Management of corticosteroid-induced osteoporosis. UK Consensus Group Meeting on Osteoporosis

Bench to Bedside: Animal Models of Radiation Induced Musculoskeletal Toxicity

Ionizing radiation is a critical aspect of current cancer therapy. While classically mature bone was thought to be relatively radio-resistant, more recent data have shown this to not be the case. Radiation therapy (RT)-induced bone loss leading to fracture is a source of substantial morbidity. The mechanisms of RT likely involve multiple pathways, including changes in angiogenesis and bone vasculature, osteoblast damage/suppression, and increased osteoclast activity. The majority of bone loss appears to occur rapidly after exposure to ionizing RT, with significant changes in cortical thickness being detectable on computed tomography (CT) within three to four months. Additionally, there is a dose–response relationship. Cortical thinning is especially notable in areas of bone that receive >40 gray (Gy). Methods to mitigate toxicity due to RT-induced bone loss is an area of active investigation. There is an accruing clinical trial investigating the use of risderonate, a bisphosphonate, to prevent rib bone loss in patients undergoing lung stereotactic body radiation therapy (SBRT). Additionally, several other promising therapeutic/preventative approaches are being explored in preclinical studies, including parathyroid hormone (PTH), amifostine, and mechanical loading of irradiated bones.

Cortical Thinning and Structural Bone Changes in Non-Human Primates after Single-Fraction Whole-Chest Irradiation

Stereotactic body radiation therapy (SBRT) is associated with an increased risk of vertebral compression fracture. While bone is typically considered radiation resistant, fractures frequently occur within the first year of SBRT. The goal of this work was to determine if rapid deterioration of bone occurs in vertebrae after irradiation. Sixteen male rhesus macaque non-human primates (NHPs) were analyzed after whole-chest irradiation to a midplane dose of 10 Gy. Ages at the time of exposure varied from 45-134 months. Computed tomography (CT) scans were taken 2 months prior to irradiation and 2, 4, 6 and 8 months postirradiation for all animals. Bone mineral density (BMD) and cortical thickness were calculated longitudinally for thoracic (T) 9, lumbar (L) 2 and L4 vertebral bodies; gross morphology and histopathology were assessed per vertebra. Greater mortality (related to pulmonary toxicity) was noted in NHPs <50 months at time of exposure versus NHPs >50 months ( P = 0.03). Animals older than 50 months at time of exposure lost cortical thickness in T9 by 2 months postirradiation ( P = 0.0009), which persisted to 8 months. In contrast, no loss of cortical thickness was observed in vertebrae out-of-field (L2 and L4). Loss of BMD was observed by 4 months postirradiation for T9, and 6 months postirradiation for L2 and L4 ( P < 0.01). For NHPs younger than 50 months at time of exposure, both cortical thickness and BMD decreased in T9, L2 and L4 by 2 months postirradiation ( P < 0.05). Regions that exhibited the greatest degree of cortical thinning as determined from CT scans also exhibited increased porosity histologically. Rapid loss of cortical thickness was observed after high-dose chest irradiation in NHPs. Younger age at time of exposure was associated with increased pneumonitis-related mortality, as well as greater loss of both BMD and cortical thickness at both in- and out-of-field vertebrae. Older NHPs exhibited rapid loss of BMD and cortical thickness from in-field vertebrae, but only loss of BMD in out-of-field vertebrae. Bone is sensitive to high-dose radiation, and rapid loss of bone structure and density increases the risk of fractures.

Management issues of congenital adrenal hyperplasia during the transition from pediatric to adult care

Steroid 21-hydroxylase deficiency is the most prevalent form of congenital adrenal hyperplasia (CAH), accounting for approximately 95% of cases. With the advent of newborn screening and hormone replacement therapy, most children with CAH survive into adulthood. Adolescents and adults with CAH experience a number of complications, including short stature, obesity, infertility, tumor, osteoporosis, and reduced quality of life. Transition from pediatric to adult care and management of long-term complications are challenging for both patients and health-care providers. Psychosocial issues frequently affect adherence to glucocorticoid treatment. Therefore, the safe transition of adolescents to adult care requires regular follow-up of patients by a multidisciplinary team including pediatric and adult endocrinologists. The major goals for management of adults with 21-hydroxylase deficiency are to minimize the long-term complications of glucocorticoid therapy, reduce hyperandrogenism, prevent adrenal or testicular adrenal rest tumors, maintain fertility, and improve quality of life. Optimized medical or surgical treatment strategies should be developed through coordinated care, both during transition periods and throughout patients' lifetimes. This review will summarize current knowledge on the management of adults with CAH, and suggested appropriate approaches to the transition from pediatric to adult care.

Bone Complications of Corticosteroids

Background:

Systemic corticosteroids, a mainstay of treatment for severe dermatosis, are associated with systemic complications. Adverse effects of corticosteroids to bone represent a significant adverse effect that, is poorly understood and poorly managed.

Objectives:

The purpose of this article is to educate dermatologists to the current understanding of the pathogenesis, diagnosis, and treatment options available for bone complications of corticosteroids.

Results:

Virtually all patients chronically exposed to high-dose corticosteroid therapy lose bone mass and are at risk for osteoporotic fractures. In addition, osteonecrosis is an unpredictable complication of corticosteroid therapy that may occur with even low-dose corticosteroids.

Conclusion:

Optimal risk management of corticosteroid therapy includes understanding the risk factors associated with bone complications and improving communication with patients.

Risedronate therapy for the prevention of steroid-induced osteoporosis in patients with minimal-change nephrotic syndrome

BACKGROUND

Minimal-change nephrotic syndrome (MCNS) is treated by the administration of prednisolone (PSL) at high doses. Steroid-induced osteoporosis is a serious adverse effect of this drug.

METHODS

Patients with MCNS were randomly assigned to two groups, the risedronate (2.5 mg/day) + alfacalcidol (0.25 µg/day) group (n=20) and the alfacalcidol (0.25 µg/day)-alone group (n=20). All the patients had received PSL and the clinical characteristics were compared between the two groups at baseline and at 12 months.

RESULTS

A significant decrease of the mean bone mineral density (BMD) of the lumbar spine from 0.710±0.162 (g/cm(2)) to 0.588±0.125 was observed in the alfacalcidol-alone group (p=0.02), while no such decrease of the bone mineral density was found in the risedronate + alfacalcidol group (0.663±0.169 at baseline and 0.626±0.129 at 12 months). No significant differences in the results of other biochemical tests performed at the baseline and at 12 months were observed between the two groups. The likelihood of development of steroid-induced osteoporosis was influenced by the cumulative dose of PSL, the mean BMD at the baseline, occurrence of disease relapse, and risedronate therapy.

CONCLUSION

Risedronate appears to be effective in preventing steroid-induced osteoporosis. It is necessary to use bisphosphonates to maintain the BMD in patients with MCNS receiving prolonged steroid therapy.

