Osteoporosis in patients with cystic fibrosis

Web-Based Survey Piloting Process as a Model for Developing and Testing Past Contraceptive Use and Pregnancy History: Cystic Fibrosis Case Study

BACKGROUND

Individuals with complex, chronic diseases are now living longer, making reproductive health an important topic to address in the health care setting. Self-respondent surveys are a feasible way to collect past contraceptive use and pregnancy history to assess contraceptive safety and effectiveness. Because sensitive topics, such as contraception and pregnancy outcomes, can vary across social groups or cultures, piloting questions and evaluating survey administration procedures in the target population are necessary for precise and reliable responses before wide distribution.

OBJECTIVE

This study aimed to develop a precise and reliable survey instrument and related procedures among individuals with cystic fibrosis regarding contraceptive use and obstetrical history.

METHODS

We piloted and tested web-based questions related to contraceptive use and pregnancy history among 50 participants with and those without cystic fibrosis aged 18 to 45 years using a 3-tier process. Findings from each tier informed changes to the questionnaire before testing in the subsequent tier. Tier 1 used cognitive pretesting to assess question understanding and the need for memory prompts. In tier 2, we used test-retest self- and interviewer-administered approaches to assess question reliability, evaluate response missingness, and determine confidence between 2 types of survey administration approaches. In tier 3, we tested the questionnaire for clarity, time to complete, and whether additional prompts were necessary.

RESULTS

In tier 1, respondents suggested improvements to the web-based survey questions and to the written and visual prompts for better recall regarding past contraceptive use. In tier 2, the test-retest reliability between self- and interviewer-administrative procedures of "ever use" contraceptive method questions was similar, with percent absolute agreement ranging between 84% and 100%. When the survey was self-administered, the percentage of missing responses was higher and respondent confidence about month and year when contraceptive methods were used was lower. Most respondents reported that they preferred the self-administered survey because it was more convenient and faster to complete.

CONCLUSIONS

Our 3-tier process to pilot web-based survey questions related to contraceptive and obstetrical history in our complex disease population helped us tailor content and format questions before wide dissemination to our target population. Results from this pilot study informed the subsequent larger study design to include a 10% respondent test-retest self- and interviewer-administered quality control component to better inform imputation procedures of missing data.

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.

Challenges Faced by Women with Cystic Fibrosis

Women with cystic fibrosis (CF) face several unaddressed concerns related to their health. These areas of concern include explanations and guidance on a sex disparity in outcomes, timing of puberty, effects of contraception, prevalence of infertility and impact of pregnancy, and prevention of urinary incontinence and osteoporosis. These understudied topics leave women with numerous unanswered questions about how to manage sexual and reproductive health in the setting of CF. Because people with CF are living longer and healthier lives, there is an increasing awareness of these important aspects of care and multiple ongoing studies to address these understudied topics.

Exercise as medicine - evidence for prescribing exercise as therapy in 26 different chronic diseases

This review provides the reader with the up-to-date evidence-based basis for prescribing exercise as medicine in the treatment of 26 different diseases: psychiatric diseases (depression, anxiety, stress, schizophrenia); neurological diseases (dementia, Parkinson's disease, multiple sclerosis); metabolic diseases (obesity, hyperlipidemia, metabolic syndrome, polycystic ovarian syndrome, type 2 diabetes, type 1 diabetes); cardiovascular diseases (hypertension, coronary heart disease, heart failure, cerebral apoplexy, and claudication intermittent); pulmonary diseases (chronic obstructive pulmonary disease, asthma, cystic fibrosis); musculo-skeletal disorders (osteoarthritis, osteoporosis, back pain, rheumatoid arthritis); and cancer. The effect of exercise therapy on disease pathogenesis and symptoms are given and the possible mechanisms of action are discussed. We have interpreted the scientific literature and for each disease, we provide the reader with our best advice regarding the optimal type and dose for prescription of exercise.

Lactose malabsorption is a risk factor for decreased bone mineral density in pancreatic insufficient cystic fibrosis patients

As decreased bone mineral density (BMD) is a common problem in cystic fibrosis (CF) and milk products may have pivotal dietary role affecting BMD, we aimed to assess the potential influence of adult-type hypolactasia (ATH) and lactose malabsorption (LM) on BMD in adolescent and young adult patients. In 95 CF pancreatic-insufficient patients aged 10-25 years (without liver cirrhosis, steatosis and cholestasis, diabetes mellitus, systemic glucocorticoid therapy), lumbar BMD, the nutritional status, pulmonary function, vitamin D3 concentration, calcium intake and single-nucleotide polymorphism upstream of the lactase gene were assessed. In subjects with the -13910 C/C genotype predisposing to ATH, the presence of LM was determined with the use of a hydrogen-methane breath test (BT). BMD and calcium intake were significantly lower in patients with the C/C genotype (P<0.028 and P<0.043, respectively). The abnormal BMD was stated more frequently in patients with the C/C genotype (P<0.042) and with LM (P<0.007). BMD, daily calcium intake and serum vitamin D concentration were significantly lower in LM subjects than in the other patients (P<0.037, P<0.000004 and P<0.0038, respectively). In logistic regression analysis, the relationship between examined parameters and BMD, was found to be statistically significant (P<0.001). However, only standardized body weight and LM were documented to influence BMD (P<0.025 and P<0.044, respectively). In conclusion, LM seems to be an independent risk factor for decreased BMD in CF patients.

