Bone Parameters and Risk of Hip and Femur Fractures in Patients on Hemodialysis

Risk factors and clinical prediction models for osteoporosis in pre-dialysis chronic kidney disease patients

BACKGROUND

Osteoporosis in pre-dialysis chronic kidney disease (CKD) patients has been overlooked, and the risk factors of osteoporosis in these patients have not been adequately studied.

OBJECTIVE

To identify risk factors for osteoporosis in pre-dialysis CKD patients and develop predictive models to estimate the likelihood of osteoporosis.

METHODS

Dual-energy X-ray absorptiometry was used to measure bone mineral density, and clinical examination results were collected from 326 pre-dialysis CKD patients. Binary logistic regression was employed to explore the risk factors associated with osteoporosis and develop predictive models.

RESULTS

In this cohort, 53.4% (n = 174) were male, 46.6% (n = 152) were female, and 21.8% (n = 71) were diagnosed with osteoporosis. Among those diagnosed with osteoporosis, 67.6% (n = 48) were female and 32.4% (n = 23) were male. Older age and low 25-(OH)-Vitamin D levels were identified as risk factors for osteoporosis in males. For females, older age, being underweight, higher bone alkaline phosphatase (NBAP), and advanced CKD (G5) were significant risk factors, while higher iPTH was protective. Older age, being underweight, and higher NBAP were risk factors for osteoporosis in the G1-4 subgroup. In the G5 subgroup, older age and higher NBAP increased the risk, while high 25-(OH)-Vitamin D or iPTH had protective effects. Nomogram models were developed to assess osteoporosis risk in pre-dialysis patients based on gender and renal function stage.

CONCLUSION

Risk factors for osteoporosis vary by gender and renal function stages. The nomogram clinical prediction models we constructed may aid in the rapid screening of patients at high risk of osteoporosis.

Skeletal parathyroid hormone hyporesponsiveness: a neglected, but clinically relevant reality in chronic kidney disease

PURPOSE OF REVIEW

Defining the optimal parathyroid hormone (PTH) target in chronic kidney disease (CKD) is challenging, especially for bone outcomes, due to the substantial variability in the skeleton's response to PTH. Although PTH hyporesponsiveness is as integral a component of CKD-mineral bone disorder as elevated PTH levels, clinical awareness of this condition is limited. In this review, we will discuss factors and mechanisms contributing to PTH hyporesponsiveness in CKD. This knowledge may provide clues towards a personalized approach to treating secondary hyperparathyroidism in CKD.

RECENT FINDINGS

Indicates a link between disturbed phosphate metabolism and impaired skeletal calcium sensing receptor signaling as an important mediator of PTH hyporesponsiveness in CKD. Further, cohort studies with diverse populations point towards differences in mineral metabolism control, rather than genetic or environmental factors, as drivers of the variability of PTH responsiveness.

IN SUMMARY

Skeletal PTH hyporesponsiveness in CKD has a multifactorial origin, shows important interindividual variability, and is challenging to estimate in clinical practice. The variability in skeletal responsiveness compromises PTH as a biomarker of bone turnover, especially when considering populations that are heterogeneous in ethnicity, demography, kidney function, primary kidney disease and mineral metabolism control, and in patients treated with bone targeting drugs.

Active Vitamin D Use and Fractures in Hemodialysis Patients: Results from the International DOPPS

Active vitamin D is commonly used to control secondary hyperparathyroidism in dialysis patients, but it is unknown whether active vitamin D directly improves bone strength, independently of its ability to suppress parathyroid hormone (PTH). We analyzed the association between the prescription of active vitamin D and incidence of any fracture and hip fracture in 41,677 in-center hemodialysis patients from 21 countries in phases 3 to 6 (2005 to 2018) of the Dialysis Outcomes and Practice Patterns Study (DOPPS). We used Cox regression, adjusted for PTH and other potential confounders, and used a per-protocol approach to censor patients at treatment switch during follow-up. We also used a facility preference approach to minimize confounding by indication. Overall, 55% of patients were prescribed active vitamin D at study enrollment. Event rates (per patient-year) were 0.024 for any fracture and 0.010 for hip fracture. The adjusted hazard ratio (95% confidence interval) comparing patients prescribed versus not prescribed active vitamin D was 1.02 (0.90 to 1.17) for any fracture and 1.00 (0.81 to 1.23) for hip fracture. In the facility preference approach, there was no difference in fracture rate between facilities with higher versus lower active vitamin D prescriptions. Thus, our results do not suggest a PTH-independent benefit of active vitamin D in fracture prevention and support the current KDIGO guideline suggesting the use of active vitamin D only in subjects with elevated or rising PTH. Further research is needed to determine the role of active vitamin D beyond PTH control. © 2023 American Society for Bone and Mineral Research (ASBMR).

