Renal osteodystrophy in predialysis and hemodialysis patients: comparison of histologic patterns and diagnostic predictivity of intact PTH

Assessment of regional and total skeletal metabolism using 18F-NaF PET/CT in patients with chronic kidney disease

OBJECTIVE

The study aims to assess regional and total bone metabolic activity in patients with chronic kidney disease using Na[18F]F PET and correlation between semi-quantitative indices and blood parameters.

METHODS

Seventy-two subjects (mean age 61.8 ± 13.8 years) were included. Of these 24/72 patients had end-stage renal disease (ESRD) (GFR < 15 mL/min/1.73 m2), 38/72 had chronic kidney disease (CKD) (GFR between 60 and 15 mL/min/1.73 m2), and 10/72 were controls with normal renal function. All subjects underwent Na[18F]F PET-CT with a dose activity of 0.06 mCi/Kg. Regional and total skeletal metabolism were assessed with mean SUVs in a skeletal volume of interest (VOI), bone to soft tissue index (B/S), global SUV mean (GSUV mean) of the whole bone, and uptake in the femoral neck.

RESULTS

Statistically significant differences were observed in a number of 18F-NaF metrics like femoral neck metabolism in CKD and ERSD groups in comparison to control in right (P = 0.003) and left femur (P = 0.006), bone to soft tissue index in the femur (P = 0.016) and GSUV5 (P = 0.006). There is also a significant difference in SUV mean in lumbar vertebrae (L1-L4) among CKD, ESRD, and controls. There was a moderate correlation between 18F-NaF PET scan uptake and blood parameters such as ALP and PTH. Na[18F]F uptake parameters were significantly different in low versus high bone turnover state.

CONCLUSIONS

The assessment of total skeleton and regional metabolism and bone turnover in CKD patients is feasible with Na[18F]F PET. Na[18F]F can help to detect early changes in bone metabolism and assess the progression of bone disease in this complex condition. Quantification with Na[18F]F PET might provide better assessment of the bone turnover. The difference in Na[18F]F uptake in CKD compared to controls is likely related to a change in bone turnover which, however, requires further validation.

Fractal characteristics of the trabecular pattern of the mandible in patients with renal transplantation

OBJECTIVE

In this study, we examined the mandibular trabecular bone structures by performing fractal dimension (FD) analysis in patients who underwent renal transplantation (RTx).

METHODS

Our study is an observational study with 69 RTx patients and 35 control group patients. The mean FD values of the patient and control groups were calculated and compared. In addition, biochemical parathyroid hormone (PTH), serum calcium, phosphorus, alkaline phosphatase (ALP), and vitamin-D parameters and FD values of both groups were analyzed.

RESULTS

FD values were significantly lower in the patient group than in the healthy group (p < .05). In the RTx group compared to the control group, ALP (90.71 ± 34.25-66.54 ± 16.8, respectively) (p < .001) and PTH (75.76 ± 38.01-38.17 ± 12.39, respectively) (p < .001) values were higher. There was a positive correlation between the FD values and ALP (rspearman  = .305, p = .011) and a negative correlation between FD values and vitamin-D (rspearman  = .287, p = .017) of patients with RTx.

CONCLUSION

FD values were found to be lower in patients who underwent RTx compared to the control group. It should be considered that FD analysis can be a method that can be used to evaluate trabecular bone structure in patients undergoing RTx.

Bone marrow-derived exosomes promote inflammation and osteoclast differentiation in high-turnover renal osteodystrophy

Introduction: Renal osteodystrophy (ROD) is a type of bone metabolic disorder in patients with chronic kidney disease (CKD). Inflammation is associated with bone loss in ROD. However, its precise mechanism has not yet been elucidated. The present study was conducted to investigate whether exosomes (Exos) in bone marrow (BM) are involved in the pathogenesis of high-turnover ROD.Methods: Bone mass, osteoclast number, and pro-inflammatory cytokines levels of BM supernatant were detected in adenine-induced ROD rats. The effect of Exos derived from BM (BM-Exos) of ROD (ROD-Exos) on inflammatory genes and osteoclast differentiation of BM-derived macrophages (BMMs) were further examined. Then, exosomal miRNA sequencing was performed and an miRNA-mRNA-pathway network was constructed.Results: we found increased osteoclasts and decreased bone mass in ROD rats, as well as inflammatory activation in the BM niche. Furthermore, BMMs from ROD rats displayed overproduction of proinflammatory cytokines and increased osteoclast differentiation, accompanied by nuclear factor κB (NF-κB) signaling activation. Mechanistically, we found that ROD-Exos activates NF-κB signaling to promote the release of proinflammatory cytokines and increase osteoclast differentiation of BMMs. Meanwhile, a total of 24 differentially expressed miRNAs were identified between BM-Exos from ROD and normal control (NC). The miRNA-mRNA-pathway network suggests that rno-miR-9a-5p, rno-miR-133a-3p, rno-miR-30c-5p, rno-miR-206-3p, and rno-miR-17-5p might play pivotal roles in inflammation and osteoclast differentiation. Additionally, we validated that the expression of miR-9a-5p is upregulated in ROD-Exos.Conclusion: The BM niche of ROD alters the miRNA cargo of BM-Exos to promote inflammation and osteoclast differentiation of BMMs, at least partially contributing to the pathogenesis of high-turnover ROD.

Incident vertebral fracture and longitudinal BMD change in Chinese postmenopausal women with early CKD: Peking Vertebral Fracture Study

Early chronic kidney disease (CKD) and non-CKD individuals had similar morphometric vertebral fracture (mVF) incidence and longitudinal bone mineral density (BMD) change. CKD did not modify the association between BMD and incident mVF status. Patients with a higher baseline BMD had a higher longitudinal BMD loss in early CKD.

PURPOSE

The aim of this 5-year longitudinal cohort study was to compare the risk of incident morphometric vertebral fracture (mVF) and longitudinal bone mineral density (BMD) change between individuals with early chronic kidney disease (CKD) and those without CKD.

METHODS

A total of 869 Chinese postmenopausal women were enrolled in the study. Serum creatinine levels were assessed using standard methods, and estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. Incident mVF was confirmed through lateral radiographs of the thoracolumbar spine. BMDs at the lumbar spine (LS) and femoral neck (FN) were measured using dual-energy X-ray absorptiometry. CKD was defined based on eGFR values: 60-89 mL/min/1.73m2 for stage 2 (n = 511) and 30-59 mL/min/1.73m2 for stage 3 (n = 92). The non-CKD group included individuals with an eGFR greater than or equal to 90 mL/min/1.73m2.