Vitamin D in organ transplantation

Vitamin D deficiency is prevalent among patients with end-stage organ failure awaiting transplant. Low serum 25-hydroxyvitamin D (25-OHD) levels in these patients may be related to many disease-specific factors, as well as decreased sunlight exposure and limited intake of foods containing vitamin D. Low serum 25-OHD levels are also extremely common following solid organ transplantation, both during the immediate postoperative period and in long-term graft recipients. Demographic and lifestyle factors are important in determining D status in transplant recipients. Worse vitamin D status is associated with poorer general health, lower albumin, and even decreased survival among these patients. Although several studies have demonstrated that active forms of vitamin D and its analogues prevent bone loss following transplantation, the data do not show consistent benefit. These therapies may have particular utility after renal transplantation. However, given the narrow therapeutic window with respect to hypercalcemia and hypercalciuria, and the demonstrated efficacy of bisphosphonates to prevent post-transplantation bone loss, we regard these agents as adjunctive rather than primary therapy for transplantation osteoporosis. The effects of 1,25(OH)(2)D on the immune system, which are still being elucidated, may have potential for reducing infections and preventing allograft rejection after transplantation.

Osteoporosis following organ transplantation: pathogenesis, diagnosis and management

Organ transplantation has become popular for the management of various chronic illnesses. With the advent of modern immunosuppressive treatments, the longevity of transplant recipients has increased. Consequently, morbid complications such as osteoporosis and bone fractures are seen at an increasing frequency in this population. In most transplant recipients, bone mineral density (BMD) falls shortly after transplantation. However, bone fracture rate plateaus in all except for post-renal transplant patients. Although the underlying pathophysiologic mechanism for this difference is not fully understood, potential mechanisms for sustained bone loss in renal transplant recipients may be persistent phosphorus wasting and defective bone mineralization. Current treatment regimens are based on studies in a small numbers of subjects with BMD as the primary outcome. Although BMD is recognized as a gold standard in the assessment of bone fracture risk, to date, its association with bone fracture risk in the general post-transplant population is not robust. Therefore, randomized controlled trials with bone fracture as the primary end point are crucial. The development of noninvasive bone markers in distinguishing bone turnover and bone mineralization status is also pivotal since skeletal lesions are heterogeneous in various organ transplantations. The elucidation of these underlying skeletal lesions is necessary for the consideration of selective treatment in this population.

Relation of bone mineral density with clinical and laboratory parameters in pre-pubertal children with cystic fibrosis

To study bone mineral density (BMD) of pre-pubertal cystic fibrosis (CF) children, and its relation with clinical and laboratory parameters, we enrolled 16 CF (8 girls) (4-8 years), and 16 control children (8 girls) (4-8 years). After anthropometric measurements, BMD, serum calcium, phosphorus, total alkaline phosphatase (ALP), 25-hydroxy vitamin D (25-OHD), parathyroid hormone, osteocalcin, tumor necrosis factor (TNF)-alpha, soluble TNF-alpha receptor 2 (sTNFR2), and soluble IL-2 receptor (sIL-2R) levels, and urinary calcium and hydroxyproline excretions were assessed. Disease severity of CF patients was determined with Shwachman-Kulczycki clinical and Brasfield radiological scoring systems.The mean Shwachman-Kulczycki and Brasfield scores of CF patients were indicating well-controlled disease. The anthropometric measurements, mean BMD values, and serum calcium, phosphorus and parathyroid hormone levels were within normal range and similar in both groups. Serum osteocalcin levels were lower, and ALP and 25-OHD levels were higher in CF. Although 24-hr urinary calcium excretions was higher in CF patients, hydroxyproline excretions were similar in both groups. There was no difference between two groups for the serum levels of sIL-2R, TNF-alpha and sTNFR2. Children with low vertebral z-scores had higher serum sIL-2R levels in both groups, but the same relation could not be shown for TNF-alpha and sTNFR2.We may speculate that younger, healthier and well-nourished patients with CF may have normal BMD, but the bone disease develop as patients get older because of the other contributing factors. Future well-designed longitudinal studies with large cohorts might show a relation with BMD and cytokines in CF.

Chronic pediatric inflammatory diseases: effects on bone

In children, chronic inflammatory diseases present a significant challenge to long-term skeletal health. These conditions are often associated with poor appetite and suboptimal overall nutrition, altered nutrient utilization, delayed puberty, inactivity, and reduced muscle mass, all of which can alter bone metabolism. In addition, bone cell activity is susceptible to the effects of the immune response that characterizes these diseases. Moreover, drugs used to treat these maladies, notably glucocorticoids, may have negative effects on bone formation and on linear growth in developing children. As a result, predicted peak bone mass may not be achieved, and fracture risk may be increased in the short term or in the future. Studies using primarily dual energy X-ray absorptiometry have documented that deficits in bone mass are common in these diseases. However, there are wide variations in the prevalence of low bone mass, largely due to differences in the characteristics of each study population. Recent studies provide insight into the pathogenesis of decreased bone mass in these conditions. In this paper we will provide an overview of the effects of chronic inflammatory conditions on bone mass in children. We will also present relevant data from adult patients, when pediatric data are scant or not available.

