Glucocorticoid-induced osteoporosis and its treatment

Hormone-Related and Drug-Induced Osteoporosis: A Cellular and Molecular Overview

Osteoporosis resulting from an imbalance of bone turnover between resorption and formation is a critical health issue worldwide. Estrogen deficiency following a nature aging process is the leading cause of hormone-related osteoporosis for postmenopausal women, while glucocorticoid-induced osteoporosis remains the most common in drug-induced osteoporosis. Other medications and medical conditions related to secondary osteoporosis include proton pump inhibitors, hypogonadism, selective serotonin receptor inhibitors, chemotherapies, and medroxyprogesterone acetate. This review is a summary of the cellular and molecular mechanisms of bone turnover, the pathophysiology of osteoporosis, and their treatment. Nuclear factor-κβ ligand (RANKL) appears to be the critical uncoupling factor that enhances osteoclastogenesis. In contrast, osteoprotegerin (OPG) is a RANKL antagonist secreted by osteoblast lineage cells. Estrogen promotes apoptosis of osteoclasts and inhibits osteoclastogenesis by stimulating the production of OPG and reducing osteoclast differentiation after suppression of IL-1 and TNF, and subsequent M-CSF, RANKL, and IL-6 release. It can also activate the Wnt signaling pathway to increase osteogenesis, and upregulate BMP signaling to promote mesenchymal stem cell differentiation from pre-osteoblasts to osteoblasts rather than adipocytes. Estrogen deficiency leads to the uncoupling of bone resorption and formation; therefore, resulting in greater bone loss. Excessive glucocorticoids increase PPAR-2 production, upregulate the expression of Dickkopf-1 (DKK1) in osteoblasts, and inhibit the Wnt signaling pathway, thus decreasing osteoblast differentiation. They promote osteoclast survival by enhancing RANKL expression and inhibiting OPG expression. Appropriate estrogen supplement and avoiding excessive glucocorticoid use are deemed the primary treatment for hormone-related and glucocorticoid-induced osteoporosis. Additionally, current pharmacological treatment includes bisphosphonates, teriparatide (PTH), and RANKL inhibitors (such as denosumab). However, many detailed cellular and molecular mechanisms underlying osteoporosis seem complicated and unexplored and warrant further investigation.

Osteoporosis Due to Hormone Imbalance: An Overview of the Effects of Estrogen Deficiency and Glucocorticoid Overuse on Bone Turnover

Osteoporosis is a serious health issue among aging postmenopausal women. The majority of postmenopausal women with osteoporosis have bone loss related to estrogen deficiency. The rapid bone loss results from an increase in bone turnover with an imbalance between bone resorption and bone formation. Osteoporosis can also result from excessive glucocorticoid usage, which induces bone demineralization with significant changes of spatial heterogeneities of bone at microscale, indicating potential risk of fracture. This review is a summary of current literature about the molecular mechanisms of actions, the risk factors, and treatment of estrogen deficiency related osteoporosis (EDOP) and glucocorticoid induced osteoporosis (GIOP). Estrogen binds with estrogen receptor to promote the expression of osteoprotegerin (OPG), and to suppress the action of nuclear factor-κβ ligand (RANKL), thus inhibiting osteoclast formation and bone resorptive activity. It can also activate Wnt/β-catenin signaling to increase osteogenesis, and upregulate BMP signaling to promote mesenchymal stem cell differentiation from pre-osteoblasts to osteoblasts, rather than adipocytes. The lack of estrogen will alter the expression of estrogen target genes, increasing the secretion of IL-1, IL-6, and tumor necrosis factor (TNF). On the other hand, excessive glucocorticoids interfere the canonical BMP pathway and inhibit Wnt protein production, causing mesenchymal progenitor cells to differentiate toward adipocytes rather than osteoblasts. It can also increase RANKL/OPG ratio to promote bone resorption by enhancing the maturation and activation of osteoclast. Moreover, excess glucocorticoids are associated with osteoblast and osteocyte apoptosis, resulting in declined bone formation. The main focuses of treatment for EDOP and GIOP are somewhat different. Avoiding excessive glucocorticoid use is mandatory in patients with GIOP. In contrast, appropriate estrogen supplement is deemed the primary treatment for females with EDOP of various causes. Other pharmacological treatments include bisphosphonate, teriparatide, and RANKL inhibitors. Nevertheless, more detailed actions of EDOP and GIOP along with the safety and effectiveness of medications for treating osteoporosis warrant further investigation.

