Low bone mineral density and fractures in long-term hemodialysis patients: a meta-analysis

Calcium-based phosphate binders and bone mineral density in patients undergoing hemodialysis: a retrospective cohort study

BACKGROUND

Calcium supplements are commonly prescribed to prevent fractures in patients with osteoporosis. Nonetheless, they are generally eschewed in hemodialysis patients because they increase vascular calcification and induce cardiovascular disease. This retrospective cohort study aimed to investigate the effect of calcium-based phosphate binders (CBPB) on bone mineral density (BMD) in hemodialysis patients.

METHODS

Outpatients on dialysis who underwent BMD measurement from January to December 2017, whose data on BMD trends and CBPB administration were recorded over the next 4 years, were enrolled. Patients receiving anti-osteoporotic medications were excluded. The association between the presence and duration of CBPB administration and changes in BMD was evaluated.

RESULTS

The femoral neck's BMD decreased from 0.836 g/cm2 (0.702-0.952) to 0.764 g/cm2 (0.636-0.896) (P < 0.001) in the non-CBPB group (patients who never received CBPB over 4 years, n = 32). The CBPB group (n = 56) exhibited only a minute decrease from 0.833 g/cm2 (0.736-0.965) to 0.824 g/cm2 (0.706-0.939) (P = 0.004). Multivariate linear regression analysis revealed better BMD maintenance in the CBPB group [β-coefficient (95% CI): 0.033 (0.001-0.065); P = 0.046] than in the non-CBPB group. Additionally, the prolonged-CBPB administration group showed superior BMD preservation [β-coefficient (95% CI): 0.038 (0.001-0.076); P = 0.042].

CONCLUSION

CBPB administration may be associated with BMD maintenance.

Effect of RANKL on Lower Depressive Symptoms In Hemodialysis Patients

Depression and osteoporosis are common diseases in dialysis patients. In addition, patients with osteoporosis are more susceptible to depression. Contrary to previous anti-osteoporosis agents, denosumab and romosozumab could be used in dialysis patients and have similar action mechanisms for blocking RANKL. RANKL causes bone resorption after binding RANKL, but binding with OPG leads to suppress of bone resorption. In recent mice study, inhibition of RANKL with denosumab improved depressive-like phenotype. Besides, it was found that OPG was associated with depression. Therefore, this study aimed to investigate the association of depressive symptoms with RANKL and OPG in hemodialysis patients. We conducted a cross-sectional study with a total of 172 hemodialysis patients. The participants were measured for plasma RANKL, OPG, MMP-2, and MMP-9 levels. Logistic regression analysis was performed to evaluate the effect of RANKL and OPG on the presence of depressive symptoms. The depressive symptoms were observed in 90 (52.3%) subjects. RANKL tertile 3 had negative association with BDI score (β - 4.527, 95% CI - 8.310 to - 0.743) in univariate analysis, and this association persisted even after multivariate adjustments (β - 5.603, 95% CI - 9.715 to -1.491) in linear regression. In logistic regression between RANKL tertiles and depressive symptoms, RANKL tertile 3 had significantly lower unadjusted OR (0.40, 95% CI 0.19-0.86), and multivariate-adjusted OR (0.31, 95% CI 0.12-0.82) for depressive symptoms. OPG was not significantly associated with depressive symptoms. Higher plasma RANKL concentrations were significantly associated with lower depressive symptoms in HD patients.Trial registration WHO registry, No. KCT0003281, date: January 12, 2017.

Long-term effects of denosumab on bone mineral density and turnover markers in patients undergoing hemodialysis

INTRODUCTION

Denosumab, a fully human anti-RANKL monoclonal antibody, is a widely used osteoporosis treatment that is increasingly being used in patients undergoing dialysis; however, its long-term efficacy and safety in these patients remain unknown.

MATERIALS AND METHODS

This observational study comprised individuals aged ≥ 20 years undergoing hemodialysis and receiving denosumab. After denosumab administration, we analyzed the long-term changes in bone mineral density (BMD) and levels of bone turnover markers (BTMs) and calcium.

RESULTS

The study included 45 patients who have been receiving denosumab for a median duration of 3.8 (interquartile range, 2.5-6.7) years. Tartrate-resistant acid phosphatase 5b (TRACP-5b) levels decreased from a median of 595 (434-778) mU/dL at baseline to 200 (141-430) mU/dL after 6 months of denosumab administration (P < 0.001) and remained low thereafter. Similarly, bone-specific alkaline phosphatase (BAP) levels decreased from a median of 18.2 (15.9-25.8) μg/L at baseline to 12.4 (9.9-15.6) μg/L after 6 months (P < 0.001) and remained low thereafter. Meanwhile, BMD, as assessed with dual energy X-ray absorptiometry and measured at the distal 1/3 of the radius, did not decrease (0.465 ± 0.112 g/cm2 at baseline vs. 0.464 ± 0.112 g/cm2 after administration; P = 0.616). Regarding hypocalcemia, corrected calcium levels reached were the lowest at 7 days after administration and normalized within 30 days.

CONCLUSION

The study showed long-term suppression of TRACP-5b and BAP levels and sustaining BMD after denosumab administration over an extended period in patients undergoing hemodialysis.

Vitamin D Therapy in Adults With CKD: A Systematic Review and Meta-analysis

RATIONALE & OBJECTIVE

Vitamin D is widely used to manage chronic kidney disease-mineral and bone disorder (CKD-MBD). We evaluated the effects of vitamin D therapy on mortality, cardiovascular, bone, and kidney outcomes in adults with CKD.

STUDY DESIGN

Systematic review of randomized controlled trials (RCT) with highly sensitive searching of MEDLINE, Embase, and CENTRAL, through February 25, 2023.

SETTING & STUDY POPULATIONS

Adults with stage 3, 4, or 5 CKD, including kidney failure treated with dialysis. Recipients of a kidney transplant were excluded.

SELECTION CRITERIA FOR STUDIES

RCTs with≥3 months of follow-up evaluating a vitamin D compound.

DATA EXTRACTION

Data were extracted independently by three investigators.

ANALYTICAL APPROACH

Treatment estimates were summarized using random effects meta-analysis. Primary review endpoints were all-cause death, cardiovascular death, and fracture. Secondary outcomes were major adverse cardiovascular events, hospitalization, bone mineral density, parathyroidectomy, progression to kidney failure, proteinuria, estimated glomerular filtration rate, hypercalcemia, hyperphosphatemia, biochemical markers of CKD-MBD, and various intermediate outcome measures of cardiovascular disease. Risk of bias was assessed using the Cochrane Risk of Bias (RoB) 2 tool. Evidence certainty was adjudicated using GRADE.

RESULTS

Overall, 128 studies involving 11,270 participants were included. Compared with placebo, vitamin D therapy probably had no effect on all-cause death (relative risk [RR], 1.04; 95% CI, 0.84-1.24); and uncertain effects on fracture (RR, 0.68; 95% CI, 0.37-1.23) and cardiovascular death (RR, 0.73; 95% CI, 0.31-1.71). Compared with placebo, vitamin D therapy lowered serum parathyroid hormone and alkaline phosphatase, but increased serum calcium.

LIMITATIONS

Data were limited by trials with short-term follow-up periods, small sample size, and the suboptimal quality.

CONCLUSIONS

Vitamin D therapy did not reduce the risk of all-cause death in people with CKD. Effects on fracture and cardiovascular and kidney outcomes were uncertain.

TRIAL REGISTRATION

Registered at PROSPERO with study number CRD42017057691.

PLAIN-LANGUAGE SUMMARY

Chronic kidney disease (CKD) is associated with increased risk of death, cardiovascular disease, and fractures. This excess risk is thought to be related to changes in bone and mineral metabolism, leading to the development of CKD-mineral and bone disorder (CKD-MBD) which is characterized by vascular calcification and reduced bone quality. Vitamin D is commonly used in the treatment of this condition. We reviewed randomized controlled trials examining the effect of vitamin D therapy in CKD. We found that vitamin D therapy affects serum biomarkers, including an increase in serum calcium. However, it probably has no effect on risk of all-cause death in CKD, and the effects on other clinical bone, cardiovascular, and kidney outcomes are uncertain.

Vitamin K supplementation and bone mineral density in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial

BACKGROUND

Vitamin K deficiency is highly prevalent in patients on dialysis and may contribute to their low bone mineral density (BMD) and increased risk of fracture. This study investigated the effect of menaquinone-7 (MK-7) supplementation on BMD in patients on chronic dialysis.

METHODS

In a multicentre, double-blind, placebo-controlled intervention trial, 123 patients on chronic dialysis were randomised to a daily oral supplement of either MK-7 360 µg or placebo for 2 years. BMD of the distal radius (1/3, mid, ultradistal and total), femoral neck, lumbar spine (L1-L4) and whole body was assessed by dual-energy X-ray absorptiometry. Serum levels of vitamin K1 and MK-7 and plasma levels of total osteocalcin, dephosphorylated-uncarboxylated matrix Gla protein and protein induced by vitamin K absence II were measured to assess vitamin K status.

