and a QDR 4500 A-upgraded to Discovery DXA device (Hologic, Waltham, MA, USA) were used.

RESULTS

Forty-eight patients (31 males,17 females, mean+/-SD 20+/5 years) were studied. Anthropometric features were: height 169+/- 10 cm, SDS 0.05+/-0.12, body mass index 19.8+/- 2.5 kg/m(2), SDS -0.56+/-0.14. Bone mineral density and total cross-sectional area of the forearm and body composition were normal, whereas cortical thickness was significantly reduced in males (mean Z-score - 1.22, p < 0.05), and in females (mean Z-score - 1.61, p < 0.05). Total body lean mass correlated more strongly with cortical thickness (r = 0.72, p < 0.001) than with total bone mineral density at the proximal radius (r = 0.39, p < 0.05).

CONCLUSIONS

Adolescents and young adults with cystic fibrosis, presenting with only a slight degree of underweight, have at the radius a preserved bone mineral density but a reduced cortical thickness.

Bone mass density and associated factors in cystic fibrosis patients of young age

AIM

To investigate bone mineral status in young cystic fibrosis (CF) patients and determine risk factors related with the development of low bone mineral density (BMD).

METHODS

We determined, in 81 patients with CF, 4 to 23-years-old, BMD as well as factors, which are thought to play a role in the development of reduced BMD.

RESULTS

BMD Z-score was between -1 and -2.5 in 27 (33%) and lower than -2.5 in 9 (11%). Means of BMD Z-score were lower than the expected value of 0 in the three groups of children, adolescents and young adults (P = 0.004; P < 0.001; P = 0.048, respectively), but they did not differ among them (P = 0.114). Analysis showed that Shwachman-Kulczycki (SK) score, gender and levels of 25-hydroxy-vitamin D were significant predictors of BMD Z-score. Significant also was the interaction between gender and SK score.

CONCLUSIONS

Our study supports that BMD may be reduced from a young age in CF patients though this needs to be confirmed using true volumetric measures of BMD. This defect is related to disease severity with males being more vulnerable. Inefficient levels of vitamin D are very common and contribute significantly to impaired bone health. The latter finding underlines the need for higher supplementation doses.

Pediatric dual-energy X-ray absorptiometry: technique, interpretation, and clinical applications

This article reviews the dual-energy x-ray absorptiometry (DXA) technique, its interpretation, and clinical applications with emphasis on the considerations unique to pediatrics. Specifically, the use of DXA in children requires the radiologist to be a "clinical pathologist," monitoring the technical aspects of the DXA acquisition, a "statistician" knowledgeable in the concepts of Z-scores and least significant changes, and a "bone specialist," aware of the DXA findings in a large number of clinical diseases, providing the referring clinician with a meaningful context for the numeric result obtained with DXA.

Docosahexaenoic acid is associated with endosteal circumference in long bones in young males with cystic fibrosis

In children, but not adults with cystic fibrosis (CF), associations between essential fatty acids (FA) and bone mass have been reported. Low bone mineral density (BMD) is common in these patients. Previously we found a normal annual increase of BMD, suggesting a potential for attaining normal bone mass. The aim of the present study was to investigate phospholipid FA pattern in relation to bone in young adult men with CF compared with healthy controls. Fourteen male patients with CF were compared with forty-two healthy controls, using dual-energy X-ray absorptiometry for total bone, lumbar spine and femur and peripheral quantitative computerised tomography for tibia and radius. A questionnaire concerning physical activity and nutrition was used. FA in serum phospholipids were measured using capillary GLC. CF patients did not differ in physical activity and anthropometry from controls. There were no differences in bone parameters between the two groups, but patients chronically colonised withPseudomonas aeruginosahad lower BMD than non-colonised patients. The trabecular BMD in the tibia differed between patients and controls, but not after adjustment for age and weight. The endosteal circumference of the radius was significantly associated with serum phospholipid concentration of DHA and inversely with then-6:n-3 FA ratio in CF patients but not in controls. The present study showed that young physically active adult males with classical CF obtained similar bone mass as controls, although influenced by pseudomonas colonisation. The association between DHA and long bone endosteal circumference suggested a later peak bone mass in those with CF compared with controls.