Post-transplantation osteoporosis

Osteoporosis is prevalent in transplant recipients and is related to pre- and post-transplantation factors. Low bone density and fractures may antedate transplantation, related to traditional risk factors for osteoporosis, effects of chronic illness, and end-stage organ failure and its therapy, on the skeleton. Bone loss after transplantation is related to adverse effects of immunosuppressive drugs (glucocorticoids and calcineurin inhibitors) on bone remodeling. Newer immunosuppressive medications may permit lower doses of glucocorticoids and may be associated with decreased bone loss and fractures. Bisphosphonates are currently the most effective agents for the prevention and treatment of post-transplantation osteoporosis.

Quantitative ultrasound in adults with cystic fibrosis: correlation with bone mineral density and risk of vertebral fractures

In several conditions, including cystic fibrosis (CF) and corticosteroid-induced osteoporosis, bone mineral density (BMD) measurements provide a modest prediction of fracture risk. We investigated in adult CF patients whether quantitative ultrasound (QUS) parameters were able to discriminate between patients with and without prevalent vertebral fractures. One hundred seventy-two adults with CF, 91 men and 81 women, often on chronic oral or inhaled corticosteroid therapy, were studied. BMD at the lumbar spine, proximal femur, and total body were measured by dual-energy X-ray absorptiometry (DXA). QUS parameters were assessed by Achilles Express at the calcaneus and by the DBM Sonic 1200 at the phalanges. All bone measurements by DXA and QUS were significantly correlated with each other, with the exception of phalangeal amplitude-dependent speed of sound versus spine BMD. The mean T-score values in CF patients with and without prevalent vertebral fractures were similar for all DXA measurements and for stiffness index. A significant difference between the two groups was observed only for phalangeal ultrasound bone profile index (UBPI) values (relative risk = 1.25, 95% confidence interval 1.05-1.49 for each decrease in T score), and this difference was maintained after adjusting the values for age, body weight, forced expiratory volume in 1 second, gender, and corticosteroid use. In conclusion, only a phalangeal QUS parameter (UBPI), in contrast with calcaneus QUS or DXA measurements, was able to discriminate CF patients with from those without vertebral fractures, possibly as a result of qualitative alterations of bone tissue independent of BMD.

Update on maintaining bone health in cystic fibrosis

PURPOSE OF REVIEW

The high prevalence of decreased bone density in adults with cystic fibrosis is now well recognized, and guidelines for screening and treatment of cystic fibrosis-related bone disease have recently been published. This review summarizes the current best practices for optimizing bone health in cystic fibrosis and highlight recent findings that provide insight into the etiology of cystic fibrosis-related bone disease.

RECENT FINDINGS

Recent research suggests that cystic fibrosis-related bone disease actually starts during childhood, when individuals with cystic fibrosis fail to demonstrate normal bone calcium accretion. The failure to reach peak bone mass is made worse by increased osteoclast activity and bone resorption. This combination results in decreased bone density and an increased risk of fracture. Recent clinical studies suggest that multiple contributing factors need to be addressed in cystic fibrosis to optimize bone health: malnutrition, vitamin and mineral malabsorption, recurrent infections, inadequate sex hormones, and lack of exercise. Oral bisphosphonates have been demonstrated to be effective in cystic fibrosis and should be used when osteoporosis or progressive osteopenia is present.

SUMMARY

Research suggests cystic fibrosis-related bone disease actually begins during childhood, and guidelines now exist to aid in identifying and treating those with decreased bone density.

Osteoclastogenesis during Infective Exacerbations in Patients with Cystic Fibrosis

RATIONALE

Adults with cystic fibrosis (CF) are at increased risk of developing osteoporosis. During infective exacerbations, increased production of proinflammatory cytokines and markers of bone resorption have been reported.

OBJECTIVE

The aim of this study is to investigate the growth and proliferation of potential osteoclast precursor cells before, during, and after intravenous antibiotic treatment of infective exacerbations in patients with CF.

METHODS

Hematopoietic precursor cell growth was examined using colony formation assays using Methocult culture medium. Circulating potential osteoclast precursors were identified using four-color flow cytometry by CD14, CD33, CD34, and CD45 expression.

RESULTS

At the start of an infective exacerbation increases in hematopoietic precursor colony formation (15.42 colonies/10(5) cells plated, p = 0.025), proliferation (28.5%, p < 0.001), and the numbers of circulating potential osteoclast precursors (6.5%, p < 0.001) were seen in comparison with baseline levels. These increases declined after treatment with intravenous antibiotics to a level close to baseline.

CONCLUSIONS

The results demonstrate an increase in the production of potential osteoclast precursors in the peripheral blood during CF infective exacerbations. This may result in increased bone resorption and contribute to bone loss in patients with CF.

Failure of high-dose ergocalciferol to correct vitamin D deficiency in adults with cystic fibrosis

RATIONALE

Treatment guidelines for vitamin D monitoring and supplementation in cystic fibrosis (CF) have recently been developed and published by a consensus committee, but have not been prospectively tested.