RESULTS

After 2 years, an accelerated BMD loss of the 1/3 distal radius was found with MK-7 supplementation {mean difference of changes relative to placebo -0.023 g/cm2 [95% confidence interval (CI) -0.039 to -0.008]}, whereas the decrease in lumbar spine BMD seen in the placebo group was prevented [mean difference of changes between groups 0.050 g/cm2 (95% CI 0.015-0.085)]. No significant effects were observed at the remaining skeletal sites. Vitamin K status strongly improved in MK-7-supplemented participants.

CONCLUSION

Compared with placebo, an accelerated BMD loss of the 1/3 distal radius was found after 2 years of MK-7 supplementation, whereas a decline in lumbar spine BMD was prevented. As such, MK-7 supplementation might modify BMD site-specifically in patients on dialysis. In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.

Trabecular bone score and phalangeal quantitative ultrasound are associated with muscle strength and fracture risk in hemodialysis patients

There is growing interest in the relationship between chronic kidney disease (CKD) and fragility fracture risk. Bone mineral density (BMD) is a major determinant of bone strength, although its role as a predictor of fracture in advanced CKD and hemodialysis is still under debate. We aimed to further investigate surrogates of bone quality and their associations with muscle strength and fracture risk in hemodialysis. Multiple clinical risk factors for fracture and an estimated 10-year probability of fracture, BMD at lumbar spine and femur, trabecular bone score (TBS), X-ray vertebral morphometry, phalangeal bone quantitative ultrasonography (QUS), tibial pulse-echo ultrasonography (PEUS), and handgrip strength were evaluated in a setting of hemodialysis patients in treatment with acetate-free biofiltration (AFB) or bicarbonate hemodialysis. The bone ultrasound measurements, both at phalangeal and tibial sites, were significantly associated with lumbar and femoral DXA values. Handgrip strength was significantly associated with the 10-year probability of fracture (r = -0.57, p < 0.001 for major fractures and r = -0.53, p < 0.001 for hip fracture, respectively), with femur neck, total femur, and L1-L4 BMD values (r = 0.47, p = 0.04; r = 0.48, p = 0.02; r = 0.58, p = 0.007, respectively), with TBS at the lumbar spine (r = 0.71, p < 0.001) and with the phalangeal QUS measure of AD-SoS (r = 0.369, p = 0.023). In the hemodialysis group, 10 participants (24.3%) reported at least one morphometric vertebral fracture (Vfx); conversely, only six participants (15%) showed Vfx in the control group. In the hemodialysis group, participants with Vfx compared with participants without Vfx reported significantly different TBS, bone transmission time (BTT), cortical thickness, and handgrip strength (p < 0.05). At multiple regression analysis, by identifying as dependent variable the 10-year fracture risk for major fracture, after correcting for age, BMI, time since dialysis, AD-SoS, cortical bone thickness, and handgrip strength, only BTT (β = -15.21, SE = 5.91, p = 0.02) and TBS (β = -54.69, SE = 21.88, p = 0.02) turned out as independently associated with fracture risk. In conclusion, hemodialysis patients showed a higher fracture risk and lower surrogate indices of bone strength as TBS and QUS parameters. In this cohort of patients, handgrip strength measurements appeared to be a useful instrument to identify high-fracture-risk subjects.

Meta-analyses of the quantitative computed tomography data in dialysis patients show differential impacts of renal failure on the trabecular and cortical bones

Dialysis patients have compromised bone health that increases their fracture risk due to low bone mass and deterioration in bone microarchitecture. Through meta-analyses of published studies, we conclude that dialysis patients suffer from impaired compartmental bone parameters compared with healthy controls.

INTRODUCTION

We performed meta-analyses to determine the effect of chronic kidney disease (CKD) patients under dialysis on the trabecular and cortical parameters of radius and tibia.

METHODS

This is a meta-analysis of cross-sectional and prospective clinical studies. PubMed, Web of Science, Google Scholar, and Scopus were searched using various permutation combinations. Dialysis patients were compared with non-CKD healthy controls using quantitative computed tomography. High-resolution peripheral quantitative computed tomography (HR-pQCT) and pQCT data of dialysis patients were dissected from eligible studies for pooled analysis of each parameter.

RESULTS

Ten studies met the inclusion criteria that included data from 457 dialysis patients and 2134 controls. Pooled analysis showed a significant decrease (a) in total vBMD at distal radius [standard deviation of the mean (SDM) = -0.842, p = 0.000] and tibia (SMD = -0.705, p = 0.000) and (b) in cortical vBMD (SDM = -1.037, p = 0.000) at radius of dialysis patients compared with control. There were strong correlations between total vBMD and microarchitecture parameters at tibia in dialysis patients.

CONCLUSIONS

At radius and tibia, bone mass, microarchitecture, and geometry at trabecular and cortical envelopes displayed impairments in dialysis patients compared with control. Tibial vBMD may have diagnostic value in dialysis. HR-pQCT and pQCT may be used to further understand the compartmental bones response to CKD-induced loss at different stages of CKD.

Serum Sclerostin Level Is Negatively Associated with Bone Mineral Density in Hemodialysis Patients

Background and Objectives: Sclerostin and Dickkopf-1 (DKK1) modulate osteoblastogenesis, but their role in bone loss in hemodialysis (HD) patients is inconclusive. This study investigated relationships among lumbar bone mineral density (BMD), serum sclerostin, and DKK1 in HD patients. Materials and Methods: Blood samples were obtained from 75 HD patients. Dual-energy X-ray absorptiometry measured lumbar BMD of the lumbar vertebrae (L2−L4). Enzyme-linked immunosorbent assay revealed serum sclerostin and DKK1 concentrations. Results: There were 10 (13.3%), 20 (26.7%), and 45 (60%) patients defined as presenting with osteoporosis, osteopenia, or normal BMD, respectively. Age, alkaline phosphatase, urea reduction rate, fractional clearance index for urea, sclerostin level, and percentage of female patients are significantly negatively associated with the lumbar BMD and T-score, while the body mass index and waist circumference significantly positively associated with the lumbar BMD and T-score. Multivariate forward stepwise linear regression analysis indicated that serum sclerostin (β = −0.546, adjusted R2 change = 0.454; p < 0.001), age (β = −0.216, adjusted R2 change = 0.041; p = 0.007), and percentage of female HD patients (β = −0.288, adjusted R2 change = 0.072; p = 0.0018) were significantly negatively associated with lumbar BMD in HD patients. Conclusions: Advanced age, female gender, and serum sclerostin level, but not DKK1, were negatively associated with BMD in HD patients.

Serum Osteoprotegerin Level Is Negatively Associated with Bone Mineral Density in Patients Undergoing Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Osteoprotegerin (OPG), a potent osteoclast activation inhibitor, decreases bone resorption and plays a role in mediating bone mineral density (BMD). Our aim was to evaluate the relationship between BMD and serum OPG in maintenance hemodialysis (MHD) patients.

MATERIALS AND METHODS

Fasting blood samples were obtained from 75 MHD patients. BMD was measured by dual-energy X-ray absorptiometry in lumbar vertebrae (L2-L4). The WHO classification criteria were applied to define osteopenia and osteoporosis. A commercial enzyme-linked immunosorbent assay was used to measure serum OPG values.

RESULTS

Among all MHD patients, seven (9.3%) and 20 patients (26.7%) were defined as osteoporosis and osteopenia, respectively. Female patients had lower lumbar BMD than males (p = 0.002). Older age (p = 0.023), increased serum OPG (p < 0.001) urea reduction rate (p = 0.021), Kt/V (p = 0.027), and decreased body mass index (p = 0.006) and triglycerides (p = 0.020) were significantly different between the normal, osteopenia, and osteoporosis groups. Lumbar spine BMD was positively correlated with body mass index (BMI) (p < 0.001) but negatively correlated with OPG (p < 0.001) and age (p = 0.003). After grouping patients into T scores < -1 and < -2.5, female sex and OPG (adjusted odds ratio [aOR] 1.022, 95% confidence interval [C.I.] 1.011-1.034, p < 0.001) were predictors of T scores < -1, whereas only OPG was predictive of T scores < -2.5 (aOR 1.015, 95% C.I. 1.005-1.026, p = 0.004) by multivariate stepwise logistic regression analysis. The areas under the curve for predicting T scores < -1 or < -2.5 were 0.920 (95% C.I. 0.834-0.970, p < 0.001) and 0.958 (95% C.I. 0.885-0.991, p < 0.001), respectively.

CONCLUSIONS

Increased serum OPG negatively correlated with lumbar BMD and could be a potential biomarker predictive of osteoporosis in MHD patients.