The effect of pay for performance on risk incidence of hip fracture in type 2 diabetic patients: a nationwide population-based cohort study

OBJECTIVES

Diabetes mellitus (DM) increases the risk of hip fracture. The literature rarely discusses the importance of pay-for-performance (P4P) programs for the incidence of hip fractures in patients with type 2 DM (T2DM). This study aimed to examine the impact of the P4P program on hip fracture risk in patients with T2DM.

METHODS

This retrospective cohort study focused on data from T2DM patients aged 45 and older between 2001 and 2012. We continued to track these data until 2013. The data were collected from the National Health Insurance Research Database in Taiwan. To minimize selection bias, T2DM patients were divided into P4P enrollees and non-enrollees. Propensity score matching by greedy matching technique (1:1 ratio) was used to include 252,266 participants. A Cox proportional hazard model was performed to examine the impact of the P4P program on hip fracture risk. We used the bootstrap method to perform sensitivity analysis by random sampling with replacement.

RESULTS

Our results showed that the risk of hip fracture in P4P enrollees was 0.92 times that of non-enrollees. (hazards ratio [HR] = 0.92; 95% confidence interval [CI]: 0.85-0.99). P4P enrollees who received regular treatment had lower risk in the first 4 years (HR = 0.90; 95%CI: 0.84-0.96) but no statistically significant difference after 4-year enrollment (HR = 0.99; 95%CI: 0.93-1.06). There was no statistically significant difference in the effect of hip fractures between P4P non-enrollees and P4P enrollees with irregular treatment (HR = 0.94, 95%CI: 0.87-1.03). Through sensitivity analysis, the results also showed P4P enrollees had a lower risk of hip fracture compared to P4P non-enrollees (mean HR = 0.919; 95% CI: 0.912-0.926). Stratified analysis showed that patients without DM complications (DCSI = 0) who enrolled in P4P had lower risks of hip fractures than the non-enrollees (HR = 0.90; 95% CI: 0.82-0.98).

CONCLUSION

T2DM patients enrolled in P4P program can reduce the risks of hip fracture incidence. Early inclusion of patients without DM complications in the P4P program can effectively reduce hip fractures.

Mechanisms of bone fragility in a mouse model of glucocorticoid-treated rheumatoid arthritis: implications for insufficiency fracture risk

OBJECTIVE

Glucocorticoid (GC) therapy is associated with increased risk of fracture in patients with rheumatoid arthritis (RA). To elucidate the cause of this increased risk, we examined the effects of chronic erosive inflammatory arthritis and GC treatment on bone quality, structure, and biomechanical properties in a murine model.

METHODS

Mice with established arthritis and expressing human tumor necrosis factor α (TNFα) transgene (Tg) and their wild-type (WT) littermates were continually treated with GC (prednisolone 5 mg/kg/day via subcutaneous controlled-release pellet) or placebo for 14, 28, or 42 days. Microstructure, biomechanical properties, chemical composition, and morphology of the tibiae and lumbar vertebral bodies were assessed by micro-computed tomography, biomechanical testing, Raman spectroscopy, and histology, respectively. Serum markers of bone turnover were also determined.

RESULTS

TNF-Tg and GC treatment additively decreased mechanical strength and stiffness in both the tibiae and the vertebral bodies. GC treatment in the TNF-Tg mice increased the ductility of tibiae under torsional loading. These changes were associated with significant alterations in the biochemical and structural composition of the mineral and organic components of the bone matrix, a decrease in osteoblast activity and bone formation, and an increase in osteoclast activity.