Pediatric DXA: clinical applications

Normal bone mineral accrual requires adequate dietary intake of calcium, vitamin D and other nutrients; hepatic and renal activation of vitamin D; normal hormone levels (thyroid, parathyroid, reproductive and growth hormones); and neuromuscular functioning with sufficient stress upon the skeleton to induce bone deposition. The presence of genetic or acquired diseases and the therapies that are used to treat them can also impact bone health. Since the introduction of clinical DXA in pediatrics in the early 1990s, there has been considerable investigation into the causes of low bone mineral density (BMD) in children. Pediatricians have also become aware of the role adequate bone mass accrual in childhood has in preventing osteoporotic fractures in late adulthood. Additionally, the availability of medications to improve BMD has increased with the development of bisphosphonates. These factors have led to the increased utilization of DXA in pediatrics. This review summarizes much of the previous research regarding BMD in children and is meant to assist radiologists and clinicians with DXA utilization and interpretation.

Serum phospholipid fatty acid pattern is associated with bone mineral density in children, but not adults, with cystic fibrosis

Essential fatty acids (EFA) have proved to be important for normal bone mineral density (BMD) and bone growth in animal studies. Patients with cystic fibrosis often have low serum EFA levels, and low BMD has also been reported in patients with normal anthropometry. The aim of the present study was to analyse if BMD during a 2-year period was related to fatty acid status in patients with cystic fibrosis. Fifty-four patients, aged 6–33 years, were studied prospectively. BMD was measured with dual X-ray absorptiometry, and fatty acid concentrations in serum phospholipids were determined with capillary GLC. The cystic fibrosis patients showed low linoleic acid concentration and a high arachidonic acid (AA):DHA ratio in serum. The high eicosatrienoic acid:AA ratio, an indicator of EFA deficiency, increased further over 2 years, as did the total concentration of saturated fatty acids. In the adults there were no significant changes in fatty acids during the study. In the children, positive correlations were found between palmitic acid and bone mineral content in the lumbar spine and femoral neck. The lumbar spine BMDZscore correlated negatively with the AA:DHA ratio. No correlation was seen in adults except for a positive correlation between EFA deficiency index and the areas of lumbar spine and femoral neck. The present results imply that fatty-acid status influenced BMD in cystic fibrosis children, but not in adults, indicating that fatty-acid status wouldbe important for bone growth.

Low bone mineral density in young children with cystic fibrosis

RATIONALE

Low bone mineral density (BMD) is a frequent problem for adult patients with cystic fibrosis (CF). Only limited information is available for young patients.

OBJECTIVES

The aim of this study was to evaluate BMD of children with CF younger than 6 years.

METHODS

BMD was measured at the lumbar spine (LS) after adjustment for height, sex, and pubertal status in 25 children with CF younger than 6 years, 53 prepubertal children aged 6 to 10 years, and 36 adolescents aged 11 to 18 years. Nutritional status, body composition, pulmonary disease severity, corticosteroid usage, dietary calcium, caloric intake, and vitamin D status were evaluated as potential correlates of BMD.

MEASUREMENTS AND MAIN RESULTS

The mean LS z score in the youngest group was significantly lower than normal (-0.96; SEM, 0.3). It did not differ significantly from that of children aged 6 to 10 years (-0.91; SEM, 0.2) or adolescents (-1.4; SEM, 0.2). LS z score was positively correlated with fat-free mass in multiple regression analysis. LS z score was less than -1 in 34% of the patients with mild pulmonary disease and normal nutritional status.

CONCLUSIONS

These data suggest that the origin of CF bone disease in early childhood may be independent of nutritional status or disease severity.

Analysis of bone mineral density and turnover in patients with cystic fibrosis: associations between the IGF system and inflammatory cytokines

BACKGROUND

Cystic fibrosis (CF) patients present an increased risk of osteoporosis, and increased fracture rate. Several factors have been identified as modulators of bone metabolism and bone mineral density (BMD).

AIMS

To evaluate BMD and serum markers of bone turnover and establish their relationships with serum concentrations of interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF)-alpha, IGF-I, IGF-II, IGF binding protein (IGFBP)-2, IGFBP-3, and parathyroid hormone (PTH) in young adult CF patients.

METHODS

Seventeen young adult CF patients (4 M, 13 F; mean age: 26.6 +/- 1.1 years) were enrolled in the study and analysed as a whole and as two subgroups according to the Shwachman-Kulczycki score. BMD was assessed at the lumbar spine (L1-L4) by dual energy X-ray absorptiometry (DXA Hologic QDR 2000). Bone turnover was assessed by measuring serum levels of osteocalcin (OC) and serum carboxyterminal propeptide of type I collagen (PICP) as markers of bone formation, and serum cross-linked carboxyterminal telopeptide of type I collagen (ICTP) as a marker of bone resorption. Serum IGFs, IGFBPs, and cytokines were assayed using special commercial kits. Daily calcium intake and weekly physical activity were estimated by questionnaires. Forced expiratory volume in one second was used to assess pulmonary function.

