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

Ten tips on how to assess bone health in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) experience a several-fold increased risk of fracture. Despite the high incidence and the associated excess morbidity and premature mortality, bone fragility in CKD, or CKD-associated osteoporosis, remains a blind spot in nephrology with an immense treatment gap. Defining the bone phenotype is a prerequisite for the appropriate therapy of CKD-associated osteoporosis at the patient level. In the present review, we suggest 10 practical 'tips and tricks' for the assessment of bone health in patients with CKD. We describe the clinical, biochemical, and radiological evaluation of bone health, alongside the benefits and limitations of the available diagnostics. A bone biopsy, the gold standard for diagnosing renal bone disease, is invasive and not widely available; although useful in complex cases, we do not consider it an essential component of bone assessment in patients with CKD-associated osteoporosis. Furthermore, we advocate for the deployment of multidisciplinary expert teams at local, national, and potentially international level. Finally, we address the knowledge gaps in the diagnosis, particularly early detection, appropriate "real-time" monitoring of bone health in this highly vulnerable population, and emerging diagnostic tools, currently primarily used in research, that may be on the horizon of clinical practice.

Comparative use of ultrasound and radiography for the detection of fractures: a systematic review and narrative synthesis

Background

Traditionally, X-rays have remained the standard modality for bone fracture diagnosis. However, other diagnostic modalities most notably ultrasound have emerged as a simple, radiation-safe, effective imaging tool to diagnose bone fractures. Despite the advantages, there is a prevalent scarcity of literature recognizing its significance in bone trauma management. This review investigates the effectiveness of ultrasound in the diagnosis of various bone fractures when compared to conventional radiography such as X-rays.

Methodology

Electronic databases such as PubMed/Medline, SCOPUS, and Web of Science (WOS) were reviewed for observational studies and review articles from the years 2017-2022 utilizing MESH terminology in a broad term search strategy. The search returned a total of 248 articles. After removal of duplicates, abstract, and full-text screening this systematic review ultimately utilized data from 31 articles. All searches were performed and analyzed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) methodology and were conducted during August 2022. In accordance with the guidelines for assessing the quality of included systematic reviews, we used the AMSTAR 2020, Supplemental Digital Content 2, http://links.lww.com/MS9/A241 (A Measurement Tool to Assess Systematic Reviews) tool to evaluate the methodological quality of the included studies. A data extraction form based on the Cochrane Consumers and Communication Review group's extraction template for quality assessment and evidence synthesis was used for data extraction. The information extracted included details such as author information, database, journal details, type of study, etc. Studies included will be classified into long bones, short bones, pneumatic bones, irregular bones, ankle and knee, stress fractures, hip fractures, POCUS, and others. All included studies considered bias and ethical criteria and provided valuable evidence to answer the research question.

Results

The search returned a total of 248 articles, with 192 articles remaining after the removal of duplicates. Primary screening of the title and abstract articles from the database search and additional sources identified 68 relevant articles for full-text screening. This systematic review ultimately used data from 33 articles of the remaining articles we included all of them because they had more than 70% certainty, using the STROBE tool for observational articles, narrative reviews with the ENTREQ guide, and systematic reviews and meta-analyses with the PRISMA guide; however, two articles were excluded at the eligibility stage because of risk of bias.

Conclusion

This systematic review provides insightful evidence on safety and effectiveness of ultrasound in diagnosing fractures when compared to the conventional imaging modalities such as X-rays. This shall promote further large-scale, multi-centre research that can eventually guide clinic practice in diagnosing and managing various bone fractures.