New Markers of Bone Fragility in Hemodialysis Patients: A Monocentric Study

INTRODUCTION

Mechanisms underlying bone fragility in patients under dialysis are various. The assessment of bone disorder is not yet codified in these patients. Our study aimed to determine the relationship between the serum fibroblast growth factor 23 (FGF23) level and bone fragility. We also aimed to assess the bone alkaline phosphatase (bAP) to the C-terminal telopeptide of type I (CTX) ratio and the FGF23*bAP product to CTX ratio in patients under hemodialysis.

METHODOLOGY

We conducted a cross-sectional study, including 76 patients under hemodialysis. To assess bone fragility, we measured bAP, CTX, and FGF 23. We calculated the bAP to the CTX ratio (bAP/CTX) and the FGF23*bAP product to the CTX ratio (FGF23*bAP/CTX). We defined bone fragility as the existence of osteoporosis or fragility fractures. Receiver operating characteristic (ROC) curves were evaluated for each biological using the existence of osteoporosis or fragility fracture as the gold standard for bone fragility.

RESULTS

There were 51 men. The mean age was 53.36 ± 14.27 years. Bone fragility was noted in 25 cases. Patients with osteoporosis had higher FGF*bAP/CTX and bAP/CTX ratios. The ability of the ratio (bAP/CTX) to distinguish patients with osteoporosis from those without osteoporosis was good, with a ROC AUC of 0.707. The optimal ratio cut-off value with the highest accuracy was 9.72. The ability of the ratio (FGF23*bAP/CTX) to distinguish patients with bone fragility was good, with a ROC AUC of 0.701. The optimal ratio cut-off value with the highest accuracy was 1621.89 (sensitivity 60%, specificity 78.4%).

CONCLUSION

Our study showed FGF23, FGF23*bAP product to CTX ratio, and the bAP to CTX ratio can be used as markers of bone fragility in hemodialysis patients. Therefore, these noninvasive and relatively inexpensive methods may serve to diagnose bone fragility in patients under hemodialysis.

Risks of Hip and Nonvertebral Fractures in Patients With CKD G3a-G5D: A Systematic Review and Meta-analysis

RATIONALE & OBJECTIVE

Disordered mineral metabolism complicates chronic kidney disease (CKD), but the effect of reduced kidney function on fracture risk has not been fully established. We conducted a systematic review and meta-analysis of the risks for hip and nonvertebral fractures in people with CKD. We also investigated the effects of age, sex, and CKD stage.

STUDY DESIGN

Systematic review and meta-analysis.

STUDY POPULATION

Adults with CKD glomerular filtration rate (GFR) categories 3a-5D (G3a-G5D) compared with adults without CKD G3a-G5D.

SELECTION CRITERIA FOR STUDIES

Observational studies.

DATA EXTRACTION

Data extraction was conducted by 1 reviewer and checked by a second reviewer.

ANALYTICAL APPROACH

MEDLINE, EMBASE, and Cochrane databases were searched in March 2018 and an update was conducted in November 2019. We used random-effects models to calculate pooled risk estimates and 95% CIs.

RESULTS

17 studies met the inclusion criteria. We included 13 studies in the hip fracture systematic review and 10 studies in the meta-analysis. Studies reported data from 250,440,035 participants; 5,798,566 with CKD G3a-G5D and 363,410 with hip fractures. 4 studies were included in the nonvertebral fracture analysis, reporting data from 1,396,976 participants; 464,978 with CKD G3a-G5D and 115,284 fractures. Studies reported data from participants aged 18 to older than 90 years. We found a significant increase in fracture risk both for hip (relative risk [RR], 2.36; 95% CI, 1.64-3.39) and nonvertebral fractures (RR, 1.47; 95% CI, 1.15-1.88). For hip fractures, younger patients (<65 years) had higher relative risk (RR, 7.66; 95% CI, 2.76-21.26) than older patients (>65 years; RR, 2.11; 95% CI, 1.41-3.16). Greater GFR loss was associated with higher relative risk for fractures.

LIMITATIONS

We could not assess the effects of bone mineral density, biochemical abnormalities, renal osteodystrophy, frailty, falls, or medications on risk for fractures.

CONCLUSIONS

Risks for hip and nonvertebral fractures are increased in CKD G3a-G5D. The relative risk of hip fracture is greater in the younger than the older population and increases progressively with loss of GFR. We suggest that fracture prevention should be a consideration in CKD at any age.

Mineral bone disorder and osteoporosis in hemodialysis patients

BACKGROUND

Bone disease is common in patients undergoing hemodialysis. It is the result of bone turnover abnormalities and the decrease of bone mineral density (BMD). We aimed to determine the usefulness of serum bone turnover markers and BMD measurement by dual-energy x-ray absorptiometry (DXA) in hemodialysis patients.

METHODS

We conducted a cross-sectional study including 90 hemodialysis for more than 12 months. Bone mineral density was assessed by DXA. Peripheral blood samples were obtained from each patient before dialysis in a fasting state within a week of the DXA. Biochemical variables of calcium and phosphate were measured. One bone formation marker (bone-specific alkaline phosphatase (bAP), one bone resorption marker (carboxy-terminal telopeptides of type 1 collagen (CTX)) were measured. Total alkaline phosphatase (TAP), intact parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) which is a bone-derived hormone were also measured.

RESULTS

CTX values were 6.25 times higher than the normal limit of the assay. Bone alkaline phosphatase levels were less than 10 ng/mL in 28.8% of cases. 23% of patients have osteoporosis and 45% have osteopenia. Femoral BMD had negative correlations with age and PTH levels. FGF23 levels were significantly increased in patients with osteoporosis affecting the lumbar. The levels of bAP and CTX showed a positive correlation. Both circulating bAP and CTX levels showed also positive correlations with PTH levels. Fractures, observed in 12.2% of cases, were associated with low PTH values and the existence of osteoporosis.

CONCLUSIONS

Our study showed that osteoporosis and fracture are common in dialysis patients. The reduced BMD was associated with advanced age and elevated levels of PTH. Markers of bone turnover and FGF23 may play a role in the diagnosis of bone disease in hemodialysis patients. DXA measurement is necessary for the monitoring for bone loss.

Association between frailty and bone loss in patients undergoing maintenance hemodialysis

Frailty is significantly associated with bone loss in the general population. However, it is unclear whether this association also exists in patients undergoing hemodialysis who have chronic kidney disease-mineral and bone disorder (CKD-MBD). This study aimed to assess the association between frailty and bone loss in patients undergoing hemodialysis. This cross-sectional study included 214 (90 women, 124 men) Japanese outpatients undergoing maintenance hemodialysis three times per week, with a mean age of 67.1 years (women) and 66.8 years (men). Frailty was defined based on criteria set forth by the Cardiovascular Health Study (CHS)-19 (21.1%) women and 47 (37.9%) men were robust, 41 (45.6%) women and 43 (34.7%) men were pre-frail, and 30 (33.3%) women and 34 (27.4%) men were frail. For bone mass, quantitative ultrasound (QUS) parameters (speed of sound, broadband ultrasound attenuation, stiffness index) of the calcaneus were measured. The association between frailty and QUS parameters was determined separately for women and men using multivariate analysis of covariance (ANCOVA), with adjustments for clinical characteristics including age, body mass index, hemodialysis vintage, diabetes, current smoking, serum albumin, phosphate, corrected calcium, intact parathyroid hormone, and medication for CKD-MBD (vitamin D receptor activator, calcimimetics). ANCOVA revealed that all QUS parameters declined significantly with increasing levels of frailty in both sexes (P < 0.05). In conclusion, frailty (as defined by CHS criteria) should be considered a risk factor for bone loss in patients undergoing hemodialysis.

Chronic hemodialysis is associated with lower trabecular bone score, independent of bone mineral density: a case-control study

We measured trabecular bone score (TBS) in 98 patients on permanent hemodialysis (HD) and 98 subjects with similar bone mineral density and normal kidney function. TBS was significantly lower in HD patients, indicating deteriorated bone microarchitecture, independent of bone mass. This might partially explain the increased fracture risk in HD.

PURPOSE

In the general population, trabecular bone score (TBS) was shown to predict fracture independent of bone mineral density (BMD). In end-stage renal disease patients on hemodialysis (HD), the value of TBS is beyond that of BMD in currently unclear. Our aim was to assess lumbar spine (LS) TBS in HD patients compared with subjects with normal kidney function matched for age, sex, and LS BMD.

METHODS

We assessed TBS and LS and femoral neck (FN) BMD in 98 patient on permanent HD (42.8% males; mean age 57.5 ± 11.3 years; dialysis vintage 5.5 ± 3.8 years) and 98 control subjects (glomerular filtration rate > 60 mL/min) using DXA. We simultaneously controlled for sex, age (± 3 years), and LS BMD (± 0.03 g/cm²).

