High bone turnover elevates the risk of denosumab-induced hypocalcemia in women with postmenopausal osteoporosis

Changes in Testing and Treatment Methods in Osteoporosis Care

Osteoporosis treatment plays a crucial role in preventing fractures, particularly in bedridden patients. We conducted a questionnaire survey presenting hypothetical clinical cases in 2015 and 2020 to investigate trends over a 5-year period. The target population included physicians working in clinics and hospitals within our neighbourhood. The cases were presented, and the questionnaire was administered in a confidential format. The orthopaedic surgeons were matched for age and practice, resulting in 74 cases being included in the analysis. Comparing the 2015 and 2020 results, we observed a notable increase in physicians who would perform "bone mineral density measurements of the lumbar spine and hip." Furthermore, there was a significant rise in the percentage of respondents willing to test for bone metabolic markers, such as serum type I collagen cross-linked N-telopeptide (NTX), procollagen I N-terminal propeptide (P1NP), and tartrate-resistant acid phosphatase 5b (TRACP-5b). Regarding therapeutic agents, bisphosphonates decreased in usage, whereas parathyroid hormone and romosozumab witnessed an increase. In conclusion, the percentage of physicians requesting bone mineral density measurements of the lumbar spine and hip increased over the five-year period. In addition, more physicians chose to utilise bone metabolic markers due to their ease of measurement through blood tests and reduced diurnal variation. Finally, there was a marked trend towards the administration of drugs capable of rapidly and effectively increasing bone mineral density at an early stage of treatment.

Hypocalcemia in Patients With Osteoporosis and Normal Renal Function, Treated With Denosumab, a Retrospective Analysis

Objective

The reported hypocalcemia in postmenopausal women with osteoporosis who received Denosumab was low (0.05%-1.7% to 7.4%). The major prediction factors were vitamin D and calcium levels and renal function. The objective is to evaluate the incidence of hypocalcemia in patients with osteoporosis, normal renal function, and vitamin D who received Denosumab.

Method

A retrospective analysis was conducted using the medical records (2022-2023). We looked for hypocalcemia (albumin-adjusted calcium lower than 2.2 mmol/L).

Results

Two hundred one postmenopausal women diagnosed with osteoporosis and received denosumab treatment were included. All patients received vitamin D3 capsules and calcium supplementation. The mean age of the patient was 75.7 ± 7.0 years (56-91 years). Hypocalcemia was observed in 46 (23%) patients following a subcutaneous dose of Denosumab 60 mg. Median calcium was 2.25 mmol/L (minimum: 0.890 mmol/L, maximum: 2.6 mmol/L). Fourteen (30.4%) patients had severe hypocalcemia (<1.8 mmol/L) and required parenteral correction. A comparison between hypocalcemia and patients with normal calcium indicated that the significant predictor of hypocalcemia was pretreatment parathyroid hormone levels (9.9 ± 11.8vs 7.6 ± 2.56 pmol/L, respectively; P < .005). The prognostic role of parathyroid hormone for the denosumab-associated hypocalcemia was assessed using ROC curve analysis. For the cut-off value of Parathyroid hormone = 6.8 pmol/L, giving serum parathyroid measurement an AUC of 0.668 (0.599-0.737) - P = .0007; sensitivity 85%; specificity 52%.

Conclusion

Hypocalcemia induced by the denosumab treatment is more prevalent than previously shown in patients with osteoporosis receiving adequate calcium and vitamin D supplements. An elevated parathyroid hormone predicts hypocalcemia related to denosumab therapy in patients with normal calcium and vitamin D levels.

Prevalence of denosumab-induced hypocalcemia: a retrospective observational study of patients routinely monitored with ionized calcium post-injection

We assessed the prevalence of hypocalcemia after denosumab injections in a real-world cohort routinely monitored for calcium during up to 7.5 years of treatment. Among 1096 injections in 242 patients, 6.3% resulted in hypocalcemia, and was independent of the injection number. Severe hypocalcemia was rare (1%).

PURPOSE

To assess the prevalence of and risk factors for hypocalcemia after administration of denosumab in a patient cohort routinely monitored for ionized calcium after each dose.

METHODS

In this retrospective observational study, we analyzed denosumab-induced hypocalcemia in a real-world cohort who were routinely followed up with ionized calcium pre- and post-injection (within 31 days after injection) during the period 2011 to 2020.

RESULTS

In total, we included data from 1096 denosumab injections in 242 individuals (1-15 injections per patient). The mean age for the first injection was 74 ± 10 years, and 88% were female. Post-injection hypocalcemia occurred after 6.3% of all injections (4.6% mild, 0.6% moderate, and 1.1% severe) and was independent of the number of injections (rate of hypocalcemia varied from 3-8%). Risk factors for hypocalcemia were male sex, severe renal failure, pre-injection hypocalcemia, hypomagnesemia, hypophosphatemia, and vitamin D insufficiency. Furthermore, older age was not associated with an increased hypocalcemia risk.

CONCLUSIONS

Denosumab-induced hypocalcemia is a prevalent adverse event, which occurs independently of the number of injections. However, severe hypocalcemia is a rare occurrence, and severe renal failure and nutritional status appear to be important predictive factors. Magnesium and phosphate might add value in the pre-injection risk assessment; however, this observation needs to be confirmed in larger cohorts.

Morroniside Inhibits Inflammatory Bone Loss through the TRAF6-Mediated NF-κB/MAPK Signalling Pathway

Osteoporosis is a chronic inflammatory disease that severely affects quality of life. Cornus officinalis is a Chinese herbal medicine with various bioactive ingredients, among which morroniside is its signature ingredient. Although anti-bone resorption drugs are the main treatment for bone loss, promoting bone anabolism is more suitable for increasing bone mass. Therefore, identifying changes in bone formation induced by morroniside may be conducive to developing effective intervention methods. In this study, morroniside was found to promote the osteogenic differentiation of bone marrow stem cells (BMSCs) and inhibit inflammation-induced bone loss in an in vivo mouse model of inflammatory bone loss. Morroniside enhanced bone density and bone microstructure, and inhibited the expression of IL6, IL1β, and ALP in serum (p < 0.05). Furthermore, in in vitro experiments, BMSCs exposed to 0-256 μM morroniside did not show cytotoxicity. Morroniside inhibited the expression of IL6 and IL1β and promoted the expression of the osteogenic transcription factors Runx2 and OCN. Furthermore, morroniside promoted osteocalcin and Runx2 expression and inhibited TRAF6-mediated NF-κB and MAPK signaling, as well as osteoblast growth and NF-κB nuclear transposition. Thus, morroniside promoted osteogenic differentiation of BMSCs, slowed the occurrence of the inflammatory response, and inhibited bone loss in mice with inflammatory bone loss.