Effect on growth of long-term treatment with intranasal triamcinolone acetonide aqueous in children with allergic rhinitis

BACKGROUND

Guidelines recommend treatment with intranasal corticosteroids for patients with allergic rhinitis (AR), but concerns remain about possible adverse effects.

OBJECTIVE

To present the 1- and 2-year growth results for children with AR treated with triamcinolone acetonide aqueous nasal spray.

METHODS

Thirty-nine children (aged 6.1-14.3 years at study entry) were treated with triamcinolone acetonide aqueous for 1 year, and a subset of 30 children completed a second year of treatment. The dose was physician titered to achieve control over AR symptoms. For each child, statural heights at baseline and at the 1- and 2-year (where available) visits, together with growth rates, were measured and were compared with predicted values.

RESULTS

There were no significant differences between measured and predicted heights at the 1- and 2-year visits. The mean (SD) measured--predicted difference was 0.3 (2.2) cm (95% confidence interval, -0.4 to 1.0 cm) at the 1-year visit and 0.5 (3.0) cm (95% confidence interval, -0.6 to 1.6 cm) at the 2-year visit. Mean differences in measured and predicted growth rates were nonsignificant at the 1- and 2-year visits.

CONCLUSIONS

Triamcinolone acetonide aqueous titered to control AR symptoms and given for 1 or 2 years had no significant effect on statural growth in children with AR.

Systematic review of trends in prophylaxis of corticosteroid-induced osteoporosis: the need for standard audit guidelines

Corticosteroid-induced osteoporosis (CIOP) is currently undertreated. Systematic review of the literature revealed that the percentage of patients treated adequately is dependent on study quality. Therefore, it remains unknown whether adherence to the guidelines is really so poor. Five major quality criteria provide the standard for future studies on this scope.

INTRODUCTION

It has recently been stated that the degree of prophylaxis of corticosteroid-induced osteoporosis (CIOP) is low and effort should be put into determining reasons for non-prescribing of preventive agents. The aim of this study was to identify: how many studies adequately audit the prevalent guideline; the longitudinal trends in prevention of CIOP; which patient groups appear to be most undertreated; and which intervention strategies are effective.

METHODS

We performed a comprehensive search of MEDLINE and systematically recorded the outcomes and quality of published studies, using five major criteria.

RESULTS

Twenty-four studies were included in the analysis. The quality of the included studies was poor (31%) or moderate (37%). There was a longitudinal increase in quality of the studies and percentage of prevention. Multivariable linear regression showed that the quality of the study was the only independent predictor of the prevention rate reported in the study.

CONCLUSIONS

The results show undertreatment of CIOP might be due to insufficient quality of the studies rather than poor practice or failure to recognise the right patients. Future interventions should comply with five major quality criteria, and a multifaceted approach is required in order to make an impact on the underprescribing of CIOP prophylaxis.

Inductive effects of dexamethasone on the mineralization and the osteoblastic gene expressions in mature osteoblast-like ROS17/2.8 cells

We examined the effects of dexamethasone (Dex), a synthetic glucocorticoid, on the formation of mineralized bone nodules and the gene expressions of the late osteoblastic markers, bone sialoprotein (BSP), osteocalcin (OC), and osteopontin (OPN) in mature osteoblast ROS17/2.8 cells. Treatment of ROS17/2.8 cells with Dex resulted in the induction of mineralization accompanied with increasing BSP and OC expressions. Previous reports have demonstrated that BSP and OC expressions are regulated by Runx2. Then, we hypothesized that Dex might promote osteoblastic differentiation and mineralization on ROS17/2.8 by Runx2. In this study, no effect was observed in mRNA and protein expression of Runx2. However, the transcriptional activity of Runx2 was enhanced by Dex treatment. Furthermore, the Dex-induced BSP and OC expressions decreased after the transfection of Runx2 small-interfering RNAs (siRNAs). These results suggested that the enhancement of Runx2 transcriptional activity by Dex treatment may be followed by the activation of osteoblast marker genes, such as BSP and OC to thereby produce a bone-specific matrix that subsequently becomes mineralized.

Congenital adrenal hyperplasia in adults: a review of medical, surgical and psychological issues

Our knowledge of the experience of adults with congenital adrenal hyperplasia (CAH) as they pass through life is only now emerging. In this review we gather medical, surgical and psychological literature pertaining to adults with CAH and consider this alongside practical experience gained from a dedicated adult CAH clinic. There is increasing awareness for the need for multidisciplinary teams who have knowledge of CAH particularly with respect to gynaecological surgery and clinical psychology for women and testicular function in men. Routine management of CAH comprises adjustment of glucocorticoid and mineralocorticoid treatment according to individual needs balancing biochemical markers, compliance and long term risks. Bone density is one such long term concern and is not greatly reduced in most individuals with CAH. More recently, attention has turned to cardiovascular risk factors and catecholamine deficiency in adults with CAH. Women with CAH require access to an experienced gynaecologist, specialised pregnancy care and psychosexual support. The very low fertility rates for women with CAH previously reported appear to be improving with time. Men with CAH are often lost to follow up and therefore miss out on surveillance for hypogonadism either through the effect of adrenal rests of from suppression of gonadotrophins resulting in a high prevalence of oligospermia.

An evaluation of managing and educating patients on the risk of glucocorticoid-induced osteoporosis

OBJECTIVE

To assess the impact of risk management activities on patient risk of glucocorticoid-induced osteoporosis.

METHODS

Ninety-six adult patients taking chronic glucocorticoid therapy in 15 community pharmacies. Patients in the control group received usual and customary care. Patients in the treatment pharmacies received education and an educational pamphlet about the risks of glucocorticoid-induced osteoporosis. In addition, the treatment group pharmacists monitored the patients' drug therapy, to identify and address drug-related problems. Data including the glucocorticoid taken by the patient, medications, and osteoporosis risk factors were collected at baseline and after 9 months of monitoring, via Web-based survey completed in the pharmacy. Using an intent to treat approach, the pre-post frequency changes were compared with contrasts for presence of bisphosphonate therapy, presence of estrogen therapy, presence of calcium supplement, discussion of glucocorticoid-induced osteoporosis risk, discussion of bone density test, presence of bone mineral density test, reported inactivity, and reported low calcium diet.

RESULTS

The contrast was significant in favor of the treatment pharmacies for the frequency of patients taking a calcium supplement (Control [-6.9%] vs. Treatment [17.1%], P < 0.05). No other contrast was significant.

CONCLUSIONS

Community pharmacists are capable of increasing calcium supplementation among patients at risk for glucocorticoid-induced osteoporosis. Pharmacists who educate at-risk patients can impact the self-care of these patients.

