Bone density and heel ultrasound testing do not identify patients with dialysis-dependent renal failure who have had fractures

Trabecular Bone Score in Assessing Bone Mineralization Status in Children with End- Stage Renal Disease: A Promising Tool

Areal-bone mineral density (aBMD) of lumbar-spine dual energy X-ray absorptiometry (DXA) scan is the most frequently used tool in evaluating BMD in pediatric patients, however its size dependency have significant impact on measurements accuracy in children with chronic kidney disease (CKD). This study aimed to evaluate the usefulness of trabecular bone score (TBS) computed during lumbar-spine DXA scan in assessing bone status in children on maintenance hemodialysis (HD). Ninety-three children on HD (aged 9-18 years) were subjected to lumbar-spine DXA-scan to obtain aBMD (g/cm2) and TBS.Z-scores of aBMD for chronological-age (aBMDZ-CA), height-age (aBMDZ-HA), and TBSZ-score were calculated using mean and SD values of 442 healthy controls. aBMD and TBS were significantly lower in short-for-age and normal height-for-age patients compared to the corresponding values of controls (p < 0.05 for all). Degraded vertebral microarchitecture (TBSZ-score < -2) was detected in 48% and 44% of male and female patients respectively. There were no significant differences in median TBSZ-score between short-for-age and normal height-for-age HD patients in male (p = 0.425) and in female (p = 0.316) patients. TBSZ-score correlated significantly with aBMDZ-CA (r = 0.234; p = 0.024) but not with aBMDZ-HA (r = 0.077; p = 0.462). Patients with history of fractures (5 patients only) had significantly lower TBS scores compared to those without fracture history (p = 0.016).

CONCLUSION

TBS is significantly reduced in children on maintenance HD and is associated with increased fracture incidence. TBS has shown to be a promising tool in assessing bone quality (trabecular microarchitecture) in children with CKD being not size-dependent as is a-BMD, for further evaluation of its potential role in therapeutic and follow-up decisions.

WHAT IS KNOWN

• In children with CKD, bone demineralization starts as early as CKD stage 2, so assessment of bone health is mandatory for follow up and therapeutic decisions. • aBMD of lumbar-spine DXA scan is the most used tool in evaluating BMD in pediatric patients, however its size dependency have significant impact on measurements made in children with CKD.

WHAT IS NEW

• TBS is significantly reduced in children on maintenance HD and associated with increased fracture incidence. • TBS has shown to be a promising tool in assessing bone quality (trabecular microarchitecture) in children with CKD being not size-dependent as is a-BMD.

Comparison of bone microstructures via high-resolution peripheral quantitative computed tomography in patients with different stages of chronic kidney disease before and after starting hemodialysis

Chronic kidney disease (CKD) negatively affects bone strength; however, the osteoporotic conditions in patients with CKD are not fully understood. Moreover, the changes in bone microstructure between pre-dialysis and dialysis are unknown. High-resolution peripheral quantitative computed tomography (HR-pQCT) reveals the three-dimensional microstructures of the bone. We aimed to evaluate bone microstructures in patients with different stages of CKD. This study included 119 healthy men and 40 men admitted to Nagasaki University Hospital for inpatient education or the initiation of hemodialysis. The distal radius and tibia were scanned with HR-pQCT. Patient clinical characteristics and bone microstructures were evaluated within 3 months of initiation of hemodialysis (in patients with CKD stage 5 D), patients with CKD stage 4-5, and healthy volunteers. Cortical bone parameters were lower in the CKD group than in healthy controls. Tibial cortical and trabecular bone parameters (cortical thickness, cortical area, trabecular volumetric bone mineral density, trabecular-bone volume fraction, and trabecular thickness) differed between patients with CKD stage 5 D and those with CKD stage 4-5 (p < 0.01). These differences were also observed between patients with CKD stage 5 and those with CKD stage 5 D (p < 0.017), but not between patients with CKD stage 4 and those with CKD stage 5, suggesting that the bone microstructure rapidly changed at the start of hemodialysis. Patients with CKD stage 5 D exhibited tibial microstructural impairment compared with those with CKD stage 4-5. HR-pQCT is useful for elucidation of the pathology of bone microstructures in patients with renal failure.

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.

Single-centre cross-sectional study on the impact of cumulative erythropoietin on bone mineral density in maintenance dialysis patients

OBJECTIVES

Numerous factors are associated with the risk of osteoporosis in patients with chronic kidney disease, including vitamin D deficiency, hypocalcaemia, hyperphosphataemia and secondary hyperparathyroidism. This study aimed to assess the correlation between cumulative erythropoietin (EPO) doses and osteoporosis risk in patients on chronic dialysis. A further objective was to determine the bone mineral density (BMD) of patients undergoing dialysis and its correlation with specific clinical and biochemical factors.

SETTING

The study was undertaken at a tertiary care centre within the southern region of the Taipei Metropolitan area.

PARTICIPANTS

This cross-sectional study included 165 participants aged 41-90 years. Dual-energy X-ray absorptiometry was used to measure BMD. A total of 108 age-matched and sex-matched participants were selected for further analysis. Stepwise multiple regression analysis was used to investigate the relationship between bone measurements and bone diseases' risk factors.

PRIMARY AND SECONDARY OUTCOMES

The primary outcome of this study was to assess the T-scores of the participants who received dialysis for more than 3 months in our institution. The secondary outcome was using a receiver operating curve to predict osteoporosis development in patients on dialysis who received EPO treatments.

RESULTS

The mean age of the participants was 66.6±11.1 years. A total of 99 (60%) participants (41 men, 58 women) were diagnosed as having osteoporosis. Fifty-four (32.7%) participants with T-scores >-2.5 but <-1.0 were diagnosed as having osteopenia. Osteoporotic participants received 1.61±1.52 million units EPO compared with nonosteoporotic participants, who received 1.01±0.64 million units (EPO1 model), p=0.015. The cumulative EPO dose negatively correlated with the T-scores of participants (p<0.0001).

CONCLUSION

On the basis of the results of the study, cumulative EPO doses show a negative correlation with BMD development in patients on chronic dialysis.

Bone Biopsy for Histomorphometry in Chronic Kidney Disease (CKD): State-of-the-Art and New Perspectives

The use of bone biopsy for histomorphometric analysis is a quantitative histological examination aimed at obtaining quantitative information on bone remodeling, structure and microarchitecture. The labeling with tetracycline before the procedure also allows for a dynamic analysis of the osteoblastic activity and mineralization process. In the nephrological setting, bone biopsy is indicated to confirm the diagnosis of subclinical or focal osteomalacia and to characterize the different forms of renal osteodystrophy (ROD). Even if bone biopsy is the gold standard for the diagnosis and specific classification of ROD, the use of this approach is very limited. The main reasons for this are the lack of widespread expertise in performing or interpreting bone biopsy results and the cost, invasiveness and potential pain associated with the procedure. In this regard, the sedation, in addition to local anesthesia routinely applied in Italian protocol, significantly reduces pain and ameliorates the pain perception of patients. Concerning the lack of widespread expertise, in Italy a Hub/Spokes model is proposed to standardize the analyses, optimizing the approach to CKD patients and reducing the costs of the procedure. In addition, new tools offer the possibility to evaluate the osteogenic potential or the ability to form bone under normal and pathological conditions, analyzing mesenchymal stem cells and their ability to differentiate in the osteogenic lineage. In the same way, circulating microRNAs are suggested as a tool for exploring osteogenic potential. The combination of different diagnostic approaches and the optimization of the bioptic procedure represent a concrete solution to spread the use of bone biopsy and optimize CKD patient management.

Diagnosis and Management of Osteoporosis in Advanced Kidney Disease: A Review

Osteoporosis and fractures are common in persons with advanced chronic kidney disease (CKD) and on maintenance dialysis. Although the diagnosis of osteoporosis in this population can be difficult, imaging, especially with dual-energy x-ray absorptiometry (DXA), is helpful in identifying persons with CKD at the highest risk of fracture. Although blood biomarkers including parathyroid hormone and bone-specific alkaline phosphatase concentrations can aid in assessing bone turnover state, bone biopsy remains the gold standard in determining bone turnover in persons with advanced kidney disease and osteoporosis. With the increasing armamentarium of osteoporosis drugs, it now may be possible to prevent many fractures in advanced CKD. Unfortunately, data on these drugs are limited in persons with advanced CKD. Clinicians, aided by advances in imaging, biomarkers, and bone biopsy can now use these novel agents to target bone turnover abnormalities such as adynamic bone disease and high bone turnover disease. This review will discuss the most recent literature surrounding the diagnosis, management, and monitoring of osteoporosis and fractures in persons with advanced CKD or on maintenance dialysis.