Hypocalcemia Risk of Denosumab Across the Spectrum of Kidney Disease: A Population-Based Cohort Study

Denosumab can be used in patients with chronic kidney disease (CKD) but has been linked with cases of severe hypocalcemia. The incidence of and risk factors for hypocalcemia after denosumab use are not well established. Using linked health care databases at ICES, we conducted a population-based cohort study of adults >65 years old with a new prescription for denosumab or a bisphosphonate between 2012 and 2020. We assessed incidence of hypocalcemia within 180 days of drug dispensing and stratified results by estimated glomerular filtration rate (eGFR in mL/min/1.73 m² ). We used Cox proportional hazards to assess risk factors for hypocalcemia. There were 59,151 and 56,847 new denosumab and oral bisphosphonate users, respectively. Of the denosumab users, 29% had serum calcium measured in the year before their prescription, and one-third had their serum calcium checked within 180 days after their prescription. Mild hypocalcemia (albumin corrected calcium <2.00 mmol/L) occurred in 0.6% (95% confidence interval [CI] 0.6, 0.7) of new denosumab users and severe hypocalcemia (<1.8 mmol/L) in 0.2% (95% CI 0.2, 0.3). In those with an eGFR <15 or receiving maintenance dialysis, the incidence of mild and severe hypocalcemia was 24.1% (95% CI 18.1, 30.7) and 14.9% (95% CI 10.1, 20.7), respectively. In this group, kidney function and baseline serum calcium were strong predictors of hypocalcemia. We did not have information on over-the-counter vitamin D or calcium supplementation. In new bisphosphonate users, the incidence of mild hypocalcemia was 0.3% (95% CI 0.3, 0.3) with an incidence of 4.7% (95% CI 1.5, 10.8) in those with an eGFR <15 or receiving maintenance dialysis. In this large population-based cohort, we found that the overall risk of hypocalcemia with new denosumab use was low but increased substantially in those with eGFR <15 mL/min/1.73 m² . Future studies should investigate strategies to mitigate hypocalcemia. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Humulus lupulus L. Extract Protects against Senior Osteoporosis through Inhibiting Amyloid β Deposition and Oxidative Stress in APP/PS1 Mutated Transgenic Mice and Osteoblasts

As aging progresses, β-amyloid (Aβ) deposition and the resulting oxidative damage are key causes of aging diseases such as senior osteoporosis (SOP). Humulus lupulus L. (hops) is an important medicinal plant widely used in the food, beverage and pharmaceutical industries due to its strong antioxidant ability. In this study, APP/PS1 mutated transgenic mice and Aβ-injured osteoblasts were used to evaluate the protective effects of hops extracts (HLE) on SOP. Mice learning and memory levels were assessed by the Morris water maze. Mice femurs were prepared for bone micro-structures and immunohistochemistry experiments. The deposition of Aβ in the hippocampus, cortex and femurs were determined by Congo red staining. Moreover, protein expressions related to antioxidant pathways were evaluated by Western blotting. It was found that HLE markedly improved learning abilities and ameliorated memory impairment of APP/PS1 mice, as well as regulated antioxidant enzymes and bone metabolism proteins in mice serum. Micro-CT tests indicated that HLE enhanced BMD and improved micro-architectural parameters of mice femur. More importantly, it was discovered that HLE significantly reduced Aβ deposition both in the brain and femur. Further in vitro results showed HLE increased the bone mineralization nodule and reduced the ROS level of Aβ-injured osteoblasts. Additionally, HLE increased the expression of antioxidant related proteins Nrf2, HO-1, NQO1, FoxO1 and SOD-2. These results indicated that Humulus lupulus L. extract could protect against senior osteoporosis through inhibiting Aβ deposition and oxidative stress, which provides a reference for the clinical application of hops in the prevention and treatment of SOP.

High-Dose Intravenous Iron with Either Ferric Carboxymaltose or Ferric Derisomaltose: A Benefit-Risk Assessment

The intravenous iron formulations ferric carboxymaltose (FCM) and ferric derisomaltose (FDI) offer the possibility of administering a large amount of iron in one infusion. This results in faster correction of anemia and the formulations being better tolerated than oral iron formulations. This triad of logistic advantages, improved patient convenience, and fast correction of anemia explains the fact that intravenous iron formulations nowadays are frequently prescribed worldwide in the treatment of iron deficiency anemia. However, these formulations may result in hypophosphatemia by inducing a strong increase in active fibroblast growth factor-23 (FGF-23), a hormone that stimulates renal phosphate excretion. This effect is much more pronounced with FCM than with FDI, and therefore the risk of developing hypophosphatemia is remarkably higher with FCM than with FDI. Repeated use of FCM may result in severe osteomalacia, which is characterized by bone pain, Looser zones (pseudofractures), and low-trauma fractures. Intravenous iron preparations are also associated with other adverse effects, of which hypersensitivity reactions are the most important and are usually the result of a non-allergic complement activation on nanoparticles of free labile iron-Complement Activation-Related Pseudo-Allergy (CARPA). The risk on these hypersensitivity reactions can be reduced by choosing a slow infusion rate. Severe hypersensitivity reactions were reported in < 1% of prospective trials and the incidence seems comparable between the two formulations. A practical guideline has been developed based on baseline serum phosphate concentrations and predisposing risk factors, derived from published cases and risk factor analyses from trials, in order to establish the safe use of these formulations.

The relationship between chronic kidney disease and denosumab-induced hypocalcemia in high-age osteoporotic patients

PURPOSE

A few studies have reported the safety of the treatment of elderly osteoporotic patients with chronic kidney disease (CKD) and the possibility of hypocalcemia. The aim of the present study was to examine the relationship between the incidence of hypocalcemia and the CKD stage in elderly osteoporotic patients treated with denosumab.