OBJECTIVES

To use these guidelines to determine the percentage of adults with CF requiring vitamin D repletion therapy and to evaluate the effectiveness of the currently recommended high-dose oral ergocalciferol repletion protocol.

METHODS

Prospective study of clinical outcomes after therapy with the recommended vitamin D repletion algorithm.

RESULTS

Of 134 adults with CF, 109 (81.3%) were found to have 25-hydroxyvitamin D (25-OHD) levels below the recommended 30 ng/ml. Sixty-six of these adults completed the recommended course of 400,000 IU of oral ergocalciferol over 2 months, and only five (8%) responded with correction of their serum 25-OHD to the goal of 30 ng/ml or greater (mean change, +0.3 ng/ml; from 18.8 to 19.1 ng/ml). In the 33 adults with CF who also completed the recommended second course of 800,000 IU of ergocalciferol over 2 months, none demonstrated correction of their deficiency (mean change, -1.2 ng/ml).

CONCLUSION

The results of this study demonstrate that a majority of adults with CF have serum 25-OHD levels below 30 ng/ml, and the currently recommended ergocalciferol repletion regimen often does not fully correct vitamin D deficiency and may need to be revised to include even higher dosing of ergocalciferol. Further work is needed to establish the ideal 25-OHD level for maximizing calcium absorption and bone health in CF.

Clinical effects of growth hormone on bone: a review

Growth hormone (GH) stimulates bone turnover. Deficiency of GH due to hypopituitarism is related to low bone mineral density and increased fracture risk. GH substitution increases and thus normalizes bone mineral density in these patients, which is one of a number of arguments for GH substitution in hypopituitarism. In contrast, a possible therapeutic use of GH in idiopathic osteoporosis and glucocorticoid-induced osteoporosis is speculative and not established. Reduction of osteoporosis risk is an argument brought up for a use of GH in healthy elderly persons (anti-aging medicine). However, since only very limited data are available yet, this cannot be based on scientific evidence, and there are important concerns about the safety of use of GH in healthy elderly persons.

Randomised double blind placebo controlled trial investigating the effect of calcium and vitamin D supplementation on bone mineral density and bone metabolism in adult patients with cystic fibrosis

BACKGROUND

Low bone mineral density (BMD) is prevalent in adults with cystic fibrosis and might be related to calcium and vitamin D malabsorption from the gastrointestinal tract. The aim of this study was to investigate the effect of calcium and vitamin D supplementation on BMD and bone metabolism in these subjects.

METHODS

Patients were invited to participate if they had a BMD Z score of -1 or less in the lumbar spine, proximal femur or distal forearm. Patients were randomised to receive calcium 1 g+vitamin D 800 IU or placebo daily, in addition to their regular vitamin D supplements (900 IU/day). BMD and bone biochemical markers were measured before and after 1 year of treatment.

RESULTS

After 12 months, the treatment group (n=15) showed a reduced rate of bone loss compared with the control group (n=15) in the lumbar spine (mean difference 1.9% [CI -0.9% to 4.6%]), total hip (mean difference 0.7% [CI -2.2% to 3.5%]) and distal forearm (mean difference 1.7% [CI -2.2% to 5.5%]), but these changes did not reach statistical significance. There was also a trend towards a reduction in bone turnover in the treatment group.

CONCLUSIONS

Calcium and vitamin D supplementation reduced the rate of bone turnover and bone loss in adult patients with cystic fibrosis, but these changes did not reach statistical significance. These data suggest that a longer term trial of this simple intervention would be justified.

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.

Prevalence and correlates of vertebral fractures in adults with cystic fibrosis

INTRODUCTION

Osteoporosis associated with cystic fibrosis (CF) is becoming increasingly important as the life expectancy of patients continues to increase.

MATERIALS AND METHODS

We studied 191 adults with CF (18-50 years old; 100 men, 91 women). Total body, lumbar spine, and total proximal femur bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry, and lateral spinal radiographs were taken for assessment of vertebral fractures. A range of anthropometric, clinical and biochemical variables were evaluated as potential correlates.

RESULTS

BMD T score values at the lumbar spine lower than -2.5 SD were observed in 27.3% and 11.2% of male and female patients, respectively. These proportions fell to 14% and 9.9% for total hip and 10.4% and 12.1% for total body, in men and women, respectively. Vertebral deformities were identified in 26.7% of the patients with a slightly higher prevalence in males (32%) than in females (21%, P = 0.058). Multiple vertebral deformities were observed in 12% and 7.7% of men and women, respectively. BMD values were significantly related to body weight, FEV1, age of puberty and occasionally to cumulative steroid dose in both genders. BMD values were also significantly related with serum albumin, IgG and cholinesterase. Serum estradiol levels were found below the normal range in 23% of the women and 27% of the men, and was significantly related to femur BMD values in both women and men. Significantly lower serum estradiol and free testosterone levels were observed in men with vertebral fractures. Serum osteocalcin was below the normal range in 36% and urinary deoxypyridinoline above the normal range in 51% of the patients.