Clinical utility of bone turnover markers in patients with chronic kidney disease

PURPOSE OF REVIEW

The burden of fractures is very high in patients with chronic kidney disease (CKD). It is increasingly recognized that knowledge of bone turnover is of paramount importance in guiding mineral metabolism and osteoporosis therapy in CKD. Bone histomorphometry is the gold standard to assess bone turnover, but is seldomly performed in clinical practice. Bone turnover markers (BTMs) may be the long awaited noninvasive diagnostic that may help to close the therapeutic gap in patients with advanced CKD presenting with bone fragility.

RECENT FINDINGS

Mounting evidence indicates that BTMs may be useful in skeletal and nonskeletal risk stratification, in guiding mineral metabolism and osteoporosis therapy, and in monitoring the therapeutic response.

SUMMARY

BTMs provide information that is complementary to other clinical tests. It may be envisioned that in the near future, the assessment of nonkidney cleared BTMs may become part of routine clinical evaluation and monitoring of bone health in CKD patients, integrated with clinical risk factors, imaging data and, eventually, bone histomorphometry. Panels of BTMs will likely be more informative than single markers, and the same might hold true for trends as opposed to single time point data.

Prevalence and predictors of asymptomatic vertebral fracture in patients with end-stage renal disease

Objective

This study aimed to investigate the prevalence and predictors of asymptomatic vertebral fracture in patients with end-stage renal disease undergoing hemodialysis.

Methods

This cross-sectional study included 80 patients with end-stage renal disease undergoing hemodialysis. Medical history, Fracture Risk Assessment Tool and anteroposterior and lateral radiographs of the thoracolumbar and lumbosacral spine were obtained. Vertebral fractures were identified using the Genant semiquantitative assessment.

Results

Radiography demonstrated asymptomatic vertebral fracture in 22 patients (27.5%). FRAX® results for major osteoporotic fracture (area under the curve, 0.64) and hip fracture (area under the curve, 0.62) were able to discriminate patients with prevalent asymptomatic vertebral fracture. A multivariate analysis demonstrated that a 1-year average corrected calcium (odds ratio, 0.38), steroid use (odds ratio, 8.99), and a serum albumin concentration <25 g/dL (odds ratio, 28.82) significantly predicted prevalent asymptomatic vertebral fracture (clinical model; area under the curve, 0.82). Combining the 1-year average corrected calcium and serum albumin concentration <25 g/dL with FRAX® results for major osteoporotic fracture (area under the curve, 0.78) and FRAX® results for hip (area under the curve, 0.75) produced a significantly greater area under the curve value to predict fracture when compared with FRAX® result for major osteoporotic fracture and FRAX® result for hip (P = 0.022).

Conclusion

Asymptomatic vertebral fracture is prevalent. FRAX® results for major osteoporotic fracture and hip provided lower ability in predicting asymptomatic vertebral facture when compared to the clinical model. Combining a 1-year average corrected calcium and serum albumin concentration <25 g/dL with FRAX® result for major osteoporotic fracture or hip improved the model's performance and provided comparable area under the curve to the clinical model.