RESULTS

The incidence of mVF was not statistically different between individuals with early CKD and those without CKD (4.1% in non-CKD, 6.3% in CKD stage 2, and 7.6% in CKD stage 3; p = 0.348). Neither eGFR nor CKD status was significantly associated with incident mVF in the multivariate logistic regression analysis. Baseline BMD T-scores were negatively associated with incident mVF (LS T-score, OR = 0.603, 95% CI = 0.468-0.777; FN T-score, OR = 0.511, 95% CI = 0.350-0.746). No evidence of interaction between BMD T-scores and CKD status were identified (p = 0.284-0.785) . The differences in longitudinal BMD changes between non-CKD and CKD groups were comparable (FN BMD: -6.31 ± 7.20% in non-CKD, -5.07 ± 8.20% in CKD stage 2, and -4.49 ± 8.40% in CKD stage 3, p = 0.556; LS BMD: -1.38 ± 8.18% in non-CKD, -0.32 ± 7.14% in CKD stage 2, and 1.5 ± 6.97% in CKD stage 3, p = 0.406). Individuals with a higher baseline FN BMD showed a greater longitudinal FN BMD loss (r = -0.185, p < 0.001) .

CONCLUSIONS

Our study revealed that early CKD was not associated with an increased risk of incident mVF or greater longitudinal BMD loss. Moreover, CKD did not modify the association between BMD and the risk of incident mVF, suggesting that the management and prevention of fractures in early CKD should be approached similarly to those without CKD. Measurement of BMD appears to be crucial for predicting incident mVF risk and longitudinal bone loss in early CKD.

Serum and Urinary Soluble α-Klotho as Markers of Kidney and Vascular Impairment

This study was designed to investigate the controversy on the potential role of sKlotho as an early biomarker in Chronic Kidney Disease–Mineral Bone Disorder (CKD-MBD), to assess whether sKlotho is a reliable marker of kidney α-Klotho, to deepen the effects of sKlotho on vascular smooth muscle cells (VSMCs) osteogenic differentiation and to evaluate the role of autophagy in this process. Experimental studies were conducted in CKD mice fed a normal phosphorus (CKD+NP) or high phosphorus (CKD+HP) diet for 14 weeks. The patients’ study was performed in CKD stages 2–5 and in vitro studies which used VSMCs exposed to non-calcifying medium or calcifying medium with or without sKlotho. The CKD experimental model showed that the CKD+HP group reached the highest serum PTH, P and FGF23 levels, but the lowest serum and urinary sKlotho levels. In addition, a positive correlation between serum sKlotho and kidney α-Klotho was found. CKD mice showed aortic osteogenic differentiation, together with increased autophagy. The human CKD study showed that the decline in serum sKlotho is previous to the rise in FGF23. In addition, both serum sKlotho and FGF23 levels correlated with kidney function. Finally, in VSMCs, the addition of sKlotho prevented osteogenic differentiation and induced autophagy. It can be concluded that serum sKlotho was the earliest CKD-MBD biomarker, a reliable indicator of kidney α-Klotho and that might protect against osteogenic differentiation by increasing autophagy. Nevertheless, further studies are needed to investigate the mechanisms of this possible protective effect.

Bone Disease in Chronic Kidney Disease and Kidney Transplant

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) comprises alterations in calcium, phosphorus, parathyroid hormone (PTH), Vitamin D, and fibroblast growth factor-23 (FGF-23) metabolism, abnormalities in bone turnover, mineralization, volume, linear growth or strength, and vascular calcification leading to an increase in bone fractures and vascular disease, which ultimately result in high morbidity and mortality. The bone component of CKD-MBD, referred to as renal osteodystrophy, starts early during the course of CKD as a result of the effects of progressive reduction in kidney function which modify the tight interaction between mineral, hormonal, and other biochemical mediators of cell function that ultimately lead to bone disease. In addition, other factors, such as osteoporosis not apparently dependent on the typical pathophysiologic abnormalities resulting from altered kidney function, may accompany the different varieties of renal osteodystrophy leading to an increment in the risk of bone fracture. After kidney transplantation, these bone alterations and others directly associated or not with changes in kidney function may persist, progress or transform into a different entity due to new pathogenetic mechanisms. With time, these alterations may improve or worsen depending to a large extent on the restoration of kidney function and correction of the metabolic abnormalities developed during the course of CKD. In this paper, we review the bone lesions that occur during both CKD progression and after kidney transplant and analyze the factors involved in their pathogenesis as a means to raise awareness of their complexity and interrelationship.

Renal impairment and time to fracture healing following surgical fixation of distal radius fracture

INTRODUCTION

Despite the prevalence of renal impairments, the existing literature examining fracture healing in the upper limb in patients with renal impairment is sparse. This study hence aims to investigate the effect of renal impairment on time to fracture healing after distal radius fracture fixation surgery.

MATERIALS AND METHODS

Patients above 50 years old who underwent distal radius fracture fixation via volar plating were included. Time to fracture healing was defined as duration between day of surgery and presence of radiographic union as evidence by bridging of callus or osseous bone. To assess for renal impairment, estimated glomerular filtration rate (eGFR) was calculated based on the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Pre-existing comorbidities were also collected and analysed.

RESULTS

Ninety-nine consecutive patients took mean 65.5 ± 8.0 days to fracture healing post-operatively. Patients with renal impairment had longer time to fracture healing than patients without (67.1 ± 50.4 days versus 50.4 ± 31.8 days, p = 0.044). Patients ≥ 65 years also had a longer duration to fracture healing compared to patients < 65 years (mean 63.7 ± 53.0 days versus 50.2 ± 27.2 days, p = 0.033). Similarly, patients with ASA Class I had a shorter mean time to fracture healing than patients with ASA Class II and above (mean 42.5 ± 22.8 days versus 62.8 ± 47.6 days, p = 0.028).

CONCLUSIONS

Time to fracture healing post-distal radius fracture fixation was significantly related to renal impairment, age and ASA classification.