Impact of serum magnesium and bone mineral density on systemic fractures in chronic hemodialysis patients

Introduction

Bone mineral density (BMD) measured with dual-energy X-ray absorptiometry (DXA) can be used to predict fractures, but its clinical utility has not been fully established in chronic kidney disease (CKD) patients. Magnesium is an essential trace element. Although magnesium is associated with the risk of fractures in non-CKD populations, the relationship is unknown in CKD patients.

Methods

BMD and serum magnesium levels were measured in 358 stable outpatients undergoing maintenance hemodialysis therapy. The primary outcome was fragility fracture. Patients were divided into groups according to the median level of magnesium and the normal threshold value of lumbar spine BMD.

Results

During the median follow-up period of 36 months, 36 (10.0%) fractures occurred. The cumulative incidence rates of fractures were 17.6% and 5.2% [adjusted hazard ratio (aHR) 2.31, 95% confidence interval (CI) 1.03–5.17, P = 0.030] in the lower (<2.6 mg/dL) and higher (≥2.6 mg/dL) magnesium (Mg) groups, respectively, and 21.2% and 7.3% (aHR 2.59, 95% CI 1.09–6.16, P = 0.027) in the low- and high-BMD groups, respectively. The lower-Mg and low-BMD group had a 9.21-fold higher risk of fractures (95% CI; 2.35–47.00; P = 0.0010) than the higher-Mg and high-BMD group. Furthermore, adding both magnesium levels and lumbar spine BMD levels to the established risk factors significantly improved the prediction of fractures (C-index: 0.784 to 0.830, p = 0.041).

Discussion/Conclusions

The combination of serum magnesium and lumbar spine BMD can be used for fracture risk stratification and synergistically improves the prediction of fractures in CKD patients.

Expression of Circulating MicroRNAs Linked to Bone Metabolism in Chronic Kidney Disease-Mineral and Bone Disorder

The pathophysiology of chronic kidney disease-mineral and bone disorder (CKD-MBD) is complex and multifactorial. Recent studies have identified a link between microRNAs (miRNAs) and bone loss. In this study, we investigated the expression of miRNAs in CKD-MBD. In this case-control study, we included thirty patients with CKD-MBD (cases) and 30 age- and gender-matched healthy individuals (controls). Bone mineral density (BMD) and trabecular bone score (TBS) evaluation was performed with dual X-ray absorptiometry. The selected panel of miRNAs included: hsa-miRNA-21-5p; hsa-miRNA-23a-3p; hsa-miRNA-24-2-5p; hsa-miRNA-26a-5p; hsa-miRNA-29a-3; hsa-miRNA-124-3p; hsa-miRNA-2861. The majority of cases had low BMD values. The relative expression of miRNA-21-5p was 15 times lower [fold regulation (FR): -14.7 ± 8.1, p = 0.034), miRNA-124-3p, 6 times lower (FR: -5.9 ± 4, p = 0.005), and miRNA-23a-3p, 4 times lower (FR: -3.8 ± 2.0, p = 0.036) in cases compared to controls. MiRNA-23a-3p was significantly and inversely correlated with TBS, adjusted for calcium metabolism and BMD values (beta = -0.221, p = 0.003, 95% CI -0.360, -0,081) in cases. In a receiver operating characteristic (ROC) analysis, expression of miRNA-124-3p demonstrated 78% sensitivity and 83% specificity in identifying CKD patents with osteoporosis. Serum expression of miRNAs related to osteoblasts (miRNA-23a-3p) and osteoclasts (miRNA-21-5p, miRNA-124-3p) is significantly altered in patients with CKD-MBD.

Trabecular bone score may indicate chronic kidney disease-mineral and bone disorder (CKD-MBD) phenotypes in hemodialysis patients: a prospective observational study

BACKGROUND

In the general population, the trabecular bone score (TBS) represents the bone microarchitecture and predicts fracture risk independent of bone mineral density (BMD). A few studies reported that TBS is significantly reduced in dialysis patients. Chronic kidney disease-mineral and bone disorder (CKD-MBD) are accompanied by increased fracture risk, cardiovascular morbidity, and mortality. We investigated whether TBS is associated with comorbidity related to CKD-MBD or frailty in hemodialysis patients.

METHODS

In this prospective observational study, TBS was obtained using the TBS iNsight software program (Med-Imaps) with BMD dual energy x-ray absorptiometry (DXA) images (L1-L4) from prevalent hemodialysis patients. A Tilburg frailty indicator was used to evaluate frailty, and hand grip strength and bio-impedance (InBody) were measured. A patient-generated subjective global assessment (PG-SGA) was used for nutritional assessment. The history of cardiovascular events (CVE) and demographic, clinical, laboratory, and biomarker data were collated. We then followed up patients for the occurrence of CKD-MBD related complications.

RESULTS

We enrolled 57 patients in total. The mean age was 56.8 ± 15.9 years (50.9% female). Prevalence of Diabetes mellitus (DM) was 40.4% and CVE was 36.8%. Mean TBS was 1.44 ± 0.10. TBS significantly reduced in the CVE group (1.38 ± 0.08 vs. 1.48 ± 0.10, p <  0.001). Multivariable regression analysis was conducted adjusting for age, sex, dialysis vintage, DM, CVE, albumin, intact parathyroid hormone, fibroblast growth factor 23, handgrip strength, and phosphate binder dose. Age (ß = - 0.030; p = 0.001) and CVE (ß = - 0.055; p = 0.024) were significant predictors of TBS. During the follow up period after TBS measurements (about 20 months), four deaths, seven incident fractures, and six new onset CVE were recorded. Lower TBS was associated with mortality (p = 0.049) or new onset fracture (p = 0.007, by log-rank test).

CONCLUSION

Lower TBS was independently associated with increased age and CVE prevalence in hemodialysis patients. Mortality and fracture incidence were significantly higher in patients with lower TBS values. These findings suggest that TBS may indicate a phenotype of frailty and also a CKD-MBD phenotype reciprocal to CVE.

The prevalence and incidence of vertebral fractures in end-stage renal disease and the role of parathyroid hormone

The risk of vertebral fracture is unclear in end-stage renal disease. We report a high vertebral fracture prevalence and incidence in transplantation-eligible patients on dialysis, suggesting that these patients may benefit from radiographic screening for vertebral fractures. Parathyroid hormone had a U-shaped association with vertebral fracture risk.

INTRODUCTION

Vertebral fractures are often overlooked, but even undiagnosed vertebral fractures negatively impact physical functioning, quality of life, and mortality. The risk of vertebral fractures in end-stage renal disease (ESRD) patients is unclear, and parathyroid hormone (PTH) might play a role in the development of vertebral fractures. We therefore determined vertebral fracture prevalence and incidence in ESRD patients and assessed associations of vertebral trabecular bone mineral density (BMD) and PTH with vertebral fracture.

METHODS

In 146 transplantation-eligible patients on dialysis, we determined vertebral fractures on lateral chest radiographs, which image the thoracic and upper lumbar spine. We determined incident vertebral fractures in 70 patients with follow-up radiographs (23 received a kidney transplant) after median 1.8 years. Vertebral trabecular BMD was measured with computed tomography, and PTH measured with 2-site immunoassays, categorized in tertiles with the middle tertile as reference. We used Poisson regression to assess associations of vertebral trabecular BMD and PTH with vertebral fracture.

RESULTS

Mean age of the study population was 52 ± 13 years, and 98 (67%) were male. Median dialysis duration was 26 (IQR 13-55) months. Vertebral fractures were present in 50/146 patients (34%) and incident vertebral fractures occurred in 20/70 patients (29%). Vertebral trabecular BMD was not associated with vertebral fracture prevalence (relative risk 0.97, 95% CI 0.89 to 1.04). For the lowest PTH tertile (< 11 pmol/L), the relative risk of vertebral fracture was greater although not significant (2.28, 95% CI 0.97 to 5.97) and was significantly greater for the highest PTH tertile (≥ 30 pmol/L; 2.82, 95% CI 1.22 to 7.27) after adjustment for potential confounders.