Current use of glucocorticoids in patients with rheumatoid arthritis in Germany

OBJECTIVE

To describe the current use of glucocorticoids in German patients with rheumatoid arthritis (RA).

METHODS

We analyzed clinical and patient-derived data from 10,068 outpatients with RA from the national database of the German Collaborative Arthritis Centres for the year 2001 collected by more than 80 rheumatologists in hospitals and private practices.

RESULTS

Systemic glucocorticoid therapy was prescribed for 60% of all patients with RA in rheumatologic care. The proportion of patients receiving systemic glucocorticoids in addition to disease-modifying antirheumatic drug (DMARD) therapy ranged from 53% to 81% of the patients for the various DMARDs. Glucocorticoid therapy was administered more often in combination with tumor necrosis factor inhibitors (81%), cyclosporin A (80%), or leflunomide (77%) than with more traditional DMARDs such as methotrexate (63%) or sulfasalazine (55%). Regarding the prevention and treatment of osteoporosis, 63% of patients taking systemic glucocorticoids were also receiving some type of osteoporosis therapy, as opposed to only 26% of those not taking glucocorticoids.

CONCLUSION

Glucocorticoids play a pivotal role in the management of RA. This is reflected in the extensive use of low-dose glucocorticoids by German rheumatologists. Even if highly effective DMARDs are prescribed, they are accompanied by glucocorticoids, at least in the initial phase. High-dose glucocorticoids are prescribed for only a small proportion of the patients. There is increasing awareness of the risk of osteoporosis in long-term glucocorticoid treatment, demonstrated by the fact that osteoporosis medication is prescribed for a large proportion of patients taking glucocorticoids.

Corticosteroid use in the treatment of neuromuscular disorders: empirical and evidence-based data

Corticosteroids have been used to treat neuromuscular disorders for many years. With few randomized, controlled trials, efficacy has been established primarily from empirical data. This has led to a range of treatment regimens varying in terms of initial dosing, dosing schedules, and taper rates. The goals of this review were to examine the literature for data concerning corticosteroid pharmacokinetics and for evidence-based treatment regimens in several prototypic neuromuscular disorders. The results provide a number of sound principles for corticosteroid use, but also indicate that corticosteroid regimens and patient management are largely based on empirical clinical experiences.

Access to bone densitometry increases general practitioners' prescribing for osteoporosis in steroid treated patients

BACKGROUND

Availability of access to bone densitometry in the UK varies widely and there are concerns as to appropriate prescribing. Studies suggest inadequate use of osteoporosis prophylaxis in steroid users, despite recent guidelines.

OBJECTIVE

To examine in a case-control study whether access to bone densitometry affects GPs' osteoporosis prescribing in high risk steroid users.

METHOD

10 general practices were included, five from primary care trusts (PCTs) with access to bone densitometry and five with limited access. Patients receiving prednisolone for >3 months were identified by database search. Patients receiving no prophylaxis other than calcium and vitamin D (Ca/D) were subsequently included. Appropriate patients in five practices were offered DXA scan (cases) and review. Patients in practices without access to scans (controls) were reviewed. GPs' opinions leading to treatment were sought by structured questionnaire.

RESULTS

132 (0.12%) patients were receiving prednisolone for >/=3 months, but no osteoporosis prophylaxis other than Ca/D. Pre-study prophylaxis ranged from 18 to 36%. Of 48 patients scanned, 21 (44%) were abnormal and 18 (38%) received new treatment. 13/44 (30%) controls received new treatment. 10/21 (48%) with abnormal scans started a bisphosphonate, compared with 7/44 (16%) controls (RR = 3, p = 0.004). No difference in risk factors for fracture was found in treated and untreated controls.

CONCLUSIONS

GPs were three times more likely to start potent osteoporosis treatment after abnormal scans than GPs relying on clinical information. In practice, risk factors were not adequately assessed. Database searches may identify patients needing osteoporosis prophylaxis; however, DXA enables more appropriate patient treatment.

Examination, prevention and treatment of osteoporosis in patients with inflammatory bowel disease: recommendations and reality

BACKGROUND

Patients with inflammatory bowel disease (IBD) are at increased risk of developing osteopenia and osteoporosis. Our aim was to evaluate the current practices of examination, prevention and treatment of osteoporosis in IBD patients in a routine clinical setting.

METHODS

A total of 154 consecutive patients with IBD (63 female, 91 male; 36 ulcerative colitis, 115 Crohn's disease, 3 indeterminate colitis), referred to two gastroenterological units for scheduled follow-up examinations, were included. Patient charts were evaluated regarding bone densitometry already performed and any prophylactic or therapeutic interventions in cases of low bone mineral density.

RESULTS

Bone mineral density (BMD) measurements had been performed only in 38 patients (25%). BMD was abnormally low in 27 of the examined patients (71%), 20 of whom had osteopenia and seven had osteoporosis. Among the subgroup of patients on long-term steroid therapy (77 patients), 30 had been referred to bone densitometry during the course of disease, and 21 of them were found to have low bone mineral density. Preventive measures were prescribed in 12 patients (9% of the whole study population). In the majority of the patients with low bone mineral density, calcium and vitamin D were used as treatment.

CONCLUSIONS

Despite the high prevalence of osteopenia and osteoporosis in patients with IBD, only a minority of these patients were included in a structured program in accordance with modern guidelines for diagnosing and preventing this extraintestinal complication in a routine clinical setting.

Corticosteroid-Induced osteoporosis: detection and management

Corticosteroid-induced osteoporosis is a major cause of morbidity and is the leading secondary cause of osteoporosis today. Unfortunately, despite this knowledge, patients receiving corticosteroid therapy are often not offered any preventative treatment. Recent research has focused attention on the critical role the osteoblast has played in the pathophysiology of corticosteroid-induced osteoporosis. In addition to an initial increase in bone resorption, there is evidence that corticosteroids induce osteoblast and osteocyte apoptosis and as a result are important contributors to bone loss. Interesting work has suggested that the bisphosphonates and calcitonin may help to prevent osteoblast apoptosis from occurring. Large scale randomised controlled trials have also been completed with a variety of therapeutic agents. Of the many different therapies, it is now clear that the bisphosphonates have the greatest evidence to support their use. Increases in bone mineral density when compared with a control group, not only at the spine but also at the hip, have been demonstrated. These studies have shown clinically significant reductions in vertebral fracture rates seen for the most part in postmenopausal women. Other therapies may well be effective, as evidenced by maintenance of bone mass in the spine; however, maintenance of bone mass in the hip and reductions in fracture rate have yet to be demonstrated for many of these therapies. Given our current knowledge and the evidence that is outlined in this review, it is hoped that patients who require therapy with corticosteroids for more than 3 months will be offered appropriate preventative treatment.

Prevalence of long term steroid treatment and the frequency of decision making to prevent steroid induced osteoporosis in daily clinical practice

BACKGROUND

The use of oral corticosteroids (CS) is one of the most common causes of iatrogenic osteoporosis. Recently, therapeutic guidelines dealing with the skeletal complication of CS have been published.