RESULTS

HD patients had significantly lower LS TBS (0.07 [95% CI 0.03-0.1]; p = 0.0004), TBS T-score (0.83 SD [95% CI 0.42-1.24]; p = 0.0001)) and TBS Z-score (0.81 SD [95% CI 0.41-1.20]; p = 0.0001) than matched controls. TBS significantly correlated with LS BMD in both HD patients (r = 0.382; p = 0.001) and controls (r = 0.36; p = 0.002). The two regression lines had similar slopes (0.3 vs. 0.28; p = 0.84) with different intercepts (0.88 vs. 0.98). TBS adjustment significantly increased the 10-year fracture risk from 3.7 to 5.3 for major osteoporotic fracture and from 0.9 to 1.5 for hip fracture.

CONCLUSIONS

HD patients have lower TBS than controls matched for LS BMD, indicating altered bone microarchitecture. Also, the magnitude of TBS reduction in HD patients is constant at any LS BMD. Adjustment for TBS partially corrects the absolute 10-year fracture risk.

The effect of a previous created distal arteriovenous-fistula on radial bone DXA measurements in prevalent renal transplant recipients

Background

Accelerated bone loss occurs rapidly following renal transplantation due to intensive immunosuppression and persistent hyperparathyroidism. In renal transplant recipients (RTRs) due to the hyperparathyroidism the non-dominant forearm is often utilized as a peripheral measurement site for dual-energy x-ray absorptiometry (DXA) measurements. The forearm is also the site of previous created distal arteriovenous fistulas (AVF). Although AVF remain patent long after successful transplantation, there are no data available concerning their impact on radial bone DXA measurements.

Methods

In this cross-sectional study we performed DXA in 40 RTRs with preexisting distal AVF (RTRs-AVF) to assess areal bone mineral density (aBMD) differences between both forearms (three areas) and compared our findings to patients with chronic kidney disease (CKD, n = 40), pre-emptive RTRs (RTRs-pre, n = 15) and healthy volunteers (n = 20). In addition, we assessed relevant demographic, biochemical and clinical aspects.

Results

We found a marked radial asymmetry between the forearms in RTRs with preexisting AVF. The radial aBMD at the distal AVF forearm was lower compared to the contralateral forearm, resulting in significant differences for all three areas analyzed: the Rad-1/3: median (interquartile range) in g/cm², Rad-1/3: 0.760 (0.641–0.804) vs. 0.742 (0.642, 0.794), p = 0.016; ultradistal radius, Rad-UD: 0.433 (0.392–0.507) vs. 0.420 (0.356, 0.475), p = 0.004; and total radius, Rad-total: 0.603 (0.518, 0.655) vs. 0.599 (0.504, 0.642), p = 0.001). No such asymmetries were observed in any other groups. Lower aBMD in AVF forearm subregions resulted in misclassification of osteoporosis.

Conclusions

In renal transplant recipients, a previously created distal fistula may exert a negative impact on the radial bone leading to significant site-to-site aBMD differences, which can result in diagnostic misclassifications.

Abdominal aortic calcification score among several vascular calcification scores of plain radiograph is the most reliable predictor of severe coronary artery calcification in dialysis patients

Aim: Coronary artery calcification (CAC) score on computed tomography (CT) or vascular calcification (VC) scores on plain radiographs are associated with cardiovascular events and fracture. We investigated which VC score among several VC scores on plain radiographs is predictor of CAC, and whether VC scores are related with bone mineral density (BMD) in dialysis patients.

Methods: We checked several plain radiographs (hands and pelvis [HP], feet and lateral lumbar spine), BMD and multidetector CT scans of 55 patients maintaining dialysis in this cross-sectional study. We analyzed data to find predictors for severe CAC which was defined as CAC scores >400 on CT.

Results: Patients with severe CAC on CT had a higher proportion of abdominal aortic calcification (AAC) score ≥5, HP score ≥3 and feet ≥1 than those without severe CAC. The CAC score on CT was positively correlated with all VC scores on plain radiographs. The AAC and CAC scores were negatively correlated with T-scores for the BMD at the forearm and positively correlated with osteoprotegerin levels. Among several VC scores on plain radiographs, the AAC ≥5 were independently associated with severe CAC on CT.

Conclusions: Several plain radiographs evaluating VC scores, including a lateral lumbar spine view at the very least, can replace CT checking CAC score in dialysis patients. The AAC score ≥5 may not only reveal severe CAC but also give a hint of low bone mass at the forearm.

The trabecular bone score is associated with bone mineral density, markers of bone turnover and prevalent fracture in patients with end stage kidney disease

Fracture risk increases in end-stage kidney disease (ESKD), but bone mineral density (BMD) measurement is less predictive of risk than in the general population. In this study of patients with ESKD, a lower trabecular bone score (TBS), indicative of microarchitectural deterioration, was associated with higher bone turnover markers and prevalent non-vertebral fracture.

INTRODUCTION

Declining renal function carries increased fracture risks, but BMD is less predictive of fracture for dialysis patients than the general population. The TBS, obtained from lumbar spine dual-energy X-ray absorptiometry (DXA) images, provides information on microarchitectural integrity not captured by BMD. The aim of this study was to assess associations of the TBS to clinical, DXA, radiological, and laboratory measures in patients with ESKD undergoing kidney and simultaneous pancreas kidney (SPK) transplantation.

METHODS

A total of 147 patients with ESKD underwent pre-transplant laboratory testing, DXA, lateral spine X-ray, and structured history within 4 weeks of transplantation. Associations of the TBS to demographic data, prevalent fracture, BMD, and laboratory variables were assessed.

RESULTS

Of 147 patients (60% male, mean age 48 ± 13 years), 36% had diabetes mellitus (DM) and 54 patients had fractures: 21 prevalent vertebral fractures only, 22 non-vertebral fractures only, and 11 had both. The mean TBS (1.345 ± 0.125) was lower in patients undergoing SPK than kidney-only transplants (1.292 vs. 1.364, p = 0.001). The TBS correlated to spine and total hip BMD, body mass index and inversely to parathyroid hormone, alkaline phosphatase and procollagen 1 N-propeptide. By multivariable logistic regression, lower TBS was significantly associated to prior non-vertebral fracture (p = 0.026).

CONCLUSIONS

A lower TBS, suggestive of increased microarchitectural damage, was associated with type 1 DM, markers of higher bone turnover, and prevalent fracture. These data support the need for prospective studies to evaluate whether TBS inclusion improves fracture prediction in patients with ESKD.

Bone density of the femoral neck in patients on maintenance dialysis

Background

Our institution recently started using the femoral neck (FN), as well as the non-shunted distal radius (Rd), to measure bone mineral density (BMD) in patients with chronic kidney disease. We examined the utility and characteristics of this measurement in patients on maintenance dialysis.

Methods

We selected 293 patients on chronic dialysis. We measured Rd and FN BMD using dual-energy X-ray absorptiometry, and we reviewed blood test findings, which included hemoglobin, albumin, blood urea nitrogen, creatinine, adjusted calcium, phosphorus, alkaline phosphatase, and intact parathyroid hormone. We conducted a multiple linear regression analysis that was stratified according to sex, age, body weight, height, and dialysis vintage. The Rd and FN BMD values were the dependent variables, and the blood test findings were the independent variables. We compared the areas under the curve (AUCs) of Rd and FN BMD using receiver operating characteristic curve analysis to differentiate between patients with and without fractures.

Results

FN BMD was significantly lower than Rd BMD. The general risk factors for osteoporosis, such as low body weight, older age, muscle mass loss, and malnutrition, influenced FN BMD. FN and Rd BMD were not correlated with calcium, phosphorous, or intact parathyroid hormone, whereas a significant, negative correlation with alkaline phosphatase was detected. Both men and women with a history of fragility fractures had significantly lower Rd and FN BMDs than patients without such a history. However, there was no significant difference between the AUCs of FN and Rd BMD for fractures in both men and women.

Conclusions

FN BMD was significantly lower than Rd BMD. Additionally, FN BMD was not inferior to Rd BMD for assessing the risk of fracture in patients on maintenance dialysis.

Management of Osteoporosis in Chronic Kidney Disease

Chronic kidney disease (CKD) patients with coexisting osteoporosis are becoming common. Many of the therapeutic agents used to treat osteoporosis are known to be affected by the renal function. It is generally thought that osteoporosis in G1 to G3 CKD patients can be treated as in non-CKD patients with osteoporosis. In stage 4 or more advanced CKD patients and CKD patients on dialysis with osteoporosis, however, bisphosphonates must be used with caution, bearing in mind the potential development of such disorders as adynamic bone disease. The use of vitamin D preparations in low doses is relatively safe. In postmenopausal women, raloxifene must be administered with caution. When using denosumab, the serum calcium concentrations should be monitored carefully to prevent the development of hypocalcemia, and active vitamin D preparations should be administered concomitantly. The present article provides an overview of the management of osteoporosis in CKD patients.