CONCLUSIONS

The prevalence and incidence of vertebral fractures is high even in relatively young and healthy ESRD patients. Vertebral trabecular BMD is not associated with vertebral fracture, and the association of PTH with vertebral fracture risk appears U-shaped. Nevertheless, our study did not measure vertebral BMD using DXA and assessed vertebral fractures using lateral chest radiographs and not spine radiographs.

Predictive value of quantitative ultrasound parameters in individuals with chronic kidney disease: A population-based analysis of CARTaGENE

BACKGROUND

The use of calcaneal quantitative ultrasound (QUS) to predict fractures has not been well studied in early CKD populations. We compared the association of QUS with incidental fractures and its predictive properties in non-CKD and CKD individuals.

METHODS

Analysis of a prospective population-based survey of 40- to 69-year-old individuals recruited between 2009 and 2010. QUS parameters (stiffness index [SI], speed of sound [SOS], broadband attenuation [BUA]) were measured at baseline. Renal function was measured using baseline creatinine and was classified into CKD stages (non-CKD, stage 2, stage 3). Fracture incidence at any site or at major osteoporotic fracture sites for up to 7 years of follow-up was identified in administrative databases using a validated algorithm. The association (age-adjusted hazard ratio per standard deviation decrease in Cox models), discrimination (c-statistic) and calibration (standardized incidence ratio [SIR]) of QUS parameters with fracture outcomes was computed in each CKD stratum.

RESULTS

We included 18,306 individuals (9,011 non-CKD; 8,595 CKD stage 2; 700 CKD stage 3). During a median follow-up of 70 months, we identified 782 fractures at any site and 326 major osteoporotic fractures. Although all QUS parameters (SI, SOS and BUA) were associated with any or major fracture incidence in non-CKD and CKD patients, the magnitude of these associations was lower for any fracture and for BUA. QUS parameters moderately discriminated incidental fractures across CKD strata but underestimated fracture incidence in CKD stage 3 even after adjustment for demographics and clinical risk factors. At a given QUS value, CKD stage 3 patients had higher fracture risk than non-CKD and CKD stage 2 patients.

CONCLUSIONS

QUS parameters are associated with fracture incidence in both non-CKD and CKD but underestimate fracture incidence in individuals with early CKD.

Thoracic vertebral fractures and hyperkyphosis in elderly patients with end-stage kidney disease; do these patients have different clinical outcomes?

BACKGROUND AND OBJECTIVES

Elderly patients with end-stage kidney disease (ESKD) are at high risk for fractures. However, the prevalence of vertebral fractures and hyperkyphosis is not studied well. This is relevant, because in the general population, both vertebral fractures and hyperkyphosis are associated with poor outcome. Therefore, the primary aim of our study was to assess the prevalence of vertebral fractures and hyperkyphosis in the ESKD population. The secondary aim was to assess if patients with vertebral fractures and/or hyperkyphosis more often have poor outcome after starting dialysis, such as accidental falling, functional decline and mortality compared to the patients without vertebral fractures and/or hyperkyphosis.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

This study included patients ≥65 years with ESKD who were enrolled in the Geriatric assessment in Older patients starting Dialysis (GOLD) study of whom a lateral chest radiograph was available. Chest radiographs were scored independently by two observers for vertebral fractures (Genant ≥1) and hyperkyphosis (≥50 degrees). The relation between vertebral fractures and hyperkyphosis with clinical outcomes (falls, decline in ADL and IADL, mortality) was studied using the Chi-square test.

RESULTS

Of the 196 enrolled patients, chest radiographs were available for 160 patients. Mean age was 75.3 (SD ±6.9), and 35% were female. The prevalence of vertebral fractures was 43% and of hyperkyphosis 22%. Patients with hyperkyphosis had a higher one-year mortality compared to patients without hyperkyphosis (20% vs. 8%, p = 0.04). No differences were observed between patients with and without hyperkyphosis, vertebral fractures and the remaining outcomes after six months of follow-up.

CONCLUSIONS

In patients ≥65 years old with ESKD starting dialysis, vertebral fractures are highly prevalent. In contrast to the general population, patients with vertebral fractures did experience poor outcome as often as patients without vertebral fractures. Remarkably, patients with hyperkyphosis did have a higher one-year mortality. However, these patients did not experience more functional decline or accidental falls.

Association of Bone Mineral Density With Fractures Across the Spectrum of Chronic Kidney Disease: The Regina CKD-MBD Study

Background:

Recent studies have demonstrated that measurement of areal bone mineral density by dual-energy x-ray absorptiometry (DXA) predicts fractures in patients with chronic kidney disease (CKD). However, whether fracture risk prediction through bone mineral density (BMD) is enhanced due to the assessment of biochemical markers of chronic kidney disease and mineral and bone disease (CKD-MBD) or clinical risk factors is not clear. We hypothesized that in a select cohort of patients managed in a CKD clinic, that combining T-Scores with biochemical markers would optimize fracture discrimination than using DXA alone.

Objective:

To examine the relationships among BMD, biochemical markers of CKD-MBD, and fracture risk across Kidney Disease Improving Global Outcomes (KDIGO) glomerular filtration rate (GFR) categories G3a to G5.

Design:

Retrospective study.

Setting:

Patients were recruited from the multidisciplinary CKD clinic, Regina General Hospital, Canada.

Patients:

A total of 374 patients who received a DXA scan upon initial referral to Regina Multidisciplinary CKD Program from January 31, 2001 to January 31, 2010, were included in this study. The patients were followed for a total of 5 years.

Methods:

We conducted a retrospective review of 374 consecutive patients who underwent DXA imaging at the point of entry into our multidisciplinary CKD program. Areal BMD, T- and Z-Scores were obtained at the lumbar spine, total hip, mean of left and right femoral neck, and the one-third radius. We collected data on demographic, cross-sectional biochemical markers of mineral metabolism and fractures (identified through self-reported questionnaires, hospital electronic medical records, and physician billing records). We were able to gather data on 8/11 variables of Fracture Risk Assessment (FRAX) tool.

Results:

In our cohort, 14.3% of GFR categories G3a and G3b, 15.7% of GFR category G4, and 19.7% of GFR category G5 experienced a clinical fracture during the study period. On multivariate analysis, each decline of 1.0 SD in total hip BMD T-Score was associated with a significant increase in the risk of fracture (OR = 1.46, 95% confidence interval [CI], 1.12-1.89). Adding CKD-MBD markers and clinical risk factors did not further contribute to the model. Low BMD was the only independent risk factor for fracture in patients with CKD.

Limitations:

Self-reporting by patients and administrative records were used to identify fractures. We did not perform spine imaging to ascertain morphometric vertebral fractures. We were unable to gather all 11 variables of FRAX score and information on ethnicity. We were unable to capture site of fracture (hips, spine, etc) from billing records. Albumin excretion rates were not collected at baseline. Treatment of the underlying bone disease with pharmacotherapeutic agents may have attenuated patients’ fracture risk and thus underestimated the association between BMD and future fracture.

Conclusions:

Our findings confirm that BMD predicts fracture. The addition of cross-sectional CKD-MBD parameters and clinical risk factors to BMD did not add to fracture prediction. Prospective studies should investigate the utility of longitudinal biochemical markers on improving fracture risk assessment.

Progression of Osteoporosis After Kidney Transplantation in Patients With End-Stage Renal Disease

BACKGROUND

This study investigated the prevalence of osteoporosis and the risk factors for its progression in kidney transplant recipients (KTRs).

METHODS

Dual energy X-ray absorptiometry was used to prospectively measure changes in bone mineral density (BMD) before kidney transplantation (KT) and 1 year after transplantation in 207 individuals. We also analyzed the risk factors of osteoporosis progression during this period.

RESULTS

Prior to KT, the mean BMD score (T-score of the femur neck area) was -2.1 ± 1.2, and the prevalence of osteoporosis was 41.5% (86/207). At 1 year post-transplantation, the mean BMD score significantly decreased to -2.3 ± 1.1 (P < .001), and the prevalence of osteoporosis increased to 47.3% (98/207; P = .277). The BMD score worsened over the study period in 69.1% (143/207) of patients, improved in 24.1% (50/207), and showed no change in 6.8% (14/207). Minimal intact parathyroid hormone (iPTH) improvement after KT was found to be an independent risk factor of osteoporosis progression.