CONCLUSION

Our findings indicate that the concomitant decrease in bone strength and increase in bone ductility associated with chronic inflammation and GC therapy, coupled with the significant changes in the bone quality and structure, may increase the susceptibility of the bone to failure under low-energy loading. This may explain the mechanism of symptomatic insufficiency fractures in patients with RA receiving GC therapy who do not have radiographic manifestations of fracture.

Activity restriction increases deoxypyridinoline excretion in hospitalized high-risk pregnant women

PURPOSE

Activity restriction (AR), one of the most common interventions used in high-risk pregnancies, may exacerbate loss of bone mass. The purpose of this study was to determine changes over time in bone resorption in hospitalized AR women during late pregnancy.

METHODS

This was a short-term prospective study conducted in two tertiary-care obstetric hospitals. We measured urinary deoxypyridinoline (Dpd) excretion, a marker of bone resorption, once per week in a convenience sample of 14 hospitalized AR women in the third trimester and compared values at 28-31 and 34-36 weeks' gestation to those of 11 ambulatory control women. Both groups completed a bone-loading questionnaire, 3-day food intake record, and pedometer step counts at the same gestational age.

RESULTS

Urinary Dpd excretion increased from Days 1-7 (2.60 ± 0.32 nmol/mmol creatinine) to Days 22-28 (5.36 ± 0.83 nmol/mmol creatinine; p ≤ .05). Dpd excretion was higher in AR women (4.51 ± 0.31 nmol/mmol creatinine) than ambulatory women (2.72 ± 0.39 nmol/mmol creatinine) at 34-36 weeks' gestation (p ≤ .05). Energy intake between ambulatory and AR women was not different (p ≥ .05). All women met the daily requirements for calcium and vitamin D intake during pregnancy. Average daily pedometer steps for the AR women were significantly less compared to controls (1,329 ± 936 and 8,024 ± 1,890 steps/day, respectively; p ≤ .05).

CONCLUSIONS

AR leads to increased bone resorption in hospitalized pregnant women, which may impact future risk of developing osteopenia and osteoporosis.

Raman spectroscopy detects deterioration in biomechanical properties of bone in a glucocorticoid-treated mouse model of rheumatoid arthritis

Although glucocorticoids are frequently prescribed for the symptomatic management of inflammatory disorders such as rheumatoid arthritis, extended glucocorticoid exposure is the leading cause of physician-induced osteoporosis and leaves patients at a high risk of fracture. To study the biochemical effects of glucocorticoid exposure and how they might affect biomechanical properties of the bone, Raman spectra were acquired from ex vivo tibiae of glucocorticoid- and placebo-treated wild-type mice and a transgenic mouse model of rheumatoid arthritis. Statistically significant spectral differences were observed due to both treatment regimen and mouse genotype. These differences are attributed to changes in the overall bone mineral composition, as well as the degree of phosphate mineralization in tibial cortical bone. In addition, partial least squares regression was used to generate a Raman-based prediction of each tibia's biomechanical strength as quantified by a torsion test. The Raman-based predictions were as accurate as those produced by microcomputed tomography derived parameters, and more accurate than the clinically-used parameter of bone mineral density. These results suggest that Raman spectroscopy could be a valuable tool for monitoring bone biochemistry in studies of bone diseases such as osteoporosis, including tests of drugs being developed to combat these diseases.

Decreased bone mineral density and vertebral compression fractures in a young adult male with 21-hydroxylase deficiency congenital adrenal hyperplasia (CAH): is CAH an unrecognized population at risk for glucocorticoid-induced osteoporosis?

BACKGROUND

CAH, most often due to a molecular defect in the 21-OH enzyme, results in inadequate cortisol production and subsequent life-long GC replacement.

AIMS

To heighten awareness for risk of GIO in children with CAH including (1) ongoing assessment of GC dosing, (2) screening for bone health, and (3) prophylactic measures/early intervention once GIO is identified.

PATIENT

23 year-old male with 21OHD CAH referred for osteopenia.