Update on imaging in chronic kidney disease-mineral and bone disorder: promising role of functional imaging

Disorders of mineral metabolism and bone disease are common complications in chronic kidney disease (CKD) patients and are associated with increased morbidity and mortality. Bone biopsies, bone scintigraphy, biochemical markers, and plain films have been used to assess bone disorders and bone turnover. Of these, functional imaging is less invasive than bone/marrow sampling, more specific than serum markers and is therefore ideally placed to assess total skeletal metabolism. ¹⁸F-sodium fluoride (NaF) PET/CT is an excellent bone-seeking agent superior to conventional bone scan in CKD patients due to its high bone uptake, rapid single-pass extraction, and minimal binding to serum proteins. Due to these properties, ¹⁸F-NaF can better assess the skeletal metabolism on primary diagnosis and following treatment in CKD patients. With the increased accessibility of PET scanners, it is likely that PET scanning with bone-specific tracers such as ¹⁸F-NaF will be used more regularly for clinical assessment and quantitation of bone kinetics. This article describes the pattern of scintigraphic/functional appearances secondary to musculoskeletal alterations that might occur in patients with CKD.

Adynamic bone disease: Revisited

The bone and mineral disorders form an integral part of the management of a chronic kidney disease (CKD) patient. Amongst various types of bone pathologies in chronic kidney disease-mineral bone disorder (CKD-MBD), the prevalence of adynamic bone disease (ABD) is increasing. The present review discusses the updated pathophysiology, risk factors, and management of this disorder.

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.

The Correlation between Estimated Glomerular Filtration Rate and Parathyroid Hormone Levels in Predialysis-chronic Kidney Disease Adult Patients at Sanglah General Hospital, Bali, Indonesia

BACKGROUND: Chronic kidney disease (CKD) is a structural or functional kidney disease for more than 3 months. In predialysis CKD patients, the serum parathyroid hormone levels increase progressively since the early stages of the disease to maintain phosphate homeostasis. Glomerular filtration rate (GFR) has been widely accepted to assess renal function. The GFR assessment is used to determine the CKD stadium. AIM: This study aims to analyze the correlation between GFR and parathyroid hormone levels in predialysis CKD patients undergoing treatment at Sanglah General Hospital Denpasar. METHODS: A cross-sectional observational study was conducted among predialysis CKD patients undergoing treatment at Sanglah General Hospital Denpasar who met the inclusion and exclusion criteria. The inclusion criteria were adult patients (≥18 years) who were accepting to participate in the study. Exclusion criteria were patients with predialysis CKD after thyroidectomy and/or parathyroidectomy and liver disease. The parathyroid hormone levels, blood urea nitrogen, creatinine, and GFR were examined and analyzed by SPSS version 17 for Windows. RESULTS: A total of 77 patients with predialysis CKD in this study obtained a median of e-GFR of 21.09 (4.72–75.80) mL/min/1.73 m2. The median level of parathyroid hormone was 82.07 pg/mL (15.83–716.60 pg/mL). Spearman’s correlation analysis results obtained a strong and significant negative correlation between the e-GFR value and parathyroid hormone levels (r = −0.540; p = 0.000). CONCLUSION: The parathyroid hormone levels assessment could be used as a recommendation in evaluating the CKD progressivity among predialysis adult patients at Sanglah General Hospital, Bali, Indonesia, due to the strong significant correlation.

Adynamic bone disease: Revisited

The bone and mineral disorders form an integral part of the management of a chronic kidney disease (CKD) patient. Amongst various types of bone pathologies in chronic kidney disease-mineral bone disorder (CKD-MBD), the prevalence of adynamic bone disease (ABD) is increasing. The present review discusses the updated pathophysiology, risk factors, and management of this disorder.

A retrospective study of end-stage kidney disease patients on maintenance hemodialysis with renal osteodystrophy-associated fragility fractures

BACKGROUND

Nephropathy associated metabolic disorder induces high incidence of fragility fracture in end-stage renal disease (ESRD) patients. As the risk factors and prognosis of fragility fracture in ESRD patients are unclear, more research is needed. This study aimed to evaluate various risk factors for ESRD-related fragility fractures, explore factors affecting the prognosis of patients with such fractures, and provide information for prevention and treatment of renal osteopathy to improve the prognosis of patients.

METHODS

In this retrospective case-control study, the case notes of 521 ESRD patients who received maintenance dialysis for at least 3 months were examined. Finally, 44 patients diagnosed with fragility fractures were assigned to the fragility fracture (FF) group and 192 patients were included in the control group (CG). Demographic information, underlying diseases, nutritional, bone metabolism, and renal function parameters, along with the number and causes of any deaths, were recorded for multiple statistical analysis.

RESULTS

The FF group had increased incidences of essential hypertension and diabetes mellitus and higher serum calcium, corrected calcium, alkaline phosphatase, and hemoglobin levels. Immunoreactive parathyroid hormone (iPTH), total cholesterol (TC), and low density lipoprotein (LDL) levels were higher in the CG. Multivariate Cox regression analysis revealed that fragility fracture was an independent risk factor for all-cause mortality in ESRD patients (P < .001, RR: 4.877, 95% CI: 2.367-10.013).

CONCLUSIONS

Essential hypertension and diabetes, high serum calcium and alkaline phosphatase levels, and reduced iPTH levels were risk factors for fragility fracture in ESRD patients. Maintaining iPTH and serum TC levels may protect against fragility fractures in them. Fragility fractures may yield poor prognosis and shorter lifespan. The presence of fragility fracture was an independent predictor of all-cause death in ESRD patients.

Circulating Levels of Dickkopf-Related Protein 1 Decrease as Measured GFR Declines and Are Associated with PTH Levels

BACKGROUND

The Wnt/β-catenin pathway has been implicated in the development of adynamic bone disease in early-stage chronic kidney disease (CKD). Dickkopf-related protein 1 (DKK1) and sclerostin are antagonists of the Wnt/β-catenin pathway yet have not been widely used as clinical indicators of bone disease. This study characterized levels of DKK1, sclerostin, and other biomarkers of mineral metabolism in participants across a spectrum of inulin-measured glomerular filtration rate (GFR).

METHODS

GFR was measured by urinary inulin clearance (mGFR) in 90 participants. Blood samples were obtained for measurement of circulating DKK1, sclerostin, fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), calcium, phosphate, α-klotho, and vitamin D metabolites including 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3. Spearman correlations and linear regressions were used where appropriate to examine the associations between measured values.

RESULTS

The median [IQR] age was 64 years [53.0-71.0], and the median [IQR] mGFR was 32.6 [21.7-60.6] mL/min. DKK1 decreased (r = 0.6, p < 0.001) and sclerostin increased (r = -0.4, p < 0.001) as kidney function declined, and both were associated with phosphate, PTH, FGF-23, and 1,25-dihydroxyvitamin D3 in the unadjusted analysis. After adjustment for age and mGFR, DKK1 remained significantly associated with PTH.