Vitamin D Supplementation and Its Impact on Different Types of Bone Fractures

Vitamin D helps to balance the levels of calcium and phosphorus to maintain proper bone structure. It is also involved in essential biological roles and displays a wide spectrum of potential benefits in the human body. Since there are many types of fractures that occur at specific ages and due to different circumstances, the influence of vitamin D on the frequency of a particular fracture may differ. Thus, the authors investigated the possible preventive effect of vitamin D on the risks of vertebral fractures, hip fractures, stress fractures and pediatric fractures. Additional aspects of vitamin D, especially on recuperation after injures and its impact on the severity of particular fractures, were also discussed. It was suggested that vitamin D supplementation may contribute to a reduction in hip fracture risk due to reduced bone turnover, decreased frequency of falls and improved muscle function. Furthermore, vitamin D appears to lower the risk of stress fractures in athletes and military recruits. Due to a nonunified protocol design, presented investigations show inconsistencies between vitamin D supplementation and a decreased risk of vertebral fractures. However, a vitamin D preventive effect on pediatric fractures seems to be implausible.

Cardiovascular Safety of Anti-Sclerostin Therapy in Chronic Kidney Disease

The significance of sclerostin for bone and cardiovascular health in patients with chronic kidney disease (CKD) is complex and incompletely understood. Experimental evidence suggests that anti-sclerostin therapy shows diminished efficacy on bone in the setting of CKD. Limited clinical evidence suggests that the osteoanabolic and anti-resorptive activity is attenuated, but hypocalcemia is more prevalent in patients with advanced CKD (eGFR < 30 mL/min) treated with anti-sclerostin (romosozumab) therapy as compared to patients without kidney disease. Furthermore, sclerostin is prominently expressed in uremic arteries. Whether the inhibition of sclerostin has adverse effects on cardiovascular health in CKD is currently unknown. This review summarizes the current understanding of the physiology and pathophysiology of sclerostin in CKD, with a focus on the cardiovascular safety of anti-sclerostin therapy in patients with or without CKD.

Pharmacodynamics of Oral Cholecalciferol in Healthy Individuals with Vitamin D Deficiency: A Randomized Open-Label Study

Comparative pharmacodynamic (PD) analyses on different dosing schedules for cholecalciferol supplementation are limited. This was an open-label, randomized, parallel-group study involving 75 healthy individuals deficient in vitamin D (baseline 25OHD < 20 ng/mL) receiving oral cholecalciferol with three different dosing regimens: Group A: 10,000 IU/day for 8 weeks followed by 1000 IU/day for 4 weeks; Group B: 50,000 IU/week for 12 weeks and Group C: 100,000 IU every other week for 12 weeks. Regulators of calcium and phosphate homeostasis, bone turnover markers and Wnt inhibitors were measured at baseline, Day 28, 53, 84, and 112. The 1,25OH2D increased at each time point. The increase was greater (p < 0.05) for group A vs. B and C at Day 28, and vs. group B at Day 56. No significant difference among groups was observed for the other biomarkers. The 24,25OH2D remained stable over time. PTH decreased at Day 84 and FGF-23 increased at all time points. CTX-I and PINP increased slightly at Day 28. BALP decreased from Day 56 onward. Dkk-1 increased from Day 56 onward, while sclerostin did not show significant changes. In healthy individuals deficient in vitamin D, vitamin D supplementation exerted effects on multiple regulators of calcium, phosphate and bone metabolism, without marked differences using the three regimens.

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.

Non-Invasive Imaging for Evaluating Cardiovascular Involvement in Patients with Primary and Lupus Nephritis

Background:

Evidence suggests that proteinuric diseases, such as primary or secondary glomerulonephritis, increase cardiovascular risk, but few studies confirmed this association.

Methods:

This is a cross-sectional, observational study on 32 patients, 17 with Primary Glomerulonephritis (PG) and 15 with Lupus Glomerulonephritis (LG). The control group consisted of 32 healthy individuals. Intima-media thickness (IMT) of the left common carotid artery, carotid bifurcation and internal carotid artery was measured by ultrasound. Left ventricular myocardial deformation was assessed by the use of the Global Circumferential Strain (GCS) and the Global Longitudinal Strain (GLS) following 2-Dimensional (2D) echocardiography in all participants.