METHODS

Chart review; radiological, serological and urine assessment.

RESULTS

Patient has old vertebral compression fractures and diminished BMD, the onset of which likely corresponds to excessive GC dosing during adolescence.

CONCLUSION

As with other GC-dependent conditions, children with CAH may represent a previously unrecognized population at risk for GIO. Physicians need to be cognizant of the consequences of excessive GC dosing on bone health, especially during infancy and adolescence, critical periods for both linear growth as well as bone accretion.

Once-weekly oral alendronate 70 mg in patients with glucocorticoid-induced bone loss: a 12-month randomized, placebo-controlled clinical trial

OBJECTIVE

Glucocorticoid-induced osteoporosis is the most common iatrogenic form of osteoporosis. We evaluated the efficacy and safety of once-weekly bisphosphonate therapy for prevention and treatment of bone loss in patients on glucocorticoid therapy.

METHODS

We conducted a 12-month, multicenter, randomized, double-blind, placebo-controlled trial with 114 and 59 patients in the treatment and placebo arms, respectively. Participants were stratified according to the duration of prior oral glucocorticoid therapy at randomization. Participants received alendronate 70 mg once weekly (ALN OW) or placebo; all received supplemental daily calcium (1000 mg) and 400 IU vitamin D. Clinical evaluations were performed at baseline, 3, 6, 9, and 12 months.

RESULTS

At 12 months, there was a significant mean percentage increase from baseline in the ALN OW group for lumbar spine (2.45%), trochanter (1.27%), total hip (0.75%), and total body (1.70%) bone mineral density (BMD). Comparing ALN OW versus placebo at 12 months, a significant treatment difference for the mean percentage change from baseline was observed for lumbar spine (treatment difference of 2.92%; p </= 0.001), trochanter (treatment difference 1.66%; p = 0.007), and total hip (treatment difference 1.19; p = 0.008) BMD. Biochemical markers of bone remodeling also showed significant mean percentage decreases from baseline.

CONCLUSION

Over 12 months ALN OW significantly increased lumbar spine, trochanter, total hip, and total body BMD compared with baseline among patients taking glucocorticoid therapy. A significant treatment difference versus placebo was observed at 12 months for the mean percentage change from baseline for lumbar spine, trochanter, and total hip.

Calreticulin mediated glucocorticoid receptor export is involved in beta-catenin translocation and Wnt signalling inhibition in human osteoblastic cells

Wnt signalling pathway is a multicomponent cascade involving interaction of several proteins and found to be important for development and function of various cells and tissues. There is increasing evidence that the Wnt/beta-catenin pathway constitutes also one of the essential molecular mechanisms controlling the metabolic aspects of osteoblastic cells. However, in bone, glucocorticoids (GCs) have been reported to weaken Wnt signalling. Therefore, the aim of this study was to characterize the mechanisms behind the cross-talk of these two signalling pathways in human osteoblastic cells. Based on our findings, liganded glucocorticoid receptor (GR) modulated Wnt signalling pathway by decreasing beta-catenin's nuclear accumulation and increasing its relocalization to cell membranes rather than affecting its degradation in human osteoblastic cells. The region of GR responsible for this inhibitory effect located into an area, which harbours the DNA binding as well as nuclear export domains. In further studies, a chaperone protein calreticulin (CRT), known to bind the DNA binding domain of GR and regulate receptor export, was found to be involved in the GR-mediated downregulation of Wnt signalling: GR mutants containing incomplete CRT binding sites were not able to translocate beta-catenin to cell surface. In addition, the inhibitory effect of GCs on endogenous Wnt target gene, cyclin D1, was abolished, when the expression of CRT was attenuated by the RNAi technique. Furthermore, GR and beta-catenin were shown to exist in the same immunocomplex, while interaction between CRT and beta-catenin was observed only in the presence of GR as a mediator molecule. In addition, the GR mutant lacking CRT binding ability impaired the complex formation between beta-catenin and CRT. Together with GR, beta-catenin could thus be co-transported from the nucleus in a CRT-dependent way. These observations represent a novel mechanism for GCs to downregulate Wnt signalling pathway in human osteoblastic cells. Knowledge of these molecular mechanisms is important for understanding the network of multiple signalling cascades in bone environment. Functional Wnt signalling pathway is a prerequisite for proper osteoblastogenesis, and this modulative cross-talk between the steroid pathway and Wnt cascade could therefore explain some of the two-edged effects of GCs on osteoblastic differentiation and function.