CONCLUSIONS

This study demonstrates progressive loss of BMD after KT and sustained secondary hyperparathyroidism might influence the progression of osteoporosis.

Low-trauma fractures without osteoporosis

In clinical practice, areal bone mineral density (aBMD) is usually measured using dual-energy X-ray absorptiometry (DXA) to assess bone status in patients with or without osteoporotic fracture. As BMD has a Gaussian distribution, it is difficult to define a cutoff for osteoporosis diagnosis. Based on epidemiological considerations, WHO defined a DXA-based osteoporosis diagnosis with a T-score <-2.5. However, the majority of individuals who have low-trauma fractures do not have osteoporosis with DXA (i.e., T-score <-2.5), and some of them have no decreased BMD at all. Some medical conditions (spondyloarthropathies, chronic kidney disease and mineral bone disorder, diabetes, obesity) or drugs (glucocorticoids, aromatase inhibitors) are more prone to cause fractures with subnormal BMD. In the situation of fragility fractures with subnormal or normal BMD, clinicians face a difficulty as almost all the pharmacologic treatments have proved their efficacy in patients with low BMD. However, some data are available in post hoc analyses in patients with T score >-2. Overall, in patients with a previous fragility fracture (especially vertebra or hip), treatments appear to be effective. Thus, the authors recommend treating some patients with a major fragility fracture even if areal BMD T score is above -2.5.

Evaluation of fracture risk in chronic kidney disease

Chronic kidney disease (CKD) is associated with mineral and bone disorders (MBD) that are now considered as a syndrome. Bone fragility and a four to tenfold increased rate of skeletal fractures are often reported in CKD patients. The evaluation of the risk of these fractures in CKD patients should explore the same risk factors identified for the general population including low body weight, menopause, personal and familial history of osteoporosis, chronic inflammatory diseases, and corticosteroid therapy. The aim of this article is to provide a critical review of the tools used for the evaluation of bone loss and the risk of fracture in CKD patients, ranging from the measurement of bone mineral density (BMD), fracture risk assessment (Frax™), quantitative computed tomography (QCT), high-resolution peripheral quantitative computed tomography (HRpQTC), to circulating biomarkers of bone metabolism including vitamin D, parathyroid hormone (PTH), bone-specific alkaline phosphatase, osteocalcin, and some collagen type 1-related molecules indicators of bone remodeling.

Cystatin C is Better than Serum Creatinine for Estimating Glomerular Filtration Rate to Detect Osteopenia in Chronic Kidney Disease Patients

PURPOSE

Recent studies have reported that loss of bone mass is associated with renal function decline and increased fracture risks in chronic kidney disease (CKD) patients. The aim of this study was to investigate the best estimated glomerular filtration rate (eGFR) equation to detect osteopenia in CKD patients.

MATERIALS AND METHODS

This was a cross-sectional study, and 780 patients aged 50 years or above were classified into normal bone mass or osteopenia groups according to the -1.0 of T-scores at total hip and femur neck. Comparisons of area under the receiver operating characteristic (ROC) curves (AUC) were performed to investigate significant differences among three eGFR formulas: Modification of Diet in Renal Disease, CKD-Epidemiology Collaboration (EPI) creatinine, and CKD-EPI cystatin C (CKD-EPI-Cys).

RESULTS

The mean age was 61 years old and the proportion of females was 37.3%. The total hip osteopenia group showed lower CKD-EPI-Cys eGFR levels (osteopenia group, 33.3±19.0 mL/min/1.73 m²; normal group, 48.1±26.2 mL/min/1.73 m², p<0.001). In multiple logistic regression analysis, CKD-EPI-Cys eGFR was independently associated with osteopenia at the total hip (per 1 mL/min/1.73 m² increase, odds ratio 0.98, 95% confidence interval 0.97-0.99, p=0.004) after adjusting for confounding variables. ROC curve analyses indicated that CKD-EPI-Cys shows the largest AUC for osteopenia at the total hip (AUC=0.678, all p<0.01) and the femur neck (AUC=0.665, all p<0.05).

CONCLUSION

Decreased renal function assessed by CKD-EPI-Cys equation correlates with osteopenia better than creatinine-based methods in CKD patients, and the CKD-EPI-Cys formula might be a useful tool to assess skeletal-related event risks.

Cortical porosity not superior to conventional densitometry in identifying hemodialysis patients with fragility fracture

Hemodialysis (HD) patients face increased fracture risk, which is further associated with elevated risk of hospitalization and mortality. High-resolution peripheral computed tomography (HR-pQCT) has advanced our understanding of bone disease in chronic kidney disease by characterizing distinct changes in both the cortical and trabecular compartments. Increased cortical porosity (Ct.Po) has been shown to be associated with fracture in patients with osteopenia or in postmenopausal diabetic women. We tested whether the degree of Ct.Po identifies hemodialysis patients with prevalent fragility fractures in comparison to bone mineral density (BMD) assessed by dual X-ray absorptiometry (DXA). We performed a post-hoc analysis of a cross-sectional study in 76 prevalent hemodialysis patients. Markers of mineral metabolism, coronary calcification score, DXA-, and HR-pQCT-data were analyzed, and Ct.Po determined at radius and tibia. Ct.Po was significantly higher in patients with fracture but association was lost after adjusting for age and gender (tibia p = 0.228, radius p = 0.5). Instead, femoral (F) BMD neck area (p = 0.03), F T-score neck area (p = 0.03), radius (R) BMD (p = 0.03), R T-score (p = 0.03), and cortical HR-pQCT indices such as cortical area (Ct.Ar) (tibia: p = 0.01; radius: p = 0.02) and cortical thickness (Ct.Th) (tibia: p = 0.03; radius: p = 0.02) correctly classified patients with fragility fractures. Area under receiver operating characteristic curves (AUC) for Ct.Po (tibia AUC: 0.711; p = 0.01; radius AUC: 0.666; p = 0.04), Ct.Ar (tibia AUC: 0.832; p<0.001; radius AUC: 0.796; p<0.001), and F neck BMD (AUC: 0.758; p = 0.002) did not differ significantly among each other. In conclusion, measuring Ct.Po is not superior to BMD determined by DXA for identification of HD patients with fragility fracture.

Evaluation of three risk assessment tools in discriminating fracture status among Chinese patients undergoing hemodialysis

We evaluated three risk assessment tools, including bone mineral density (BMD) measurement by dual energy X-ray absorptiometry (DXA), osteoporosis self-assessment tool for Asians (OSTA), and fracture risk assessment tool (FRAX), for the prediction of fracture status among Chinese patients undergoing hemodialysis. All of the three assessment tools have a reasonable capability in discriminating fractures.

INTRODUCTION

Fractures are common in hemodialysis patients however insufficiently assessed. Our study aimed to assess the ability of three widely used tools [BMD, OSTA, and FRAX] to discriminate fracture status in patients with renal failure undergoing hemodialysis.

METHODS

We enrolled 136 hemodialysis patients in a tertiary teaching hospital setting. BMD was measured using DXA at the lumbar spine and the hip region. OSTA was calculated from weight and age. FRAX score was calculated based upon online availability. Discriminative abilities of BMD, OSTA, and FRAX in fracture status were analyzed by receiver operator characteristic (ROC) curves.

RESULTS

There were total 16 fractures (11.76 %) identified in 136 hemodialysis patients. BMD at any site (lumbar spine L1-L4, femoral neck, and total hip) was independently associated with fracture. Areas under the curves (AUC) of BMD (lumbar spine L1-L4, femoral neck, total hip), OSTA, FRAX1 (non-BMD model), and FRAX2 (BMD model) were 0.669 (95 % CI 0.583, 0.747), 0.708 ( 95 % CI 0.624, 0.783), 0.736 (95 % CI 0.654, 0.808), 0.686 (95 % CI 0.601, 0.763), 0.715 (95 % CI 0.631, 0.789), and 0.697 (95 % CI 0.613, 0.773), respectively. The differences of their performance were not significant.

CONCLUSIONS

All of the three risk assessment tools had the ability to discriminate fracture status among hemodialysis patients; FRAX BMD model did not improve the discriminative ability of BMD or FRAX non-BMD model alone.