MATERIALS AND METHODS

This study was designed as a parallel-group comparison study between the denosumab-associated hypocalcemia (DAH) groups: the concentration of serum calcium was under 8.6 mg/dl and the normal calcium (NC) groups: the concentration of serum calcium was over 8.6 mg/dl. Fifty-two subjects over 70 years old were enrolled in this study, with 16 patients classified into the DAH group and 36 patients assigned to the NC group. All patients were further classified into two subgroups according to their age, into an around 75 years group to clarify the relevance of old age and an around 85 years group and also into a mild CKD group and a moderate CKD group by based on estimated glomerular filtration (eGFR). Serum calcium concentration, tartrate-resistant acid phosphatase (TRACP-5b), and type 1 procollagen N terminal propeptide (P1NP) were measured, and adverse drug reactions were evaluated.

RESULTS

The eGFR and serum calcium were significantly lower in the DAH group than in the NC group in the starting phase. Moreover, TRACP-5b was significantly higher in the DAH group than in the NC group in the starting phase. There were no significant differences in P1NP. The incidence of hypocalcemia was significantly higher in the around 85 groups than in the around 75 groups. The frequency of hypocalcemia was also significantly higher in the severe CKD group than in the mild CKD group.

CONCLUSION

Advanced age combined with low eGFR and low serum Ca status appear to be associated with the incidence of hypocalcemia when using denosumab for the treatment of osteoporosis.

Denosumab-induced hypocalcemia in a patient with hyperthyroidism: a case report

Denosumab is a humanized monoclonal antibody targeting the receptor activator of nuclear factor kappa-B ligand (RANKL). Denosumab is an effective treatment for osteoporosis but can cause hypocalcemia. We present a case of denosumab-induced hypocalcemia in a patient with hyperthyroidism with a high bone turnover state. A 48-year-old postmenopausal woman was diagnosed with hyperthyroidism and osteoporosis and received antithyroid drugs (propylthiouracil 200 mg/day) and denosumab. After 2 months of taking medication, the patient complained of numbness and tingling in the hands and feet and was diagnosed with hypocalcemia (calcium, 5.8 mg/dL; ionized calcium, 0.83 mmol/L). Alfacalcidol (0.5 μg/day) and calcium carbonate (3000 mg/day) were prescribed. Subsequently, the patient's symptoms improved, and her serum calcium level normalized. The risk of denosumab-induced hypocalcemia may be increased in patients with diseases related to high bone turnover, such as hyperthyroidism; therefore, caution is needed.

Denosumab-Induced Hypocalcemia and Hyperparathyroidism in de novo Kidney Transplant Recipients

INTRODUCTION

Denosumab represents a realistic treatment option to increase bone mineral density in kidney transplant recipients (KTRs). It is still unknown how and at what extent posttransplantation bone disease and graft function influence the effects of denosumab on mineral metabolism indexes. In this study, we analyze risk factors of hypocalcemia and parathyroid hormone (PTH) increase after denosumab administration in eighteen de novo KTRs and its management before and after this treatment.

METHODS

We conducted a monocentric, observational, prospective study on de novo KTRs. All KTRs enrolled received a single 60 mg subcutaneous dose of denosumab every 6 months. Before kidney transplantation, no patients were treated with calcio-mimetic. After kidney transplantation and before antiresorptive therapy, no patients were treated with calcio-mimetic drugs and/or vitamin D receptor agonists, while all patients received nutritional vitamin D supplementation (from 1,000 IU to 1,500 IU daily).

RESULTS

Hypocalcemia was related to the degree of lumbar osteoporosis (p = 0.047); the increase in the PTH level was correlated to baseline bone turnover markers (bone alkaline phosphatase, serum osteocalcin, and β-C-terminal telopeptide), the 25 OH status, and eGFR. The introduction of calcitriol, after the PTH increase, in addition to cholecalciferol was necessary to ensure an adequate control of serum calcium and PTH during a follow-up of 15 months. Following the treatment with denosumab, it was observed an improvement of areal bone mineral density both at lumbar and femoral sites with a mean percentual increase of 1.74% and 0.25%, respectively.

CONCLUSIONS

Denosumab is an effective treatment for bone disease in KTRs. In our study, the increase in PTH is not a transient event but prolonged throughout the follow-up period and requires continuous supplementation therapy with calcitriol.

Short-term efficacy and safety of zoledronate acid or denosumab in Japanese patients with postmenopausal osteoporosis

INTRODUCTION

We aimed to compare the efficacy after switching from either bisphosphonates (BPs) or non-BPs (NBPs) to combination therapies of denosumab (DMAb) or zoledronic acid (Zol) with eldecalcitol (ELD) in bone mineral density (BMD) and bone metabolism and investigate the prognostic and risk factors of side effects of this therapy.

MATERIALS AND METHODS

One-hundred forty-eight patients with postmenopausal osteoporosis were recruited; their therapy was switched from BPs or NBPs to Zol or DMAb plus ELD (BP-Zol: 43, NBP-Zol: 32, BP-DMAb: 35, and NBP-DMAb: 38). Longitudinal changes in bone metabolic markers (P1NP and TRACP-5b) and BMD were evaluated.

RESULTS

In the BP-Zol group, P1NP did not change after 6 months and increased by 38.9% after 12 months. TRACP-5b decreased 15.8% after 6 months, but came back to baseline values 12 months after administration. In the rest of the groups, the bone metabolic markers remained suppressed after 6 and 12 months. Compared with baseline, all groups showed increase in BMD after 6 and 12 months. Bone metabolic markers at baseline were correlated with %change in lumbar spine BMD from baseline to 12 months. P1NP and 25-hydroxy vitamin D levels at baseline were identified as potential predictors of development of acute-phase reactions.

CONCLUSIONS

The combination therapy of Zol or DMAb and ELD may increase BMD at 12 months after the first administration in Japanese patients with postmenopausal osteoporosis, regardless of BPs pretreatment. Bone metabolic markers at baseline may be useful predictors for reaction to the therapy and side effects caused by these combination therapies in postmenopausal osteoporosis.

