The pathogenesis, epidemiology and management of glucocorticoid-induced osteoporosis

Postmenopausal Canarian women receiving oral glucocorticoids have an increased prevalence of vertebral fractures and low values of bone mineral density measured by quantitative computer tomography and dual X-ray absorptiometry, without significant changes in parathyroid hormone

BACKGROUND

Daily doses higher than 7.5 mg/daily of prednisone or equivalents confer a great risk of vertebral and hip fractures with a clear dose dependence of fracture risk. Information regarding the utility in assessing trabecular bone mineral density by quantitative computer tomography (QCT) in these patients, either in the Canaries or in Spain, is lacking. Moreover, in this setting, the importance of secondary hyperparathyroidism is still controversial.

DESIGN, PATIENTS AND METHODS

Cross-sectional observational study performed on 1177 consecutive Canary postmenopausal women who attended our Bone Metabolic Unit. The Patient Group was composed of 88 postmenopausal women who were taking oral corticosteroids in dose higher than 7.5 mg/day of prednisone or equivalent for more than 6 months (OG group). The Control Group included 838 postmenopausal women who did not take steroids. A complete validated questionnaire for osteoporosis risk assessment and a complete physical examination were performed. A lateral X-ray of the spine was performed on every woman. Bone mineral density (BMD) was measured at the lumbar spine (LS) by dual X-ray Absorptiometry (DXA) and QCT and at the femoral neck by DXA. Fasting serum and 24 hour urine was collected and biochemical markers of bone remodelling were studied.

RESULTS

Both groups were comparable in general characteristics and calcium intake. The OG group showed lower values of BMD estimated both by DXA and QCT (p<0.05). LS BMD was closely correlated by using both methods (r=0.636, p<0.001). The OG group showed lower values of osteocalcin (p=0.023) and TRAP (p=0.026) without significant differences in PTH. Patients in OG group had a higher prevalence of vertebral fractures than controls (13.3% vs 8.6%; crude values: p=0.049, OR: 1.63 (0.99-2.67); age adjusted: p=0.003, OR 2.29 (1.33-9.93)).

CONCLUSIONS

In postmenopausal Canarian women, chronic glucocorticoid therapy is associated with low bone mineral density, measured either by DXA or QCT, with evidence of low turnover and high prevalence of fractures without significant changes in PTH. DXA and QCT provide similar information in the assessment of this high risk population.

Risk factors associated with incident fractures in Japanese men with rheumatoid arthritis: a prospective observational cohort study

There are limited data in the literature concerning risk factors for incident fractures in men with rheumatoid arthritis (RA). We evaluated the association between potential risk factors and incident clinical fractures in male Japanese patients with RA. A total of 1050 male patients with RA were enrolled in a prospective, observational cohort study from 2000 to 2005. Participants were followed from 6 to 66 months (median follow-up, 48.7 months) and classified into three groups according to their incident fracture status from baseline: no new fracture, any new nonvertebral fracture, and new clinical vertebral fracture. The associations of potential risk factors were analyzed by Cox proportional hazards models. During follow-up, 30 patients (2.9%) developed a new nonvertebral fracture or a vertebral fracture. The baseline age, history of total knee replacement (TKR), and serum C-reactive protein (CRP) levels were associated with any nonvertebral fracture [baseline age: hazard ratio (HR), 1.08, 95% confidence interval (CI), 1.03-1.14; history of TKR: HR 6.02, 95% CI 1.19-30.42; and CRP: HR 0.60, 95% CI 0.38-0.95]. The baseline Japanese health assessment questionnaire (HAQ) score and daily dose of prednisolone were also associated with the incidence of clinical vertebral fractures (HR 7.74, 95% CI 2.10-28.48, and HR 1.28, 95% CI 1.14-1.45, respectively). Older age, history of TKR, and low serum CRP levels appear to be associated with any incident nonvertebral fracture in Japanese men with RA. High HAQ disability score and baseline doses of daily prednisolone may correlate with incident clinical vertebral fracture in Japanese men with RA.