Effect of arteriovenous fistula and usage of arm with fistula on bone mineral density in hemodialysis patients

We aimed to determine the incidence of osteoporosis in hemodialysis patients, to evaluate the differences due to arteriovenous fistula on bone mineral density (BMD) and to investigate whether usage of arm with fistula has an effect on BMD. In this cross-sectional study, 96 patients with chronic renal disease undergone to dialysis were included. Place of fistula (radial and brachial) and dominant hand were recorded. All patients were asked to complete Likert's scale in order to determine the frequency of their usage of arm with fistula. Patients were assigned in two groups: age >51 and < 50 years. Age-matched control group included 60 subjects. BMD measurements were done on lumbar vertebra, femur and both forearms. BMD measurement of proximal femur and total radius were significantly lower in patients >50 years compared to healthy controls and bone density measurement of lumbar vertebra, proximal femur, 1/3 distal and total radius were significantly lower in patients < 50 years compared to healthy controls (p < 0.05). BMD measurement was significantly lower in arms with fistula, especially with radial fistula, compared to both arms without fistula and healthy controls (p < 0.05). When all patients were evaluated, BMD scores were lowering by increasing age, duration of dialysis and fistula and decreasing usage of arm with fistula. BMD in hemodialysis patients is lower than normal population. BMD of arm with fistula is lower than arm without fistula and healthy controls. Both radial and brachial fistula affect negatively ipsilateral BMD. Movement of arm with fistula has positive effects on BMD.

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.

Bone imaging and fracture risk assessment in kidney disease

Fractures are more common and are associated with greater morbidity and morality in patients with kidney disease than in members of the general population. Thus, it is troubling that in chronic kidney disease (CKD) patients there has been a paradoxical increase in fracture rates over the past 20 years compared to the general population. Increased fracture incidence in CKD patients may be driven in part by the lack of screening for fracture risk. In the general population, dual energy X-ray absorptiometry (DXA) is the clinical standard to stratify fracture risk, and its use has contributed to decreases in fracture incidence. In contrast, in CKD, fracture risk screening with DXA has been uncommon due to its unclear efficacy in predicting fracture and its inability to predict type of renal osteodystrophy. Recently, several prospective studies conducted in patients across the spectrum of kidney disease have demonstrated that bone mineral density measured by DXA predicts future fracture risk and that clinically relevant information regarding fracture risk is provided by application of the World Health Organization cutoffs for osteopenia and osteoporosis to DXA measures. Furthermore, novel high-resolution imaging tools, such as high-resolution peripheral quantitative computed tomography (HR-pQCT), have been used to elucidate the effects of kidney disease on cortical and trabecular microarchitecture and bone strength and to identify potential targets for strategies that protect against fractures. This review will discuss the updated epidemiology of fractures in CKD, fracture risk screening by DXA, and the utility of state-of-the art imaging methods to uncover the effects of kidney disease on the skeleton.

Bone mineral density predicts fractures in chronic kidney disease

Fractures are common in chronic kidney disease (CKD). The optimal methods by which to assess fracture risk are unknown, in part, due to a lack of prospective studies. We determined if bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), and/or high-resolution peripheral quantitative computed tomography (HRpQCT) could predict fractures in men and women ≥18 years old with stages 3 to 5 CKD. BMD was measured by DXA (at the total hip, lumbar spine, ultradistal, and 1/3 radius) and by HRpQCT (at the radius), and subjects were followed for 2 years for incident morphometric spine fractures and low-trauma clinical fractures. The mean age of the subjects was 62 years with equal numbers having stages 3, 4, and 5 CKD. Over 2 years there were 51 fractures in 35 subjects. BMD by DXA at baseline was significantly lower at all sites among those with incident fractures versus those without. For example, the mean BMD at the total hip in those with incident fractures was 0.77 g/cm2 (95% confidence interval [CI], 0.73 to 0.80) and in those without fracture was 0.95 g/cm2 (95% CI, 0.92 to 0.98). Almost all baseline HRpQCT measures were lower in those with incident fracture versus those without. For example, volumetric BMD in those with incident fractures was 232 mg HA/cm3 (95% CI, 213 to 251) and in those without fracture was 317.6 mg HA/cm3 (95% CI, 306 to 329.1). Bone loss occurred in all subjects, but was significantly greater among those with incident fractures. Our data demonstrate that low BMD (by DXA and HRpQCT) and a greater annualized percent decrease in BMD are risk factors for subsequent fracture in men and women with predialysis CKD.

Longitudinal assessment of bone quality in pediatric patients with chronic kidney disease in relation to treatment modality

Children with chronic kidney disease (CKD) are at high risk of developing impaired bone quality. Our aim was to investigate changes of bone quality in children with CKD in relation to their treatmant using two imaging techniques-dual energy X-ray absorptiometry and quantitative ultraSonography (QUS). Thirty-three patients with CKD (18 boys and 15 girls, mean age 10.37 ± 3.37 years) were evaluated with bone mineral density (BMD) measured by DXA at the lumbar spine and hip and with speed of sound (SOS) measured by QUS at the radius and tibia at the beginning and at the end of the study. The patient cohort consisted of 14 patients with CKD stage 3-4 not treated with dialysis (CKD group), 5 patients on peritoneal dialysis treatment (PD group) and 14 patients after kidney transplantation (RTx group). BMD measurements did not show any significant changes in CKD and PD patients during the study. There was a reduction in BMD measured at the lumbar spine, femoral neck and total hip in RTx patients that was approaching significance. During the 2-year follow-up, SOS measurements at the radius decreased significantly in PD patients, whereas SOS measurements at the tibia significantly improved in RTx patients. No significant changes in QUS parameters were recorded for patients in the CKD group. In conclusion, our study shows that QUS parameters seem to better reflect the state of hyperparathyroidism of renal osteodystrophy as they deteriorate significantly in patients on dialysis and improve after renal transplantation.

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.

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.

Fragility fractures and osteoporosis in CKD: pathophysiology and diagnostic methods

Both chronic kidney disease (CKD) and osteoporosis are major public health problems associated with an aging population. Osteoporosis is characterized by reduced bone mineral density, while CKD results in qualitative changes in bone structure; both conditions increase the predisposition to fragility fractures. There is a significant coprevalence of osteoporotic fractures and CKD, particularly in the elderly population. Not only is the risk of fracture higher in the CKD population, but clinical outcomes are significantly worse, with substantial health care costs. Management of osteoporosis in the CKD population is particularly complex given the impact of renal osteodystrophy on bone quality and the limited safety and hard outcome data for current therapy in patients with severe CKD or on dialysis therapy. In this review, we discuss the pathophysiology of osteoporosis, the impact of CKD on bone strength, and the role of novel imaging techniques and biomarkers in predicting underlying renal osteodystrophy on bone histomorphometry in the context of CKD.

The clinical utility of FRAX to discriminate fracture status in men and women with chronic kidney disease

We assessed the ability of the World Health Organization's fracture risk assessment tool (FRAX), bone mineral density (BMD), and age to discriminate fracture status in adults with pre-dialysis chronic kidney disease (CKD). In adults with CKD, FRAX was able to discriminate fracture status but performed no better than BMD alone.

INTRODUCTION

Patients with CKD are at increased risk for fracture but the best method to assess fracture risk is not known.

METHODS

We assessed the ability of the World Health Organization's FRAX, compared with BMD at the femoral neck (FN), and age to discriminate fracture status (prevalent clinical nonspine and/or morphometric vertebral) in men and women, 18 years and older with pre-dialysis CKD. Results are presented as area under receiver operator characteristic curves (AUC) with 95% confidence intervals (CI).

RESULTS

We enrolled 353 subjects; mean age was 65 ± 14 years; weight was 79 ± 18 kg, and estimated glomerular filtration rate was 28 ml/min/1.73 m(2). About one third of the subjects had a prevalent clinical nonspine and/or morphometric vertebral fracture. FRAX was able to discriminate among those with prevalent clinical nonspine fractures (AUC, 0.72; 95% CI, 0.65-0.78), morphometric vertebral fractures (AUC, 0.66; 95% CI, 0.59-0.73), and any fracture (AUC, 0.71; 95% CI, 0.65-0.77). The discriminative ability of BMD at the FN alone was similar to FRAX for morphometric vertebral and any fractures; FRAX performed better than BMD for prevalent clinical nonspine fractures (AUC for BMD alone, 0.66; 95% CI, 0.60-0.73). Compared to FRAX, the AUC for age alone was lower for all fracture types.