OBJECTIVE

To evaluate how CS are used in the community and the frequency of active intervention against corticosteroid induced osteoporosis in daily clinical practice.

MATERIAL AND METHODS

After approval by the Committee on Medical Ethics and the Data Protection Commission all prescriptions for CS which were filled by pharmacies in the northeast area of Iceland (population 26,664) during a two year period were collected. Thereafter, clinical information was obtained from medical records at the healthcare centres and from the local hospital. Patients who were taking CS for at least three months a year or for repeated periods (for a total of three months annually) were included in the study. These patients also received a questionnaire about hormone replacement therapy, bisphosphonates, and dietary consumption of calcium and vitamin D.

RESULTS

A total of 191 patients were included in the study or 0.7% of the population. Their mean age was 66 years (17-93) and 106/191 (55%) were women. Only 63 (33%) patients had no registered complication due to the treatment, according their medical records. Thirty nine (20%) patients had had an osteoporosis related fracture and 50 (26%) of the patients had presumed CS induced osteoporosis. A total of 52% patients were receiving supplementary vitamin D (fish liver oil) and 37% were taking calcium tablets regularly, while 91% of the patient group were consuming milk products regularly. Only 17 (9%) patients were taking bisphosphonates and 18/81 (22%) of the postmenopausal women were receiving hormone replacement therapy.

CONCLUSIONS

Relatively few patients receiving long term treatment with CS are also receiving primary prevention against CS induced osteoporosis, although several patients are taking vitamin D and calcium tablets. Specific treatment against osteoporosis was in most cases instituted secondary to osteoporotic complications. Thus although there are available treatment alternatives against CS induced osteoporosis, the doctors who prescribed CS did not make use of this form of treatment for their patients.

Inhaled corticosteroids reduce bone mineral density in early postmenopausal but not premenopausal asthmatic women

Inhaled corticosteroids are widely used in the treatment of bronchial asthma, but it is still uncertain whether long-term use of the inhaled corticosteroids affects bone metabolism in asthmatic patients. In this study, we examined the effect of inhaled beclomethasone dipropionate (BDP) on bone mineral density (BMD) and biochemical markers of bone metabolism in pre- and early postmenopausal asthmatic women. Thirty-six (17 premenopausal and 19 early postmenopausal) asthmatic women and 45 healthy control (24 premenopausal and 21 early postmenopausal) women were investigated. All the asthmatic patients were treated with BDP (542 +/- 298 microg/day; 100-1200 microg/day) without any systemic administration of corticosteroids for at least 1 year. In premenopausal women, BMD as well as the biochemical markers of bone metabolism did not differ between control subjects and BDP-treated asthmatic patients. By contrast, in early postmenopausal women, BMD was significantly lower in BDP-treated asthmatic patients than in control subjects. In these early postmenopausal women, serum intact osteocalcin concentration was lower in the BDP-treated asthmatic patients than in the control subjects whereas urinary free pyridinoline (F-PYD) and free deoxypyridinoline (F-DPD) concentrations did not differ between the groups. Thus, early postmenopausal, but not premenopausal, asthmatic patients who were treated with inhaled BDP had reduced BMD, which was associated with a decreased level of the bone formation marker. Ovarian hormones may be protective against the adverse effect of inhaled BDP on bone metabolism in the premenopausal patients.

Data driven attempt to create a clinical algorithm for identification of women with rheumatoid arthritis at high risk of osteoporosis

OBJECTIVES

To examine relations between osteoporosis and low bone mass and demographic and clinical variables in patients with rheumatoid arthritis (RA), in an attempt to develop a data driven clinical tool for identification of patients at high risk of osteoporosis.

METHODS

All patients were recruited from a county based register and were examined cross sectionally with a variety of clinical and health status measures as well as bone density measures (anteroposterior spine L2-4, total hip, and femoral neck). Associations between osteoporosis (T score < or = -2.5SD) and low bone mass (T score < or = -1SD), on the one hand, and demographic and clinical measures, on the other, were examined bivariately and by logistic regression analyses.

RESULTS

394 patients with a mean age of 54.8 years were examined. The percentages having osteoporosis/low bone mass were 16.8/45.8, 14.7/54.5 and 14.7/55.5 in spine L2-4, total hip, and femoral neck, respectively. Osteoporosis and low bone mass were bivariately related to age, body mass index (BMI), disease duration, disease process measures, presence of deformed joints, physical disability, current use of corticosteroids, and history of non-vertebral fracture. In multivariate analyses, age >60 years, low BMI, and current use of corticosteroids were consistently related to osteoporosis and to low bone mass at all sites. The presence of deformed joints was associated with osteoporosis at the total hip, and a history of previous non-vertebral fracture with osteoporosis at the femoral neck. The Modified Health Assessment Questionnaire (MHAQ) > or = 1.5 and non-vertebral fracture were also independently associated with low bone mass at the hip. The logistic regression analyses models could, however, only predict osteoporosis with a sensitivity of about 50-60% and a specificity of 80-90% at the various measurement sites, and low bone mass with a sensitivity and specificity of about 70%.

CONCLUSION

Consideration of demographic and disease markers may be of some help in predicting presence of osteoporosis or low bone mass, but a combination of markers cannot be used as a clinical tool with sufficient sensitivity and specificity for the identification of osteoporosis or low bone mass in patients with RA.

Comparative response in growth and bone status to three dexamethasone treatment regimens in infant piglets

The objectives of this study were 1) to determine whether a zenith in bone formation (indicated by circulating osteocalcin) existed at night in early life, and 2) to compare the effects of three different dexamethasone (DEX) treatment regimens on bone turnover, bone mineral content, and growth. Three DEX treatment regimens were tested in 8-d-old piglets (n = 8/group): 1) low evening dose of DEX (0.5 mg/kg/d) as 70% in the morning and 30% in the evening for 10 d; 2) tapering course of DEX (0.5, 0.3, and 0.2 mg/kg/d) as 50% in the morning and 50% in the evening for 14 d; and 3) constant dose of DEX (0.5 mg/kg/d) as 50% in the morning and 50% in the evening for 10 d. Oral water placebo groups were tested with the same time courses. At pretreatment, plasma osteocalcin was significantly higher (p < 0.05) at 0100 than at 0900 and 1700. At necropsy, measures for DEX groups were calculated as Z-scores using values from the placebo groups. The low evening DEX dose led to a significantly lower reduction in plasma osteocalcin compared with the tapered and constant dosing regimens (p < 0.05). The significant weight. reduction in the DEX group occurred at d 9 in the low evening dose regimen but at d 7 in the constant dosing regimen, compared with the placebo group. Bone mineral content Z-score was reduced similarly in all DEX-treated groups across the three dosing regimens. We conclude that a plasma osteocalcin zenith at night exists in early life. A high DEX dose in the morning and low DEX dose in the evening may partially attenuate corticosteroid-induced suppression of bone formation and growth restriction.