Corticotropin-releasing factor receptor-1: a therapeutic target for cardiac autonomic disturbances

Corticotropin-releasing factor (CRF), a neuropeptide involved in triggering a myriad of responses to fear and stress, is favourably positioned in the CNS to modulate the sympathetic and parasympathetic branches of the cardiac autonomic nervous system. In vivo studies suggest that central CRF inhibits vagal output and stimulates sympathetic activity. Therefore, CRF may function to inhibit exaggerated vagal activation that results in severe bradycardia or even vasovagal syncope. On the other hand, CRF receptor-1 (CRF(1)) antagonists increase cardiac vagal and decrease sympathetic activity, thereby also implicating CRF(1) as a therapeutic target for autonomic disturbances resulting in elevated sympathetic activity, such as hypertension and coronary heart disease. The central distribution of CRF(1) and the cardiovascular effects of CRF(1) agonists and antagonists, suggest it mediates CRF-induced autonomic changes. However, there is insufficient information regarding the autonomic effects of CRF(2)-selective compounds to rule out CRF(2) contribution. This review provides an update on the autonomic effects of CRF and the neuronal projections thought to mediate these cardiovascular responses.

Glucocorticoid-induced osteoporosis

PURPOSE OF REVIEW

To present an overview of the peer-reviewed literature relating to glucocorticoid-induced osteoporosis that has been published since January 2006.

RECENT FINDINGS

Understanding the pathophysiology of bone loss resulting from glucocorticoid use has become clearer. The role of the receptor-activated nuclear factor kappaB-ligand-osteoprotogerin system has been clarified and will likely lead to better targeted therapies. Minimal trauma fractures occur in patients treated with glucocorticoids at higher bone mineral density than is seen with other primary or secondary causes of osteoporosis. Uncertainty still remains about the lowest dose of glucocorticoids that is not associated with bone loss. Bisphosphonates remain the treatment of choice for glucocorticoid-induced osteoporosis, but despite this effective therapy the disease remains under recognized and undertreated.

SUMMARY

Glucocorticoid-induced osteoporosis is a leading cause of secondary osteoporosis, one of the more devastating consequences of glucocorticoid therapy. Bone mineral density underestimates the risk of fragility fractures in glucocorticoid-induced osteoporosis, which may account for the underrecognition and undertreatment of the disease prior to fracture.

Post-transplantation osteoporosis

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

Medication-induced osteoporosis

Osteoporosis, a condition of low bone mass and microarchitectural deterioration, results in fractures with minimal trauma. Secondary osteoporosis is defined as bone loss resulting from either specific clinical disorders or medications. Some medications that can induce osteoporosis are discussed. Specifically, this article reviews the pathogenesis of glucocorticoid-induced bone loss and demonstrates the means to successfully manage the condition with a combination of calcium and vitamin D supplementation and, depending on the severity of the bone loss, bisphosphonates or parathyroid hormone. In addition, the pathophysiology of bone loss from aromatase inhibitors in women, gonadotropin-releasing hormone agonists in men, anticonvulsant medications, and proton pump inhibitors is outlined. Finally, this review offers suggestions on evaluation and management of bone health in individuals treated with these medications for prolonged times.

Teriparatide or alendronate in glucocorticoid-induced osteoporosis

BACKGROUND

Bisphosphonate therapy is the current standard of care for the prevention and treatment of glucocorticoid-induced osteoporosis. Studies of anabolic therapy in patients who are receiving long-term glucocorticoids and are at high risk for fracture are lacking.

METHODS

In an 18-month randomized, double-blind, controlled trial, we compared teriparatide with alendronate in 428 women and men with osteoporosis (ages, 22 to 89 years) who had received glucocorticoids for at least 3 months (prednisone equivalent, 5 mg daily or more). A total of 214 patients received 20 microg of teriparatide once daily, and 214 received 10 mg of alendronate once daily. The primary outcome was the change in bone mineral density at the lumbar spine. Secondary outcomes included changes in bone mineral density at the total hip and in markers of bone turnover, the time to changes in bone mineral density, the incidence of fractures, and safety.

RESULTS

At the last measurement, the mean (+/-SE) bone mineral density at the lumbar spine had increased more in the teriparatide group than in the alendronate group (7.2+/-0.7% vs. 3.4+/-0.7%, P<0.001). A significant difference between the groups was reached by 6 months (P<0.001). At 12 months, bone mineral density at the total hip had increased more in the teriparatide group. Fewer new vertebral fractures occurred in the teriparatide group than in the alendronate group (0.6% vs. 6.1%, P=0.004); the incidence of nonvertebral fractures was similar in the two groups (5.6% vs. 3.7%, P=0.36). Significantly more patients in the teriparatide group had at least one elevated measure of serum calcium.

CONCLUSIONS

Among patients with osteoporosis who were at high risk for fracture, bone mineral density increased more in patients receiving teriparatide than in those receiving alendronate. (ClinicalTrials.gov number, NCT00051558 [ClinicalTrials.gov].).