Hyporesponsiveness or resistance to the action of parathyroid hormone in chronic kidney disease

Secondary hyperparathyroidism (SHPT) is an integral component of the chronic kidney disease-mineral and bone disorder (CKD-MBD). Many factors have been associated with the development and progression of SHPT but the presence of skeletal or calcemic resistance to the action of PTH in CKD has often gone unnoticed. The term hyporesponsiveness to PTH is currently preferred and, in this chapter, we will not only review the scientific timeline but also some of the molecular mechanisms behind. Moreover, the presence of resistance to the biological action of PTH is not unique in CKD since resistance to other hormones has also been described ("uremia as a receptor disease"). This hyporesponsiveness carries out important clinical implications since it explains, at least partially, not only the progressive nature of the pathogenesis of CKD-related PTH hypersecretion and parathyroid hyperplasia but also the increasing prevalence of adynamic bone disease in the CKD population. Therefore, we underline the importance of PTH control in all CKD stages, but not aiming to completely normalize PTH levels since a certain degree of SHPT may represent an adaptive clinical response. Future studies at the molecular level, i.e. on uremia or the recent description of the calcium-sensing receptor as a phosphate sensor, may become of great value beyond their significance to explain just the hyporesponsiveness to PTH in CKD.

Erythropoietin treatment and the risk of hip fractures in hemodialysis patients

Erythropoietin (EPO) is the primary regulator of bone marrow erythropoiesis. Mouse models have provided evidence that EPO also promotes bone remodeling and that EPO-stimulated erythropoiesis is accompanied by bone loss independent of increased red blood cell production. EPO has been used clinically for three decades to treat anemia in end-stage renal disease, and notably, although the incidence of hip fractures decreased in the United States generally after 1990, it rose among hemodialysis patients coincident with the introduction and subsequent dose escalation of EPO treatment. Given this clinical paradox and findings from studies in mice that elevated EPO affects bone health, we examined EPO treatment as a risk factor for fractures in hemodialysis patients. Relationships between EPO treatment and hip fractures were analyzed using United States Renal Data System (USRDS) datasets from 1997 to 2013 and Consolidated Renal Operations in a Web-enabled Network (CROWNWeb) datasets for 2013. Fracture risks for patients treated with <50 units of EPO/kg/week were compared to those receiving higher doses by multivariable Cox regression. Hip fracture rates for 747,832 patients in USRDS datasets (1997-2013) increased from 12.0 per 1000 patient years in 1997 to 18.9 in 2004, then decreased to 13.1 by 2013. Concomitantly, average EPO doses increased from 11,900 units/week in 1997 to 18,300 in 2004, then decreased to 8,800 by 2013. During this time, adjusted hazard ratios for hip fractures with EPO doses of 50-149, 150-299, and ≥ 300 units/kg/week compared to <50 units/kg/week were 1.08 (95% confidence interval [CI], 1.01-1.15), 1.22 (95% CI, 1.14-1.31), and 1.41 (95% CI, 1.31-1.52), respectively. Multivariable analyses of 128,941 patients in CROWNWeb datasets (2013) replicated these findings. This study implicates EPO treatment as an independent risk factor for hip fractures in hemodialysis patients and supports the conclusion that EPO treatment may have contributed to changing trends in fracture incidence for these patients during recent decades. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Differentiating the causes of adynamic bone in advanced chronic kidney disease informs osteoporosis treatment

Patients with chronic kidney disease (CKD) have an increased fracture risk because of impaired bone quality and quantity. Low bone mineral density predicts fracture risk in all CKD stages, including advanced CKD (CKD G4-5D). Pharmacological therapy improves bone mineral density and reduces fracture risk in moderate CKD. Its efficacy in advanced CKD remains to be determined, although pilot studies suggest a positive effect on bone mineral density. Currently, antiresorptive agents are the most commonly prescribed drugs for the prevention and therapy of osteoporosis. Their use in advanced CKD has been limited by the lack of large clinical trials and fear of causing kidney dysfunction and adynamic bone disease. In recent decades, adynamic bone disease has evolved as the most predominant form of renal osteodystrophy, commonly associated with poor outcomes, including premature mortality and progression of vascular calcification. Evolving evidence indicates that reduction of bone turnover by parathyroidectomy or pharmacological therapies, such as calcimimetics and antiresorptive agents, are not associated with premature mortality or accelerated vascular calcification in CKD. In contrast, chronic inflammation, oxidative stress, malnutrition, and diabetes can induce low bone turnover and associate with poor prognosis. Thus, the conditions causing suppression of bone turnover rather than the low bone turnover per se may account for the perceived association with outcomes. Anabolic treatment, in contrast, has been suggested to improve turnover and bone mass in patients with advanced CKD and low bone turnover; however, uncertainty about safety even exceeds that of antiresorptive agents. Here, we critically review the pathophysiological concept of adynamic bone disease and discuss the effect of low bone turnover on the safety and efficacy of anti-osteoporosis pharmacotherapy in advanced CKD.