CONCLUSIONS

This study indicates that osteoporosis is a common complication of CF, being related to disease progression and apparently due to both excess bone resorption and inadequate bone formation. Estradiol deficiency may have a significant role in the pathogenesis in both genders. Vertebral fracture prevalence is high and greater than expected from prevalent BMD values.

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.

Inflammatory related changes in bone mineral content in adults with cystic fibrosis

BACKGROUND

Proinflammatory cytokines stimulate osteoclast activity and this could lead to increased bone resorption in patients with cystic fibrosis. The aim of this study was to determine whether markers of systemic inflammation are related to changes in bone mineral content (BMC) in adults with cystic fibrosis.

METHODS

Total body BMC was assessed by dual energy x ray absorptiometry in 100 patients (54 male) of mean (SD) age 25.6 (7.1) years and forced expiratory volume in 1 second (FEV(1)) 61.8 (24.1)% predicted on recruitment to the study and 1 year later. Blood was also taken at these time points to measure markers of systemic inflammation.

RESULTS

After 1 year BMC had reduced by 16.1 (62.1) g, p = 0.01; (0.6 (2.8)%). The change in BMC was related to mean levels of interleukin (IL)-6 (r(s) = -0.39, p<0.001) and C reactive protein (r(s) = -0.34, p = 0.002), intravenous antibiotic use (r(s) = -0.27, p = 0.006) and oral corticosteroid use (r(s) = -0.20, p = 0.045). Urinary markers of osteoclast activity were also related to IL-6 (r(s) = 0.27, p = 0.02). Multiple linear regression revealed that IL-6 (coefficient -2.2 (95% CI -3.4 to -1.0) per pg/ml, p = 0.001), colonisation with Burkholderia cepacia (coefficient -46.8 (95% CI -75.5 to -18.1), p = 0.002), and annual change in BMI (coefficient 15.4 (95% CI 3.6 to 27.2) per kg/m(2), p = 0.011) were independently significant predictors of annual change in BMC.

CONCLUSIONS

These data suggest a pathophysiological mechanism by which chronic pulmonary infection results in bone loss in patients with cystic fibrosis.

CALCIUM AND BONE MINERAL METABOLISM IN CHILDREN WITH CHRONIC ILLNESSES

Increased longevity and improved medical management of children with chronic illnesses has led to a focus on the short- and long-term consequences of these conditions on bone health. Bone loss is influenced by diet, malabsorption, and disease-related imbalances in bone turnover. It may be exacerbated by common medications, especially corticosteroids. Assessment of bone mass and quality, calcium absorption, kinetically derived rates of bone turnover, and biochemical markers of bone turnover have increased our knowledge of the pathophysiology of bone loss in these children as well as provided insights into possible therapeutic interventions. Increased intake of calcium and vitamin D, while useful, is unlikely to prevent or resolve bone loss in many chronically ill children. Emphasis on combination of nutritional interventions with exercise and newer bone-sparing therapies may be necessary.

Exercise testing and training in German CF centers

Physical exercise is increasingly recognized as a valuable diagnostic and therapeutic modality for patients with cystic fibrosis (CF). We sought to characterize the use of exercise testing and training as well as the attitude toward both issues through a national survey. A questionnaire was sent to 107 specialized CF centers (caring for a total of 5,231 patients) and 7 inpatient rehabilitation institutions. Answers were available from 62 specialized centers caring for 3,580 patients and from 4 rehabilitation centers with 520 treatment episodes per year. Sixty percent of specialized centers performed some sort of exercise testing at an average frequency of 1 in 2.3 years for patients aged 8 and above. However, protocols and indication criteria were often unstandardized or not specified at all. Equipment availability was no major problem, and the majority of tests were conducted by a physician alone. Nineteen centers had adopted exercise testing as part of their diagnostic routine. Two thirds of caregivers advised their patients to engage in physical activity, but failed to discuss specific modalities and potential hazards. Nevertheless, physical exercise was viewed as "extremely important" or "very important" by 87%. In a rehabilitation setting, an exercise test was conducted 1.1 times per patient stay, and a training program offered in 100% of cases. In conclusion, standardized exercise testing and training programs appear to be underused in German CF centers, despite a high degree of interest in the topic. Supplementary material for this article can be found on the Pediatric Pulmonology website (http//www.interscience.wiley.com/jpages/8755-6863/suppmat).

Musculoskeletal manifestations in cystic fibrosis

Although bone and joint manifestations are common in children with cystic fibrosis (CF), they have received little attention in adults. As compared to healthy individuals, bone mineral density is low, even with calcium intakes greater than 1500 mg/d. Nevertheless, calcium and phosphate levels in blood and urine are often normal, and vitamin D levels vary. Short stature with a low body mass index and central hypogonadism are the rule in these patients. Fractures and kyphosis are often reported. CF arthropathy occurs in 2-8.5% of patients. Arthritis develops, and there may be skin eruptions. Non-steroidal antiinflammatory drug therapy is effective. Hypertrophic osteoarthropathy associated with respiratory failure is present in 2-7% of patients. Rheumatoid arthritis, spondyloarthropathies, sarcoidosis, and amyloidosis have been reported in association with CF. Knee pain due to patellofemoral syndrome, quinolone-induced arthropathy, and mechanical back pain have been described. Rheumatoid factor titers are higher than in healthy controls, particularly in patients with episodic arthritis. No data are available on antiperinuclear factor or antikeratin antibody titers. Tests for antinuclear antibody are usually negative. Circulating immune complex levels and antibodies to heat shock proteins may be elevated. Antineutrophil cytoplasmic antibody of the bactericidal/permeability-increasing protein (BPI) or azurocidin (AZ) type has been reported, often in high titers (up to 40%).