Denosumab in chronic kidney disease: a narrative review of treatment efficacy and safety

People with chronic kidney disease (CKD) are at high risk of bone fractures. In this review, we summarize the complexity of fracture prevention in CKD, describe the usefulness of a medication called denosumab, and review its safety in this population. Our article will help doctors manage brittle bones in CKD and encourage researchers to conduct more studies to improve bone health in CKD.

PURPOSE

Patients with CKD are at increased risk of fragility fractures and associated consequences. We discuss the complexity of fracture prevention in CKD, summarize the efficacy and safety of denosumab, and provide an approach to denosumab-induced hypocalcemia.

METHODS

Using predefined terms, we searched PubMed, MEDLINE, and Google Scholar for studies on fracture prevention in CKD and the efficacy and safety of denosumab. We included observational studies, randomized controlled trials (RCTs), meta-analyses, evidence-based reviews, and clinical practice guidelines.

RESULTS

The diagnosis of osteoporosis and prevention of related fragility fractures is complex in CKD, particularly in those with advanced and end-staged kidney disease (ESKD). Prior to initiating denosumab, it is important to assess for and optimize CKD-mineral and bone disorders (CKD-MBD). In observational studies and small RCTs, denosumab has been shown to improve bone mineral density and reduce bone turnover in CKD, but there have been no studies focused upon its fracture efficacy. Denosumab-induced hypocalcemia has also been reported, which disproportionately impacts those with ESKD. Risk factors for hypocalcemia with denosumab use in CKD include lower baseline serum calcium and 25 hydroxyvitamin D and both low and high bone turnover. Choosing the "right patient" for denosumab, supplementing with calcium and vitamin D, adjusting calcium dialysate, and close clinical monitoring are essential if considering this drug.

CONCLUSION

With optimization of CKD-MBD, calcium and vitamin D supplementation, and close monitoring, denosumab can be considered in CKD. There are however opportunities to better understand its fracture efficacy and safety in an RCT setting.

Denosumab-Induced Proximal Myopathy in a Child

Denosumab, a fully humanized monoclonal antibody, has been used for the treatment of osteoporosis, in complications resulting from bone metastatic disease and in giant cell tumor in both adults and skeletally mature adolescents. Denosumab is an inhibitor of the receptor activator of nuclear factor kappa-B ligand and belongs to a new class of antiresorptive medications. We report a unique case of myopathy in a 13-year-old boy prescribed denosumab for enchondromatosis. The boy presented with hypovitaminosis D, elevated parathyroid hormone, suppressed alkaline phosphatase, hypocalcemia, and hypophosphatemia after a single dose of denosumab. Our case points to altered calcium–vitamin D homeostasis induced by denosumab. Myopathy associated with denosumab has not been described previously in children. Early recognition of myopathy and adequate supplementation with calcium–vitamin D may ensure a more favorable clinical outcome.

Analysis of the subsequent treatment of osteoporosis by transitioning from bisphosphonates to denosumab, using quantitative computed tomography: A prospective cohort study

Purpose

Denosumab reduces bone resorption and improves bone mineral density (BMD). Studies have analyzed subsequent treatment transitioning from bisphosphonates to denosumab based on dual-energy X-ray absorptiometry scanning (DXA). Quantitative computed tomography (QCT) can help assess cortical and trabecular bones separately in three dimensions without the interference of the surrounding osteophytes. In the present study, we analyzed the subsequent treatment transition from bisphosphonates to denosumab using QCT.

Methods

Thirty-two patients with postmenopausal osteoporosis to be treated with denosumab were recruited. The patients were divided into two groups (15 prior bisphosphonate and 17 naïve) based on their previous treatment. BMD of the lumbar spine and hip were evaluated by DXA and QCT at baseline and 12 months following denosumab treatment.

Results

The percentage change in volumetric BMD assessed by QCT at 12 months significantly improved in the naïve group compared with that in the prior bisphosphonate group. The region-specific assessment of femur at 12 months revealed that denosumab treatment was effective in both cortical and trabecular bones except the trabecular region of the prior bisphosphonate group.

Conclusion

Our study suggests that although denosumab treatment was useful in both treatment groups, BMD increase was significantly higher in the naïve group than in the prior-bisphosphonate group. Interestingly, in the prior-bisphosphonate group, denosumab treatment was more effective in the cortical region than the trabecular region. Our study offers insights into the subsequent treatment and permits greater confidence when switching to denosumab from bisphosphonates.

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We analyzed the treatment transition from bisphosphonates to denosumab using QCT.

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Percentage change in volumetric BMD at 12 months significantly improved in the naïve group.

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Denosumab treatment was more effective on the cortical region than the trabecular region.

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Our study offers insights into the subsequent treatment when switching to denosumab.

The effect of denosumab on pedicle screw fixation: a prospective 2-year longitudinal study using finite element analysis

BACKGROUND

Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis.

METHODS

This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation.

RESULTS

BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months).

CONCLUSION

To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.

The safety profile of denosumab in oncology beyond the safety of denosumab as an anti-osteoporotic agent: still more to learn

INTRODUCTION

Initially endorsed as an antiosteoporotic agent, denosumab ‒ human monoclonal antibody inhibiting the receptor activator of nuclear factor kappa-B ligand (RANKL)‒ has currently shown an anticancer potential, rationalizing its exploitation in oncology. A prerequisite for leveraging denosumab in oncology is a favorable safety profile.

AREAS COVERED

The present review provides an overview of the adverse events of denosumab in oncology, with a focus on hypocalcemia, medication-related osteonecrosis of the jaw, atypical femoral fracture(s), post-denosumab vertebral fractures, increased risk of infections, and excess of second primary cancer. Representative studies addressing the safety and efficacy of denosumab compared to bisphosphonates in oncology are summarized. Critical gaps in the literature concerning the safety of denosumab in oncology are highlighted as opposed to plenty of available safety data on denosumab as an antiosteoporotic agent.

EXPERT OPINION

Despite the generally acceptable safety profile of denosumab in oncology, many issues remain unresolved. Further research is mandatory to counteract current challenges, namely: (i) validation of risk factors for adverse events; (ii) elucidation of the pathophysiology of the adverse events in search of actionable molecular pathways; (iii) illumination of the association of denosumab with increased risk of infections and/or second primary cancer; (iv) establishment of optimal diagnostic, and therapeutic protocols.