Bone Quality Assessment as Measured by Trabecular Bone Score in Patients With End-Stage Renal Disease on Dialysis

Patients with end-stage renal disease (ESRD) on maintenance hemodialysis (HD) exhibit osteoporosis and increased fracture risk. Dual-energy X-ray absorptiometry scan measurements and calculation of fracture risk assessment toll score underestimate fracture risk in these patients and do not estimate bone quality. Trabecular bone score (TBS) has been recently proposed as an indirect measure of bone microarchitecture. In this study, we investigated alterations of bone quality in patients with ESRD on HD, using TBS. Fifty patients with ESRD on HD, with a mean age 62 years, and 52 healthy individuals matched for age, body mass index, and gender, were enrolled. All participants had a bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry scan at the lumbar spine, femoral neck, total hip, and 1/3 radius. TBS was evaluated using TBS iNsight. Serum fetuin-A and plasma fibroblast growth factor-23 (FGF-23) (C-terminal) were also measured. Patients on dialysis had significantly lower BMD values at all skeletal sites measured. Plasma FGF-23 levels significantly increased and serum fetuin-Α significantly decreased in patients on dialysis compared with controls. TBS was significantly reduced in patients on dialysis compared with controls (1.11 ± 0.16 vs 1.30 ± 0.13, p < 0.001, respectively) independently of age; BMD; duration of dialysis; and serum levels of alkaline phosphatase, 25-OH-vitamin D, parathyroid hormone, fetuin-A, or plasma FGF-23. Patients on HD who were diagnosed with an osteoporotic vertebral fracture had numerically lower TBS values, albeit without reaching statistical significance, compared with patients on dialysis without a fracture (1.044 ± 0.151 vs 1.124 ± 0.173, respectively, p = 0.079). Bone microarchitecture, as assessed by TBS, is significantly altered in ESRD on patients on HD independently of BMD values and metabolic changes that reflect chronic kidney disease-mineral and bone disorder.

The use of bone mineral density measured by dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed microtomography in chronic kidney disease

Chronic kidney disease (CKD) is a risk factor for fractures. The current evaluation of fracture risk is based upon the combination of various clinical factors and quantitative imaging of bone. X-ray-based tools were developed to evaluate bone status and predict fracture risk. Dual energy X-ray absorptiometry (DXA) is available worldwide. Longitudinal studies showed that low areal Bone Mineral Density (BMD) measured by DXA predicts fractures in the CKD population as it does in non uremic populations, with good specificity and moderate sensitivity. Peripheral quantitative computed tomography (pQCT) and high resolution pQCT are research tools which measure volumetric BMD at the tibia and radius. They are able to discriminate between the cortical and trabecular envelopes which are differentially affected by renal osteodystrophy. In CKD, a rapid thinning and increased porosity at the cortex is observed which is associated with increased the risk for fracture.

Denosumab for Male Hemodialysis Patients with Low Bone Mineral Density: A Case-Control Study

Denosumab increases bone mineral density (BMD) in patients not receiving hemodialysis therapy. However, limited data are available in the literature concerning the use of denosumab in hemodialysis patients. We treated male hemodialysis patients with low radius BMD with denosumab therapy for 1 year and evaluated its effect on radius BMD. Seventeen patients were treated with denosumab 60 mg every 6 months, and 20 patients were not treated with denosumab (control group). At seven days, the mean corrected calcium level decreased from 9.2 ± 0.5 mg to 8.5 ± 0.5 mg (P < 0.01), and mean serum phosphorus decreased from 5.0 ± 1.3 mg/dl to 4.2 ± 0.9 mg/dl (P < 0.01). At 1 month, the corrected calcium and serum phosphorus levels were 9.2 ± 0.9 mg/dl and 4.0 ± 1.1 mg/dl, respectively. At 1 year, BMD increased by 2.6%  ± 4.4% in the denosumab group and decreased by 4.5%  ± 7.7% in the control group (P < 0.001). In our observational study, denosumab therapy represents an effective treatment for male dialysis patients with low BMD.

Osteoporosis in Frail Patients: A Consensus Paper of the Belgian Bone Club

In this consensus paper, the Belgian Bone Club aims to provide a state of the art on the epidemiology, diagnosis, and management of osteoporosis in frail individuals, including patients with anorexia nervosa, patients on dialysis, cancer patients, persons with sarcopenia, and the oldest old. All these conditions may indeed induce bone loss that is superimposed on physiological bone loss and often remains under-recognized and under-treated. This is of particular concern because of the major burden of osteoporotic fractures in terms of morbidity, mortality, and economic cost. Therefore, there is an urgent need to appreciate bone loss associated with these conditions, as this may improve diagnosis and management of bone loss and fracture risk in clinical practice.

Effects of parathyroidectomy on bone metabolism in haemodialysis patients with secondary hyperparathyroidism

OBJECTIVE

To evaluate the outcome of bone metabolism and bone mineral density (BMD) in haemodialysis patients after parathyroidectomy (PTX).

METHODS

A total of 31 haemodialysis patients with secondary hyperparathyroidism (SHPT) were treated with PTX. BMD of lumbar spine (LS) and femoral neck (FN) was determined by dual energy X-ray absorptiometry.

RESULTS

Parathyroidectomy ledds to significant decrease of serum β-crosslaps (β-CTX), osteocalcin (OC) and procollagen type I amino-terminal propeptide (PINP) while serum sclerostin (SOST) increased after surgery. BMD was markedly improved in both LS and FN after PTX. Z-scores analysis further confirmed that PTX significantly benefited bone metabolism in haemodialysis patients, which well correlated with the improvement of serum iPTH and OC.

CONCLUSIONS

Parathyroidectomy leads to significant improvement of serum OC, PINP, β-CTX and SOST, which may beneficially modify calcium-phosphorus metabolism and BMD in haemodialysis patients with SHPT.

Differentially expressed miR-3680-5p is associated with parathyroid hormone regulation in peritoneal dialysis patients

Mineral and bone disorder (MBD) is observed universally in patients with chronic kidney disease (CKD). Detrimental MBD-related skeletal changes include increased prevalence of fracture, cardiovascular disease, and mortality. MicroRNAs (miRNAs) have been identified as useful biomarkers in various diseases, and the aim of this study was to identify miRNAs associated with parathyroid hormone level in peritoneal dialysis (PD) patients. Fifty-two PD patients were enrolled and grouped by their intact parathyroid hormone (iPTH) level; 11 patients had low iPTH (<150 pg/mL) and 41 patients had high iPTH (≥150 pg/mL). Total RNA was extracted from whole blood samples. Total RNA from 15 patients (7 and 8 patients in the low and high iPTH groups, respectively) underwent miRNA microarray analysis, and three differentially upregulated (>2-fold change) miRNAs previously associated with human disease were selected for real-time quantitative PCR (qPCR) analysis. Interaction analyses between miRNAs and genes were performed by using TargetScan and the KEGG pathway database. Microarray results revealed 165 miRNAs were differentially expressed between patients with high iPTH levels and low iPTH levels. Of those miRNAs, 81 were upregulated and 84 were downregulated in patients with high iPTH levels. Expression levels of miR-1299, miR-3680-5p, and miR-548b-5p (previously associated with human disease) in 52 patients were analyzed by using qPCR. MiR-3680-5p was differentially expressed in low and high iPTH patients (P < 0.05). The predicted target genes of miR-3680-5p were USP6, USP32, USP46, and DLT, which are involved in the ubiquitin proteolysis pathway. This pathway has roles in PTH and parathyroid hormone related protein degradation and proteolysis. The mechanisms involved in the associations among low PTH, adynamic bone disease, miR-3680-5p, and the target genes should be explored further in order to elucidate their roles in CKD-MBD development.

An update on bone imaging and markers in chronic kidney disease

Bone disorders in chronic kidney disease (CKD) are associated with heightened risks of fractures, vascular calcification, poor quality of life and mortality compared to the general population. However, diagnosis and management of these disorders in CKD are complex and appreciably limited by current diagnostic modalities. Areas covered: Bone histomorphometry remains the gold standard for diagnosis but is not widely utilised and lacks feasibility as a monitoring tool. In practice, non-invasive imaging and biochemical markers are preferred to guide therapeutic decisions. Expert commentary: This review aims to summarize the risk factors for, and spectrum of bone disease in CKD, as well as appraise the clinical utility of dual energy X-ray densitometry, peripheral quantitative computed tomography, high-resolution peripheral quantitative computed tomography, and bone turnover markers.

Chronic Kidney Disease-Mineral Bone Disorder in the Elderly Peritoneal Dialysis Patient

PURPOSE

The purpose of this paper was to review the literature concerning the treatment of chronic kidney disease-mineral bone disorder (CKD-MBD) in the elderly peritoneal dialysis (PD) patient.