Hyporesponsiveness or resistance to the action of parathyroid hormone in chronic kidney disease

Secondary hyperparathyroidism (SHPT) is an integral component of the chronic kidney disease-mineral and bone disorder (CKD-MBD). Many factors have been associated with the development and progression of SHPT but the presence of skeletal or calcemic resistance to the action of PTH in CKD has often gone unnoticed. The term hyporesponsiveness to PTH is currently preferred and, in this chapter, we will not only review the scientific timeline but also some of the molecular mechanisms behind. Moreover, the presence of resistance to the biological action of PTH is not unique in CKD since resistance to other hormones has also been described ("uremia as a receptor disease"). This hyporesponsiveness carries out important clinical implications since it explains, at least partially, not only the progressive nature of the pathogenesis of CKD-related PTH hypersecretion and parathyroid hyperplasia but also the increasing prevalence of adynamic bone disease in the CKD population. Therefore, we underline the importance of PTH control in all CKD stages, but not aiming to completely normalize PTH levels since a certain degree of SHPT may represent an adaptive clinical response. Future studies at the molecular level, i.e. on uremia, or the recent description of the calcium-sensing receptor as a phosphate sensor, may become of great value beyond their significance to explain just the hyporesponsiveness to PTH in CKD.

Longitudinal Bone Loss Occurs at the Radius in CKD

Introduction

Chronic kidney disease (CKD) exposes to an increased incidence of fragility fractures. International guidelines recommend performing bone mineral density (BMD) if the results will impact treatment decisions. It remains unknown where bone loss occurs and what would preclude the longitudinal loss in patients with CKD. Here, we aimed to investigate factors influencing BMD and to analyze the longitudinal BMD changes.

Methods

In the NephroTest cohort, we measured BMD at the femoral neck, total hip, lumbar spine, and proximal radius, together with circulating biomarkers and standardized measured glomerular filtration rate (mGFR) by ⁵¹Cr-EDTA in a subset of patients with CKD stage 1 to 5 followed during 4.3 ± 2.0 years. A linear mixed model explored the longitudinal bone loss and the relationship of associated factors with BMD changes. A total of 858 patients (mean age 58.9 ± 15.2 years) had at least 1 and 477 had at least 2 BMD measures.

Results

At baseline, cross-sectional analysis showed a significantly lower BMD at femoral neck and total hip and a significant higher serum parathyroid hormone (PTH) along with CKD stages. Baseline age, gender, tobacco, low body mass index (BMI), and high PTH levels were significantly associated with low BMD. Longitudinal analysis during the mean 4.3 years revealed a significant bone loss at the radius only. BMD changes at the femoral neck were associated with BMI, but not CKD stages or basal PTH levels.

Conclusions

CKD is associated with low BMD and high PTH in the cross-sectional analysis. Longitudinal bone loss occurred at the proximal radius after 4.3 years.

European Consensus Statement on the diagnosis and management of osteoporosis in chronic kidney disease stages G4-G5D

Controlling the excessive fracture burden in patients with chronic kidney disease (CKD) Stages G4-G5D remains an impressive challenge. The reasons are 2-fold. First, the pathophysiology of bone fragility in patients with CKD G4-G5D is complex and multifaceted, comprising a mixture of age-related (primary male/postmenopausal), drug-induced and CKD-related bone abnormalities. Second, our current armamentarium of osteoporosis medications has not been developed for, or adequately studied in patients with CKD G4-G5D, partly related to difficulties in diagnosing osteoporosis in this specific setting and fear of complications. Doubts about the optimal diagnostic and therapeutic approach fuel inertia in daily clinical practice. The scope of the present consensus paper is to review and update the assessment and diagnosis of osteoporosis in patients with CKD G4-G5D and to discuss the therapeutic interventions available and the manner in which these can be used to develop management strategies for the prevention of fragility fracture. As such, it aims to stimulate a cohesive approach to the management of osteoporosis in patients with CKD G4-G5D to replace current variations in care and treatment nihilism.