Denosumab-associated hypocalcemia: Does gender play a role?

OBJECTIVE

It is well recognized that the presentation, treatment, and outcomes of various diseases may differ between men and women. We recently reported a 7.4% rate of denosumab-associated hypocalcemia in community-dwelling osteoporotic patients. This study sought to investigate the role of gender in this complication.

STUDY DESIGN

Retrospective community-dwelling cohort.

METHOD

The databases of a large health maintenance organization were searched for adult patients treated with denosumab for osteoporosis in 2010-2018. Rates and predictors of denosumab-associated hypocalcemia (serum calcium ≤8.5 mg/mL) were analyzed by gender.

RESULTS

The cohort included 1871 women and 134 men. Compared with the women, the men were characterized by older median age (81 vs. 77 years, p = 0.005), higher likelihood to receive denosumab as a first-line treatment (22% vs. 6%, p < 0.001), less treatment with calcium supplements (42% vs. 53%, p = 0.012), and lower median eGFR level (66.1 vs. 79.8 mL/min/1.73m², p < 0.001). Denosumab-associated hypocalcemia developed in 133 women (7.1%) and 16 men (11.9%) (p = 0.04); the drug was discontinued in 75% and 61%, respectively. The strongest predictors of hypocalcemia in women were levels of pretreatment albumin-adjusted serum calcium (OR 0.08, 95% CI (0.04, 0.14)) and creatinine (OR 2.43, 95% CI (1.45, 4.05)). There were no predictors in men. On propensity matching of 126 men and 126 women, gender was not a predictor of hypocalcemia.

CONCLUSION

Denosumab-treated men were significantly older than treated women and had a lower eGFR and more advanced osteoporosis. These findings suggest that selection bias rather than male genderper se underlies the higher rate of denosumab-associated hypocalcemia in men.

Puerarin improves the bone micro-environment to inhibit OVX-induced osteoporosis via modulating SCFAs released by the gut microbiota and repairing intestinal mucosal integrity

SCOPE

Half of women over the age of 50 will experience a fracture related osteoporosis in their lifetime. The common treatment is estrogen replacement therapy, which can cause many side effects. Puerarin as a phytoestrogen has been proven to improve postmenopausal osteoporosis. However, the mechanisms of anti-osteoporosis remain unclear due to its low bioavailability. The aim of this study is to investigate whether the anti-osteoporosis effects of puerarin are related to modulations in the gut microbiota and focus on the mechanism of gut / bone axis.

METHODS

We established ovariectomized (OVX) rats as osteoporosis model. The femur was analyzed by microcomputed tomography (μ-CT) and we measured serum biochemical indices and inflammatory factors. 16S rRNA sequencing was employed to evaluate the gut microbiota composition in the fecal samples. Short-chain fatty acids (SCFAs) was analyzed by GC. The expression of intestinal inflammatory factors and adhesion proteins was confirmed by western blotting and qPCR.

RESULTS

Puerarin increased the BMD and improved the intestinal mucosal integrity to reduce the systemic inflammation. The disorder of gut microbiota was improved and its metabolites SCFAs were elevated. Metabolic pathways such as amino acid metabolism, LPS biosynthesis and butyrate metabolism were enriched.

CONCLUSION

Puerarin treatment modulated the gut microbiota disorder to elicit the anti-osteoporosis effects in OVX rats, by improving the bone micro-environment via regulating the SCFAs levels and repairing the intestinal mucosal integrity.

Denosumab-Induced Hypocalcemia after Billroth II Gastric Bypass Surgery

Hypocalcemia is a known risk following bariatric surgery and can contribute to the development of osteoporosis. Osteoporosis is commonly treated with denosumab, though denosumab can exacerbate underlying abnormalities in calcium homeostasis. We present the case of a 59-year-old female with severe hypocalcemia who had been treated with denosumab for osteoporosis three months before and had Billroth II gastric bypass surgery 15 years before, for bariatric purposes. Intravenous calcium supplementation was used to correct the initial electrolyte abnormality, and the patient was able to maintain appropriate calcium levels on high doses of oral calcium before discharge. Denosumab-induced hypocalcemia has been previously reported in patients with predisposing conditions including chronic kidney disease, primary sclerosing cholangitis, Crohn's disease, and a history of sleeve gastrectomy for marginal gastric ulcers. A few cases of hypocalcemia have been reported in patients with a history of bariatric surgery secondary to vitamin D deficiency, but this report is unique in demonstrating denosumab-induced hypocalcemia after bariatric surgery with normal vitamin D levels, suggesting a primary malabsorption of calcium. The risk of severe hypocalcemia should be considered before initiating denosumab to treat osteoporosis in patients with a history of bariatric surgery. If denosumab is initiated, serum calcium levels should be closely monitored, and patients should be educated about the importance of adherence to calcium supplementation.

Repurposing denosumab in lung cancer beyond counteracting the skeletal related events: an intriguing perspective

INTRODUCTION

Repurposing denosumab in lung cancer therapeutics capitalizes on its well-established role in preventing the skeletal related events (SREs) and its emerging, yet elusive, bone-independent role, assigned to inhibit the contribution of RANKL to cancer initiation and progression.

AREAS COVERED

The present review presents the available preclinical and clinical data indicating that denosumab may provide survival benefit to lung cancer patients beyond the counteraction of SREs.

EXPERT OPINION

Despite the preliminary data heralding the potential of denosumab to increase overall survival in lung cancer, the embracement of this strategy in clinical practice cannot be advocated until large randomized clinical trials consolidate its safety and efficacy. Given the improvement of lung cancer prognosis ascribed to revolutionary targeted treatment agents, the possibility of denosumab-related increased risk of second primary malignancies merits further evaluation. Many challenges in endorsing denosumab as a strategy to treat lung cancer beyond SREs prevention are pending counteraction, including: (i) patient selection guided by validated predictive and prognostic biomarkers; (ii) assessment of long-term outcomes; (iii) evaluation of benefit-risk ratio; (iv) translational research; (v) combination of denosumab with other targeted therapies; (vi) integration of genomic biomarkers, immune-related biomarkers, and biomarkers of active RANKL pathway to guide the decision-making process.