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.

Endogenous fecal losses of calcium compromise calcium balance in pancreatic-insufficient girls with cystic fibrosis

OBJECTIVE

Bone mineral density is compromised in individuals with cystic fibrosis (CF); calcium is the major bone mineral. This study examined the impact of endogenous fecal calcium (V(endo)) losses on calcium balance in girls with CF. Study design V(endo) was measured in 12 girls with CF (aged 7-18 years): 7 younger, premenarcheal girls with compromised nutritional status; and 5 older, postmenarcheal girls with adequate nutritional status. V(endo) was measured as the amount of intravenously administered (42)Ca, a calcium stable isotope, in stool relative to urine over 6 days. V(endo) was compared between pre- and postmenarcheal girls by Student's t test. Actual calcium balance [absorbed calcium-(urinary calcium (V(u))+V(endo))] was compared with estimated balance (assuming V(endo)=1.6 mg/kg/day calcium) by paired t test.

RESULTS

V(endo) was 99.3+/-42.3 mg/day. By body weight, V(endo) was highest among premenarcheal girls (3.37+/-1.09 mg/kg/day), resulting in excess losses (>1.6 mg/kg/day) of 55.0+/-45.7 mg/day. Over 1 year, this represents 20.1+/-16.7 g of unattained bone calcium or 6.7+/-4.2% of the bone calcium content of these girls.

CONCLUSIONS

V(endo) is a significant source of calcium loss in individuals with CF and may limit calcium availability for bone mineral deposition.

A comparison of nutrient intake between infants and toddlers with and without cystic fibrosis

OBJECTIVE

To compare the micronutrient and energy intake of infants and toddlers with cystic fibrosis (CF) to the intake of matched control children and dietary reference index (DRI) levels.

DESIGN

A two-group comparison study. Nutrient and energy intakes were measured via 3-day diet diaries. Anthropometric data were collected within 1 week of study enrollment.

SUBJECTS/SETTING

A clinical sample of 35 infants and toddlers with CF (mean=18.6, SD=8.1 months) matched to a community sample of 34 healthy controls.

STATISTICAL ANALYSES PERFORMED

Children with CF and controls were compared on anthropometric and nutrient data using independent sample t tests. Mean nutrient and energy intake for children in each group were compared with the age-appropriate DRI for targeted nutrients using percentages.

RESULTS

Children with CF and controls were similar on measures of growth (height, weight, or weight-for-height percentile). Four children with CF were at or below the 10th percentile for weight-for-height, compared with one control child. Children with CF and controls did not differ on average daily protein, calcium, zinc, and energy intake. Overall, children met or exceeded DRI levels for nutrient intakes. A notable exception was iron, for which mean intakes were lower for control children. Toddlers with CF consumed only 89% of the RDA per day for energy.

APPLICATIONS/CONCLUSIONS

Infants and toddlers with CF are likely obtaining adequate micronutrient intakes from food. Interventions to increase total energy intake in infants and toddlers with CF are needed. Dietitians may want to focus more on calorie intake and percent calories from fat than on micronutrient intake in their nutrition counseling in young children with CF.

Recipient selection

Since international recommendations for lung transplant recipients were made in 1998, newer tools for predicting mortality in patients who have end-stage lung disease have been investigated. This article reviews studies for predicting mortality in obstructive, restrictive, pulmonary vascular, and suppurative/bronchiectatic lung disease. Newer considerations for alternative treatments, postoperative risks, and contraindications are also examined. The article aims to provide more accurate data for selecting patients who will benefit from lung transplantation.

Efficiency of calcium absorption is not compromised in clinically stable prepubertal and pubertal girls with cystic fibrosis

BACKGROUND

Reduced bone mass is common in both children and adults with cystic fibrosis (CF) and may be a consequence of inadequate calcium absorption. The effect of CF on intestinal calcium absorption and retention has not been described in children.

OBJECTIVE

Calcium absorption and urinary losses were characterized in clinically stable girls with CF consuming self-selected diets and following usual pancreatic enzyme regimens.

DESIGN

The percentage of calcium absorption was assessed in 23 girls (aged 7-18 y) with CF by using oral ((44)Ca) and intravenous ((42)Ca) stable isotopes. Girls were grouped according to Tanner stage of breast development. True calcium absorption (V(a)) was determined as the product of percentage calcium absorption and average 4-d daily calcium intake. Calcium balance was estimated by subtracting urinary calcium and estimated endogenous fecal losses from the measure of V(a). Analysis of variance was used to compare outcomes among pubertal groups, and regression analysis was used to describe the relations of percentage and total calcium absorption to calcium intake and of urinary calcium to sodium excretion.