Twelve-week intradialytic cycling exercise improves physical functional performance with gain in muscle strength and endurance: a randomized controlled trial

Objective:

To evaluate the effect of intradialytic cycling exercise on physical functional performance with gain in muscle strength and endurance in end-stage renal disease patients with haemodialysis.

Design:

Randomized controlled trial, with repeated measurements at baseline and after 4, 8, and 12 weeks of intradialytic cycling exercise.

Setting:

A 50-bed haemodialysis centre in a regional hospital in Taiwan.

Subjects:

Seventy-six regular haemodialysis patients, recruited and equally and randomly assigned to exercise and control groups.

Intervention:

The intradialytic cycling exercise was performed for 12 weeks and comprised warm-up, main, and cool-down exercise phases. A stationary cycling equipment was used, which involved aerobic and resistance modalities. The intensity was maintained at somewhat hard exertion. Each intradialytic cycling exercise was implemented for 30 minutes, starting at the second hour of treatment.

Main measure:

Measured outcomes were 6-minute walk distance, time taken to complete 10 sit-to-stand-to-sit cycles and number of sit-to-stand-to-sit cycles in 60 seconds.

Results:

Average (standard deviation) participant age was 55.47 (13.00) years. Therefore, the 6-minute walk distance was significantly different at weeks 8 ( P = 0.01) and 12 ( P < 0.001) in the exercise group compared with that in the control group at baseline. Notably, sit-to-stand-to-sit outcomes ( P = 0.01) significantly influenced the 6-minute walk distance. Sit-to-stand-to-sit outcomes significantly improved in the exercise group ( P < 0.05).

Conclusion:

Twelve-week intradialytic exercise for patients on haemodialysis can improve physical functional performance with gain muscle strength and endurance. This is a safe and effective method for improving health.

Hip Fracture Risk among Hemodialysis-Dependent Patients Prescribed Opioids and Gabapentinoids

BACKGROUND

Despite opioids' known association with hip fracture risk in the general population, they are commonly prescribed to patients with ESKD. Whether use of opioids or gabapentinoids (also used to treat pain in patients with ESKD) contributes to hip fracture risk in patients with ESKD on hemodialysis remains unknown.

METHODS

In a case-control study nested within the US Renal Data System, we identified all hip fracture events recorded among patients dependent on hemodialysis from January 2009 through September 2015. Eligible cases were risk-set matched on index date with ten eligible controls. We required >1 year of Medicare Parts A and B coverage and >3 years of part D coverage to study cumulative longer-term exposure. To examine new, short-term exposure, we selected individuals with >18 months of Part D coverage and no prior opioid or gabapentinoid use between 18 and 7 months before index. We used conditional logistic regression to estimate unadjusted and multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (95% CI).

RESULTS

For the longer-term analyses, we identified 4912 first-time hip fracture cases and 49,120 controls. Opioid use was associated with increased hip fracture risk (adjusted OR, 1.39; 95% CI, 1.26 to 1.53). Subgroups of low, moderate, and high use yielded adjusted ORs of 1.33 (95% CI, 1.20 to 1.47), 1.53 (95% CI, 1.36 to 1.72), and 1.66 (95% CI, 1.45 to 1.90), respectively. The association with hip fractures was also elevated with new, short-term use (adjusted OR, 1.38; 95% CI, 1.25 to 1.52). There were no associations between gabapentinoid use and hip fracture.

CONCLUSIONS

Among patients dependent on hemodialysis in the United States, both short-term and longer-term use of opioid analgesics were associated with hip fracture events.

Fracture risk and treatment in chronic kidney disease

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with the development of mineral bone disorder (MBD), osteoporosis, and fragility fractures. The purpose of this review is to provide an update on recent findings in the diagnosis and treatment of osteoporosis in patients with CKD.

RECENT FINDINGS

Multiple observational studies have shown that bone mineral density measurement using DEXA is equally predictive in CKD stages 1-3, as in the general population. Post hoc analyses from randomized trials of bisphosphonates, SERM, RANKL inhibitors and PTH agonists all suggest equal efficacy in mild-moderate CKD. A recent systematic review also found evidence for efficacy of bisphosphonates in patients with a kidney transplant.