Hypocalcaemia following denosumab in prostate cancer: A clinical review

OBJECTIVES

Denosumab is often used in men with advanced prostate cancer to prevent skeletal-related events, but can be associated with severe hypocalcaemia. Our objective was to review the pathophysiology, identify risk factors and provide recommendations for prevention and management of denosumab-associated hypocalcaemia.

DESIGN

We reviewed the literature regarding denosumab-associated severe hypocalcaemia, defined as necessitating hospitalization for intravenous calcium treatment, in the context of prostate cancer.

PATIENTS

Men with prostate cancer with severe denosumab-associated hypocalcemia.

RESULTS

We identified 20 men with prostate cancer with severe denosumab-associated hypocalcemia, including the present case. Median age (range) was 70 years (45-86). All had skeletal metastases and presented with symptomatic hypocalcemia 16 days (4-35) after the initial (n = 18) or second (n = 2) denosumab treatment, with a serum total calcium of 1.36 mmol/L (1.13-1.91). The key risk factor was presence of active osteoblastic metastases, evidenced by elevated serum alkaline phosphatase, 838 U/L (58-2620) and supportive imaging. Other risk factors reported in some men included vitamin D deficiency (<50 nmol/L), 25-OH vitamin D 44 nmol/L (22-81), renal impairment, serum creatinine 103 μmol/L (62-1131) and hypomagnesaemia, 0.82 mmol/L (0.29-1.20). Men received intravenous calcium infusions for 16 days (1-90), and median total intravenous elemental calcium requirements were 3.17 g (0.47-26.65).

CONCLUSIONS

Denosumab treatment in men with metastatic prostate cancer can be associated with life-threatening hypocalcaemia requiring prolonged hospitalization for intravenous calcium treatment. Modifiable risk factors should be corrected before denosumab administration. In men with active osteoblastic metastases, consideration should be given to delay denosumab treatment until underlying disease activity is controlled, and/or be administered with close monitoring and proactive treatment with calcium and calcitriol.

Denosumab-induced hypocalcemia in patients with osteoporosis: can you know who will get low?

Hypocalcemia was reported at low rates (0.05-1.7%) in denosumab-treated postmenopausal women with osteoporosis. This real-life study shows a 7.4% rate of denosumab-induced hypocalcemia in community-dwelling osteoporotic men and women. Pretreatment serum calcium and creatinine levels are major predictors for this complication. Serum-calcium monitoring may help to identify and prevent severe hypocalcemia.

PURPOSE

RCTs have reported a 0.05-1.7% rate of hypocalcemia in denosumab-treated postmenopausal women with osteoporosis, but long-term real-life data are lacking. We assessed the rate of hypocalcemia in osteoporotic community-dwelling patients treated with denosumab.

METHODS

A retrospective analysis was conducted based on medical records (2010-2018) from a large HMO. An albumin-adjusted serum calcium concentration lower than 8.5 mg/dL was defined as hypocalcemia.

RESULTS

We included 2005 patients (93% women, mean age 76 ± 9 years). Hypocalcemia developed during treatment in 149 patients (7.4%; 1% less than 8 mg/dL): in 66 after 0.5-1 years; 48 after 1-2 years; 35 after > 2 years. On comparison of the hypocalcemic and normocalcemic patients, the strongest predictors of hypocalcemia were pretreatment levels of albumin-adjusted serum calcium (9.1 ± 0.4 vs. 9.4 ± 0.5 mg/dL, respectively; p < 0.05) and creatinine (0.9 ± 0.5 vs. 0.8 ± 0.3 mg/dL, respectively; p < 0.05). The hypocalcemia rate increased in parallel to a decrease in eGFR (p = 0.032 for the difference between eGFR ranges). Baseline calcium level ≤ 9.31 mg/dL predicted hypocalcemia with a sensitivity of 77% and specificity of 56%. A model of (- 2)*calcium + creatinine predicted hypocalcemia (3.7% when lower and 17.1% when higher than - 17.4). Gender, age, 25-hydroxyvitamin-D, parathyroid hormone, alkaline phosphatase, and whether denosumab was given as first or advanced line of osteoporotic therapy had no predictive value.

CONCLUSION

Real-life rates of denosumab-induced hypocalcemia are higher than previously reported. Hypocalcemia might develop after each dose of denosumab in ongoing treatment. Adequate calcium and vitamin D supplementation are needed. Serum calcium monitoring is advised in high-risk patients for early detection of severe hypocalcemia.

The Calcium Culprit: A Case of Denosumab-induced Hypocalcemia

Denosumab is a fully human monoclonal antibody which is used to treat osteoporosis and has been shown to cause hypocalcemia in patients with underlying prostatic and bone malignancies, renal impairment, postmenopausal state, and/or vitamin D deficiency. We present a case of a male patient, with a past medical history negative for the aforementioned conditions, who presented with right shoulder pain and was found to be severely hypocalcemic secondary to denosumab.

Pharmacological Management of Osteoporosis in Postmenopausal Women: An Endocrine Society* Clinical Practice Guideline

OBJECTIVE

The objective is to formulate clinical practice guidelines for the pharmacological management of osteoporosis in postmenopausal women.

CONCLUSIONS

Evidence from clinical trials and insights from clinical experience with pharmacologic therapies for osteoporosis were critically evaluated in formulating this guideline for the management of postmenopausal osteoporosis. Patient preferences, data on adherence and persistence, and risks and benefits from the patient and provider perspectives were also considered in writing committee deliberations. A consensus by the Writing Committee members was achieved for four management principles: (i) The risk of future fractures in postmenopausal women should be determined using country-specific assessment tools to guide decision-making. (ii) Patient preferences should be incorporated into treatment planning. (iii) Nutritional and lifestyle interventions and fall prevention should accompany all pharmacologic regimens to reduce fracture risk. (iv) Multiple pharmacologic therapies are capable of reducing fracture rates in postmenopausal women at risk with acceptable risk-benefit and safety profiles.

Humulus lupulus L. Extract Prevents Ovariectomy-Induced Osteoporosis in Mice and Regulates Activities of Osteoblasts and Osteoclasts

OBJECTIVE

To systematically evaluate the protective effects of Humulus lupulus L. extract (HLE) on osteoporosis mice.

