Vascular calcifications and renal osteodystrophy in chronic hemodialysis patients: what is the relationship between them?

Interrelationships between sarcopenia, bone turnover markers and low bone mineral density in patients on hemodialysis

BACKGROUND

Hemodialysis (HD) patients are at risk for sarcopenia (SP) and bone loss, which may impact falls and bone fragility and lead to poor prognosis. Patients with HD and those with osteoporosis (OP) are still underdiagnosed and untreated. The aims of the present study were to evaluate the factors that affect bone mineral density (BMD) loss in HD patients, and explore traditional and novel approaches to manage chronic kidney disease-mineral-bone disorder (CKD-MBD).

METHODS

Patients who underwent regular HD at the First Affiliated Hospital of Soochow University were retrospectively evaluated. According to the WHO osteoporosis criteria, patients were categorized into three groups: normal BMD, osteopenia, and osteoporosis. Demographic and clinical data, skeletal muscle mass, and bone turnover markers(BTM) were compared between the three groups. The correlation between bone density and muscle mass was calculated, and related risk factors were analyzed.

RESULTS

This study enrolled 130 HD patients, 36 patients were diagnosed with sarcopenia (27.7%), 44 patients were diagnosed with osteopenia (33.8%), 19 patients were diagnosed with osteoporosis (14.6%), and 23 patients were diagnosed with osteosarcopenia (17.7%). The SMI was positively correlated with the BMD of the lumbar spine (r = 0.23, p < 0.01) and femoral neck (r = 0.22, p < 0.05). In ordinal logistic regression analysis, the odds ratio (OR) for low BMD was high for patients with sarcopenia (OR = 5.894, 95% CI 1.592-21.830, p < 0.01), older age (OR = 1.095, 95% CI 1.041-1.153, p < 0.001), higher TRACP-5b levels (OR = 1.597, 95% CI 1.230-2.072, p < 0.01), and lower 25-OH vitamin D levels (OR = 0.631, 95% CI 0.544-0.733, p < 0.001).

CONCLUSION

The preservation of skeletal muscle mass could be important to prevent a BMD decrease in HD patients. Adequate intake of vitamin D and control of TRACP-5b levels will help reduce the occurrence and progression of osteopenia/sarcopenia in HD patients.

Association of Serum Osteoprotegerin Level With Myocardial Injury and Cardiovascular Calcification in Chronic Kidney Disease Patients

Background

Chronic kidney disease has emerged as a significant independent risk factor for cardiovascular disease. Cardiovascular calcification is an active process involving a complex interaction of inducers and inhibitors. High sensitivity cardiac troponin T assay detects troponin T with higher sensitivity and precision at an earlier point of time than the conventional assays, and is associated with poor outcomes. Serum osteoprotegerin is classed as an inhibitory factor for cardiovascular calcification. It is involved in the pathological processes of vascular damage and linked to the excess cardiovascular morbidity. The aim of the present study was to evaluate the extent of cardiovascular calcification and serum high sensitivity cardiac troponin T level, and their association with serum osteoprotegerin level in patients with chronic kidney disease stages 3-5.

Methods

90 chronic kidney disease patients were enrolled in this study, and they were divided into two groups: group (1) included 45 non-dialysis-dependent chronic kidney disease patients (stages 3-5) and group (2) included 45 chronic hemodialysis patients. Each group further subdivided according to the presence of cardiovascular calcification into subgroup A and B. Vascular calcifications were assessed by lateral lumbar, pelvis and hands X-ray radiographs. Valvular calcification was assessed by echocardiography. Serum cardiac troponin T was measured by high sensitivity assay and serum osteoprotegerin was measured by ELISA.

Results

Cardiovascular calcification distribution was 22.2% in group (1) and 33.3% in group (2). Serum osteoprotegerin and troponin T in calcification groups (1A and 2A) were significantly higher than non-calcification groups (1B and 2B; P < 0.001). Osteoprotegerin correlated positively with high sensitivity cardiac troponin T (rs = 0.72, P < 0.001). cardiovascular calcification correlated positively with osteoprotegerin, troponin T, and phosphorus. osteoprotegerin and phosphorus were significant independent predictors of cardiovascular calcification at cut-off values ≥4.6 ng/L and ≥6.95 mg/dl, respectively (P < 0.001). Serum phosphorus and creatinine were independent predictors of osteoprotegerin (P < 0.001 and 0.048, respectively).

Conclusion

Osteoprotegerin is strongly associated with cardiovascular calcification and high sensitivity cardiac troponin T. In addition, there is a positive association between calcification and troponin T. This suggests a role for osteoprotegerin in the pathogenesis and risk stratification of cardiovascular calcification and myocardial injury in chronic kidney disease patients with a potential role as a therapeutic target.