Glucocorticoid-Induced osteoporosis: clinical and therapeutic aspects

Glucocorticoid-induced osteoporosis (GIO) is the most common form of secondary osteoporosis. Fractures, which are often asymptomatic, may occur in as many as 30_50% of patients receiving chronic glucocorticoid therapy. Vertebral fractures occur early after exposure to glucocorticoids, at a time when bone mineral density (BMD) declines rapidly. Fractures tend to occur at higher BMD levels than in women with postmenopausal osteoporosis. Glucocorticoids have direct and indirect effects on the skeleton. They impair the replication, differentiation, and function of osteoblasts and induce the apoptosis of mature osteoblasts and osteocytes. These effects lead to a suppression of bone formation, a central feature in the pathogenesis of GIO. Glucocorticoids also favor osteoclastogenesis and as a consequence increase bone resorption. Bisphosphonates are the most effective of the various therapies that have been assessed for the management of GIO. Anabolic therapeutic strategies are under investigation. Teriparatide seems to be also efficacious for the treatment of patients with GIO.

Glucocorticoid-induced osteoporosis: pathophysiology and therapy

Glucocorticoid-induced osteoporosis (GIO) is the most common form of secondary osteoporosis. Fractures, which are often asymptomatic, may occur in as many as 30-50% of patients receiving chronic glucocorticoid therapy. Vertebral fractures occur early after exposure to glucocorticoids, at a time when bone mineral density (BMD) declines rapidly. Fractures tend to occur at higher BMD levels than in women with postmenopausal osteoporosis. In human subjects, the early rapid decline in BMD is followed by a slower progressive decline in BMD. Glucocorticoids have direct and indirect effects on the skeleton. The primary effects are on osteoblasts and osteocytes. Glucocorticoids impair the replication, differentiation and function of osteoblasts and induce the apoptosis of mature osteoblasts and osteocytes. These effects lead to a suppression of bone formation, a central feature in the pathogenesis of GIO. Glucocorticoids also favor osteoclastogenesis and as a consequence increase bone resorption. Bisphosphonates are effective in the prevention and treatment of GIO. Anabolic therapeutic strategies are under investigation.

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.

Besonderheiten der steroidinduzierten Osteoporose

Glucocorticoid-induced osteoporosis (GIOP) is characterized by disturbed bone remodelling with consequent reduced bone mass and abnormally low quality of the bone tissue, resulting in an elevated risk of fracture. Glucocorticoids (GC) inhibit processes of bone formation and accelerate bone degradation, all of which must be taken into account especially in the case of long-term treatment with GC. Appropriate diagnostic procedures must be implemented early in the treatment and throughout the course, as must any preventive (improvement of general condition, calcium, vitamin D) and curative treatment required. When indications are carefully observed and the dosage is constantly checked and adjusted as needed, however, GC are not only helpful and beneficial in the treatment of the basic illnesses they are prescribed for, but on balance can even have a positive effect on bone in phases of high inflammatory activity.

Glucocorticoids induce osteocyte apoptosis by blocking focal adhesion kinase-mediated survival. Evidence for inside-out signaling leading to anoikis

Bone fragility induced by chronic glucocorticoid excess is due, at least in part, to induction of osteocyte apoptosis through direct actions on these cells. However, the molecular mechanism by which glucocorticoids shorten osteocyte life span has remained heretofore unknown. We report that apoptosis of osteocytic MLO-Y4 cells induced by the synthetic glucocorticoid dexamethasone is abolished by the glucocorticoid receptor antagonist RU486, but not by inhibition of protein or RNA synthesis. Dexamethasone-induced apoptosis is preceded by a decrease in the number of cytoplasmic processes, an indicator of cell detachment. In addition, the focal adhesion kinase FAK prevents dexamethasone-induced apoptosis, whereas the FAK-related kinase Pyk2 increases the basal levels of apoptosis. Dexamethasone-induced apoptosis is also prevented in cells expressing kinase-deficient or phosphorylation-defective (Y402F) dominant negative mutants of Pyk2. Consistent with the requirement of tyrosine 402, dexamethasone induces rapid Pyk2 phosphorylation in this residue. Moreover, knocking down Pyk2 expression abolishes apoptosis and cell detachment induced by dexamethasone, and transfection with human Pyk2 rescues both responses. Furthermore, induction of apoptosis as well as cell detachment by dexamethasone is abolished by inhibiting the activity of JNK, a recognized downstream target of Pyk2 activation. These results demonstrate that glucocorticoids promote osteocyte apoptosis via a receptor-mediated mechanism that does not require gene transcription and that is mediated by rapid activation of Pyk2 and JNK, followed by inside-out signaling that leads to cell detachment-induced apoptosis or anoikis.