METHODS

In vivo experiment, a total of 35 12-week-old female ICR mice were equally divided into 5 groups: the sham control group (sham); the ovariectomy with vehicle group (OVX); the OVX with estradiol valerate [EV, 0.2 mg/(kg•d)] the OVX with low- or high-dose HLE groups [HLE, 1 g/(kg•d) and 3 g/(kg•d)], 7 in each group. Treatment began 1 week after the ovariectomized surgery and lasted for 12 weeks. Bone mass and trabecular bone mircoarchitecture were evaluated by micro computed tomography, and bone turnover markers in serum were evaluated using enzyme-linked immunosorbent assay (ELISA) kits. In vitro experiment, osteoblasts and osteoclasts were treated with HLE at doses of 0, 4, 20 and 100 µg/mL. Biomarkers for bone formation in osteoblasts and bone resorption in osteoclasts were analyzed.

RESULTS

Compared with the OVX group, HLE exerted bone protective effects by the increase of estradiol (P<0.05), the improvement of cancellous bone structure, bone mineral density (P<0.01) and the reduction of serum alkaline phosphatase (ALP), tartrate resistant acid phosphatase (TRAP), bone gla-protein, c-terminal telopeptides of type I collagen (CTX-I) and deoxypyridinoline levels (P<0.01 for all). In vitro experiment, compared with the control group, HLE at 20 µg/mL promoted the cell proliferation (P<0.01), and increased the expression of bone morphogenetic protein-2 and osteopontin levels in osteoblasts (both P<0.05). HLE at 100 µg/mL increased the osteoblastic ALP activities, and HLE at all dose enhanced the extracellular matrix mineralization (both P<0.01). Furthermore, compared with the control group, HLE at 20 µg/mL and 100 µg/mL inhibited osteoclastic TRAP activity (P<0.01), and reduced the expression of matrix metalloproteinase-9 and cathepsin K (both P<0.05).

CONCLUSION

HLE may protect against bone loss, and have potentials in the treatment of osteoporosis.

Severe Hypocalcemia and Dramatic Increase in Parathyroid Hormone after Denosumab in a Dialysis Patient: A Case Report and Review of the Literature

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is frequently present in advanced stages of chronic kidney disease (CKD) patients with high risk of fracture and elevated socioeconomic burden. Denosumab, an injectable human monoclonal antibody with affinity for nuclear factor-kappa ligand (RANKL), is an effective treatment for osteoporosis in postmenopausal women and men. Unlike the bisphosphonates, the pharmacokinetics and pharmacodynamics of denosumab are not influenced by the renal function and are being increasingly used for patients having CKD-MBD with low bone mineral density (BMD) to reduce the risk of fragility fractures. Hypocalcemia is a known side effect of this drug along with compensatory increase in parathyroid hormone (PTH). However, limited information is available in the literature regarding this potentially life-threatening side effect with denosumab in end-stage renal disease (ESRD) patients on dialysis. We present a patient with ESRD on peritoneal dialysis who developed severe symptomatic hypocalcemia and dramatic increase in PTH following denosumab therapy. She was conservatively managed with calcium supplementation and appropriate adjustment in calcium dialysate. We have also reviewed the literature on the use of denosumab in dialysis patients and looked at additional factors that may precipitate severe hypocalcemia in these patients. We believe that denosumab should be used with caution in dialysis patients since it may lead to profound hypocalcemia. Clinicians should ensure special attention in recognizing patients at risk of developing this serious adverse effect, so that prompt treatment and preventive strategies can be implemented.

ERα and Wnt/β‑catenin signaling pathways are involved in angelicin‑dependent promotion of osteogenesis

Reports of the ameliorative effect of angelicin on sex hormone deficiency-induced osteoporosis have highlighted this compound as a candidate for the treatment of osteoporosis. However, the molecular mechanisms of action of angelicin on osteoblast differentiation have not been thoroughly researched. The aim of the present study was to evaluate the effect of angelicin on the proliferation, differentiation and mineralization of rat calvarial osteoblasts using a Cell Counting Kit-8, alkaline phosphatase activity and the expression of osteogenic genes and proteins. Treatment with angelicin promoted the proliferation, matrix mineralization and upregulation of osteogenic marker genes including collagen type I α 1 and bone γ-carboxyglutamate in fetal rat calvarial osteoblasts. Furthermore, angelicin promoted the expression of β-catenin and runt related transcription factor 2, which serve a vital role in the Wnt/β-catenin signaling pathway. Consistently, the osteogenic effect of angelicin was attenuated by the use of a Wnt inhibitor. Moreover, angelicin increased the expression of estrogen receptor α (ERα), which also serves a key role in osteoblast differentiation. Taken together, these results demonstrated that angelicin may promote osteoblast differentiation through activation of ERα and the Wnt/β-catenin signaling pathway.

Potential association with early changes in serum calcium level after starting or switching to denosumab combined with eldecalcitol

The aims of this study are to investigate changes in serum calcium (Ca) level after switching from either non-therapy, bisphosphonate, selective estrogen receptor modulators (SERM) or teriparatide treatments to a combination therapy of denosumab (DMAb), and eldecalcitol, and the association between early changes in serum calcium and changes in bone metabolic markers and bone mineral density (BMD). 129 patients with postmenopausal osteoporosis (32 non-pretreatment, 50 bisphosphonates, 18 SERM, and 29 teriparatide) were recruited and switched to DMAb plus eldecalcitol. Serum calcium levels, bone metabolism markers, and BMD measurements of the lumbar spine and femoral neck were evaluated. All groups showed an increase in BMD 6 months and 1 year after DMAb administration compared to baseline via suppression of bone metabolism markers. The TPD group showed a significant decrease in serum calcium level 1 week after the first injection of DMAb and eldecalcitol compared to baseline and the bisphosphonate group. Changes in serum calcium level from baseline to 1 week after the first injection of DMAb trended to correlate with changes in bone metabolism markers and lumbar BMD. The risks of DMAb-induced hypocalcemia are different between starting and switching from bone resorption inhibitors and bone formation promoters. Therefore, appropriate assessment before administration of DMAb, including pretreatment therapy as well as serum Ca and bone metabolic markers will help identify the risk of hypocalcemia following DMAb in combination with eldecalcitol. Our findings also showed that early change in serum Ca level after DMAb initiation could potentially predict the efficacy for therapy reaction.