CONCLUSION

The results of this study demonstrate opposing trends in Wnt/β-catenin pathway inhibitors, DKK1 and sclerostin, as mGFR declines. Unlike sclerostin, DKK1 levels decreased significantly as mGFR declined and was independently associated with PTH. Future studies should determine whether measurement of Wnt signaling inhibitors may be useful in predicting bone histomorphometric findings and important clinical outcomes in patients with CKD.

Skeletal manifestations in end-stage renal disease patients and relation to FGF23 and Klotho

Chronic kidney disease affects patients of all ages and, as it progresses, it greatly affects their lives, especially with the complications it causes. One major complication is renal osteodystrophy (ROD) which starts to develop from the early stages of the disease, but becomes most apparent in patients in need of renal replacement therapy. Diagnosing ROD in the early stages remains a challenge, which brings up the need to find novel biomarkers. Studies are focusing on the role of fibroblast growth factor 23 and Klotho in the bone and mineral homeostasis, but the results are conflicting. ROD remains a major complication in CKD patients, therefore we need to gain a better understanding from the pathophysiological point of view, in order to be able to adjust the medical therapy.

Serum Markers of Low-Turnover Bone Disease in Mexican Children with Chronic Kidney Disease Undergoing Dialysis

Background

The frequency of low-turnover bone disease (LTBD) in patients with chronic kidney disease (CKD) has increased in past years. This change is important because LTBD is associated with bone pain, growth delay, and higher risk for bone fractures and extraosseous calcifications. LTBD is a histological diagnosis. However, serum markers such as parathyroid hormone (PTH) and calcium levels offer a noninvasive alternative for diagnosing these patients.

Objective

To describe the prevalence of LTBD in pediatric patients with renal failure undergoing some form of renal replacement therapy, using serum calcium and intact PTH levels as serum markers.

Methods

In this cross-sectional study, 41 children with CKD undergoing dialysis treatment (31 on continuous ambulatory peritoneal dialysis and 10 on hemodialysis) were included. There were no inclusion restrictions with respect to gender, cause of CKD, or dialysis modality. The children were studied as outpatients. The demographic data, CKD course, time on dialysis, phosphate-binding agents, and calcitriol prescription were registered, as well as weight, height, Z-score for height, linear growth rate, and Z-score for body mass index. Serum calcium, phosphorus, aluminum, PTH, alkaline phosphatase, osteocalcin, glucose, creatinine, urea, cholesterol, and triglycerides were measured.

Results

There were 20 (48.8%) children with both PTH <150 pg/mL and corrected total calcium >10 mg/dL who were classified as having LTBD[(+)]; the remaining 21 (51.2%) children were classified as having no LTBD[(–)]. The LTBD(+) patients were younger (11.2 ± 2.7 vs 13.2 ± 2.4 years, p < 0.01) but they had no differences regarding Z-scores for height. Linear growth in 6 months was less than expected in both groups (-0.15 ± 0.23 cm/month), but the difference between expected and observed growth was higher in the LTBD(+) group (-0.24 ± 0.14 vs –0.07 ± 0.28 cm/mo, p < 0.03). LTBD(+) patients also had lower serum creatinine (8.69± 2.75 vs 11.19 ± 3.17 mg/dL, p < 0.01), higher serum aluminum levels [median (range) 38.4 (9 – 106) vs 28.1 (9 – 62) μg/L, p < 0.05], and lower systolic blood pressure (112.0 ± 10.3 vs 125.0 ±12.9 mmHg, p < 0.015) and diastolic blood pressure (76.0 ± 9.7 vs 84.5 ± 8.2 mmHg, p < 0.017). A significant correlation was found between PTH and alkaline phosphatase ( r = 0.68, p < 0.001), but not between PTH and aluminum.

Conclusion

The LTBD(+) biochemical profile was found in 48.8% of the children and was associated with impaired linear growth. Aluminum contamination, evidenced by higher serum aluminum levels, may have had a pathogenic role in these disorders. Higher systolic and diastolic blood pressure levels may be related to higher serum PTH levels.

The association between chronic kidney disease, falls, and fractures: a systematic review and meta-analysis

Patients with chronic kidney disease (CKD) are more likely to experience falls and fractures due to renal osteodystrophy and the high prevalence of risk factors for falls. However, it is not well established how great the risk is for falls and fractures for the different stages of CKD compared to the general population. The objective of this systematic review and meta-analysis was to assess whether, and in which degree, CKD was associated with falls and fractures in adults. A systematic search in PubMed, Embase, CINAHL, and The Cochrane Library was performed on 7 September 2018. All retrospective, cross-sectional, and longitudinal studies of adults (18 years of older) that studied the association between CKD, fractures, and falls were included. Additional studies were identified by cross-referencing. A total of 39 publications were included, of which two publications assessed three types of outcome and four publications assessed two types of outcome. Ten studies focused on accidental falling; seventeen studies focused on hip, femur, and pelvis fractures; seven studies focused on vertebral fractures; and thirteen studies focused on any type of fracture without further specification. Generally, the risk of fractures increased when kidney function worsened, with the highest risks in the patients with stage 5 CKD or dialysis. This effect was most pronounced for hip fractures and any type of fractures. Furthermore, results on the association between CKD and accidental falling were contradictory. Compared to the general population, fractures are highly prevalent in patients with CKD. Besides more awareness of timely fracture risk assessment, there also should be more focus on fall prevention.

Surgical osteoplasty and soft tissue excision as treatment for facial deformities in patients with renal osteodystrophy: three case reports

BACKGROUND

Renal osteodystrophy (ROD) may occur in patients presenting chronic kidney disease (CKD), leading to laboratory test alterations and changes in bone turnover with extra-skeletal calcifications. Treatment involves the medical management of secondary hyperparathyroidism, potential total parathyroidectomy, and surgical interventions concerning calcifications if causing facial deformities with esthetic and functional repercussions. In this context, the aim of the present study is to describe three cases of facial deformities caused by ROD treated through cosmetic-functional surgeries.

CASE PRESENTATION

All patients underwent osteoplasty and soft tissue excision for several purposes, including speech difficulties, chewing difficulties, airway obstructions, malocclusion, and facial disharmony. Most patients were male (n = 2, 66.7%) with a mean age of 30.0 years old. Patients underwent a mean hemodialysis time of 9 years, and the maximum mean parathyroid hormone (PTH) level was of 2384.5 pg/ml.

CONCLUSIONS

Long hemodialysis periods and elevated PTH levels were the probable factors for the development of facial deformities in this group of patients. The main complications associated to the surgical management of facial deformities in ROD patients are directly related to end-stage renal disease, with increased risks for hemorrhage and systemic drug accumulation.