RESULTS

Chronic kidney disease-mineral bone disorder is a major problem in the elderly PD patient, with its associated increased fracture risk, vascular calcification, and accelerated mortality fracture risk. Peritoneal dialysis, however, bears a lower risk than hemodialysis (HD). The approach to CKD-MBD prophylaxis and treatment in the elderly PD patient is similar to other CKD patients, with some important differences. Avoidance of hypercalcemia, hyperphosphatemia, and hyperparathyroidism is important, as in other CKD groups, and is generally easier to attain. Calcium-free phosphate binders are recommended for normocalcemic and hypercalcemic patients. Normalization of vitamin D levels to > 75 nmol/L (> 30 pg/L) and low-dose active vitamin D therapy is recommended for all patients. Hyperparathryoidism is to be avoided by using active vitamin D and cinacalcet. Particular attention should be paid to treating protein malnutrition. Fracture prophylaxis (exercise, use of walkers, dwelling modifications) are important. Hypomagnesemia is common in PD and can be treated with magnesium supplements. Vitamin K deficiency is also common and has been identified as a cause of vascular calcification. Accordingly, warfarin treatment for this age group is problematic.

CONCLUSION

While treatment principles are similar to other dialysis patient groups, physicians should be aware of the special problems of the elderly group.

Chronic Kidney Disease-Mineral and Bone Disorders (CKD-MBDs): What the Endocrinologist Needs to Know

OBJECTIVE

Chronic kidney disease-mineral and bone disorders (CKD-MBDs) are a spectrum of abnormalities involving skeletal hormones, minerals, and bone turnover and mineralization. This paper focuses on what the endocrinologist should know about the assessment and management of skeletal and metabolic disorders in CKD-MBDs.

METHODS

Relevant literature was reviewed to (1) define disturbances of minerals and hormones in the course of CKD; (2) identify the variable radiographic and histomorphometric changes of CKD-MBDs; (3) review the association among CKD-MBDs, vascular calcification, cardiovascular disease (CVD), and mortality; and (4) clarify issues in CKD-MBDs therapy.

RESULTS

Assessment and treatment of CKD-MBDs is complicated by progressive changes in bone minerals and skeletal regulatory hormones as kidney function declines. CKD-MBDs are associated with fracture risk, and studies demonstrate that bone mineral density can be used to assess bone loss and fracture risk in these patients. Treatment of CKD-MBDs continues to evolve. Use of calcium, phosphate binders, vitamin D, vitamin D-receptor analogs, and drugs for osteoporosis and CKD-MBDs treatment are discussed in the context of safety and efficacy for patients with CKD.

CONCLUSION

The association of CKD with bone disease, vascular calcification, CVD, and mortality mandates earlier recognition and treatment of CKD-MBDs. Osteoporosis as a distinct entity can be diagnosed and managed in CKD, although assessment of osteoporosis becomes challenging in late (stage 4 to 5) CKD. Diabetes is common in early (stage 1 to 3) CKD. In addition, 96% of all individuals identified as having CKD have early CKD. The endocrinologist is uniquely positioned to address and treat both diabetes and many of the metabolic and skeletal disorders associated with early CKD-MBDs, including osteoporosis.

Correlation between serum leptin and bone mineral density in hemodialysis patients

Introduction: For diagnosing of specific types of bone lesions in hemodialysis (HD) patients, it is necessary to conduct a bone biopsy as the gold standard method. However, it is an invasive procedure. While different markers have been suggested as alternative methods, none of them has been selected. The frequency of hip fractures is 80 fold in HD patients who have two-fold mortality as compared with general population.

Objectives: Recently, serum leptin has been suggested as a bone density marker. This study tries to confirm this proposal.

Patients and Methods: In this study about 104 HD patients (53.8% male and 46.2% female) were enrolled. The average age was 38.28±7.89 years. Serum leptin, bone alkaline phosphatase, intact parathyroid hormone (iPTH), 25(OH)D, calcium, phosphorus and bone mineral density (BMD) (at the femoral neck and lumbar spine, as measured by dual-energy x-ray absorptiometry [DXA]) were assessed.

Results: Analysis by polynomial regression revealed no correlation between BMD Z-score at two points and serum leptin level. According to the thresholds of 25 ng/mL and 18-24 ng/mL in some studies, we detected 25 ng/mL as the threshold in our patients. Under this threshold, the leptin effect on bone mass was negative, and above the threshold of 25 ng/mL, we found leptin had positive effect on bone mass.

Conclusion: In this investigation, we found, leptin has a bimodal effect on bone mass. Cortical bones assessment may be a better option for assessment.

Does Secondary Renal Osteopathy Exist in Companion Animals?

Secondary renal hyperparathyroidism is an inevitable consequence of chronic kidney disease. In human patients, the disease is associated with decreased bone quality and increased fracture risk. Recent evidence suggests that bone quality is also decreased in companion animals, more pronouncedly in cats compared with dogs, likely because of a longer disease course. The clinical significance of these findings is yet to be determined. However, clinicians should keep in mind that animals with chronic kidney disease have decreased bone quality and increased fracture risk.

Relationship between Fetuin A, Vascular Calcification and Fracture Risk in Dialysis Patients

Background

Fractures are a common morbidity that lead to worse outcomes in dialysis patients. Fetuin A inhibits vascular calcification (VC), potentially promotes bone mineralization and its level positively correlates with bone mineral density in the general population. On the other hand, the presence of VC is associated with low bone volume in dialysis patients. Whether the fetuin A level and VC can predict the occurrence of fractures in dialysis patients remains unknown.

Methods

We performed this prospective, observational cohort study including 685 dialysis patients (629 hemodialysis and 56 peritoneal dialysis) from a single center in Taiwan for a median follow-up period of 3.4 years. The baseline fetuin A level and status of presence of aortic arch calcification (VC) and incidence of major fractures (hip, pelvis, humerus, proximal forearm, lower leg or vertebrae) were assessed using adjusted Cox proportional hazards models, recursive partitioning analysis and competing risk models.

Results

Overall, 177 of the patients had major fractures. The incidence rate of major fractures was 3.29 per 100 person-years. In adjusted analyses, the patients with higher baseline fetuin A levels had a lower incidence of fractures (adjusted hazard ratio (HR), 0.3; 95% CI, 0.18‒0.5, fetuin A tertile 3 vs. tertile 1 and HR, 0.52; 95% CI, 0.34‒0.78, tertile 2 vs. tertile 1). The presence of aortic arch calcification (VC) independently predicted the occurrence of fractures (adjusted HR, 1.95; 95% CI, 1.34‒2.84) as well. When accounting for death as an event in competing risk models, the patients with higher baseline fetuin A levels remained to have a lower incidence of fractures (SHR, 0.31; 95% CI, 0.17‒0.56, fetuin A tertile 3 vs. tertile 1 and 0.51; 95% CI, 0.32‒0.81, tertile 2 vs. tertile 1).

Interpretations

Lower baseline fetuin A levels and the presence of VC were independently linked to higher risk of incident fractures in prevalent dialysis patients.

Safety and efficacy of denosumab in osteoporotic hemodialysed patients

BACKGROUND AND AIMS

In elderly subjects, renal insufficiency and osteoporosis often coexist with high risk of fracture and elevated socio-economic burden. Today a large number of effective anti-osteoporotic drugs are available but generally they are contraindicated in patients with chronic kidney disease (CKD) because of their progressive accumulation. Denosumab, instead, does not require dose adjustments for different degrees of renal impairment so it can be a valid treatment in osteoporotic patients with CKD. Limited data are available in the literature concerning the use of denosumab in hemodialysis (HD). The aim of our study was, therefore, to study the efficacy and tolerability of this drug in this particular subset of patients.

METHODS

We retrospectively reviewed the charts of 12 osteoporotic HD patients who received a single 60-mg subcutaneous dose of denosumab every 6 months for an observation period of 24 months. Serum electrolyte, markers of bone turnover and quantitative ultrasound (QUS) were evaluated.

RESULTS

Over 24 months, we observed a gradual improvement of bone metabolism: β-CrossLaps from 2567.08 ± 1264 to 1492.5 ± 1182.5 pg/ml; bone alkaline phosphatase (BALP) from 33.5 ± 28.8 to 11.8 ± 3.7 mcg/l, and of QUS index (T-score from -5.33 ± 1.58 to -4.84 ± 1.2; risk of fracture from 13.9 ± 4.7 to 11.07 ± 5.3 %). Few cases of hypocalcemia were detected, more significant after the first and second injection, but with careful monitoring of serum calcium and rapid therapy adjustment we could easily manage serum Ca levels.