RESULTS

Percentage calcium absorption was inversely related to calcium intake. Percentage absorption and V(a) were similar to values observed in healthy girls in other studies. Total calcium absorption and estimated calcium balance were significantly greater among girls in early puberty (Tanner stages 2-3) than in prepubertal or late-pubertal girls (P < 0.05). Urinary calcium was positively related to urinary sodium excretion (P = 0.02).

CONCLUSION

The efficiency of calcium absorption was not compromised in clinically stable girls with CF.

Osteoporosis in Canadian adult cystic fibrosis patients: a descriptive study

BACKGROUND

Cystic fibrosis is the most common fatal autosomal recessive genetic disease in the Caucasian population. Osteoporosis is increasingly being recognised as an important complication in people with cystic fibrosis.

METHODS

A descriptive study of adult cystic fibrosis patients receiving care at a Canadian tertiary care hospital was conducted to evaluate the prevalence of osteoporosis, the prevalence of non-vertebral fractures, and the change in bone mineral density during the course of a year. Data on bone mineral density were obtained for 40 adult cystic fibrosis patients by reviewing dual x-ray absorptiometry scans taken at baseline (when annual scans became standard clinical practice) and one year prior to baseline. Data on prevalent fractures were obtained by reviewing all available patient charts. Clinical and laboratory data were collected from an existing clinic database.

RESULTS

Over half of the 40 patients had reduced T- and Z-scores at baseline. For the 27 patients who had data available one year prior to baseline, total hip and lumbar spine bone mineral density had decreased by 3.04% and 0.86% after one year while total body bone mineral density had not changed significantly. Four prior non-vertebral fractures were reported in three patients (1,146 patient-years).

CONCLUSION

This study confirms that osteoporosis is a significant problem in adult cystic fibrosis patients, and constitutes the first published evidence of cystic fibrosis bone disease in Canadians.

Histomorphometric analysis of bone biopsies from the iliac crest of adults with cystic fibrosis

This study reports the results of quantitative analysis of iliac bone histology in adults with cystic fibrosis (CF) and low bone mineral density (BMD). Twenty patients with CF had bone biopsies taken after double tetracycline labeling. Histomorphometric measurements were made by image analysis, and data were compared with those of healthy control subjects. Cancellous bone area was lower in the patients with CF (p = 0.003), and there was a trend towards a decrease in cancellous bone connectivity. Bone formation rate at tissue level was significantly lower in patients with CF (p = 0.0002). Wall width, representing the amount of bone formed within individual remodeling units, was decreased (p < 0.0001), as was mineralizing perimeter and mineral apposition rate. Analysis of resorption cavities revealed lower cavity area, reconstructed surface lengths, and cavity depths (p < 0.003) in patients with CF, whereas eroded surface area was higher (p = 0.0004). Our results demonstrate low cancellous bone volume in adult patients with CF with low BMD, the main cause of which appears to be low bone formation at tissue and cellular level. Osteomalacia was diagnosed in one patient. This condition should be excluded as a cause of low bone mineral density in patients with CF and vitamin D insufficiency corrected.

A review of nutritional problems and the cystic fibrosis lung transplant patient

Lung transplantation is an option for some cystic fibrosis (CF) patients. CF is associated with a variety of non-pulmonary problems, which should be managed before and after transplantation. This commentary discusses some of the nutritional issues affecting CF patients. Theses issues include: the need for nutritional supplements; gastrostomy tube placement; osteoporosis and diabetes.

A prospective study of change in bone mineral density over one year in adults with cystic fibrosis

BACKGROUND

Low bone mineral density (BMD) is prevalent in adults with cystic fibrosis. To identify appropriate therapeutic strategies and the optimal time for intervention, it is necessary to document the natural history of cystic fibrosis related low BMD.

METHODS

114 adults with cystic fibrosis underwent bone densitometry a median (25-75% interquartile range) of 12 (12-13) months after initial assessment of bone density. BMD was measured in the lumbar spine, femoral neck, total hip, and distal forearm on recruitment to the trial and at follow up.

RESULTS

In patients <or=24 years of age (n=55, mean (SD) age 19.5 (2.6) years) in whom an annual increase in BMD would normally be expected, BMD increased by a mean (95% CI) 2.9% (1.6 to 4.2) per year in the distal forearm (p<0.001), but decreased by 2.5% (95% CI -3.8 to -1.2) per year in the femoral neck (p<0.001) and by 2.2% (95% CI -3.3 to -1.0) per year in the total hip (p<0.001). In patients >or=25 years of age (n=59, mean (SD) age 30.3 (5.4) years) in whom no annual change in BMD would normally be expected, BMD decreased by 1.9% (95% CI -2.9 to -0.8) per year in the femoral neck (p<0.001), by 1.5% (95% CI -2.4 to -0.6) per year in the total hip (p=0.001), and by 0.8% (95% CI -1.5 to -0.1) per year in the distal forearm (p=0.026). There was no significant annual change in lumbar spine BMD in either patient cohort.

CONCLUSIONS

Reduced rates of bone accretion and accelerated rates of bone loss explain the high prevalence of low BMD in adults with cystic fibrosis.