RESULTS

Lumbar BMD was normal, although there was a tendency to be lower in the patients with a lower clinical score. Both OC and PICP were increased, whereas ICTP was normal. Lumbar BMD was positively correlated with pulmonary function. IL-6 and C-reactive protein (markers of inflammation) were inversely correlated with PICP. Serum ICTP levels were correlated with serum IGF-I levels. No significant relationship was detected among lumbar BMD, markers of bone turnover and PTH, IGF-I, IGF-II, IGFBP-2, IGFBP-3, TNF-alpha, IL-1beta, and body mass index Z-score.

CONCLUSIONS

Bone turnover is abnormal in CF patients. Young adult CF patients with satisfying clinical status and nutritional conditions have normal BMD and increased serum OC and PICP levels.

Calcium acquisition rates do not support age-appropriate gains in total body bone mineral content in prepuberty and late puberty in girls with cystic fibrosis

Few longitudinal data are available characterizing bone development in adolescents with cystic fibrosis (CF) although this is a critical time for bone mineralization. Dual energy X-ray absorptiometry (DXA) scans were obtained at 1- to 4-year intervals in 18 prepubertal and pubertal girls (age 7-18 years) with CF to determine calcium (Ca) accretion rates and changes (Delta) in total body bone mineral content (TBBMC) and lumbar spine bone mineral density (LS BMD) Z-scores. Daily Ca acquisition rates were calculated assuming TBBMC was composed of 32.2% Ca. Bone Ca accretion averaged 82 mg/day (2.05 mmol/day) [(range:-38 to +197 mg/day (-0.95 to 4.9 mmol/day)] on approximately 1,200 mg/day (30 mmol/day) Ca intakes. Estimated mean peak Ca accretion was 160 mg/day (4 mmol/day) at age 13 years; losses of bone Ca occurred in late puberty. Gains in insulin-like growth factor 1 (IGF-1) predicted Ca accretion (p<0.06). Body mass index (BMI) Z-score predicted LS BMD and TBBMC Z-score cross-sectionally but did not predict DeltaTBBMC Z-score. Changes in TBBMC Z-score paralleled Ca accretion rates with age. Bone Ca accretion in girls with CF fell below rates in healthy girls during prepuberty and late puberty despite Ca intakes approaching recommendations. IGF-1 and BMI Z-scores may identify children with CF at risk of compromised bone accretion, and more data are required to elucidate roles of lung function and glucocorticoid use in compromised bone health.

Controlled longitudinal study of bone mass accrual in children and adolescents with cystic fibrosis

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.

Mild to moderate cystic fibrosis is not associated with increased fracture risk in children and adolescents

OBJECTIVES

To determine whether children and adolescents with cystic fibrosis (CF), pancreatic insufficiency (PI), and mild-to-moderate lung disease have an increased risk of fracture compared with concurrent healthy control subjects.

STUDY DESIGN

A lifetime fracture history questionnaire was administered to 186 subjects (ages 6 to 25 years) with CF, PI and mild-to-moderate lung disease and 427 healthy white control subjects (ages 4 to 25 years).

RESULTS

A fracture was reported by 24% of subjects with CF and 23% of healthy control subjects. Average age of first fracture was similar between the groups (8.3 years for subjects and 8.8 years for controls). The radius/ulna was the most common fracture site in both groups. Risk of fracture, adjusted for sex and age, was not greater in the CF group compared with the control group (hazard ratio: 0.96, 95% CI: 0.68, 1.30, P = .82).

CONCLUSION

Children and adolescents with CF, PI, and mild-to-moderate lung disease were not at an increased risk of fracture.

Pubertal development and its influences on bone mineral density in Australian children and adolescents with cystic fibrosis

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.

Growth hormone improves bone mineral content in children with cystic fibrosis

AIM

Osteoporosis and osteopenia have been reported as common complications of cystic fibrosis (CF); however, little is known about accrual of bone mineral in CF. The goal of our study was to measure bone mineral content (BMC) in non-acutely-ill, but poorly growing children with CF, and to determine the relationship between height, lean body mass and BMC. Our second aim was to evaluate the effect of one year of treatment with human recombinant growth hormone (GH) on total body BMC.