Wnt and steroid pathways control glutamate signalling by regulating glutamine synthetase activity in osteoblastic cells

Glutamate signalling has recently been found functional also outside the central nervous system, especially in bone. Glutamate is converted to glutamine by glutamine synthetase (GS), which is therefore able to regulate intracellular concentrations of glutamate. We previously characterized the induction of GS expression by glucocorticoids (GCs) in human osteoblast-like cells. Besides this observation, the mechanisms controlling GS in bone are unknown. Therefore, the aim of our present study was to investigate further the regulation of GS in osteoblastic cells. We observed that vitamin D inhibited basal and, even more efficiently, GC-stimulated GS activity by affecting both the mRNA and protein levels of the enzyme in human MG-63 osteoblast-like cells. In osteoblasts derived from rat bone marrow stem cells (rMSCs), GS activity was induced accordingly by the osteogenic culture conditions including GCs. Also in these primary cells, vitamin D clearly inhibited GS activity. In addition, the canonical Wnt signalling pathway was characterized as a negative regulator of GS activity. All these changes in GS activity were reflected on the intracellular glutamate concentration. Our results provide novel evidence that GS activity and expression are regulated by several different signalling pathways in osteoblastic cells. Therefore, GS is a strategic enzyme in controlling glutamate concentration in bone environment: GCs decreased the amount of this signalling molecule while vitamin D and Wnt signalling pathway increased it. Interestingly, GS activity and expression declined rapidly when the rMSC derived osteoblasts began to mineralize. Due to its downregulation during osteoblast mineralization, GS could be held as a marker for osteoblast development. Further supporting this, GS activity was stimulated and intracellular glutamate concentration maintained by the N-methyl-d-aspartate (NMDA) type glutamate receptor antagonist MK801, which inhibited osteogenic differentiation of the rMSCs. GS, a novel target for both steroidal and Wnt pathways in bone, might be a central player in the regulation of osteoblastogenesis and/or intercellular signal transmission. Therefore, the proper understanding of the interplay of these three signalling cascades, i.e., steroidal, Wnt, and glutamate signalling, gives vital information on how bone cells communicate together aiming to keep bone healthy.

[Metabolic bone diseases]

Osteomalacia is caused by impaired vitamin D receptor (VDR) signaling, calcium deficiency, and altered bone mineralization. This can be due to insufficient sunlight exposure, malabsorption, reduced D hormone activation in chronic kidney disease, and rare alterations of VDR signaling and phosphate metabolism. Leading symptoms are bone pain, muscular cramps, and increased incidence of falls in the elderly. The adequate respective countermeasures are to optimize the daily intake of calcium and vitamin D3 and to replace active D hormone and phosphate if deficient. Osteoporosis is characterized by bone fragility fractures upon minor physical impact. Indications for diagnosis and treatment can be established by estimating the absolute fracture risk, taking into account bone mineral density, age, gender, and individual risk factors. Exercise, intervention programs to avoid falls, and specific drugs are capable of substantially reducing fracture risk even in the elderly. Secondary osteoporosis primarily requires both bone-altering medications and effective treatment of underlying diseases.

Nutrition and Polymyositis and Dermatomyositis

• Chronic muscle inflammation in polymyositis or dermatomyositis causes muscle weakness and fatigue.

• The chronic inflammation could lead to a catabolic state and additional loss of muscle mass.

• The chronic muscle inflammation could induce a metabolic myopathy.

• Body weight may not be reliable to measure muscle loss, rather measurement of body composition is recommended.