Long-term corticosteroid therapy induces mild changes in trabecular bone texture

The relative roles of bone mineral density (BMD) decrease and of microarchitectural changes in corticosteroid-induced osteoporosis (CIOP) are debated. Our objective has been to evaluate both bone microarchitecture (by a fractal analysis of texture on radiographs) and BMD in corticosteroid (CS)-treated patients. In this study, 60 patients from a rheumatology unit with a mean age of 60.6+/-14.8 years taking CS therapy for more than 6 months and a cumulative dose of prednisone over 1 g and 57 controls among age-matched patients and hospital staff were recruited. Bone diseases and bone-modifying drugs (except calcium, vitamin D, and hormonal replacement therapy [HRT]) were considered as exclusion criteria. A fractal analysis of trabecular bone texture was performed on calcaneus radiographs after an oriented analysis in 18 directions. The fractal analysis was based on the fractional Brownian motion model. Results were expressed by H parameter (H = 2 - fractal dimension) in each direction, Hmean being the average of 18 directions, Hmini the minimum, and Hmaxi the maximum. BMD was measured by double-energy X-ray absorptiometry (DEXA) at the femoral neck (FN) and lumbar spine (LS). The odds ratios (OR) were calculated for a variation of 1 SD. The mean duration and dose of CS therapy was 5.6+/-6.6 years and 16.9+/-19.7 g. CS therapy was significantly correlated to a decrease in FN or LSBMD: OR = 1.95, 95% confidence interval (CI, 1.29-2.97) and OR = 3.19 (CI, 1.80-5.66), respectively. The Hmean and Hmaxi were significantly lower in the cases than in the controls: P = 0.03 and P = 0.02; OR = 1.67 (CI, 1.10-2.54) and OR = 1.75 (CI, 1.05-2.37). A similar trend was observed with Hmini but the difference did not reach the level of statistical significance: P = 0.06, OR = 1.57 (CI, 1.05-2.37). This study was repeated among cases and controls who had never taken HRT (respectively, n = 40 and n = 39). The results were similar. Among patients taking CS therapy, the presence of nontraumatic fractures was inversely related to BMD values but not to texture parameters. These data have shown that long-term CS therapy induces both BMD decrease and trabecular bone texture changes. The effect of CS therapy was much stronger on BMD than on the fractal H parameter. These results are in accordance with previous studies showing a lower effect of CS therapy on bone microarchitecture than on bone mass. These results can be contrasted with those observed in women with postmenopausal osteoporosis and vertebral crush fractures in which the variations in the fractal parameters are more significant than the BMD variations.

Rheumatic manifestations of current pharmacopeia

Patient complaints arising as manifestations of medication side effects are commonly encountered in clinical practice. A rheumatologist must routinely consider side effects of drugs in the differential diagnosis of many symptoms. This review will remind the reader of certain well-described and some newly reported side effects commonly encountered in an internal medicine practice. Focal points incude arthralgias/arthritis, myopathy/myositis, ANA/drug-induced lupus, bone loss/osteoporosis, and tendon rupture.

Impaired development of bone mineral density during chemotherapy: a prospective analysis of 46 children newly diagnosed with cancer

Osteopenia and osteoporosis are becoming increasingly recognized in children with cancer, though reasons for these changes are poorly understood. The purpose of the present study was to evaluate longitudinal changes in bone mineral density (BMD) and bone turnover in newly diagnosed children with a malignancy. Lumbar spine (L2-L4) and femoral neck bone mineral density (BMDareal, g/cm2) was measured by dual-energy X-ray absorptiometry in 46 children (age 2.9-16.0, median 8.0 years; 15 leukemias, 12 lymphomas, 19 solid tumors) at diagnosis, and after 6 months from the baseline. The apparent volumetric bone mineral density (BMDvol) was calculated to minimize the effect of bone size on BMD. Serum levels of osteocalcin (OC), type I collagen carboxy-terminal propeptide (PICP), and type I collagen carboxy-terminal telopeptide (ICTP) were analyzed at diagnosis, and during a 6-month follow-up. A significant decrease in lumbar BMDvol (-2.1%, p < 0.05), and in femoral BMDareal (-9.9%, p = 0.0001) and BMDvol (-8.5%, p = 0.0001) was observed after 6 months when compared with baseline measurements. The markers of bone formation (PICP, OC) were significantly decreased, and the marker of bone resorption (ICTP) was significantly increased at diagnosis as compared with normal values. By the end the follow-up, the levels of PICP and OC were normalized, whereas the level of ICTP continued to increase indicating that there was a negative balance in bone turnover. A deficient accumulation of bone mass might predispose children with a malignancy to impaired development of peak bone mass. A controlled study determining the benefits of an early intervention on bone turnover should be considered in these patients.

Disturbance in bone turnover in children with a malignancy at completion of chemotherapy

BACKGROUND

Osteoporosis and pathological fractures have been observed in children with a malignancy. The mechanisms of osteopenia in childhood malignancies have not been well established. The purpose of the present study was to evaluate changes in bone turnover and in bone hormonal metabolism in children with a malignancy at completion of their chemotherapy.

PROCEDURE

Serum levels of human intact osteocalcin, type I collagen carboxyterminal propeptide (PICP), type I collagen carboxyterminal telopeptide (ICTP), 25-hydroxyvitamin D [25-(OH)-D], 1,25-dihydroxyvitamin D [1, 25-(OH)(2)-D], intact parathyroid hormone, insulin-like growth factor I (IGF-I), IGF binding protein 3 (IGFBP-3), alkaline phosphatase, calcium, and phosphate were analyzed in 22 children with acute lymphoblastic leukemia and in 26 children with other malignancies. Results were expressed as Z-scores [mean (95% confidence intervals)] relative to healthy Caucasian-children.

RESULTS

The marker of collagen degradation (ICTP) was significantly increased [1.43 (1.10-1.76), P < 0.0001] compared to reference values, whereas the markers of bone formation (PICP, osteocalcin) were not changed [0.07 (-0.55 to 0.49), 0.35 (-0.05 to 0.74), respectively, NS]. Serum 25-(OH)-D, 1,25-(OH)(2)-D, and calcium were significantly reduced [-0.65 (-0.87 to -0.42), -0.68 (-0.92 to -0. 42), -1.42 (-1.80 to -1.04), P < 0.0001, respectively].

CONCLUSIONS

Disturbance in bone turnover with low serum 25-(OH)-D, 1, 25-(OH)(2)-D, and calcium was observed in children with a malignancy at completion of their chemotherapy. A controlled study determining the possible benefits of vitamin D and calcium supplementation on bone turnover could be considered in these patients.