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.

Calcium-Phosphate Metabolism Disorders in Patients with Renal Failure Clinical Significance, Diagnosis and Treatment

Chronic kidney diseases (CKD) are commonly associated with calcium and phosphorus metabolism disorders. The general term of “renal osteodystrophy” (ROD) encompasses a complex spectrum of abnormalities in bone and mineral metabolism in CKD. This is one of the most serious and debilitating complications of CKD. It is related to disproportionately high direct and indirect costs of healthcare, thus posing a major burden on society. The development of ROD begins too early in the course of CKD. Some mechanisms involved in the pathogenesis of ROD are reduced calciferol production, calcium deficiency and hyperphosphatemia. Clinically, ROD occurs with varied manifestations – osteomalacia, osteoporosis, adynamic bone disease. The diagnosis and the treatment are a challenge for the physician and effort should be made to prolong the duration and quality of life of the affected patients.

Hypoalbuminemia differently affects the serum bone turnover markers in hemodialysis patients

Renal osteodystrophy (ROD) represents bone disorders related to chronic kidney disease (CKD) and several bone biomarkers are used clinically to predict ROD in CKD and hemodialysis (HD) patients. Serum albumin associates with inflammation other than nutritional status in these patients. Chronic inflammation is proved to relate with bone loss, however, the influence of hypoalbuminemia on bone biomarkers is still unclear. In this study, we evaluated the pattern of bone biomarker changes and further studied the influence of hypoalbuminemia on these biomarkers. A total of 300 maintenance HD patients were evaluated and 223 HD patients were included in the study. The patients were grouped according to serum parathyroid hormone (PTH) levels (PTH ≤150 pg/mL, PTH 150-300 pg/mL, PTH 300-600 pg/mL and PTH >600 pg/mL). Bone biomarkers and inflammatory markers were measured and their relation with PTH levels was determined. Significantly increased interleukin-6 (IL-6) and lower albumin levels were noted among PTH>600 pg/mL group. Bone turnover markers were significantly higher in PTH >600 pg/mL group (p< 0.05). Hypoalbuminemia significantly increased the fibroblast growth factor-23 (FGF-23) and procollagen type 1N-terminal propeptide (P1NP) in PTH ≤150 pg/mL, PTH 150-300 pg/mL, PTH 300-600 pg/mL groups, whereas no such relation was noted among PTH> 600 ng/dL group. In conclusion, hypoalbuminemia represents a chronic inflammation which differently relates to bone turnover markers according to serum PTH levels in SHPT patients. Thus, serum albumin measurement should be considered in determining bone disorders among these patients.

Vitamin D and kidney disease

Calcium and phosphorus are essential minerals required for many critical biologic functions including cell signaling, energy metabolism, skeletal growth and integrity. Calcium and phosphate homeostasis are maintained primarily by regulation of epithelial calcium and phosphate cotransport in the kidney and intestine, processes that are tightly regulated by hormones including 1,25 dihydroxyvitamin D (1,25(OH)2D), fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH). In patients with chronic kidney disease (CKD), as renal function declines, disruption of feedback loops between these hormones have adverse consequences on several organ systems, including the skeleton, heart and vascular system. CKD-associated mineral and bone disorder (CKD-MBD) is defined as a systemic disorder of mineral and bone metabolism due to CKD manifested by abnormalities of calcium, phosphorus, PTH or vitamin D metabolism, abnormalities of bone turnover, mineralization and volume, and ectopic soft tissue calcification. Complications of CKD-MBD include vascular calcification, stroke, skeletal fracture and increased risk of death. Increased FGF23 and PTH concentrations, and 1,25(OH)2D deficiency contribute to the pathogenesis of CKD-MBD. Therefore, treatment of patients with CKD-MBD is focused on restoring the feedback loops to maintain normal calcium and phosphate balance to prevent skeletal and cardiovascular complications.

Review on the Utility of Trabecular Bone Score, a Surrogate of Bone Micro-architecture, in the Chronic Kidney Disease Spectrum and in Kidney Transplant Recipients

Chronic kidney disease (CKD) is defined as abnormalities of kidney structure or function, present for >3 months, with implications for, among others, bone health. Advanced stages of CKD have an increased risk of fragility fractures. Trabecular bone score (TBS) is a relatively new gray-level textural parameter, which provides information on bone microarchitecture and has been shown to be a good predictor of fragility fractures independently of bone density and clinical risk factors. We aimed to review the scientific literature on TBS and its utility along the CKD spectrum and in kidney transplant recipients. In total, eight articles had investigated this topic: one article in patients with reduced kidney function, two in patients on hemodialysis, and five in kidney transplant recipients. In general, all the studies had shown an association between lower values of TBS and reduced kidney function; or lower TBS values among the hemodialysis or kidney transplant patients compared to healthy controls. Moreover, TBS was shown to be a good and independent predictor of fragility fractures in patients with CKD or who underwent kidney transplantation. TBS postulates itself as a valuable marker to be used in clinical practice as an assessor of bone microarchitecture and fracture risk predictor in these specific populations. However, evidence is to some extent limited and larger follow-up case-control studies would help to further investigate the TBS utility in the management of bone health damage and increased fracture risk in patients with CKD or kidney transplant.

[Management of bone and mineral metabolism disorders before the dialysis stage remains still perfectible. Data from the French Phosphorus and Calcium Survey Photo-Graphe]

Only limited data is available on the management of the chronic kidney disease-associated bone and mineral metabolism disorder (CKD-MBD) in the pre-dialysis stages of CKD in France. A better knowledge of current management habits could lead to an improvement in the implementation of international recommendations (KDIGO). The 3rd version of the French Phosphorus and Calcium Survey Photo-Graphe (Sanofi) included a cohort of CKD stages 4 and 5 patients, whose aim was to examine the prevalence of CKD-MBD and the quality of its management in patients under the care of 62 nephrologists from over 20 geographical regions in France. The study started in October 2011, i.e. one year after patient enrollment. We examined in particular the percentage of patients presenting with laboratory parameter abnormalities indicative of CKD-MBD who were not receiving adequate treatment. A total of 456 patients with CKD stage 4 and 154 with CKD stage 5 were studied. Their mean age was 72.9±14.2 years, and male/female ratio was 58/42. KDIGO targets of serum PTH for CKD stages 4 and 5 were not achieved in respectively 80 and 84% of the patients, for serum calcium in 8 and 22% and for serum phosphate in 12 and 46%. As a potential explanation, insufficient therapy was estimated to account for respectively 45 and 60% of insufficiently controlled secondary hyperparathyroidism, and for 36% of persistent hyperphosphatemia in stage 5. It should be noted that 55.5 and 57.5% of patients were receiving native vitamin D. In this national observatory, the management of CKD-MBD stages 4 and 5 appears suboptimal, especially as regards the control of secondary hyperparathyroidism, which remained untreated in nearly 50% of the patients. Hyperphosphatemia was also common and inadequately controlled in CKD stage 5. To improve the management of CKD-MBD, nephrologists need to be more aware of the importance of aiming for recommended laboratory targets and how this can be achieved.