Impaired residual renal function predicts denosumab-induced serum calcium decrement as well as increment of bone mineral density in non-severe renal insufficiency

Denosumab treatment of osteoporotic patients, except those with severe renal insufficiency, reduced cCa levels. Low baseline cCa, low estimated glomerular filtration rate, and high bone turnover increased the risk of lower cCa, while increasing bone mineral density. Pretreatment with antiresorptive agents was beneficial in reducing the risk of hypocalcemia.

INTRODUCTION

Although denosumab-induced hypocalcemia has been frequently observed in patients with chronic kidney disease (CKD) stages 4-5D being treated with denosumab for osteoporosis, few studies have assessed the risk factors for serum-corrected calcium (cCa) reductions in patients with non-severe renal insufficiency. This study assessed the risk factors for reduced cCa concentration following denosumab administration and analyzed factors predictive of changes in bone mineral density (BMD).

METHODS

Seventy-seven osteoporotic patients, not including those with CKD stages 4-5D, were treated with 60 mg denosumab once every 6 months. Biochemical parameters and BMD were analyzed from prior to the initial dose until 1 month after the second dose.

RESULTS

Following the first administration of denosumab, cCa levels decreased, reaching a minimum on day 7. Multiple linear regression analyses showed that baseline cCa, estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², tartrate-resistant acid phosphatase-5b (TRACP-5b), and bone alkaline phosphatase (BAP) or pretreatment with antiresorptive agents were significant factors independently associated with the absolute reduction in cCa from baseline to day 7 (ΔcCa_0-7 days). ΔcCa_0-7 days after the second dose of denosumab was significantly lower than that after the first dose. After 6 months of denosumab treatment, both LS-BMD and FN-BMD significantly increased from baseline. LS-BMD and FN-BMD correlated significantly with baseline TRACP-5b or BAP and eGFR, respectively.

CONCLUSIONS

Both low eGFR and high bone turnover were independent risk factors for denosumab-induced cCa decrement, and for increases in BMD. Pretreatment with antiresorptive agents may reduce the risk of hypocalcemia.

Use of bone turnover markers in the management of osteoporosis

PURPOSE OF REVIEW

Osteoporosis is a common public health problem that is often undertreated and underdiagnosed. The clinical management of osteoporosis is often reactionary to devastating fracture events. Bone turnover markers may improve the ease and rapidity at which osteoporosis is monitored and treated. Bone turnover markers are biochemical byproducts of bone formation or bone resorption. The clinical use of bone turnover markers is limited by significant preanalytical variability. Effective interpretation of bone turnover markers requires a detailed understanding of the variables that can affect their responses to osteoporosis treatment and monitoring.

RECENT FINDINGS

Progress is continuously being made on the standardization of bone turnover markers. The literature on the response of bone turnover markers to unique clinical situations is expanding. Data for evidence-based reference intervals for bone turnover markers has increased. Variables that affect the appropriate timing of lab draws like diurnal variation, postprandial status, exercise and alcohol use have been described. Studies examining the expected response of bone turnover markers to treatments of osteoporosis and other medications that affect bone health continue to increase.

SUMMARY

Bone turnover markers have clinical utility in the comprehensive evaluation of osteoporosis. When interpreted with caution and with a good understanding of their natural variability, bone turnover markers provide information that supplements osteoporosis management and provides useful clinical information about conditions that alter bone turnover.

Severe Hypocalcemia and Hypomagnesemia with Denosumab in Advanced Chronic Kidney Disease: Case Report and Literature Review

Background

Denosumab has become the preferred agent over zolendronic acid to help prevent skeletal-related events in patients with metastatic bone disease and multiple myeloma because it is approved for use in those with kidney dysfunction. However, denosumab has been linked to cases of hypocalcemia, particularly in those with advanced kidney disease.

Case Presentation

We present the case of a patient with metastatic prostate cancer and chronic kidney disease due to obstructive nephropathy who developed severe hypocalcemia and hypomagnesemia after denosumab injection, which required intensive care unit admission, aggressive calcium supplementation, and hemodialysis assistance. We reviewed the evidence behind the safety profile of denosumab in chronic kidney disease, and we also looked at additional factors that may precipitate severe hypocalcemia with denosumab in advanced kidney disease.

Conclusion

We believe that denosumab should be avoided in advanced chronic kidney disease due to the potential life-threatening, severe hypocalcemia that has been observed.

High bone turnover status as a risk factor in symptomatic hypocalcemia following denosumab treatment in a male patient with osteoporosis

Denosumab is a fully human monoclonal antibody against the receptor activator of nuclear factor-κB ligand (RANKL) that is used for the treatment of osteoporosis. Denosumab-induced hypocalcemia is a rare but important adverse event, which is usually asymptomatic in patients with osteoporosis. It is also known that hypocalcemia is common in patients with bone metastases and severe renal impairment. Here we report a case of symptomatic hypocalcemia following administration of 60 mg of denosumab in a patient with high bone turnover and no renal impairment (estimated glomerular filtration rate [eGFR], 71 mL/min), despite prophylactic oral vitamin D administration. This report supports our observation that there is a risk of protracted and marked denosumab-induced hypocalcemia in patients with high bone turnover, irrespective of their degree of renal impairment.

Use of bone turnover markers in postmenopausal osteoporosis

Bone turnover comprises two processes: the removal of old bone (resorption) and the laying down of new bone (formation). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that are recommended for clinical use. Bone turnover markers can be measured on several occasions in one individual with good precision. However, these markers are subject to several sources of variability, including feeding (resorption decreases) and recent fracture (all markers increase for several months). Bone turnover markers are not used for diagnosis of osteoporosis and do not improve prediction of bone loss or fracture within an individual. In untreated women, very high bone turnover marker concentrations suggest secondary causes of high bone turnover (eg, bone metastases or multiple myeloma). In people with osteoporosis, bone turnover markers might be useful to assess the response to anabolic and antiresorptive therapies, to assess compliance to therapy, or to indicate possible secondary osteoporosis. Much remains to be learnt about how bone turnover markers can be used to monitor the effect of stopping bisphosphonate therapy (eg, to identify a threshold above which restarting therapy should be considered). More studies are needed to investigate the use of bone turnover markers for assessment of the bone safety of new medications.