Risedronate therapy prevents corticosteroid-induced bone loss: a twelve-month, multicenter, randomized, double-blind, placebo-controlled, parallel-group study

OBJECTIVE

Risedronate, a new pyridinyl bisphosphonate, is a potent antiresorptive bone agent. This study examines the safety and efficacy of daily, oral risedronate therapy for the prevention of corticosteroid-induced bone loss.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group study was conducted in 224 men and women who were initiating long-term corticosteroid treatment. Patients received either risedronate (2.5 mg or 5 mg) or placebo daily for 12 months. Each patient also received 500 mg of elemental calcium daily. The primary outcome measure was the percentage of change in lumbar spine bone mineral density (BMD). Secondary measures included proximal femur BMD and incidence of vertebral fractures.

RESULTS

After 12 months, the lumbar spine BMD (mean +/- SEM) did not change significantly compared with baseline in the 5-mg (0.6 +/- 0.5%) or the 2.5-mg (-0.1 +/- 0.7%) risedronate groups, while it decreased in the placebo group (-2.8 +/- 0.5%; P < 0.05). The mean differences in BMD between the 5-mg risedronate and the placebo groups were 3.8 +/- 0.8% at the lumbar spine (P < 0.001), 4.1 +/- 1.0% at the femoral neck (P < 0.001), and 4.6 +/- 0.8% at the femoral trochanter (P < 0.001). A trend toward a decrease in the incidence of vertebral fracture was observed in the 5-mg risedronate group compared with the placebo group (5.7% versus 17.3%; P = 0.072). Risedronate was well tolerated, and the incidence of upper gastrointestinal adverse events was comparable among the 3 groups.

CONCLUSION

Risedronate therapy prevents bone loss in patients initiating long-term corticosteroid treatment.

Postpartum bone mineral density following antenatal dexamethasone therapy

The aim of this study was to determine whether the changes in bone metabolism, which we have demonstrated previously with antenatal dexamethasone therapy, are associated with a lower bone mineral density. We assessed bone mineral density in the proximal femur and lumbar spine using dual photon X-ray absorptiometry after delivery in 15 women who received dexamethasone therapy for fetal lung maturation, and in 30 women who did not have dexamethasone therapy in pregnancy. The absolute bone mineral density, T scores and Z scores at the proximal femur and lumbar spine were similar, and the median values of T and Z scores were positive in both groups. We conclude that antenatal dexamethasone therapy has no long term effect on bone mineral density.

The role of vitamin D in corticosteroid-induced osteoporosis: a meta-analytic approach

OBJECTIVE

To determine if vitamin D is more effective than no therapy or calcium alone in the management of corticosteroid-induced osteoporosis, and to determine how vitamin D compares with other osteoporosis therapies, e.g., bisphosphonates, calcitonin, or fluoride, for this condition.

METHODS

We evaluated all formulations of vitamin D, including its active metabolites and analogs. A systematic search for published and unpublished studies was conducted using MEDLINE (1966-December 1997), bibliographic references, abstracts from proceedings of recent national meetings, and contact with pharmaceutical companies and content experts. We included all randomized controlled trials lasting at least 6 months (and reporting extractable results), of patients receiving oral corticosteroids, that compared vitamin D with either 1) no therapy or calcium alone, or 2) bisphosphonates, calcitonin, or fluoride. The primary outcome measure of interest was change in lumbar spine bone mineral density.

RESULTS

We found a moderate beneficial effect of vitamin D plus calcium versus no therapy or calcium alone (9 trials) (effect size 0.60; 95% confidence interval [95% CI] 0.34, 0.85; P < 0.0001). In comparisons of vitamin D with other osteoporosis therapies, bisphosphonates were more effective than vitamin D (6 trials) (effect size 0.57; 95% CI 0.09, 1.05). Calcitonin was similar in efficacy to vitamin D (4 trials) (effect size 0.03; 95% CI -0.39, 0.45). Fluoride was more effective than vitamin D, but there were only 2 trials.

CONCLUSION

Vitamin D plus calcium is superior to no therapy or calcium alone in the management of corticosteroid-induced osteoporosis. Vitamin D is less effective than some osteoporosis therapies. Therefore, treatment with vitamin D plus calcium, as a minimum, should be recommended to patients receiving long-term corticosteroids.

Fracture risk after surgery for peptic ulcer disease: a population-based cohort study

In the 30-year period from 1956 to 1985, 471 Rochester, MN residents had an initial operation for peptic ulcer disease, 438 of whom were followed for at least 30 days (median 14.8 years per subject). In this population-based cohort, risk was elevated for all of the fracture sites traditionally associated with osteoporosis, including the proximal femur (standardized incidence ratio [SIR] 2.5, 95% CI 1.9-3.3), vertebra (SIR 4.7, 95% CI 3.8-5.7), and distal forearm (SIR 2.2, 95% CI 1.5-3.1). Fracture risk rose with age and was greater among women than men, but there was no influence on overall fracture risk of ulcer type or nature of the operation. In multivariate analyses, the independent predictors of vertebral fractures were age (hazard ratio [HR] per 10-year increase 1.8, 95% CI 1.6-2.0), use of corticosteroids (HR 2.3, 95% CI 1.01-5.2), thyroid replacement (HR 2.5, 95% CI 1.4-4.6), chronic anticoagulation (HR 2.3, 95% CI 1.1-4.6), and the presence of one or more conditions associated with secondary osteoporosis (HR 1.6, 95% CI 1.2-2.1). Gastrectomy with Billroth II reconstruction appeared to be relatively protective (HR 0.5, 95% CI 0.3-0.9), but such patients still had an increased risk of vertebral fractures compared with community residents generally (SIR 3.6, 95% CI 2.4-5.4). The independent predictors of hip fracture risk in this cohort were age (HR 2.7, 95% CI 2.1-3.5) and use of corticosteroids (HR 5.8, 95% CI 2.2-15.3) or anticonvulsants (HR 4.6, 95% CI 1.8-12.0), while higher body mass index was protective (HR 0.9, 95% CI 0.8-0.96). The independent predictors of distal forearm fractures were female gender (HR 4.7, 95% CI 2.2-10.1) and chronic anticoagulant use (HR 2.8, 95% CI 1.1-7.3). Thus, while the risk of osteoporotic fractures was significantly increased among patients operated for peptic ulcers, this appeared to be due more to specific characteristics of the cohort than to adverse effects of particular surgical procedures.

Flixotide Nebules: new for chronic severe asthma

Allen & Hanburys recently launched Flixotide Nebules for prophylactic management of severe chronic asthma in patients requiring high-dose inhaled or oral corticosteroid therapy.

Reduced bone density at completion of chemotherapy for a malignancy

OBJECTIVES

Osteoporosis and pathological fractures occur occasionally in children with malignancies. This study was performed to determine the degree of osteopenia in children with a malignancy at completion of chemotherapy.