Clinical aspects of magnesium physiology in patients on dialysis

Magnesium balance is infrequently discussed in the dialysis population, and the clinical consequences of derangements in magnesium homeostasis are incompletely understood. There is an association between hypomagnesemia and adverse outcomes including increases in cardiovascular disease and mortality, while elevated magnesium levels have also been linked with complications such as osteomalacia. In this review, we discuss the features of magnesium physiology relevant to dialysis patients and provide an updated summary of the literature linking magnesium derangements with bone disease, cardiovascular disease, sudden cardiac death, and mortality.

Pharmacological Management of Secondary Hyperparathyroidism in Patients with Chronic Kidney Disease

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD) and is part of the CKD-mineral bone disorder (CKD-MBD). SHPT is associated with increased risk of fracture and mortality; thus, SHPT control is recommended as kidney function declines. Effective SHPT management becomes more difficult once skeletal and cardiovascular adverse effects associated with severe SHPT have become established. However, interventional studies to lower parathyroid hormone (PTH) have so far shown inconsistent results in improving patient-centred outcomes such as mortality, cardiovascular events and fracture. Pharmacological treatment effect on PTH level is also inconsistent between pre-dialysis CKD and dialysis patients, which adds to the complexity of SHPT management. This review aims to give an overview on the pathophysiology, pharmacological and non-pharmacological treatment for SHPT in CKD including some of the limitations of current therapeutic options.

Chronic Kidney Disease

The definition and classification of chronic kidney disease (CKD) have evolved over time, but current international guidelines define this condition as decreased kidney function shown by glomerular filtration rate (GFR) of less than 60 mL/min per 1·73 m², or markers of kidney damage, or both, of at least 3 months duration, regardless of the underlying cause. Diabetes and hypertension are the main causes of CKD in all high-income and middle-income countries, and also in many low-income countries. Incidence, prevalence, and progression of CKD also vary within countries by ethnicity and social determinants of health, possibly through epigenetic influence. Many people are asymptomatic or have non-specific symptoms such as lethargy, itch, or loss of appetite. Diagnosis is commonly made after chance findings from screening tests (urinary dipstick or blood tests), or when symptoms become severe. The best available indicator of overall kidney function is GFR, which is measured either via exogenous markers (eg, DTPA, iohexol), or estimated using equations. Presence of proteinuria is associated with increased risk of progression of CKD and death. Kidney biopsy samples can show definitive evidence of CKD, through common changes such as glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Complications include anaemia due to reduced production of erythropoietin by the kidney; reduced red blood cell survival and iron deficiency; and mineral bone disease caused by disturbed vitamin D, calcium, and phosphate metabolism. People with CKD are five to ten times more likely to die prematurely than they are to progress to end stage kidney disease. This increased risk of death rises exponentially as kidney function worsens and is largely attributable to death from cardiovascular disease, although cancer incidence and mortality are also increased. Health-related quality of life is substantially lower for people with CKD than for the general population, and falls as GFR declines. Interventions targeting specific symptoms, or aimed at supporting educational or lifestyle considerations, make a positive difference to people living with CKD. Inequity in access to services for this disease disproportionally affects disadvantaged populations, and health service provision to incentivise early intervention over provision of care only for advanced CKD is still evolving in many countries.

Bone Histo-Morphology in Chronic Kidney Disease Mineral Bone Disorder

Chronic Kidney Disease-Mineral Bone Disorder(CKD-MBD) is a systemic disorder of the mineral and bone metabolism seen in patients with Chronic Kidney Disease(CKD). It is manifested by either one or a combination of the following: (a) Abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism. (b) Abnormalities in bone turnover, mineralization, volume, linear growth, or strength. (c) Vascular or other soft- tissue calcification. Renal osteodystrophy measures the skeletal component of CKD-MBD. To study the histomorphology of bone marrow biopsy in patients with CKD-MBD and correlate the histological features of bone biopsy with the clinicobiochemical parameters. 32 cases of diagnosed CKD-MBD formed the study group. Detailed clinical history and biochemical analysis was done for them. Bone marrow trephine biopsies were conducted and the histology was studied. The clinicobiochemical and the histomorphological findings were correlated. Based on the bone biopsy findings, Hyperparathyroid bone disease consisted of-14 cases (44%), Mixed uremic osteodystrophy of-16 cases (50%) and one case (3%) each of Low turnover disease (Adynamic bone disease) and Normal histology. The mean blood urea, S. Creatinine, S Phosphate and the S. Vit D3 were found to be statistically significant between the two major subgroups. The area of the bone trabeculae and the osteoid percentage was found to be more in the MUO group and was found to be statistically significant.

CONCLUSION

A trephine biopsy helps us in understanding the skeletal symptoms of the CKD when the clinical and biochemical parameters are not conclusive. A biopsy in unexplained bone pain/fractures, unexplained hypercalcemia and elevated phosphate levels helps in guiding the proper management of the patient.

An update on bone imaging and markers in chronic kidney disease

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

Prevalence and severity of disordered mineral metabolism in patients with chronic kidney disease: A study from a tertiary care hospital in India

BACKGROUND

Disordered mineral metabolism is common complications of chronic kidney disease (CKD). However, there are limited data on the pattern of these disturbances in Indian CKD population.

MATERIALS AND METHODS

This was a prospective observational study of CKD-mineral and bone disorder (CKD-MBD) over a period of 3 years. The biochemical markers of CKD-MBD, namely, calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone (iPTH), and 25-hydoxyvitamin Vitamin D3 (25OHD), were measured in newly diagnosed CKD Stage 3-5 and prevalent CKD Stage 5D adult patients.