CONCLUSIONS

Among men and women with CKD, FRAX is able to discriminate fracture status but performs no better than BMD alone.

A two-yr prospective study of bone health in children after renal transplantation employing two imaging techniques

The aim of this study was to prospectively and longitudinally evaluate bone properties with the use of two bone imaging techniques (dual energy X-ray absorptiometry [DXA], and quantitative ultraSonography [QUS]) in pediatric renal transplant recipients. Fourteen patients (eight boys and six girls) with a mean age of 12.25 ± 3.11 yr (range: 8-17.5 yr) completed a two-yr follow-up. Measurements of bone mineral density (BMD) by DXA at lumbar spine and hip and speed of sound (SOS) by QUS at radius and tibia were performed at the beginning and at the end of the study. A significant improvement in mean Z-score of SOS values measured at tibia (1.01 ± 1.31 vs. -0.46 ± 1.14, p = 0.005) was observed. On the contrary, mean Z-score of BMD values measured at femoral neck was significantly reduced (-1.95 ± 2.15 vs. -0.33 ± 1.13, p = 0.041). Finally, multivariate stepwise regression analyses showed that glomerular filtration rate at the beginning of the study was the best predictor of the difference in BMD Z-scores measured at lumbar spine. Additionally, values of intact parathormone (iPTH) at the beginning of the study and the change in iPTH throughout the study predicted the 72.3% of the difference in Z-score of SOS measured at radius with an inverse relationship.

Risk factors for diminished bone mineral density among male hemodialysis patients--a cross-sectional study

This cross-sectional study was performed to characterize the factors affecting bone mass in male hemodialysis subjects. We found that of all the factors analyzed, the strongest correlation was with body mass index. In fact, after adjusting for body weight, the correlations with bone turnover markers and sex hormones were no longer significant.

PURPOSE

Abnormalities in bone and mineral metabolism are commonly seen in patients with end-stage renal disease, reducing bone quality and raising the risk of fracture. This cross-sectional study was performed to characterize risk factors affecting bone mass among male hemodialysis subjects.

METHODS

For this cross-sectional study, we recruited 66 men from three local hemodialysis units. Subjects received dual emission X-ray absorptiometry assessment of three sites (lumbar spine, hip, and distal radius) and the values were correlated with the levels of sex hormones, non-renally excreted bone turnover markers, and mineral metabolism markers.

RESULTS

Subjects were found to have bone mineral density (BMD) reduced predominantly at the distal radius, with Z score < −2 seen in 15.4 % and T score < −2.5 in 21 % of men. Independent predictors of bone density included levels of bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase 5b, which were inversely correlated with the femoral neck Z score. Factors positively associated with an increased Z score included body mass index at all sites and free estradiol levels at the hip and distal radius. Markers of mineral metabolism (e.g., calcium, phosphate, and 25-hydroxyvitamin D) were not correlated with Z scores of any site or with bone turnover markers. After adjusting for body weight, the associations between BMD, sex hormones, and bone turnover markers were no longer significant.

CONCLUSION

We recommend that future studies seeking to assess the factors affecting bone strength among male hemodialysis subjects incorporate a weight-adjusted analysis. Additionally, dialysis-dependent men receiving dual emission X-ray absorptiometry should have the distal radius site added to the standard assessment.

Bone mineral density by DXA and HR pQCT can discriminate fracture status in men and women with stages 3 to 5 chronic kidney disease

Fractures are common in chronic kidney disease (CKD). We determined if bone mineral density testing by dual energy X-ray absorptiometry (DXA) and high resolution peripheral quantitative computed tomography (HR pQCT) could discriminate fracture status in CKD patients. Both tests were able to discriminate fracture status. Further, the addition of HR pQCT measurements to DXA measurements did not improve fracture discrimination.

INTRODUCTION

The optimal method to identify individuals with CKD at high fracture risk is unknown.

METHODS

We determined if bone mineral density (BMD) by DXA and HR pQCT could discriminate fracture status in 211 adult men and women with stages 3 to 5 CKD, attending predialysis clinics in Toronto Canada, using logistic regression. Results are expressed as the odds ratio (OR) of fracture (prevalent vertebral and/or low trauma since age 40 years) per standard deviation decrease in the predictor adjusted for age, weight, sex, and CKD stage. We constructed receiver operating characteristic curves to examine the discriminative ability of BMD measures for fracture.

RESULTS

Most participants were Caucasian men with a mean age of 63.3 ± 15.5 years. There were 77 fractures in 74 participants. Decreases in BMD were associated with increased fracture risk: OR = 1.56 (95% confidence interval (CI), 1.41 to 1.71) for BMD by DXA at the ultradistal radius, and OR = 1.24 (95% CI, 1.12 to 1.36) for cortical area by HR pQCT. Further, while both tests were able to discriminate fracture status, the addition of HR pQCT measures to BMD by DXA did not improve fracture discrimination ability.

CONCLUSIONS

Among CKD patients not yet requiring renal replacement therapy, BMD by DXA is able to discriminate fracture status.

Determination of bone architecture and strength in men and women with stage 5 chronic kidney disease

Fractures are common in men and women with dialysis-dependent chronic kidney disease (stage 5D CKD) and are associated with substantial morbidity and mortality. The clinical utility of dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), noninvasive measures of bone mass and architecture that reflect fracture risk in healthy men and women, is uncertain in patients with stage 5D CKD. This review will outline the epidemiology and etiology of fractures and will summarize the published data that describe the association between fractures, bone mass, and bone strength in stage 5D CKD. Fracture risk assessment in stage 5D CKD is complicated as the etiology of fractures is multifactorial and includes impairments in bone quantity and quality. Cross-sectional data suggest that bone density by DXA is lower among stage 5D CKD patients with fractures compared with those without, and that this may be particularly true at cortical sites. However, DXA does not capture bone microarchitecture and cannot differentiate between cortical and trabecular bone. Some, but not all studies, that measure cortical and trabecular bone by pQCT in stage 5D CKD, demonstrate a preferential decrease in cortical bone; however, these studies are limited by small sample sizes and cross-sectional study design. No studies have reported on longitudinal relationships between bone architecture, strength, and incident fractures in patients with stage 5D CKD. Further research is needed to identify noninvasive measures of bone strength that can be used for fracture risk assessment in stage 5D CKD.

Bone mineral density and fracture risk in older individuals with CKD

BACKGROUND AND OBJECTIVES

Kidney Disease Improving Global Outcomes guidelines recommend against bone mineral density (BMD) screening in CKD patients with mineral bone disease, due to a lack of association of BMD with fractures in cross-sectional studies in CKD. We assessed whether BMD is associated with fractures in participants with and without CKD in the Health, Aging, and Body Composition study, a prospective study of well functioning older individuals.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Hip BMD was measured by dual-energy x-ray absorptiometry. Osteoporosis was defined as a femoral neck BMD (FNBMD) T score below -2.5 and CKD as an estimated GFR <60 ml/min per 1.73 m(2). The association of BMD with incident nonspine, fragility fractures to study year 11 was analyzed using Cox proportional hazards analyses, adjusting for age, race, sex, body mass index, hyperparathyroidism, low vitamin D level, and CKD. Interaction terms were used to assess whether the association of BMD with fracture differed in those with and without CKD.

RESULTS

There were 384 incident fractures in 2754 individuals (mean age 73.6 years). Lower FNBMD was associated with greater fracture, regardless of CKD status. After adjustment, the hazard ratios (95% confidence intervals) were 2.74 (1.99, 3.77) and 2.15 (1.80, 2.57) per lower SD FNBMD for those with and without CKD, respectively (interaction P=0.68), and 2.10 (1.23, 3.59) and 1.63 (1.18, 2.23) among those with osteoporosis in patients with and without CKD, respectively (interaction P=0.75).

CONCLUSIONS

BMD provides information on risk for fracture in older individuals with or without moderate CKD.