SUMMARY

Bone mineral density measurement using DEXA is accurate in patients with CKD stages 1-3 and should be considered to guide treatment of osteoporosis. Current treatments are unaffected by mild-to-moderate decline in kidney function, and physicians should use bisphosphonates and other osteoporosis treatments in this population, whenever indicated. Studies evaluating the optimal diagnostic and management strategy in patients with CKD stages (G4-5D) are needed.

Association of renal function with bone mineral density and fracture risk in the Longitudinal Aging Study Amsterdam

Early renal dysfunction is associated with a 38% increased fracture risk in individuals aged 65 years and older. In men but not women, early renal dysfunction is associated with decreased femoral neck bone mineral density (BMD) which can be partially explained by increased parathyroid hormone (PTH) concentrations.

INTRODUCTION

It is uncertain whether early renal dysfunction is associated with osteoporosis and increased fracture risk. The aim of this study was to determine the relationship of decreased renal function with BMD and fracture risk and the role of PTH therein.

METHODS

We analyzed data of participants aged 65 years and older from the Longitudinal Aging Study Amsterdam. A 6-year fracture follow-up was obtained in 1477 participants. BMD was measured by dual-energy x-ray absorptiometry (n = 535) and vertebral fractures by lateral spinal radiograph (n = 527) in a subsample at baseline. Glomerular filtration rate (eGFR) was estimated according to the modification of diet in renal disease equation and assessed by the five stages of chronic kidney disease (CKD).

RESULTS

In men and women, eGFR < 57 ml/min/1.73 m2 (lowest quartile) compared to eGFR > 74 ml/min/1.73 m2 (highest quartile) was associated with a 38% increase in fracture risk after adjustment for relevant confounders [hazard ratio (95%CI): 1.38 (1.17 to 1.61)]. Also, CKD stages 3a and 3b were associated to a 28 and 46% increase in fracture risk, respectively, as compared to CKD stages 1 and 2 together (eGFR > 60 ml/min/1.73 m2) after adjustment for confounders. Renal function was not associated with prevalent vertebral fractures. In men, but not women, lowest quartile of eGFR was related to lower femoral neck BMD as compared to the highest quartile eGFR [unstandardized B (95%CI) - 0.052 g/cm2 (- 0.098 to - 0.006)], after adjustment for relevant confounders. Further adjustment for PTH attenuated this relationship by 27%.

CONCLUSIONS

In men and women, early decreased renal function (eGFR < 60 ml/min/1.73 m2) was related to increased incident any fracture risk but not with increased prevalence of vertebral fractures. In men, but not women, early renal dysfunction was related to lower femoral neck BMD which could statistically be partially explained by increased PTH concentrations.

Predictors of bone fractures in a single-centre cohort of hemodialysis patients: a 2-year follow-up study

PURPOSE

Bone involvement represents one of the complications of end-stage chronic kidney disease, with fractures being its major risk. The aim of our study was to assess the frequency and predictors of low-trauma fractures in a cohort of maintenance hemodialysis patients followed-up on for 2 years.

METHODS

59 patients (67.6 ± 13.1 years, 43 males) treated with hemodiafiltration underwent initially laboratory (markers of calcium-phosphate metabolism and bone turnover markers) and densitometry examination with TBS assessment (Lunar Prodigy, TBS software 2.1.2). During 24-month follow-up, the frequency of low-trauma fractures was assessed and possible predictors of increased fracture risk were identified using product-moment correlation matrices.

RESULTS

Altogether 7 (11.9%) low-trauma fractures were observed. In the whole group, age (P = 0.047), T-score in proximal femur (P = 0.04), low vitamin D, low BMI (P = 0.03 for both), and higher FRAX for major osteoporotic fracture (P = 0.01) were connected with fractures, but in multi-variate analysis only BMI remained significantly negatively associated with fractures (P = 0.047). TBS and bone turnover markers failed to predict fractures. However, women with fractures had significantly lower serum phosphate (P = 0.03) and higher parathyroid hormone (P = 0.04). Parameters of hip structure analysis significantly correlated with FRAX, but not with fractures.