RESULTS

A total of 462 patients of CKD Stage 3-5D were studied. The frequency of various biochemical abnormalities was hypocalcemia (23.8%), hypercalcemia (5.4%), hypophosphatemia (2.8%), hyperphosphatemia (55.4%), raised alkaline phosphatase (56.9%), secondary hyperparathyroidism (82.7%), and hypoparathyroidism (1.5%). 25OHD was done in 335 (72.5%) patients and 90.4% were found to have Vitamin D deficiency. About 70.6% of the patients had iPTH levels were above kidney disease outcomes quality initiative (KDOQI) target range. Nondiabetic CKD as compared to diabetic CKD had a higher alkaline phosphatase (P = 0.016), a higher iPTH (P = 0.001) a higher proportion of patients with iPTH above KDOQI target range (P = 0.09), and an elevated alkaline phosphatase (P = 0.004). The 25OHD levels were suggestive of severe Vitamin D deficiency in 33.7%, Vitamin D deficiency in 45.4%, and Vitamin D insufficiency in 11.3% patients. There was a significant positive correlation between iPTH with alkaline phosphatase (r = 0.572, P = 0.001), creatinine (r = 0.424, P = 0.001), and phosphorus (r = 0.241, P = 0.001) and a significant negative correlation with hemoglobin (r = -0.325, 0.001), age (r = -0.169, P = 0.002), and 25OHD (r = -0.126, P = 0.021). On multivariate logistic regression analysis, an elevated alkaline phosphatase was a significant predictor of hyperparathyroidism (odds ratio 9.7, 95% confidence interval 4.9-19.2, P = 0.001).

CONCLUSIONS

There was a high prevalence of CKD-MBD in Indian CKD patients. CKD-MBD is more common and more severe and has an early onset as compared to the western populations.

Serum Parathyroid Hormone Concentrations and Clinical Outcomes in ESRD: A Call for Targeted Clinical Trials

Secondary hyperparathyroidism almost universally accompanies end-stage renal disease (ESRD). In some, but not all studies, elevated serum parathyroid hormone (PTH) concentrations are associated with increased fracture rates, cardiovascular disease, and mortality in ESRD. The serum concentration of PTH required for optimal bone health and reduced cardiovascular risk in such patients remains elusive. Recent clinical trials have failed to show substantial changes in morbidity and mortality following reductions of elevated serum PTH concentrations. In this review, we will assess some of the difficulties in evaluating elevated serum PTH concentrations, and their association with skeletal fractures and mortality in ESRD patients. We are of the opinion that in the context of ESRD, elevated PTH concentrations occur in conjunction with other comorbid conditions such as diabetes mellitus, malnutrition, hypertension, volume excess, preexisting heart disease, all of which have prevented establishing a precise association between elevated serum PTH concentrations and global or skeletal outcomes. Age, gender, and racial variability among groups make interpretation exceptionally difficult. Analysis of prevalent ESRD populations with secondary hyperparathyroidism should take all these factors into account. We suggest that future clinical trials which examine the usefulness of reductions in serum PTH concentrations be conducted in age, sex, and racially balanced groups, without or with minimal coexisting confounding disease. Furthermore, trials in such populations should have as their primary outcome a reduction in fractures rather than an alteration in mortality.

Potential future uses of calcimimetics in patients with chronic kidney disease

Cinacalcet has proven effective in the treatment of secondary hyperparathyroidism (SHPT) in dialysis patients, and it may also have benefits in stage 3 and 4 chronic kidney disease (CKD). The efficacy of cinacalcet in the treatment of SHPT was investigated in a study of 54 patients with stage 3 and 4 CKD not receiving dialysis. A significant number of these patients achieved at least a 30% reduction in parathyroid hormone (PTH) from baseline with cinacalcet therapy compared with placebo (56% versus 19%; P = 0.006). Another potential use of cinacalcet is in the treatment of persistent hyperparathyroidism (HPT) after kidney transplantation. The pathophysiologic considerations for persistent HPT in patients who have undergone renal transplantation are different from those in stage 3 and 4 CKD. Post-transplant patients with normal graft function often present with hypercalcaemia, low serum phosphorus and persistently elevated levels of PTH. In eight small open-label studies including a total of 83 patients with persistent HPT after successful kidney transplantation, cinacalcet treatment effectively corrected hypercalcaemia and significantly reduced elevated PTH levels. These studies suggest that cinacalcet therapy is an effective therapy in controlling hyperparathyroidism in patients with stage 3 and 4 CKD and in post-transplant patients with persistent hyperparathyroidism.

Chronic kidney disease and the skeleton

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

Osteoporosis update: proceedings of the 2013 Santa Fe Bone Symposium

The 2013 Santa Fe Bone Symposium included plenary sessions on new developments in the fields of osteoporosis and metabolic bone disease, oral presentations of abstracts, and faculty panel discussions of common clinical conundrums: scenarios of perplexing circumstances where treatment decisions are not clearly defined by current medical evidence and clinical practice guidelines. Controversial issues in the care of osteoporosis were reviewed and discussed by faculty and participants. This is a review of the proceedings of the Santa Fe Bone Symposium, constituting in its entirety an update of advances in the understanding of selected bone disease topics of interest and the implications for managing patients in clinical practice. Topics included the associations of diabetes and obesity with skeletal fragility, the complexities and pitfalls in assessing the benefits and potential adverse effects of nutrients for treatment of osteoporosis, uses of dual-energy X-ray absorptiometry beyond measurement of bone mineral density, challenges in the care of osteoporosis in the very elderly, new findings on the role of osteocytes in regulating bone remodeling, and current concepts on the use of bone turnover markers in managing patients with chronic kidney disease who are at high risk for fracture.

Chronic kidney disease and osteoporosis: evaluation and management

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

Bone mineral metabolism and subsequent hospitalization with poor quality of life in dialysis patients

Background:

Significant impairment in health-related quality of life (HRQOL) among dialysis patients could be partly explained by some co-morbid disorders, such as chronic kidney disease-mineral and bone disorder (CKD-MBD). Also disturbance in calcium and phosphorus metabolism would increase mortality and morbidity. Therefore, further efforts to treat these abnormalities may improve the survival.

Objectives:

We designed a large multicenter population-based study in Iran to describe and assess the relation between HRQOL, hospitalization, and bone metabolism markers.

Patients and Methods:

We enrolled a total of 5820 dialysis patients from 132 dialysis centers in different parts of the country whom were volunteers to cooperate between October 2010 and August 2011. The Iranian adapted version of the Kidney disease quality of life-short form (KDQOL-SF^TM) version 1.3 questionnaire was used to assess the health related quality of life. The clinical and demographic characteristics were gathered from patients’ data files.