METHODS

Lumbar spine (L2-L4) bone mineral density (BMD; g/cm2) and femoral neck BMD were measured by dual energy x ray absorptiometry in 22 children with acute lymphoblastic leukaemia (ALL), and in 26 children with other malignancies. Apparent volumetric density was calculated to minimise the effect of bone size on BMD. Results were compared with those of 113 healthy controls and expressed as age and sex standardised mean Z scores.

RESULTS

Patients with ALL had significantly reduced lumbar volumetric (-0.77) and femoral areal and volumetric BMDs (-1.02 and -0.98, respectively). In patients with other malignancies, femoral areal and apparent volumetric BMDs were significantly decreased (-0.70 and -0.78, respectively).

CONCLUSIONS

The results demonstrate that children with a malignancy are at risk of developing osteopenia. A follow up of BMD after the completion of chemotherapy should facilitate the identification of patients who might be left with impaired development of peak bone mass, and who require specific interventions to prevent any further decrease in their skeletal mass and to preserve their BMD.

Secondary osteoporosis and the risk of vertebral deformities in women

Among an age-stratified sample of 942 Rochester, MN women, the overall prevalence of any vertebral deformity, as assessed by radiographic morphometry, was 21.3 per 100. The prevalence increased with age and, after adjusting for age, vertebral deformities were independently associated with height, weight, a history of distal forearm or hip fractures, and anticoagulant use. Altogether, 73% of the women with a vertebral deformity and 66% of controls had one or more of the conditions that have been linked with secondary osteoporosis, which in aggregate were associated with an age-adjusted 1.2-fold (95% CI 0.8-1.7) increase in risk that was not statistically significant. The prevalence of severe vertebral deformities was 11.7 per 100 women and the prevalence of very severe deformities was 5.7 per 100. There was a stronger relationship of age and most other risk factors with severe vertebral deformities than with isolated mild deformities, suggesting that a subset of mild deformities may not represent actual vertebral fractures. The metabolic disorders linked with secondary osteoporosis were associated with little increase in the risk of severe vertebral deformities, taken together, or of mild deformities. However, in aggregate these conditions were associated with a 2.3-fold increase (95% 1.1-4.8) in very severe vertebral deformities, which points to a role for rapid cancellous bone loss among women with the worst spinal osteoporosis.

Prevention and treatment of glucocorticoid-induced osteoporosis

Glucocorticoid-induced osteoporosis is a common clinical problem. This review briefly summarizes the pathogenesis of this disorder. All relevant studies on the prevention and treatment of glucocorticoid-induced osteoporosis are discussed more in detail. As the results of these studies are inconclusive, a proposal for a practical approach of the individual patient is formulated.

A UK Consensus Group on management of glucocorticoid-induced osteoporosis: an update

In the UK, over 250 000 patients take continuous oral glucocorticoids (GCs), yet no more than 14% receive any therapy to prevent bone loss, a major complication of GC treatment. Bone loss is rapid, particularly in the first year, and fracture risk may double. This review, based wherever possible on clinical evidence, aims to provide easy-to-use guidance with wide applicability. A treatment algorithm is presented for adults receiving GC doses of 7.5 mg day(-1) or more for 6 months or more. General measures, e.g. alternative GCs and routes of administration, and therapeutic interventions, e.g. cyclical etidronate and hormone replacement, are recommended.

Effects of inhaled corticosteroids on bone density and metabolism

Oral corticosteroids have adverse effects on bone density and metabolism. With the increased use of inhaled corticosteroids together with the use of higher doses for the treatment of asthma, the long-term effects of inhaled corticosteroids on bone metabolism and density must be evaluated. This article discusses the markers of bone resorption and formation together with techniques used to measure cortical and trabecular bone density. The effects of inhaled corticosteroids on bone density and metabolism as determined by these techniques are described in detail. Overall, inhaled corticosteroids are extremely safe, even at high doses, with the long-term risk of bone loss being extremely small compared with oral corticosteroids. In particular, fluticasone propionate at the recommended doses appears to be free of effects on bone density and metabolism. Finally, the use of inhaled corticosteroids results in the control of asthma, allowing patients to exercise, which itself improves bone density and protects against osteoporosis.

Mechanisms of bone loss after cardiac transplantation

To determine the mechanism of bone loss after cardiac transplantation (CTX), we studied 50 men 0.5-47 months after CTX (ages 18-64 years) who received prednisolone and cyclosporin to prevent rejection, and 40 healthy men as controls (ages 20-70 years). We measured bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA), bone resorption using urinary cross-linked N-terminal telopepides of type I collagen (NTx), and bone formation using osteocalcin (BGP) and bone alkaline phosphatase (BAP). The results from the controls were used to calculate z scores. BMD was significantly decreased at the lumbar spine, femoral neck, and total body, and bone turnover was significantly increased as assessed by NTx/creatinine, BGP, and BAP as compared with controls (p < 0.01 for all measurements). To evaluate the cause of the increased bone turnover we measured serum parathyroid hormone (PTH) by IRMA, and this was also elevated (p < 0.001). There was a significant correlation between serum PTH and BGP (r = 0.58, p < 0.01). To evaluate the cause of the increase in PTH, we measured serum calcium and it was decreased (p < 0.001), serum phosphorus was increased (p < 0.001), serum creatinine was increased (p < 0.001), and serum 1,25-dihydroxyvitamin D3 [1,25(OH)2D, RIA] was decreased (p = 0.03). Serum PTH correlated weakly with serum calcium (r = -0.41, p < 0.003) and with serum creatinine (r = 0.35, p = 0.01). There was a weak, but significant, correlation between serum creatinine and 1,25(OH)2D3 (r = 0.33, p = 0.03). Serum levels of testosterone and dehydroapiandrosterone sulfate were decreased after CTX but did not correlate with any other parameters. There was a weak negative correlation between prednisolone daily dose and serum BGP level (r = 0.29, p = 0.06) in those patients whose prednisolone current dose was >7.5 mg/day. We conclude that: (1) the low BMD found after CTX is associated with increased bone turnover which results, in turn, from renal impairment; (2) prednisolone is involved in rapid bone loss, whereas mild secondary hyperparathyroidism may be a major contributor to disorder of bone remodeling after this rapid loss; and (3) decreased androgen levels may not be a major factor resulting in bone loss in men after CTX.