CONCLUSIONS

In a group of hemodialysis patients from one centre, T-score in proximal femur, low vitamin D, low BMI, and high FRAX for major osteoporotic fracture were associated with low-trauma fractures, however, in multi-variate analysis only low BMI remained a significant predictor of fracture risk.

Changes in bone mineral density after total parathyroidectomy without autotransplantation in the end-stage renal disease patients with secondary hyperparathyroidism

Background

The patients with secondary hyperparathyroidism (SHPT) usually had reduced bone mineral density, which might lead to a substantial increase in osteoporosis, fracture and mortality. Although surgical intervention is effective in reducing parathyroid hormone (PTH) levels in suitable candidates refractory to medical therapy, the effect of surgery on bone mass changes still requires further evaluation. Thus, the aim of this study was to evaluate the characteristics of BMD changes after total parathyroidectomy (PTX) without autotransplantation and its associated factors.

Methods

The records of 34 patients who underwent successful total PTX without autotransplantation with a preoperative and postoperative dual energy X-ray absorptiometry (DEXA) scan in our institution within 4 years of operative intervention were reviewed. Correlation and regression analysis were used to identify factors that independently predict BMD changes.

Results

At baseline, we found that the prevalence of osteoporosis seemed to be much higher in the load-bearing lumbar spine than in the hip, varying greatly even between different lumbar vertebrae. The bone loss in SHPT had its predilection site in the load-bearing cancellous bone. After curative total PTX without autotransplantation, BMD improved significantly in both lumbar spine and hip overall. The largest increase in BMD occurred at L4 vertebrae with the lowest pre-operative BMD. At the most affected site L4, BMD improved in up to 94.1% of patients: 86.2% had significant improvement, 5.9% moderate improvement, and 5.9% declining bone mineral density. Correlation and regression analysis suggested that percentage changes in BMD were predicted negatively by the preoperative BMD and positively by the preoperative parathyroid mass but not intact PTH levels.

Conclusion

Total parathyroidectomy without autotransplantation could improve BMD of secondary hyperparathyroidism at L1-L4 and the hip. Furthermore, the large parathyroid glandular mass and the preoperative BMD predicted the BMD changes after surgery.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-0934-1) contains supplementary material, which is available to authorized users.

The utility of FRAX® in predicting bone fractures in patients with chronic kidney disease on hemodialysis: a two-year prospective multicenter cohort study

We assessed the FRAX® method in 718 hemodialyzed patients in estimating increased risk of bone major and hip fractures. Over two prospective years, statistical analysis showed that FRAX® enables a better assessment of bone major fracture risk in these patients than any of its components and other risk factors considered in the analysis.

INTRODUCTION

Despite the generally increased risk of bone fractures among patients with end-stage renal disease, no prediction models for identifying individuals at particular risk have been developed to date. The goal of this prospective, multicenter observational study was to assess the usefulness of the FRAX® method in comparison to all its elements considered separately, selected factors associated with renal disease and the history of falls, in estimating increased risk of low-energy major bone and hip fractures in patients undergoing chronic hemodialysis.

METHODS

The study included a total of 1068 hemodialysis patients, who were followed for 2 years, and finally, 718 of them were analyzed. The risk analysis included the Polish version of the FRAX® calculator (without bone mineral density), dialysis vintage, mineral metabolism disorders (serum calcium, phosphate, and parathyroid hormone), and the number of falls during the last year before the study.

RESULTS

Over 2 years, low-energy 30 major bone fractures were diagnosed and 13 of hip fractures among them. Area under the curve for FRAX® was 0.76 (95% CI 0.69-0.84) for major fractures and 0.70 (95% CI 0.563-0.832) for hip fractures. The AUC for major bone fractures was significantly higher than for all elements of the FRAX® calculator. In logistic regression analysis FRAX® was the strongest independent risk factor of assessment of the major bone fracture risk.

CONCLUSIONS

FRAX® enables a better assessment of major bone fracture risk in ESRD patients undergoing hemodialysis than any of its components and other risk factors considered in the analysis.