6-Methylprednisolone down-regulates IRAK-M in human and murine osteoclasts and boosts bone-resorbing activity: a putative mechanism for corticoid-induced osteoporosis

Osteoclasts are large, multinucleated cells, which originate from the fusion of macrophages. They play a central role in bone development and remodeling via the resorption of bone and are thus important mediators of bone loss, which leads to osteoporosis. IL-1R-associated kinase (IRAK)-M is a pseudokinase, which acts as a negative modulator of innate immune responses mediated by TLRs and IL-1R. Recently, it has been reported that IRAK-M also participates in the control of macrophage differentiation into osteoclasts. In addition, it was shown that IRAK-M knockout mice develop a strong osteoporosis phenotype, suggesting that down-regulation of this molecule activates osteoclast-mediated bone resorption. We studied the effect of the osteoporosis-inducing glucocorticoid, 6-methylprednisolone (6-MP), on IRAK-M expression in osteoclasts. Our results showed that osteoclasts, derived from THP-1 and RAW cells as well as human blood monocytes, differentiated into osteoclasts, express high levels of IRAK-M at mRNA and protein levels. In addition, 6-MP down-regulates IRAK-M expression, which correlates with an increased activation of bone resorption. These findings suggest a mechanism of corticosteroid-induced osteoporosis and open new avenues for treating this endemic disease of Western societies.

Haematology

This article examines some of the recent advances in haematology in both the malignant and non-malignant areas of the speciality. Improvements in survival rates after effective chemotherapy now present the haematologist with the challenges of how to minimise therapeutic side effects without affecting outcome and the role of stratification as well as specific monitoring of enzyme activity are discussed. Many treatments for haematological malignancy have significant late effects which are only now becoming a problem--what these are, how to identify them and how they can be limited are examined. The increased knowledge of the altered pathways that lead to malignancy has allowed a whole slew of new therapies to be developed often with excellent results. The role of new iron chelation agents and the so called 'universal haemostatic agent' activated factor VII are also discussed.

Glucocorticoid-Induced Osteoporosis

Glukokortikoidi su lijekovi koji najčešće uzrokuju osteoporozu, a učinci tih lijekova pobuđuju sve veću pozornost zbog njihove raširene primjene u autoimunim, plućnim, gastrointestinalnim bolestima ili nakon transplantacije organa. Glukokortikoidna osteoporoza nastaje brzo, unutar nekoliko prvih mjeseci primjene glukokortikoida, više zahvaća spužvastu nego kortikalnu kost i brzo povećava rizik nastanka prijeloma, poglavito kralježaka i kuka. Učinci glukokortikoida na skelet ovisni su i o dozi i o trajanju terapije. Mehanizmi kojima glukokortikoidi dovode do osteoporoze su mnogobrojni i nisu još potpuno jasni. Usprkos postojanju više preporuka za otkrivanje i liječenje glukokortikoidne osteoporoze i lijekova koji mogu smanjiti rizik prijeloma kralježnice, još uvijek se razmjerno mali postotak bolesnika zadovoljavajuće dijagnosticira i liječi.

Advances in the diagnosis and treatment of osteoporosis

Although severely low bone density is relatively rare in the pediatric population, it can be a significant problem in many patients with chronic illness. As peak bone formation occurs during adolescence, it is crucial that pediatricians and other care providers for this patient population recognize the significance of attainment of adequate bone. Dietary intake of vitamin D and calcium should be optimized, and correction of underlying causes of poor bone density should occur whenever possible. Assessment of bone density is difficult, as each technology available has problems, and none of the technologies are well-associated with fracture risk in pediatric patients. Once diagnosis of severely low bone density is established, treatment options are limited and poorly studied. The benefits of bisphosphonate therapy appear to outweigh the risks in patients with low bone density and frequent fragility fractures, and it appears that most improvement with bisphosphonates occurs within the first 2 to 4 years. Evidence, however, is emerging that once off therapy, bone turnover remains decreased for at least several years. During that time, improvements in bone density are decreased. Many questions remain regarding duration of therapy with bisphosphonate therapy and the long-term effects on the children who receive this medication. Anabolic therapies may become important in the future, but there is currently extremely limited information regarding their use in pediatrics.