METHODS

We measured total-body BMC using dual energy X-ray absorptiometry in 32 poorly growing (height < or =10th percentile for age) prepubertal Caucasian children (ages 7 years 6 months-12 years 9 months, 17 M and 15, F) with CF. BMC and lean tissue mass (LTM) were measured at baseline, at 6 months and one year. One half of the children were randomly assigned to receive treatment with GH (GHTX). Results were compared to reference data maintained for healthy children matched for age and ethnicity. Sex steroid and IGF-I levels were also measured.

RESULTS

Children with CF exhibited lower total body BMC and LTM than age-, ethnicity- and gender-matched controls. This was still apparent when the data were matched for height and bone age. BMC correlated with height, LTM, and IGF-I levels. Although at baseline the groups were similar, the GHTX group demonstrated significantly greater increase in height, weight, LTM and BMC than the NonTX group. These differences remained despite correction for increase in height

CONCLUSION

Our study is the first to evaluate BMC in children with CF and suggests that poor accumulation of bone mineral is a problem. We have further demonstrated that GH treatment improves accumulation of bone mineral.

Growth hormone treatment enhances nutrition and growth in children with cystic fibrosis receiving enteral nutrition

OBJECTIVES

Impaired longitudinal growth and poor weight gain are common and important problems in children with cystic fibrosis. This study evaluates the hypothesis that adjunctive growth hormone (GH) therapy augments the growth response to nutritional supplementation.

STUDY DESIGN

We recruited 18 prepubertal children who received enteral nutritional supplementation for at least 2 years before enrollment. Nine were randomly assigned to receive no GH for 1 year, followed by 1 year of GH. Nine were randomly assigned to receive 1 year of GH followed by a second year of GH. Measurements included height, weight, pulmonary function, lean tissue mass, bone mineral content, hospitalizations, outpatient antibiotic use, and caloric intake.

RESULTS

Growth hormone resulted in significant improvement in height, weight, bone mineral content, lean tissue mass, and number of hospitalizations. Pulmonary function was similar at baseline. Absolute forced vital capacity and forced expiratory volume in 1 minute significantly increased in GH treatment, but there was no significant change in percent predicted pulmonary function. Caloric intake was similar in both groups during both years.

CONCLUSIONS

These results suggest that GH is a useful for enhancing growth in children with cystic fibrosis receiving enteral nutritional supplementation.

Musculoskeletal and neuromuscular interventions: a physical approach to cystic fibrosis

Children with CF are living longer than ever before, and thus issues pertaining to quality of life rather than just longevity of life need to be addressed by the entire healthcare team. This article addressed the issues pertaining to the external support of the dysfunctional internal organs: the secondary musculoskeletal (postural) and neuromuscular control deficits that occur to the maturing child with CF. The research pointed towards starting PT interventions for these deficits during the pre-pubescent phase when postural deficits were just emerging, but a suggestion was also made to explore whether these deficits can be even more effectively monitored and treated at an earlier age. The dual relationship between the muscles used to meet the increased respiratory demands of CF and the normal postural demands of physical activities was described through a model based on a soda-pop can and pressure support. A pre-pubescent child with a typical progression of CF was presented as a case report to illustrate how a PT programme that was focused on postural deficits could be implemented and what type of outcomes might be possible. The child made significant changes within a relatively short time frame of 4 months, proposing that the musculoskeletal and neuromuscular systems may play a significant role in the medical and physical long-term outcomes of CF. For that reason, the physical as well as medical needs of the patient should be incorporated into a comprehensive multi-system approach to the disease across the lifespan.

Treatment of bone disease in cystic fibrosis

PURPOSE OF REVIEW

As individuals with cystic fibrosis (CF) have experienced marked improvements in longevity over the last three decades, bone disease has emerged as a new problem. Bone disease in CF has not been previously reviewed in this journal. Therefore, this review will give a brief overview of bone disease in CF and then concentrate on treatment options.

RECENT FINDINGS

In some series, as many as three fourths of adults with CF have low bone density. Decreased absorption of fat-soluble vitamins due to pancreatic insufficiency, altered sex hormone production, chronic inflammation, physical inactivity, and glucocorticoid treatment are some of the factors that contribute to this problem. Vitamin D depletion most likely contributes to bone disease, but identifying the safest and most efficacious vitamin D supplementation has yet to be resolved. Calcium and vitamin K supplementations are important if the diet contains less than the recommended amounts. Treatment of delayed puberty and adult hypogonadism with hormone replacement is recommended to achieve peak bone mass and maintain bone density. Bisphosphonates, including pamidronate and alendronate, are beneficial in improving bone mineral density before and after transplantation in CF adults. Bisphosphonates have not been studied in CF children.