Biomarkers Predicting Bone Turnover in the Setting of CKD

PURPOSE OF THE REVIEW

Impaired bone quality contributes to the increased fracture risk in chronic kidney disease patients. Both low and high turnover bone disease may compromise bone quality. The question arises whether bone biomarkers may be additive or replace bone histormorphometry for diagnosing the extremes of bone turnover.

RECENT FINDINGS

Studies exploring the performance of established and emerging bone biomarkers against histomorphometric assessment of bone turnover are limited and overall yield inconclusive results as to their diagnostic utility. Bone biomarkers, although promising, currently fail to meet the needed diagnostic accuracy to replace bone histomorphometry and thus are not yet ready for clinical use. Bone biomarkers have not only several advantages, but also important limitations such as high biological variability, retention with kidney disease, preanalytical issues, and interassay variability. These important issues must be considered when developing and evaluating bone biomarkers. There is an urgent need for harmonization and standardization of available assays and additional bone biopsy studies.

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.

Higher serum sclerostin levels and insufficiency of vitamin D are strongly associated with vertebral fractures in hemodialysis patients: a case control study

In hemodialysis patients, vertebral fractures were associated with elevated sclerostin levels, suggesting that sclerostin could reflect bone fragility in these patients.

INTRODUCTION

Fragility fractures are common in hemodialysis patients. The aims of our study were to determine the prevalence of vertebral fracture and analyze associations between sclerostin serum levels and vertebral fractures in hemodialysis patients.

METHODS

Ninety-two hemodialysis patients and 100 controls matched for age and sex were studied. Bone mineral density was measured by ultrasonography at non-dominant heel. The markers of bone turnover included serum osteocalcin, C-terminal telopeptide, and sclerostin. All participants underwent radiography of the thoracic and lumbar spine to ascertain the presence of vertebral fractures.

RESULTS

Bone ultrasound parameters at calcaneus were significantly lower in hemodialysis patients compared with controls; bone turnover markers and parathyroid hormone level were significantly higher, while serum of 25-OH-D3 was significantly lower in hemodialysis group. One or more moderate or severe vertebral fractures were found in 38 hemodialysis patients, whereas in control group, 10 patients had a vertebral fracture. In hemodialysis group, the comparison between patients with and without vertebral fractures showed that the patients with vertebral fractures had the serum sclerostin levels statistically higher than patients without vertebral, while serum levels of 25-OH-D3 was significantly lower in patients with vertebral fractures compared to the patients without vertebral fractures. Multivariate analysis disclosed that sclerostin levels were associated with an increased risk of vertebral fractures in hemodialysis patients after adjusting for multiple variables.

CONCLUSIONS

Our data shows high prevalence of vertebral fractures in hemodialysis patients and that it is associated with elevated sclerostin levels, reflecting bone fragility in these patients.

Parathyroid hormone metabolism and signaling in health and chronic kidney disease

Circulating parathyroid hormone (PTH) shows a complex relationship with hard outcomes in subjects with chronic kidney disease (CKD). Moreover, intervention studies directly targeting PTH failed to yield unequivocal results. Disturbed PTH metabolism, posttranslational modifications of PTH, and end-organ hyporesponsiveness to PTH may explain the poor performance of PTH as an outcome biomarker and precise target of therapy in the setting of CKD, at least in the gray middle target zone. PTH fragments accumulate in CKD patients and may exert effects that are distinct from, if not opposite to biointact (1-84)PTH. Posttranslational modification of PTH and especially oxidation may alter the interaction of PTH with its receptor. Its clinical relevance, however, remains a matter of ongoing debate. Less controversial is the issue of end-organ hyporesponsiveness to PTH. This phenomenon, formally referred to as PTH resistance, has long been recognized in CKD, but factors and mechanisms contributing to it remain poorly defined. Subsequent evidence identified downregulation of the PTH receptor and competing downstream signals as underlying pathophysiologic mechanisms. End-organ hyporesponsiveness to PTH in CKD, along with important analytical and biological variability, renders defining the PTH target range in CKD challenging. Although this may still be accomplished at the population level, it may prove to be very difficult at the individual level. This is a disillusioning thought in an era of personalized medicine. Parallel to the search of a functional and readily available assay quantifying PTH signaling tone or sensitivity, additional biomarkers (or a panel of biomarkers) should be formally evaluated.