Fracture risk assessment in patients with chronic kidney disease

Fractures are common in patients with chronic kidney disease (CKD) and associated with substantially high morbidity and mortality. Bone mass measurements are commonly used to assess fracture risk in the general population, but the utility of these measurements in patients with CKD, and specifically among those on hemodialysis, is unclear. This review will outline the epidemiology and etiology of fractures in patients with CKD with a particular emphasis on men and women on hemodialysis. As well, we will summarize the published data, which describes the association between risk factors for fracture (including bone mass measurements, biochemical markers of mineral metabolism, and muscle strength) and fractures in patients with CKD. Patients with CKD suffer from fractures due to impairments in bone quantity, bone quality, and abnormalities of neuromuscular function. There is a paucity of evidence on the associations between bone quality, bone turnover markers, neuromuscular function, and fractures in patients with CKD. Furthermore, the complex etiology of fractures combined with the technical limitations of bone mineral density testing, both by dual energy X-ray absorptiometry (DXA) and by peripheral quantitative tomography (pQCT), limits the clinical utility of bone mass measurements for fracture prediction in CKD; this is particularly true among patients with stages 4 and 5 CKD. Further prospective studies to identify noninvasive measures of bone strength that can be used for fracture risk assessment are needed.

Effects of raloxifene on bone metabolism in hemodialysis patients with type 2 diabetes

BACKGROUND

Osteoporosis and chronic kidney disease are common conditions in older adults, and often occur concurrently. Bone disease is caused by increased bone turnover accompanying secondary hyperparathyroidism, and by factors such as bone metabolic disorder accompanying kidney disease and postmenopausal or age-related osteoporosis, even in hemodialysis patients. Raloxifene is commonly used for the treatment of postmenopausal osteoporosis in the general population, and may be a treatment option for osteoporosis in hemodialysis patients. However, the effects of raloxifene in hemodialysis patients with type 2 diabetes have not been examined in detail.

OBJECTIVES

This study was performed to investigate the effects of raloxifene on bone turnover markers and bone density in postmenopausal women with type 2 diabetes mellitus who were undergoing hemodialysis in Japan.

PATIENTS AND METHODS

The subjects were 60 female patients on maintenance hemodialysis (non-diabetic, n=30; diabetic, n=30). Raloxifene hydrochloride (60 mg) was administered to 14 diabetic patients and 14 non-diabetic patients for one year, and these patients were compared with control groups (no raloxifene) of 16 diabetic patients and 16 non-diabetic patients. Serum levels of N-terminal cross-linking telopeptide of type I collagen (NTx), bone alkaline phosphatase, and intact parathyroid hormone (iPTH) were measured, and bone density was determined by quantitative heel ultrasound at the speed of sound (SOS) in the calcaneus during this period.

RESULTS

There were no significant differences in the levels of bone turnover markers except for iPTH after treatment of diabetic and non-diabetic patients with raloxifene for one year. SOS increased after treatment with raloxifene, but was significantly decreased in the control groups. Treatment with raloxifene resulted in a significant decrease in NTx and a significant increase in SOS in both diabetic and non-diabetic patients. There were no significant differences between the diabetic and non-diabetic patients who received raloxifene.

CONCLUSIONS

Treatment with raloxifene can suppress reduction in bone density in postmenopausal women with type 2 diabetes who are undergoing hemodialysis.

Tests of neuromuscular function are associated with fractures in patients with chronic kidney disease

BACKGROUND

Fractures are common in individuals with chronic kidney disease (CKD), and tests of neuromuscular function (NMT) discriminate well among fractured and non-fractured patients with Stage 5 CKD on dialysis. The ability of NMT to discriminate fracture status in patients with Stages 3-5 CKD is unknown.

METHODS

In this cross-sectional study, we sought to determine in adult patients with Stages 3-5 CKD (eGFR by the Modification of Diet in Renal Disease equation) if NMT [timed up and go (TUG), 6-min walk (6MW) and grip strength] could discriminate fracture status (self-reported low-trauma fractures since age 40 and/or vertebral fractures by morphometry). We conducted logistic regression and receiver-operating characteristic (ROC) curves for each predictor [expressed as area under the ROC curves (AUROC) with 95% confidence intervals (CI)].

RESULTS

Data was available for 125 men and 86 women. The mean age was 63.3 ± 15.5 years, duration of CKD was 96.7 ± 125.3 months and one-third had diabetes. Patients with fractures were older and fell more frequently (P < 0.05). After adjusting for age, weight and sex, for every standard deviation increase in TUG and 6MW, the risk of fracture increased [odds ratio (OR): 1.68; 95% CI: 1.40-2.02] and decreased (OR: 0.53; 95% CI: 0.52-0.54), respectively. Both the TUG and 6MW could discriminate among those with and without fractures (AUROC: 0.90; 95% CI:0.84-0.95, AUROC: 0.87; 95% CI: 0.80-0.94, respectively).

CONCLUSIONS

The TUG and 6MW are able to discriminate fracture status in patients with Stages 3-5 CKD. These tests do not require specialized expertise/equipment and are an inexpensive method to assess for the presence of fractures.

Diagnostic usefulness of bone mineral density and biochemical markers of bone turnover in predicting fracture in CKD stage 5D patients--a single-center cohort study

BACKGROUND

In chronic kidney disease stage 5D, diagnostic usefulness of bone mineral density (BMD) in predicting fracture has not been established because of variable results in previous studies. The reason for this may be the heterogeneity of underlying pathogenesis of the fracture.

METHODS

BMD was measured annually and serum biochemistry monthly for 485 hemodialyzed patients from April 2003 to March 2008, and all fractures were recorded.

RESULTS

Forty-six new episodes of any type of fracture and 29 cases of prevalent spine fracture were recorded. Serum bone-specific alkaline phosphatase (b-AP) was a very useful surrogate marker for any type of incident fracture risk [area under curve (AUC) = 0.766, P < 0.0001]. A significantly greater risk of any type of incident fracture was associated with parathyroid hormone (PTH) levels either <150 pg/mL [hazard ratio (HR) = 3.47, P < 0.01] or >300 pg/mL (HR = 5.88, P < 0.0001) compared with 150-300 pg/mL. Receiver-operating characteristic analysis demonstrated a significant predictive power for incident of any type of fracture by BMD at the total hip (AUC = 0.760, P < 0.0001) and other hip regions in females in the lower PTH group (PTH < 204 pg/mL). BMDs at every site but whole body or lumbar spine had significant power to discriminate prevalent spine fracture regardless of gender or PTH.

CONCLUSIONS

Hemodialyzed patients with low or high PTH or increased b-AP had a high fracture risk. BMD by Dual Energy X-ray Absorptiometry (DEXA), especially at the total hip region, was useful to predict any type of incident of fracture for females with low PTH or to discriminate prevalent spine fracture for every patient.

Renal osteodystrophy in the first decade of the new millennium: analysis of 630 bone biopsies in black and white patients

Renal osteodystrophy occurs early during loss of kidney function. There are 26 million American patients with chronic kidney disease (CKD), and almost all patients with CKD stage 5 have abnormal bone histology. Six hundred and thirty bone biopsies from adult CKD-5 patients on dialysis were evaluated by histomorphometry and analyzed using the turnover (T), mineralization (M), and volume (V) classification. There were racial differences; whites exhibited predominantly low turnover (62%), whereas blacks showed mostly normal or high turnover (68%). A mineralization defect was observed in only 3% of patients. In whites, cancellous bone volume was low, normal, or high in approximately the same number of patients, whereas in blacks, cancellous bone volume was high in two-thirds of the patients. More than 80% of blacks and whites with low cancellous bone volume had thin trabeculae owing to low bone formation. Cortical thickness was low in half the whites, whereas it was normal in three-quarters of blacks. Cortical porosity was high in 50% of whites, whereas three-quarters of blacks had high porosity. In summary, the TMV system gives relevant information. It should be expanded to include the architecture of cancellous and cortical bone. There are racial differences. Low bone volume and low bone turnover are more frequent than heretofore appreciated, whereas mineralization defects nowadays are observed rarely in adults. These findings call for an adjustment of the current therapeutic paradigm that takes into consideration race and risk of low bone volume and turnover. The latter have been shown to be associated with increased vascular calcifications.