CONCLUSIONS

Our pilot experience highlights the safety and efficacy of denosumab in the treatment of osteoporosis in HD patients, potentially supporting its use to reduce the burden of fractures in this patient population.

Bone loss in chronic kidney disease: Quantity or quality?

Chronic kidney disease (CKD) patients experience bone loss and fracture because of a specific CKD-related systemic disorder known as CKD-mineral bone disorder (CKD-MBD). The bone turnover, mineralization, and volume (TMV) system describes the morphological bone lesions in renal osteodystrophy related to CKD-MBD. Bone turnover and bone volume are defined as high, normal, or low, and bone mineralization is classified as normal or abnormal. All types of bone histology related to TMV are responsible for both bone quantity and bone quality losses in CKD patients. This review focuses on current bone quantity and bone quality losses in CKD patients and finally discusses potential therapeutic measures.

Fractures in chronic kidney disease: pursuing the best screening and management

PURPOSE OF REVIEW

Osteoporotic fractures are common and cause increased sickness and death. Men and women with chronic kidney disease (CKD) are at particularly high risk of osteoporotic fractures. Currently, however, there are no guidelines concerning noninvasive methods to assess fracture risk in CKD. Further, approved treatments to prevent fractures in otherwise healthy men and women are only recommended for use with caution in those with CKD. This review focuses on the recent data that support the use of noninvasive methods to assess fracture risk in CKD and highlights new therapies that could be used in fracture prevention in CKD.

RECENT FINDINGS

Data from prospective studies demonstrate that low bone mineral density predicts fracture in CKD patients. Post-hoc analyses demonstrate that agents approved for the treatment of postmenopausal osteoporosis (bisphosphonates, denosumab and teriparatide) when given to those with CKD are well tolerated and potentially efficacious with respect to fracture risk reduction.

SUMMARY

To date, patients, and nephrologists taking care of them, have largely ignored fracture risk assessment and treatment in CKD. This should change given recent data. Further studies are needed, specifically bone histomorphometric studies, which will increase our understanding of CKD-mineral bone disease (MBD) pathophysiology, and randomized clinical trials of therapy in patients with CKD.

Assessment of the geriatric competence and perceived needs of Italian nephrologists: an internet survey

An internet survey was set up to assess the geriatric competence and perceived needs of 337 members of the Italian society of nephrology (SIN). The survey assessed how well aware nephrologists are of the typical geriatric conditions and needs of their elderly chronic kidney disease (CKD) patients. SIN associates were also questioned about their current use of comprehensive geriatric assessment, prescription of potentially nephrotoxic drugs, and screening for osteoporosis. The main finding is that CKD and dialysis are almost unanimously perceived as typically geriatric conditions, but knowledge and use of geriatric tools are scanty. While use of potentially inappropriate drugs is rare, almost half of the patients are not screened for osteoporosis. The significant clinical gaps observed could greatly impair the management of older CKD patients, and call for an urgent educational intervention.

How to predict and treat increased fracture risk in chronic kidney disease

Men and women with chronic kidney disease (CKD) are at an increased risk of fracture, and this risk increases as kidney function deteriorates. Fractures are associated with morbidity, mortality and economic costs. Despite this, there is a paucity of data regarding how to evaluate risk for fractures in CKD and how to treat high-risk patients. Evidence suggests that bone mineral density (BMD) as assessed by dual-energy X-ray absorptiometry (DXA) is associated with fractures and can also predict future fractures in predialysis (stages 1-3) patients with CKD. In the absence of considerable abnormalities in markers of mineral metabolism, treatment with antiresorptive agents in men and women with early CKD at high fracture risk may be appropriate. Of note, recent data suggest that low BMD as measured by DXA can also predict fractures in patients with more advanced CKD (stages 4, 5 and 5D). However, treatment in patients with advanced CKD requires bone biopsy, the gold standard to assess bone turnover, prior to treatment. Further research, focusing on noninvasive methods to assess fracture risk and bone turnover, together with randomized controlled trials of treatments to reduce fractures in patients at all stages of CKD, is required.

Effects of Uremic Toxins from the Gut Microbiota on Bone: A Brief Look at Chronic Kidney Disease

Patients with chronic kidney disease (CKD) frequently have mineral and bone disorders (CKD-MBD) that are caused by several mechanisms. Recent research has suggested that uremic toxins from the gut such as p-cresyl sulfate (PCS) and indoxyl sulfate (IS) could also be involved in the development of bone disease in patients with CKD. IS and PCS are produced by microbiota in the gut, carried into the plasma bound to serum albumin, and are normally excreted into the urine. However, in patients with CKD, there is an accumulation of high levels of these uremic toxins. The exact mechanisms of action of uremic toxins in bone disease remain unclear. The purpose of this brief review is to discuss the link between uremic toxins (IS and PCS) and bone mineral disease in chronic kidney disease.

High Parathyroid Hormone Level and Osteoporosis Predict Progression of Coronary Artery Calcification in Patients on Dialysis

Coronary artery calcifications (CACs) are observed in most patients with CKD on dialysis (CKD-5D). CACs frequently progress and are associated with increased risk for cardiovascular events, the major cause of death in these patients. A link between bone and vascular calcification has been shown. This prospective study was designed to identify noninvasive tests for predicting CAC progression, including measurements of bone mineral density (BMD) and novel bone markers in adult patients with CKD-5D. At baseline and after 1 year, patients underwent routine blood tests and measurement of CAC, BMD, and novel serum bone markers. A total of 213 patients received baseline measurements, of whom about 80% had measurable CAC and almost 50% had CAC Agatston scores>400, conferring high risk for cardiovascular events. Independent positive predictors of baseline CAC included coronary artery disease, diabetes, dialysis vintage, fibroblast growth factor-23 concentration, and age, whereas BMD of the spine measured by quantitative computed tomography was an inverse predictor. Hypertension, HDL level, and smoking were not baseline predictors in these patients. Three quarters of 122 patients completing the study had CAC increases at 1 year. Independent risk factors for CAC progression were age, baseline total or whole parathyroid hormone level greater than nine times the normal value, and osteoporosis by t scores. Our results confirm a role for bone in CKD-associated CAC prevalence and progression.

Risk factors for osteoporosis in Japan: is it associated with Helicobacter pylori?

Background

A number of diseases and drugs may influence bone mineral density; however, there are few reports concerning the relationship between lifestyle-related diseases and osteoporosis in Japan as determined by multivariate analysis. The aim of this study was to investigate the risk factors for osteoporosis and whether infection by or eradication of Helicobacter pylori is associated with osteoporosis.

Methods

Between February 2008 and November 2014, using a cross-sectional study design, we investigated patient profile (age, sex, BMI, alcohol, smoking), H. pylori infection status, comorbidities, internal medicine therapeutic agents (calcium channel blocker, HMG-CoA reductase inhibitors, proton pump inhibitor), serum parameters (Hb, calcium, γGTP), bone turn over markers (bone-specific alkaline phosphatase (BAP) and collagen type I cross-linked N telopeptide (NTX), findings on dual-energy x-ray absorptiometry (DEXA) and upper gastrointestinal endoscopy, and Frequency Scale for the Symptoms of GERD score in consecutive outpatients aged ≥50 years at our hospital. We divided the subjects into an osteoporosis group and a non-osteoporosis group and investigated risk factors for osteoporosis between the two groups by bivariate and multivariate analyses.

Results

Of the 255 eligible study subjects, 43 (16.9%) had osteoporosis. Bivariate analysis showed that advanced age, female sex, lower body mass index, lower cumulative alcohol intake, lower Brinkman index, H. pylori positivity, lower hemoglobin, bone-specific alkaline phosphatase, lower prevalence of hiatal hernia, and endoscopic gastric mucosal atrophy were related to osteoporosis. Multivariate analysis showed that advanced age (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.07–1.19, P<0.001), female sex (OR 6.27, 95% CI 2.26–17.39, P<0.001), low BMI (OR 0.82, 95% CI 0.72–0.94, P=0.005), H. pylori positivity (OR 3.00, 95% CI 1.31–6.88, P=0.009), and BAP (OR 1.07, 95% CI 1.01–1.14, P=0.035) were related to osteoporosis.

Conclusion

Advanced age, low BMI, BAP, and H. pylori positivity were risk factors for osteoporosis; however, the success of H. pylori eradication was not a risk factor for osteoporosis in Japan.

Unilateral pedicle stress fracture in a long-term hemodialysis patient with isthmic spondylolisthesis

Most unilateral pedicle stress fractures occur on the contralateral side of patients with unilateral spondylolysis. However, there are few reports of unilateral pedicle stress fractures in patients with bilateral spondylolysis and spondylolisthesis. We report a unique case of unilateral pedicle stress fracture in a long-term hemodialysis patient with isthmic spondylolisthesis. A 65-year-old man who had undergone hemodialysis presented with lower back pain that had persisted for several years. The patient experienced severe right lower extremity pain with no history of trauma. Computed tomography revealed unilateral pedicle fracture with bilateral L5 spondylolysis and spondylolisthesis with progression of scoliosis. The patient underwent Gill laminectomy of L5 with pedicle screw fixation at L4-S1 and interbody fusion at L5-S1. The patient's leg pain ceased immediately, and he began walking without leg pain. In our present patient, development of scoliosis caused by destructive spondyloarthropathy may have contributed to a unilateral pedicle fracture.