•For patients with polymyositis or dermatomyositis it is important to provide the body with the right amount of macronutrients and trace elements for maintenance and improvement of body functions.

• One recommendation is supplementation with calcium and vitamin D.

• Another recommendation is regular physical exercise that during limited periods can be combined with supplements such as creatine, if done under the care of a physician.

Advances in the medical management of osteoporosis

Osteoporosis is a skeletal disorder characterised by compromised bone strength predisposing to increased risk of fracture, which is rapidly reaching epidemic proportions as the population ages. Many patients presenting with a fracture caused by a fall from standing height or less are not on any kind of therapy and many patients who sustain these fragility fractures are not started on therapy by their orthopaedic surgeon. In 2004, the United States Surgeon General released a report on osteoporosis recommending that physicians adopt a pyramidal approach to therapy. The base of the pyramid includes calcium, vitamin D, physical therapy and fall prevention. The second level calls for management or elimination of secondary causes of osteoporosis. The third level consists of treatment with either anti-resorptive or anabolic medications. The orthopaedic surgeon is in an ideal position to diagnose fragility fractures and suggest treatment in the hope of preventing future fractures. Anti-resorptive and anabolic therapies currently available are discussed.

An update on glucocorticoid-induced osteoporosis

PURPOSE OF REVIEW

Glucocorticoids are widely used, often long term, and a major side effect is osteoporosis and increased risk of fracture. This review considers how common is the problem, the patients who are most at risk, our current understanding of mechanisms, and how to prevent and effectively treat glucocorticoid-induced osteoporosis. The actions currently being undertaken in clinical practice are reviewed.

RECENT FINDINGS

Glucocorticoid-induced osteoporosis is an increasing problem that occurs not only in those on high-dose therapy. Advances in our knowledge of the cellular and cytokine mechanisms of bone turnover and glucocorticoid mechanisms of action are leading to a better understanding of how glucocorticoids affect bone cells and novel ways of prevention. Although there are effective treatments to prevent and control glucocorticoid-induced osteoporosis as well as guidelines for their use, they are still not being applied in routine clinical practice.

SUMMARY

Glucocorticoid-induced osteoporosis is a significant problem. Although our understanding of effective prevention and treatment strategies is improving, there needs to be better implementation of these strategies.

Stress fractures of the second metatarsal base occur in nondancers

Stress fractures of the base of the second metatarsal are common in ballet dancers and essentially are unreported in nondancers. We presumed base of the second metatarsal stress fractures in nondancers occur in a wide variety of individuals regardless of demographics, are highly associated with athletic activities, and have specific examination findings and poor clinical outcomes. Using a retrospective chart review, we identified 12 stress fractures at the base of the second metatarsal (nine patients) in nondancers. Our review suggests second metatarsal base stress fractures occur in nondancers in a diverse population, and nonoperative treatment provides limited success. Advanced radiographic study, specifically MRI, is useful to assist the early diagnosis and prognostication. All of the stress fractures were treated nonoperatively; six fractures (50%) developed nonunion and five underwent subsequent surgery. The surgery for nonunion provided successful outcomes; however, risk factors such as low bone mass and comorbidities may have played important roles in the prognosis.

Emerging consensus on prevention and treatment of glucocorticoid-induced osteoporosis

Glucocorticoid-induced osteoporosis is a common but still relatively neglected problem, with a low level of awareness among primary and secondary care physicians. Fractures appear early after initiation of treatment, and effective prophylaxis requires primary prevention in those at high risk of fracture. Bisphosphonates are the treatment of choice, and calcium and vitamin D supplements are also indicated in the majority of individuals. Organized care programs together with the use of evidence-based guidelines have the potential to improve significantly the management of this serious complication of glucocorticoid therapy.