Secondary causes of osteoporosis

Secondary causes of bone loss are not often considered in patients who are diagnosed as having osteoporosis. In some studies, 20% to 30% of postmenopausal women and more than 50% of men with osteoporosis have a secondary cause. There are numerous causes of secondary bone loss, including adverse effects of drug therapy, endocrine disorders, eating disorders, immobilization, marrow-related disorders, disorders of the gastrointestinal or biliary tract, renal disease, and cancer. Patients who have undergone organ transplantation are also at increased risk for osteoporosis. In many cases, the adverse effects of osteoporosis are reversible with appropriate intervention. Because of the many treatment options that are now available for patients with osteoporosis and the tremendous advances that have been made in understanding the pathogenesis and diagnosis of the condition, it is important that medical disorders are recognized and appropriate interventions are undertaken. This article provides the framework for understanding causes of bone loss and approaches to their management.

Diminished and erratic absorption of ergocalciferol in adult cystic fibrosis patients

BACKGROUND

Osteoporosis diminishes the quality of life in adults with cystic fibrosis (CF). Vitamin D deficiency resulting from malabsorption may be a factor in the etiology of low bone mineral density (BMD) in patients with CF.

OBJECTIVE

Absorption of oral ergocalciferol (vitamin D2) and the consequent response of 25-hydroxyvitamin D in 10 adults with CF and exocrine pancreatic insufficiency was compared with that of 10 healthy control subjects.

DESIGN

In this pharmacokinetic study, CF patients and control subjects were pair-matched on age, sex, and race. Each subject consumed 2500 microg oral vitamin D2 with a meal. The CF group also took pancreatic enzymes that provided > or = 80000 U lipase. Blood samples were obtained at baseline and at 5, 10, 24, 30, and 36 h after vitamin D2 consumption to measure serum vitamin D2 and 25-hydroxyvitamin D concentrations.

RESULTS

Vitamin D2 concentrations in all subjects were near zero at baseline. CF patients absorbed less than one-half the amount of oral vitamin D2 that was absorbed by control subjects (P < 0.001). Absorption by the CF patients varied greatly; 2 patients absorbed virtually no vitamin D2. The rise in 25-hydroxyvitamin D in response to vitamin D2 absorption was significantly lower over time in the CF group than in the control group (P = 0.0012).

CONCLUSIONS

Vitamin D2 absorption was significantly lower in CF patients than in control subjects. These results may help explain the etiology of vitamin D deficiency in CF patients, which may contribute to their low BMD.

Adverse alterations in bone metabolism are associated with lung infection in adults with cystic fibrosis

Low bone density, fractures, and kyphosis complicate the lives of adults with cystic fibrosis (CF), and inflammatory cytokines (interleukin [IL]-1beta, IL-6, and tumor necrosis factor [TNF]-alpha) that may alter bone metabolism have been previously found to be increased in the lungs and serum of CF patients. The objective of this prospective study was to determine the impact of lung infection on bone physiology in 17 adult CF patients. Serum osteocalcin, a marker of bone formation; urine N-telopeptides of type I collagen and free deoxypyridinoline, both of which are markers of bone breakdown; serum cytokines (TNF-alpha, IL-1beta, and IL-6); and general inflammatory markers (serum C-reactive protein [CRP] and chondrex) were measured at the beginning and end of treatment for an acute exacerbation of lung infection and again 3 wk later. After treatment with conventional antibiotics, decreases in N-telopeptides (147.3 +/- 77.5 [mean +/- SEM] versus 95.5 +/- 57.3 bone collagen equivalents (BCE)/mmol creatinine, p = 0.0014), deoxypyridinoline (8.42 +/- 2.8 versus 6.8 +/- 3.0 mmol/mmol creatinine, p = 0.08), IL-1beta (1.43 +/- 1.13 versus 0.65 +/- 0.63 pg/ml, p = 0.03), IL-6 (9.5 +/- 6.5 versus 4.7 +/- 3.2 pg/ml, p = 0. 012), CRP (43.1 +/- 29.3 versus 23.4 +/- 25.3 mg/ml, p = 0.04), and chondrex (151.7 +/- 111.7 versus 101.4 +/- 67.3 ng/ml, p = 0.014), and increases in osteocalcin levels (14.5 +/- 5.4 versus 22.5 +/- 8. 7 ng/ml, p = 0.010) were observed. Three weeks later, the changes in N-telopeptides and osteocalcin persisted. These data indicate that pulmonary infection, through the elaboration of inflammatory cytokines, may be linked to increased bone resorption and diminished bone formation. These results provide insights into the impact of systemic inflammation on bone health, and suggest novel mechanisms for bone disease in CF.

Osteoporosis: a new challenge in cystic fibrosis

The increased life expectancy of patients with cystic fibrosis (CF) may lead to medical complications such as osteoporosis. Based on data collected through a MEDLINE search (1985-May 1999) and review of references for additional relevant articles, nutrition status, weight, and disease severity are factors most highly correlated with osteopenia. Links also were noted with calcium and vitamin D intake, hypogonadism, chronic inflammation, and age, but findings in these areas are not consistent from one report to the next. Increased fracture rates and kyphosis are consequences of osteoporosis. Simple measures such as compliance with recommended nutrition guidelines and restrictions in corticosteroid therapy could be considered first-line management options. Further studies must be conducted to clarify factors involved in the etiology of osteoporosis in patients with CF and to identify the best treatment and prevention methods.