Results:

Patients with glomerulonephritis in both groups showed significantly lower GLS compared with controls (p=0.0005). There was also a significant difference in common carotid IMT values between the LG and GP group (0.45±0.09 vs. 0.58±0.17 mm, respectively; p=0.01), but there was no difference with the control group. In patient group (n=32), a significantly positive correlation was observed between C-reactive protein and proteinuria (r=0.98; p<0.0001), whereas negative correlations were found between common carotid IMT and creatinine clearance (r=-0.97; p<0.0001) and between carotid bifurcation IMT and phosphate levels (r=-0.97; p<0.0001)

Conclusion:

Subclinical systolic myocardial dysfunction is present early in the course of glomerular disease. The use of 2D GLS revealed that LG and PG patients with no cardiovascular symptoms or history and a preserved left ventricle ejection fraction on conventional echocardiography had subclinical reduction in LV global longitudinal systolic function compared with controls.

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.

FGF23-klotho axis, bone fractures, and arterial stiffness in dialysis: a case-control study

We performed a case-control study on 130 age- and sex-matched hemodialysis patients. In multivariate analysis, we observed that FGF23 levels were associated with fracture incidence and that soluble α-klotho levels were associated with the aortic-brachial arterial stiffness ratio.

INTRODUCTION

New bone markers such as sclerostin, Dickkopf-related protein 1 (DKK1), fibroblast growth factor-23 (FGF23), and α-klotho have been identified as potential key players in bone and vascular abnormalities of chronic kidney disease. Therefore, we aimed to assess whether these markers are associated with fractures, bone metabolism, and vascular stiffness in dialysis patients.

METHODS

In a prospective hemodialysis cohort, where plasma samples and vascular assessment were performed at baseline, we matched patients who experienced a fracture during follow-up with sex- and age-matched non-fractured patients on a 1:4 ratio. Sclerostin, DKK1, α-klotho, FGF23, and markers of bone formation (alkaline phosphatase and procollagen type 1-N terminal propeptide [P1NP]) and bone resorption (tartrate-resistant acid phosphatase 5b [TRAP5b]) were measured in baseline plasma samples. Aortic-brachial pulse wave velocity ratio, a blood pressure independent measure of arterial stiffness, was used to assess vascular stiffness at baseline.

RESULTS

We included 130 hemodialysis patients (26 fractured, 104 non-fractured) with a median follow-up of 42 months and a median age of 72 years. In multivariate Cox regression models, high FGF23 levels were associated with increased fracture incidence (adjusted HR = 2.97; 95% CI 1.18, 7.43). α-Klotho levels were associated with bone formation but not resorption markers. In both univariate and multivariable adjusted models, α-klotho levels were inversely associated with the aortic-brachial pulse wave velocity ratio (β = - 0.070; 95% CI - 0.133, - 0.006).

CONCLUSIONS

These results suggest a role for FGF23/klotho axis on bone and vascular metabolism in dialysis populations.

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.

Osteoporosis, bone mineral density and CKD-MBD complex (I): Diagnostic considerations

Osteoporosis (OP) and chronic kidney disease (CKD) independently influence bone and cardiovascular health. A considerable number of patients with CKD, especially those with stages 3a to 5D, have a significantly reduced bone mineral density leading to a high risk of fracture and a significant increase in associated morbidity and mortality. Independently of classic OP related to age and/or gender, the mechanical properties of bone are also affected by inherent risk factors for CKD ("uraemic OP"). In the first part of this review, we will analyse the general concepts regarding bone mineral density, OP and fractures, which have been largely undervalued until now by nephrologists due to the lack of evidence and diagnostic difficulties in the context of CKD. It has now been proven that a reduced bone mineral density is highly predictive of fracture risk in CKD patients, although it does not allow a distinction to be made between the causes which generate it (hyperparathyroidism, adynamic bone disease and/or senile osteoporosis, etc.). Therefore, in the second part, we will analyse the therapeutic indications in different CKD stages. In any case, the individual assessment of factors which represent a higher or lower risk of fracture, the quantification of this risk (i.e. using tools such as FRAX^®) and the potential indications for densitometry in patients with CKD could represent an important first step pending new clinical guidelines based on randomised studies which do not exclude CKD patients, all the while avoiding therapeutic nihilism in an area of growing importance.