Efficacy and safety of eldecalcitol, a new active vitamin D3 analog, in the bone metabolism of postmenopausal women receiving maintenance hemodialysis

Eldecalcitol (ELD), a new active vitamin D3 analog developed in Japan, has attracted attention as an effective osteoporotic therapeutic drug. However, because ELD leads to greater calcium absorption than does conventional active vitamin D3, it has yet to be used in patients with renal insufficiency. Therefore, we evaluated the efficacy and safety of ELD treatment in 27 postmenopausal women receiving maintenance dialysis in our institution and underwent ELD treatment (starting at 0.5 μg/day) for 6 months. The mean serum albumin-corrected calcium (Caalb) level was significantly increased following treatment (9.01 ± 0.60 before versus 9.56 ± 0.55 after treatment, mean ± SD). Severe hypercalcemia was prevented through cessation or adjustment of the dosage of calcium-containing phosphate binders or existing active vitamin D. The mean serum phosphorus and intact parathyroid hormone levels were well-controlled throughout. The median levels of bone turnover markers, bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase-5b were significantly decreased. The mean lumbar spine bone mineral density (BMD) was increased, a significant difference being observed in age-matched Z-scores (-0.60 ± 1.6 versus -0.36 ± 1.5, p = 0.018). The average change in lumbar spine BMD after ELD treatment was 3.10%, and in patients with a T-score of <-4.0, it was 5.63%. There was no effect on forearm BMD. Although this study is based on short-term observation in a single institution, our results suggest that ELD could be used to increase bone density in dialysis patients.

Low bone mineral density and fractures in stages 3-5 CKD: an updated systematic review and meta-analysis

SUMMARY

The utility of bone mineral density (BMD) testing in chronic kidney disease (CKD) is not known. We performed a meta-analysis of studies reporting on BMD and fracture in CKD. All but one study was cross-sectional. BMD was lower in those with CKD and fractures compared to those without fractures.

INTRODUCTION

CKD is associated with an increased risk of fracture. The utility of dual energy X-ray absorptiometry (DXA) to assess fracture risk in CKD is unknown.

METHODS

We performed an updated meta-analysis and systematic review of published studies that reported on the association between DXA and fracture (morphometric spine or clinical nonspine) in predialysis and dialysis CKD. We identified 2,894 potential publications, retrieved 292 for detailed review, and included 13. All but one study was cross-sectional and three reported on the ability of DXA to discriminate fracture status in predialysis CKD. Results were pooled using a random effects model and statistical heterogeneity was assessed using the I2 statistic.

RESULTS

BMD was statistically significantly lower at the femoral neck, lumbar spine, the 1/3 and ultradistal radius in subjects with fractures compared to those without regardless of dialysis status. For example, femoral neck BMD was 0.06 g/cm2 lower in dialysis subjects and 0.102 g/cm2 lower in predialysis subjects with fractures compared to those without. Lumbar spine BMD was 0.05 g/cm2 lower in dialysis subjects and 0.108 g/cm2 lower in predialysis subjects with fractures compared to those without. Our meta-analysis was limited to studies with small numbers of subjects and even smaller numbers of fractures. All of the studies were observational and only one was prospective. There was statistical heterogeneity at the lumbar spine, 1/3 and ultradistal radius.

CONCLUSIONS

Our findings suggest that BMD can discriminate fracture status in predialysis and dialysis CKD. Larger, prospective studies are needed.

Chronic kidney disease and the skeleton

Fractures across the stages of chronic kidney disease (CKD) could be due to osteoporosis, some form of renal osteodystrophy defined by specific quantitative histomorphometry or chronic kidney disease-mineral and bone disorder (CKD-MBD). CKD-MBD is a systemic disease that links disorders of mineral and bone metabolism due to CKD to either one or all of the following: abnormalities of calcium, phosphorus, parathyroid hormone or vitamin D metabolism; abnormalities in bone turnover, mineralization, volume, linear growth or strength; or vascular or other soft-tissue calcification. Osteoporosis, as defined by the National Institutes of Health, may coexist with renal osteodystrophy or CKD-MBD. Differentiation among these disorders is required to manage correctly the correct disorder to reduce the risk of fractures. While the World Health Organization (WHO) bone mineral density (BMD) criteria for osteoporosis can be used in patients with stages 1-3 CKD, the disorders of bone turnover become so aberrant by stages 4 and 5 CKD that neither the WHO criteria nor the occurrence of a fragility fracture can be used for the diagnosis of osteoporosis. The diagnosis of osteoporosis in stages 4 and 5 CKD is one of the exclusion-excluding either renal osteodystrophy or CKD-MBD as the cause of low BMD or fragility fractures. Differentiations among the disorders of renal osteodystrophy, CKD-MBD or osteoporosis are dependent on the measurement of specific biochemical markers, including serum parathyroid hormone (PTH) and/or quantitative bone histomorphometry. Management of fractures in stages 1-3 CKD does not differ in persons with or without CKD with osteoporosis assuming that there is no evidence for CKD-MBD, clinically suspected by elevated PTH, hyperphosphatemia or fibroblast growth factor 23 due to CKD. Treatment of fractures in persons with osteoporosis and stages 4 and 5 CKD is not evidence-based, with the exception of post-hoc analysis suggesting efficacy and safety of specific osteoporosis therapies (alendronate, risedronate and denosumab) in stage 4 CKD. This review also discusses how to diagnose and manage fragility fractures across the five stages of CKD.

An open-label, prospective pilot clinical study of denosumab for severe hyperparathyroidism in patients with low bone mass undergoing dialysis

CONTEXT

Denosumab is widely used for bone diseases with increased bone resorption. Its effectiveness in patients with severe secondary hyperparathyroidism on dialysis is unclear.

OBJECTIVE

This study aimed to evaluate the efficacy and safety of denosumab in patients with severe secondary hyperparathyroidism who are on dialysis.

DESIGN

This 6-month prospective, open-labeled study evaluated 12 patients (five women, seven men; mean age 53.5 ± 3.8 y). All had intact PTH (iPTH; > 1000 pg/mL), low bone mass (T-score < -1.0 SD), and bone pain and were poor surgical candidates. Serum calcium, phosphorus, alkaline phosphatase (AP), and iPTH levels were assessed at baseline and every month thereafter. Vertebral spine x-rays and bone mineral densities (BMDs) (lumbar spine and femoral neck) were assessed at the start and end of the study. All patients received denosumab (60 mg), calcitriol, phosphate binders, and dialysate calcium that were adjusted according to the biochemistry data.

RESULTS

The BMD increased in both the femoral neck (mean increase 23.7% ± 4.0%) and lumbar spine (17.1% ± 2.6%) after 6 months. In the first month, most patients had increased iPTH levels, which dramatically decreased from 1702.1 ± 181.9 to 518.8 ± 126.8 pg/mL by the end of the study after increasing the calcitriol dose. All patients had significant decreases in AP, calcium × phosphorus, and bone pain. Changes in femoral neck BMD correlated only with AP and iPTH levels.

CONCLUSIONS

Denosumab is effective in restoring bone mass and reducing bone pain in patients on dialysis with secondary hyperparathyroidism. It also allows for a more aggressive use of calcitriol to control hyperparathyroidism.

Can one evaluate bone disease in chronic kidney disease without a biopsy?

PURPOSE OF REVIEW

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a complex disorder of bone and mineral metabolism that results in an excess risk of fractures, cardiovascular events and mortality. The management of the bone disorder aspect of CKD-MBD may require bone biopsy to determine appropriate treatment strategies. However, it is unclear when biopsy may be necessary and whether or not state-of-the art imaging and serologic testing can supplant the bone biopsy as a tool to assist with management decisions.

RECENT FINDINGS

Advances in imaging methods now permit the noninvasive assessment of structural aspects of bone quality. Furthermore, common bone imaging tools, such as dual-energy X-ray absorptiometry, can be used to stratify for fracture risk. Circulating markers of bone turnover can be used to assess the risk of bone loss and fracture, but they are less useful in diagnosing the type of renal osteodystrophy.

SUMMARY

Although advances in imaging now permit the assessment of fracture risk more accurately in CKD patients, the assessment of the type of renal osteodystrophy remains poor without bone biopsy. The virtual bone biopsy will be possible only when we are able to noninvasively assess turnover with good accuracy. A bone biopsy is needed when the bone turnover is unclear.