Results:

The mean (SD) age of patients was 54.88 (16.36) years, and the range was 2 to 99 years. Of all patients, 43.1% were female. The scores of kidney disease component summary (KDCS), physical component summary, mental component summary, and total quality of life were significantly higher in the lower quartile of corrected serum calcium and higher quartile of serum parathyroid hormone (PTH) levels (P < 0.05). In a regression analysis of multilevel data, while corrected serum calcium level was associated with total KDCS and short form health survey (SF-36) scores after adjusting for other variables, hospitalization was directly correlated with serum phosphorus level and had reverse correlation with dialysis duration and quality of life.

Conclusions:

In the current study, quality of life was correlated with serum calcium level, calcium-phosphate product, and serum PTH level, while hospitalization was correlated only with serum phosphorus level. However, quality of life was inversely correlated with hospitalization.

Laboratory abnormalities in CKD-MBD: markers, predictors, or mediators of disease?

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is characterized by bone abnormalities, vascular calcification, and an array of laboratory abnormalities. The latter classically include disturbances in the parathyroid hormone/vitamin D axis. More recently, fibroblast growth factor 23 (FGF23) and klotho also have been identified as important regulators of mineral metabolism. Klotho deficiency and high circulating FGF23 levels precede secondary hyperparathyroidism in CKD patients. Levels of FGF23 and parathyroid hormone increase along the progression of CKD to maintain mineral homeostasis and to overcome end-organ resistance. It is hard to define when the increase of both hormones becomes maladaptive. CKD-MBD is associated with adverse outcomes including cardiovascular disease and mortality. This review summarizes the complex pathophysiology of CKD-MBD and outlines which laboratory abnormalities represent biomarkers of disease severity, which laboratory abnormalities are predictors of cardiovascular disease, and which laboratory abnormalities should be considered (direct) uremic toxins exerting organ damage. This information may help to streamline current and future therapeutic efforts.

Recovery versus persistence of disordered mineral metabolism in kidney transplant recipients

In patients with end-stage renal disease, successful renal transplantation improves the quality of life and increases survival, as compared with long-term dialysis treatment. Although it long has been believed that successful kidney transplantation to a large extent solves the problem of chronic kidney disease-mineral and bone disorders (CKD-MBD), increasing evidence indicates that it only changes the phenotype of CKD-MBD. Posttransplant CKD-MBD reflects the effects of immunosuppression, previous CKD-MBD persisting after transplantation, and de novo CKD-MBD. A major and often-underestimated problem after successful renal transplantation is persistent hyperparathyroidism. Besides contributing to posttransplant hypercalcemia and hypophosphatemia, persistent hyperparathyroidism may be involved in the pathogenesis of allograft dysfunction (nephrocalcinosis), progression of vascular calcification, and bone disease (uncoupling of bone formation and bone resorption and bone mineral density loss) in renal transplant recipients. Similar to nontransplanted patients, CKD-MBD has a detrimental impact on (cardiovascular) mortality and morbidity. Additional studies urgently are needed to get more insights into the pathophysiology of posttransplant CKD-MBD. These new insights will allow for a more targeted and causal therapeutic approach.

Estimated GFR and fracture risk: a population-based study

BACKGROUND AND OBJECTIVES

Although patients with ESRD have a higher fracture risk than the general population, there is conflicting evidence regarding fracture incidence in those with CKD. This study sought to determine the association between estimated GFR (eGFR) and fracture rates.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study identified 1,815,943 community-dwelling adults who had at least one outpatient serum creatinine measurement between 2002 and 2008. Patients with eGFR <15 ml/min per 1.73 m(2) and those who required dialysis were excluded. Incident fractures of the hip, wrist, and vertebrae were identified using diagnostic and procedure codes. Poisson regression was used to determine adjusted rates of each fracture type by eGFR, age, and sex.

RESULTS

The median age of the cohort was 47 years (interquartile range, 24), and 7.1% had eGFR <60 ml/min per 1.73 m(2). Over a median follow-up of 4.4 years, fracture rates increased with age at all sites. Within each age stratum, unadjusted rates increased with declining eGFR; however, adjusted rates were similar across eGFR categories. For example, among women aged 65-74 years, adjusted hip fracture rates were 3.41 per 1000 person-years (95% confidence interval, 2.30 to 4.53) and 4.58 per 1000 person-years (95% confidence interval, 0.02 to 9.14) in those with eGFR ≥90 and 15-29 ml/min per 1.73 m(2), respectively. Similar results were observed for wrist and vertebral fractures.

CONCLUSIONS

In contrast to earlier studies, patients with eGFR<60 ml/min per 1.73 m(2) do not appear to have increased rates of hip, wrist, and vertebral fractures independent of age and sex.

PTH--a particularly tricky hormone: why measure it at all in kidney patients?

Plasma parathyroid hormone (PTH) concentrations are commonly measured in the context of CKD, as PTH concentration elevation is typical in this clinical context. Much has been inferred from this raised PTH concentration tendency, both about the state of skeletal integrity and health and also about the potential clinical outcomes for patients. However, we feel that reliance on PTH concentrations alone is a dangerous substitute for the search for, and use of, more precise and reliable biomarkers. In this article, we rehearse these arguments, bringing together patient-level and analytical considerations for the first time.

Mineral and bone disorders in chronic kidney disease and end-stage renal disease patients: new insights into vitamin D receptor activation

Progressive loss of kidney function leads to reduced production of calcitriol (1,25-dihydroxyvitamin D; active vitamin D) and an imbalance in serum calcium (Ca) and phosphorus (P) levels, which are associated with progression of renal failure as well as increased rates of cardiovascular (CV) events and mortality. In addition, multifactorial hypocalcemia and resistance to parathyroid hormone (PTH) can lead to prolonged and excessive synthesis and secretion of PTH, eventually leading to development of secondary hyperparathyroidism and renal osteodystrophy. These changes associated with chronic kidney disease (CKD), extending beyond bone and related biochemical abnormalities, have prompted the development of the term CKD–mineral and bone disorder to describe its systemic nature. Excessive P loading, among other factors, will promote vascular calcification (VC), and PTH production will affect bone remodeling. Although administration of calcitriol increases serum Ca levels and decreases PTH, it is also associated with elevated Ca × P product. Therefore, compounds that selectively activate vitamin D receptors (VDR activators), potentially reducing Ca–P toxicity and distinctly affecting pathogenic mechanisms of VC, might enhance CV and renal protection, increase the vitamin D therapeutic window, and thus provide a significant clinical benefit. Moreover, selective VDR activators have been associated with improvement in survival, at least among dialysis patients. Thus, selective VDR activators should be considered a novel and interesting approach to enhance the standard of care in CKD patients.