Comparative study of quantitative ultrasonography and dual-energy X-ray absorptiometry for evaluating renal osteodystrophy in children with chronic kidney disease

Our aim was to assess bone parameters in children with chronic kidney disease (CKD) with both dual-energy X-ray absorptiometry (DXA) and quantitative ultrasonography (QUS) and additionally with biochemical markers of bone turnover. Twenty children (12 boys and 8 girls) with CKD and a mean decimal age of 9.47 ± 4.44 years were included in the study where anthropometric parameters (height and weight), pubertal status, bone mineral density (BMD) at lumbar spine, speed of sound (SOS) measured by QUS at radius and at tibia, and biochemical markers of bone metabolism were measured. Six patients (30%) had tibial SOS Z score <-1, and 52.7% had radial SOS Z score <-1, whereas only 16.67% had BMD Z score <-1. Patients had significantly increased levels of serum intact parathormone (p < 0.001), serum bone alkaline phosphatase (BAP) (p < 0.001) and serum N-terminal-mid fragment (aminoacids 1-43) of osteocalcin (p < 0.001) compared to controls, whereas serum osteoprotegerin was significantly decreased in patients compared to controls (p = 0.001). SOS was significantly correlated to BAP (r = -0.586, p = 0.013 and r = -0.709, p = 0.001, respectively, for radius and tibia). In conclusion no association between DXA and QUS measurements was documented in our study, whereas QUS was better correlated to biochemical indices of ROD.

The effects of raloxifene on bone turnover markers and bone mineral density in women on maintenance hemodialysis

BACKGROUND

Bone disease is caused not only by increased bone turnover accompanying secondary hyperparathyroidism but also by factors such as bone metabolic disorder accompanying kidney disease and postmenopausal or age-related osteoporosis in hemodialysis patients. In this study, we investigated the effects of raloxifene on bone turnover markers and bone mineral density (BMD) in female hemodialysis patients to determine involvement of estrogen deficiency in bone disease.

METHODS

The subjects were 47 female patients on maintenance hemodialysis. Raloxifene hydrochloride (60 mg) was administered to 21 patients for 1 year, and these patients were compared with a control group of 26 patients. Serum levels of N-terminal cross-linking telopeptide of type I collagen (NTx), bone alkaline phosphatase, and intact parathyroid hormone were measured, and BMD was determined by quantitative heel ultrasound as the speed of sound (SOS) in the calcaneus over this period.

RESULTS

NTx decreased after treatment with raloxifene for 1 year, but significantly increased in the control group. SOS increased after treatment with raloxifene for 1 year, but significantly decreased in the control group. Treatment with raloxifene resulted in a significant decrease of NTx and a significant increase of SOS in subgroups of patients aged <60 and ≥ 60 years.

CONCLUSIONS

Treatment with raloxifene can suppress a rise in NTx and increase bone mineral density in patients around the time of menopause and in postmenopausal patients of advanced age. A reduction in bone mineral density caused by estrogen deficiency may be involved in the development of bone disease in female hemodialysis patients.

Bone mass measurements in men and women with chronic kidney disease

PURPOSE OF REVIEW

Fractures are common in patients with chronic kidney disease (CKD) and are associated with substantial morbidity and mortality. Bone mass measurements are commonly used to assess fracture risk in the general population, but the utility of these measurements in patients with CKD is unclear.

RECENT FINDINGS

This review will outline the epidemiology and etiology of fractures in patients with CKD. Also, we will summarize the published data that describe the association between bone mass measurements and fracture in patients with CKD.

SUMMARY

Patients with CKD suffer from fractures due to impairments in bone quantity, bone quality, and abnormalities of neuromuscular function. The complex etiology of fractures combined with the technical limitations of bone mineral density testing, both by dual energy X-ray absorptiometry and by peripheral quantitative computed tomography, limits the clinical utility of bone mass measurements for fracture prediction in CKD; this is particularly true among patients with stages 4 and 5 CKD. As such, clinicians should not routinely order bone mineral density testing in patients with CKD. Further research, to determine whether bone mineral density together with other noninvasive measures to assess bone strength can predict fracture, is needed.

Bone mass and microarchitecture in CKD patients with fracture

Patients with predialysis chronic kidney disease (CKD) have increased risk for fracture, but the structural mechanisms underlying this increased skeletal fragility are unknown. We measured areal bone mineral density (aBMD) by dual-energy x-ray absorptiometry at the spine, hip, and radius, and we measured volumetric BMD (vBMD), geometry, and microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) at the radius and tibia in patients with CKD: 32 with fracture and 59 without fracture. Patients with fracture had lower aBMD at the spine, total hip, femoral neck, and the ultradistal radius, the last having the strongest association with fracture. By HR-pQCT of the radius, patients with fracture had lower cortical area and thickness, total and trabecular vBMD, and trabecular number and greater trabecular separation and network heterogeneity. At the tibia, patients with fracture had significantly lower cortical area, thickness, and total and cortical density. Total vBMD at both radius and tibia most strongly associated with fracture. By receiver operator characteristic curve analysis, patients with longer duration of CKD had area under the curve of >0.75 for aBMD at both hip sites and the ultradistal radius, vBMD and geometry at the radius and tibia, and microarchitecture at the tibia. In summary, patients with predialysis CKD and fractures have lower aBMD by dual-energy x-ray absorptiometry and lower vBMD, thinner cortices, and trabecular loss by HR-pQCT. These density and structural differences may underlie the increased susceptibility to fracture among patients with CKD.

Femoral bone mineral density reflects histologically determined cortical bone volume in hemodialysis patients

We evaluated the associations between dual energy X-ray absorptiometry (DXA) and histologically determined cancellous and cortical bone volume by controlling for vascular calcifications and demographic variables in hemodialysis (HD) patients. Femoral bone mineral density (f-BMD) was associated with cortical porosity.

INTRODUCTION

Assessment of bone mass in chronic kidney disease patients is of clinical importance because of the association between low bone volume, fractures, and vascular calcifications. DXA is used for noninvasive assessment of bone mass whereby vertebral results reflect mainly cancellous bone and femoral results reflect mainly cortical bone. Bone histology allows direct measurements of cancellous and cortical bone volume. The present study evaluates the association between DXA and histologically determined cancellous and cortical bone volumes in HD patients.

METHODS

In 38 HD patients, DXA was performed for assessment of bone mass, anterior iliac crest bone biopsies for bone volume, and multislice computed tomography for vascular calcifications.

RESULTS

While lumbar bone mineral density (l-BMD) by DXA was not associated with histologically measured cancellous bone volume, coronary Agatson score showed a borderline statistically significant association (P = 0.055). When controlled for age and dialysis duration, f-BMD by DXA was associated with cortical porosity determined by histology (P = 0.005).

CONCLUSIONS

The usefulness of l-BMD for predicting bone volume is limited most probably because of interference by soft tissue calcifications. In contrast, f-BMD shows significant association with cortical porosity.

Bone mineral density and parathyroid function in patients on maintenance hemodialysis

BACKGROUND

The relationship between parathyroid function, an important determinant of bone turnover, and bone mineral density (BMD) in patients with chronic kidney disease is not fully understood. We wanted to analyze the association between BMD and parathyroid function in hemodialysis patients in details.

METHODS

In a cross-sectional design, data from 270 patients (age 55 ± 15 years, 60% men, all Caucasian) on maintenance hemodialysis were analyzed. All patients underwent dual energy X-ray absorptiometry of the lumbar spine (LS), femoral neck (FN) and distal radius (DR). In addition to routine laboratory tests, blood samples were collected for iPTH, serum markers of bone metabolism (alkaline phosphatase, type I collagen crosslinked-C-telopeptide) and 25OH vitamin D.

RESULTS

Based on Z-scores, bone mineral density was moderately reduced only at the femoral neck in the total cohort. The average Z-score of the "low PTH" group (iPTH < 100 pg/ml) was not different from the Z-score of patients with iPTH in the "target range" (100-300 pg/ml) at any measurement site. While iPTH was negatively correlated with BMD at all measurement sites in patients with iPTH > 100 pg/ml (rho = -0.255, -0.278 and -0.251 for LS, FN and DR, respectively, P < 0.001 for all), BMD was independent of iPTH in patients with iPTH < 100 pg/ml. Furthermore, iPTH was not associated with serum markers of bone metabolism, but these markers were negatively correlated with BMD in the "low PTH" group.

CONCLUSIONS

Low PTH levels are not associated with low BMD in patients with end-stage kidney disease. Furthermore, bone metabolism seems to be independent of iPTH in patients with relative hypoparathyroidism likely reflecting skeletal resistance to PTH.