SUMMARY

Although much progress has been made in our understanding of the pathogenesis, natural history, and clinical manifestations of bone disease in CF, treatment options are still evolving. More attention to nutrition, in terms of the maintenance of lean body mass and vitamin D and calcium supplementation, is likely to decrease bone complications. Bisphosphonates can be of value in CF adults with low bone density. Several clinical trials are under way to help optimize the treatment of CF bone disease.

Severe osteopenia in CFTR-null mice

Osteoporosis is a common complication in cystic fibrosis (CF) patients. In this study, we performed a histomorphometric analysis of the bones of a mouse genetic model of human CF in which both copies of the cystic fibrosis transmembrane conductance regulator (CFTR) gene are inactivated. We find that, even in the absence of obvious nutritional and therapeutic differences, the CFTR mutation is associated with severe osteopenia. Bone mineral density (BMD) of total body and of individual bones is significantly diminished. CFTR mutants display a striking significant (50%) reduction of cortical bone width and thinner trabeculae. Analysis of dynamic parameters indicates a significant reduction of bone formation and a concomitant strong increase in bone resorption. Active osteoclasts where found mostly associated with cortical bone. Our data support the concept that CF-associated osteoporosis is part of the syndromic symptoms associated with the CFTR mutation.

Effect of oral bisphosphonates on bone mineral density and body composition in adult patients with cystic fibrosis: a pilot study

BACKGROUND

Approximately two thirds of adult patients with cystic fibrosis have reduced bone mineral density and up to one quarter have osteoporosis at one or more sites. Any bone mineral deficits are likely to be exacerbated in patients following lung transplantation by their immunosuppressive regimen. Vertebral collapse and rib fractures will impair the ability to cough and the efficacy of physiotherapy treatments.

METHODS

Patients attending the Leeds Regional Adult Cystic Fibrosis Unit with either osteopenia or osteoporosis on dual energy x ray absorptiometry (DXA) scanning were offered treatment with oral bisphosphonates after exclusion of abnormal vitamin D, calcium, or phosphate levels, abnormal thyroid function, or hypogonadism. Those declining treatment or patients with a normal initial DXA scan formed the control group. A second DXA scan was performed after a mean of 2.4 years in the treatment group and 2.9 years in the non-treatment group. Patients in the active group were asked to complete a short questionnaire detailing their adherence to treatment.

RESULTS

The medians of the differences in annual changes in bone parameters between treatment and control groups showed significant differences in bone mineralisation in favour of the treatment group at the lumbar spine (L2-L4), the femoral neck, and for total body measurements. There were no significant differences in weight, height, or body composition in either patient group. Most treated patients stated that they adhered to treatment most of the time.

CONCLUSION

Treatment with oral bisphosphonates may improve bone mineralisation in adult patients with cystic fibrosis. The results of this pilot study need to be further explored in a randomised controlled trial.

Normal annual increase of bone mineral density during two years in patients with cystic fibrosis

OBJECTIVES

To determine prospectively for 2 years the change in bone mineral density (BMD) in patients with cystic fibrosis (CF) and to correlate clinical data and routine biochemical parameters of bone metabolism and infection with BMD.

METHODS

Fifty-four patients with CF, aged 6 to 33 years, were included. BMD was measured using dual-energy x-ray absorptiometry in lumbar spine (LS) and femoral neck (FN). Anthropometric data and biochemical markers of bone metabolism and infection were measured. The number of intravenous antibiotic courses per year (ivAC) and pulmonary function were assessed.

RESULTS

The patients had normal anthropometric data and normal growth, but 36% and 33% of the patients had BMD z score <-1 standard deviation in LS and in FN, respectively. Nevertheless, BMD increased at a normal rate during the 2 years and was correlated to weight and lung function. Intact parathyroid hormone was positively correlated with the increase of BMD in both LS and FN during childhood. Blood sedimentation rate, serum concentration of immunoglobulin G, and ivAC were negatively correlated with BMD in FN. Patients with 2 more severe CF transmembrane conductance regulator mutations had significantly lower BMD in FN than other genetic combinations.