Fracture risk among patients with urolithiasis: a population-based cohort study

In a population-based retrospective cohort study, 624 Rochester, Minnesota residents with an initial symptomatic episode of urolithiasis in 1950 to 1974 were followed for 11,909 person-years for subsequent age-related fractures. During this period of observation, the number of patients with a first vertebral fracture was over four times the number expected on the basis of vertebral fracture incidence rates in the general population of Rochester [standardized morbidity ratio (SMR), 4.3; 95% confidence interval, 3.4 to 5.3]. The risk of vertebral fracture was elevated among men as well as women, and was associated with increasing age and with the use of corticosteroids for more than six months. However, vertebral fracture risk was increased nearly fourfold (SMR 3.9; 95% confidence interval, 3.0 to 4.9) among the urolithiasis patients without such exposure, which suggests that corticosteroids do not completely account for the association with vertebral fractures. There was no increase in the risk of hip, pelvis, proximal humerus or distal forearm fractures in this cohort of patients, and their survival was not impaired. Additional studies are needed to define the pathophysiology of vertebral fractures among patients with urolithiasis.

Epidemiology of spinal osteoporosis

Approximately 30% of postmenopausal white women in the United States have osteoporosis, and 16% have osteoporosis of the lumbar spine in particular. Bone density of the spine is positively associated with greater height and weight, older age at menopause, a history of arthritis, more physical activity, moderate use of alcoholic beverages, diuretic treatment, and current estrogen replacement therapy, whereas later age at menarche and a maternal history of fracture are associated with lower levels of density. Low bone density leads to an increased risk of osteoporotic fractures. Fracture risk also increase with age. Vertebral fractures affect approximately 25% of postmenopausal women, although the exact figure depends on the definition used. Recent data show that vertebral fracture rates are as great in men as in women but, because women live longer, the lifetime risk of a vertebral fracture from age 50 onward is 16% in white women and only 5% in white men. Fracture rates are less in most nonwhite populations, but vertebral fractures are as common in Asian women as in those of European heritage. Other risk factors for vertebral fractures are less clear but include hypogonadism and secondary osteoporosis; obesity is protective of fractures as it is of bone loss. Compared with hip fractures, vertebral fractures are less disabling and less expensive, costing approximately $746 million in the United States in 1995. However, they have a substantial negative impact on the patient's function and quality of life. The adverse effects of osteoporotic fractures are likely to increase in the future with the growing number of elderly people.

Overview of role of BMD measurements in managing osteoporosis

The advent of effective treatments and the opportunity to precisely and accurately measure bone mass have probably been the greatest advances in the field of osteoporosis in the last decade. Bone densitometry has become the most widespread noninvasive method for the detection of osteoporosis and to provide advice on risk of future fractures. It has achieved an unquestioned role in clinical decision making for the management of osteoporotic patients.

Secondary osteoporosis

Secondary osteoporosis is diagnosed when there is a well-established disease-related risk factor for fracture or low bone mass. Secondary osteoporosis is associated with a substantial minority of osteoporotic fractures in women perhaps with a majority of osteoporotic related fractures in men. This chapter does not review all the possible causes of low bone mass and fractures but picks out some of the more important causes of, with an emphasis on the main iatrogenic cause, that is corticosteroid induced osteoporosis. It also highlights some of the possible causes which could be avoidable. Where appropriate the methods of prevention and treatment of secondary osteoporosis are reviewed.

Dexamethasone suppresses in vivo levels of bone collagen synthesis in neonatal mice

The objective of this study was to determine the acute effects of glucocorticoids on in vivo levels of bone collagen synthesis in neonatal mice. Mice were injected with vehicle or dexamethasone at the start of the experiment. At 22 h, mice were given a 10 microCi injection of [3H]proline. At 24 h, the mice were sacrificed and the incorporation of [3H]proline into collagenase-digestible CDP labeling) and noncollagen (NCP labeling) protein in calvariae were determined by digestion with bacterial collagenase. Calvarial RNA was analyzed for COL 1A1 and osteocalcin mRNA levels by Northern blotting. After 24 h, vehicle-treated mice showed a 9.8 +/- 1.0% weight gain while dexamethasone-treated mice (1 mg/kg) had a 7.4 +/- 0.8% weight loss. Dexamethasone (1 mg/kg) decreased CDP and NCP labeling in calvariae by 51 +/- 4% and 17 +/- 4%, respectively (13 experiments). The inhibitory effect on protein labeling was selective for collagen since dexamethasone decreased the percent collagen synthesis from 25.4 +/- 1.6% to 16.6 +/- 1.0% (13 experiments). Dexamethasone at 3 mg/kg also decreased CDP labeling and the percent collagen synthesis in calvariae. There was a 30% reduction in COL1A1 mRNA levels and a 67% decrease in osteocalcin mRNA levels. To determine the reversibility of the inhibition of collagen synthesis, mice were given a single injection of dexamethasone (1 mg/kg) and then injected with [3H]proline 2 h prior to sacrifice at 24, 48, or 72 h. The reduction in CDP labeling observed at 24 h was fully reversed by 48-72 h. Moreover, by 72 h, the-rate of weight gain by dexamethasone-treated mice was similar to vehicle-treated controls. These data show that administration of dexamethasone to neonatal mice leads to a selective decrease in bone collagen synthesis within 24 h that is accompanied by down-regulation of osteocalcin and COL1A1 mRNA levels. This model will be useful in determining mechanisms by which high dose glucocorticoids inhibit bone formation in vivo.

Current and potential future drug treatments for osteoporosis

There has been a major interest in the drug treatment of osteoporosis and an increase in the number of drugs available in most countries. The ideal drug (one which increases or restores bone density and trabecular connectivity) is still not available. However, in patients with relatively preserved trabecular connectivity and moderately reduced bone density, several agents have shown substantial clinical benefit. Oestrogens are still the mainstay of drug treatment, but the risks of breast cancer versus the cardiovascular and skeletal benefits with long term use have to be assessed in the individual. Newer tissue specific oestrogens show some promise in this respect. The bisphosphonates and possibly fluoride are likely to be the major alternatives to oestrogens in the medium term. The newer bisphosphonates, alendronate and in the future risedronate, are likely to supersede etidronate. Calcitriol probably has a limited role, confined to those patients in whom HRT or bisphosphonates are not appropriate. Calcium supplementation, or an increase in dietary intake if deficient, irrespective of which agent is used, is also of benefit. In older patients there is considerable support for using a combination of calcium and vitamin D. Whether combination treatment, for example oestrogens, bisphosphonates, and calcium together, will result in greater efficacy remains to be conclusively shown, but may be an attractive option in younger patients with higher bone turnover. Apart from fluoride, bone formation stimulators are unlikely to have a major role until the next century, although it may be possible to use growth factors as part of an ADFR regimen (A = activate remodelling, D = depress resorption, F = free formation, and R = repeat). This is still an important theoretical approach and needs further work with newer agents to see if increased efficacy can be found. In addition sequential treatment may be necessary in view of the limited time periods over which particular agents, such as intermittent fluoride (four years), have been examined, and this will have to be individually tailored. Other approaches include trying to increase peak bone mineral density, although influencing the young to prevent a disease that may not manifest itself for half a century is daunting.