The cost effectiveness of bisphosphonates for the prevention and treatment of osteoporosis: a structured review of the literature

Osteoporotic fragility fractures constitute a significant public health concern. The lifetime risk of any osteoporotic fracture is very high (40-50% in women and 13-22% in men). Fractures are associated with significant mortality and morbidity and represent a substantial economic burden to society. Bisphosphonates (alendronate, etidronate, risedronate and ibandronate) are indicated for the treatment and prevention of osteoporosis but are costly compared with other treatments, such as vitamin D and calcium. Our search identified 23 studies evaluating the cost effectiveness of bisphosphonate therapy for the treatment and prevention of fragility fractures; these studies were from five geographical areas and employed a variety of comparators and assumptions. We identified 11 studies investigating bisphosphonates in women with low bone mineral density (BMD) [T-score >2.5 standard deviations {SDs} below normal {mean} peak values for young adults] and previous fractures, five studies investigating bisphosphonates in women with low BMD and no previous fracture, one study of bisphosphonates in women with osteopenia, five studies involving screening and two studies of bisphosphonates in special populations (women initiating corticosteroid treatment and men). In women with low BMD and previous fractures, bisphosphonate therapy was most cost effective in populations aged > or =70 years and was unlikely to be cost effective in populations aged < or =50 years. There was uncertainty concerning the cost effectiveness of bisphosphonates in such populations aged 60-69 years. In women with low BMD without previous fractures, treatment with alendronate or risedronate appeared to be cost effective across countries (UK, US, Denmark), but there was some uncertainty about the cost effectiveness of etidronate in patients in the highest age groups. Identifying risk factors for fractures through means such as spine radiographs to detect vertebral deformities improves the cost effectiveness of treatment. In women with osteopenia, alendronate therapy may be cost effective in women with a T-score of -2.4SD in the US. Screening for low BMD and treatment with alendronate or etidronate appears to be cost effective in postmenopausal women in general and in women with rheumatoid arthritis initiating corticosteroid therapy. Alendronate therapy without screening was also shown to be potentially cost effective in certain at-risk male populations, as well as in women initiating corticosteroid therapy after the age of 40 years. Decision makers in the US, UK and Sweden should consider funding the use of bisphosphonates for the prevention and treatment of osteoporosis in women aged >70 years, particularly if they have other risk factors for fracture. Further studies are required to make more definitive conclusions in other countries and patient populations. Screening strategies for low BMD followed by bisphosphonate treatment should also be considered in the general female population aged >65 years in the UK and US and in patients with rheumatoid arthritis initiating corticosteroid therapy.

Post-Transplant Diabetes Mellitus

New-onset diabetes mellitus in a previously non-diabetic transplant recipient is a serious adverse event that confers significant morbidity and mortality. The most significant consequences of post-transplant diabetes mellitus (PTDM) in solid organ transplant recipients include decreased patient and graft survival, an increased risk of infectious complications, and morbid cardiovascular events. The development of PTDM in the elderly is of particular concern because this group is already at increased risk of progression of cardiovascular disease. Because the elderly, especially those aged >65 years, are the fastest-growing segment of the renal transplant population, attention needs to be given to PTDM risk reduction and post-transplant management. PTDM develops as a consequence of both impaired insulin production and enhanced peripheral insulin resistance. A number of non-modifiable factors such as age, race, family history, hepatitis C, polycystic kidney disease and emerging genetic causes have been identified as risk factors for PTDM. However, a number of modifiable factors can be targets for intervention in high-risk patients, including bodyweight (through dietary restriction and exercise), hypertension, hyperlipidaemia and the effects of certain immunosuppressive agents. The two agents most responsible for PTDM are tacrolimus and corticosteroids, especially when used in combination. Attempts to modify doses and regimens designed to eliminate or avoid these drugs should be considered. Use of HMG-CoA reductase inhibitors ('statins') and ACE inhibitors is particularly helpful in controlling hypertension and hyperlipidaemia in the elderly because these agents confer protection against future adverse cardiovascular events. Bisphosphonates are also advantageous in controlling the progression of osteoporosis and possible increased risk of bone fractures. Future trials in the elderly should focus on such endpoints as PTDM, post-transplant neoplasia, cardiovascular events and bone fracture events in order to identify the safest regimens that provide the optimal control of rejection while limiting the morbidity from these secondary events.