CONCLUSION

The study suggests that low BMD in CF is multifactorial and depends on infection and nutritional parameters. Differences in BMD of LS and FN suggested higher susceptibility to infection in FN at all ages. Longitudinal studies starting early before bacterial colonization would be valuable to determine the relative role of infection in the development of BMD in CF.

Bone mineral density and bone acquisition in children and young adults with cystic fibrosis: a follow-up study

OBJECTIVE

To investigate bone mineral density and bone homeostasis in cystic fibrosis (CF) and to assess changes in a 2-year period.

METHODS

Thirty-eight patients with clinically stable CF (11 children, 16 adolescents, 11 young adults) were enrolled. No patient was treated with corticosteroids before or during the study. Weight and height Z scores and bone mineral density (BMD) Z-score at the femoral neck and the lumbar spine were recorded at the beginning of the study and after 2 years. Osteocalcin and cross-link excretion, both measurements of bone turnover were also measured. Correlations between BMD, bone turnover parameters, disease severity, pubertal stage, and nutritional state were calculated. The maternal BMD was also determined and related to that of the child.

RESULTS

Height and weight Z scores were normal in children and below normal in adolescents. Puberty was delayed in most patients. Bone age was lower than chronological age in adolescents. Lumbar spine and femoral neck BMD Z scores were below normal in each age group. Disease severity determined by Schwachman score correlated with lumbar BMD (r = 0.45, P < 0.02). BMD Z scores did not change during 2 year follow-up. Maternal and patient lumbar and femoral BMD correlated significantly (r = 0.51, P < 0.01, and r = 0.54, P < 0.01, respectively).

CONCLUSIONS

Bone deficit is present in patients with CF who have never received steroid treatment. Delay of puberty, chronic inflammation, or genetic susceptibility might be responsible for this phenomenon which was found in patients who had never received steroids and who were in relatively good clinical state.

Bone mineral density in Australian children, adolescents and adults with cystic fibrosis: a controlled cross sectional study

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.

Management of Osteoporosis in Adults with Cystic Fibrosis

Cystic fibrosis (CF) is the most common genetic disease that causes respiratory failure within the Caucasian population. The life span of patients with CF has gradually increased from a median of 2 years of age to >30 years. Concurrent with this increased lifespan, a variety of other nutritional, endocrine and bone issues have been recognised. Decreased absorption of fat-soluble vitamins (D and K in particular) because of pancreatic insufficiency, altered sex hormone production, chronic inflammation, a lack of physical activity, glucocorticoid treatment and an intrinsic hyper-resorptive bone physiology are some of the factors that contribute to the prominence of bone disease within the CF population. In some series, three-quarters of adult patients with CF have osteopenia or osteoporosis. Lung transplantation is one viable treatment for patients with end-stage CF, which requires a lifetime of antirejection medication. Immunosuppressant therapies have a detrimental effect on bone mineral density (BMD). To combat the multifactorial nature of CF-related bone disease, advances in nutritional and vitamin supplementation, and anti-resorptive and anabolic therapies have evolved. Chronic vitamin D depletion contributes to bone disease in the CF population. The isoform of vitamin D that is the best and safest supplement, with the lowest cost, has yet to be identified. However, it is clear that many patients with CF who receive the standard of care (i.e. two daily combination vitamin A, D, E and K tablets [ADEKs]) may still be vitamin D-deficient. More aggressive supplementation needs to be individualised, with close monitoring of serum 25-hydroxyvitamin D levels. Similarly, routine calcium supplementation may be important, and evidence is accumulating that vitamin K also plays an important role in maximising and maintaining BMD. Early recognition and treatment of delayed puberty in adolescents and hypogonadism in adults with hormone replacement therapy is recommended to maintain BMD in patients with CF. Bisphosphonates, including pamidronic acid, etidronic acid and alendronic acid, reduce bone resorption by inhibiting the recruitment and function of osteoclasts. Pamidronic acid is beneficial in improving BMD in CF patients before and after transplantation. Bisphosphonate therapy and minimisation of glucocorticoid dosage have been shown to be efficacious in glucocorticoid-induced osteoporosis. Teriparatide is the first US FDA-approved anabolic growth agent for bone, and has been shown to increase BMD and decrease fracture incidence in postmenopausal women. Teriparatide may offer a new avenue for treating bone disease in CF since many patients may have poor bone formation as well as accelerated bone breakdown. Numerous clinical trials are underway to optimise treatment of CF osteoporosis.