Gender-Related Differences in Chronic Kidney Disease-Associated Vascular Calcification Risk and Potential Risk Mediators: A Scoping Review

Vascular calcification (VC) involves the deposition of calcium apatite in vascular intima or media. Individuals of advanced age, having diabetes mellitus or chronic kidney disease (CKD) are particularly at risk. The pathogenesis of CKD-associated VC evolves considerably. The core driver is the phenotypic change involving vascular wall constituent cells toward manifestations similar to that undergone by osteoblasts. Gender-related differences are observed regarding the expressions of osteogenesis-regulating effectors, and presumably the prevalence/risk of CKD-associated VC exhibits gender-related differences as well. Despite the wealth of data focusing on gender-related differences in the risk of atherosclerosis, few report whether gender modifies the risk of VC, especially CKD-associated cases. We systematically identified studies of CKD-associated VC or its regulators/modifiers reporting data about gender distributions, and extracted results from 167 articles. A significantly higher risk of CKD-associated VC was observed in males among the majority of original investigations. However, substantial heterogeneity exists, since multiple large-scale studies yielded neutral findings. Differences in gender-related VC risk may result from variations in VC assessment methods, the anatomical segments of interest, study sample size, and even the ethnic origins of participants. From a biological perspective, plausible mediators of gender-related VC differences include body composition discrepancies, alterations involving lipid profiles, inflammatory severity, diversities in matrix Gla protein (MGP), soluble Klotho, vitamin D, sclerostin, parathyroid hormone (PTH), fibroblast growth factor-23 (FGF-23), and osteoprotegerin levels. Based on our findings, it may be inappropriate to monotonously assume that male patients with CKD are at risk of VC compared to females, and we should consider more background in context before result interpretation.

Bone microarchitecture in patients undergoing parathyroidectomy for management of secondary hyperparathyroidism

Background

Secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD) leads to complex bone disease, affecting both trabecular and cortical bone, and increased fracture risk. Optimal assessment of bone in patients with CKD is yet to be determined. High-resolution magnetic resonance imaging (MRI) can provide three-dimensional assessment of bone microarchitecture, as well as determination of mechanical strength with finite element analysis (FEA).

Methods

We conducted a single-centre, cross-sectional study to determine bone microarchitecture with MRI in CKD patients with SHPT undergoing parathyroidectomy. Within two weeks of surgery, MRI was performed at the distal tibia and biochemical markers of SHPT (parathyroid hormone [PTH] and alkaline phosphatase [ALP]) were collected. Trabecular and cortical topological parameters as well as bone mechanical competence using FEA were assessed. Correlation of MRI findings of bone was made with biochemical markers.

Results

Twenty patients with CKD (15 male, 5 female) underwent MRI at the time of parathyroidectomy (16 on dialysis, 3 with functioning kidney transplant, one pre-dialysis with CKD stage 5). Median PTH at the time of surgery was 138.5 pmol/L [39.6–186.7 pmol/L]. MRI parameters in patients were consistent with trabecular deterioration, with erosion index (EI) 1.01 ± 0.3, and trabecular bone volume (BV/TV) 10.8 ± 2.9%, as well as poor trabecular network integrity with surface-to-curve ratio (S/C) 5.4 ± 2.3. There was also evidence of reduced cortical thickness, with CTh 2.698 ± 0.630 mm, and FEA demonstrated overall poor bone mechanical strength with mean elastic modulus of 2.07 ± 0.44.

Conclusion

Patients with severe SHPT requiring parathyroidectomy have evidence of significant changes in bone microarchitecture with trabecular deterioration, low trabecular and cortical bone volume, and reduced mechanical competence of bone.

Relationship between serum osteoprotegerin and vascular calcifications in hemodialysis patients

BACKGROUND

Uremia is a vasculopathic process, and both cardiac calcification and vascular calcification seen from the early stages of chronic kidney disease. Osteoprotegerin could play a crucial role in atherosclerotic plaque formation, maturation and calcification. The goal of this study was to determine the relationship of serum osteoprotegerin with vascular calcification in patients with end stage kidney disease who were maintained on regular hemodialysis.

METHODS

Sixty clinically stable chronic renal failure patients undergoing regular hemodialysis were enrolled in this cross sectional study. Thirty patients (mean age 56.7 ± 10.5 years) with abdominal aortic calcification were selected by basal abdominal X-ray who underwent multi-slice computerized tomography scan to measure coronary artery calcification score; and thirty patients (mean age 56.5 ± 8.4 years) without abdominal aortic calcification. All patients were evaluated by serum calcium, phosphorus, albumin, lipid profile, intact parathyroid hormone (iPTH), serum creatinine, serum urea, serum uric acid, serum C-reactive protein, and hemoglobin. Serum osteoprotegerin samples were collected before dialysis and estimated by the ELISA kit.

RESULTS

Serum osteoprotegerin level was significantly higher in patients with vascular calcification than in those without calcifications. Serum osteoprotegerin correlated positively with serum phosphorus, calcium phosphorus product, alkaline phosphatase, iPTH, C-reactive protein, serum uric acid, low-density lipoprotein (LDL) and left ventricular mass index (LVMI) (p < 0.005), and negatively with hemoglobin, ejection fraction (p < 0.005) and HDL (p < 0.05).

CONCLUSIONS

These findings suggest that osteoprotegerin may be involved in the development of vascular calcification in hemodialysis patients.

Osteoprotegerin and uremic osteoporosis in chronic hemodialysis patients

INTRODUCTION

Osteoprotegerin (OPG) is a powerful inhibitor of osteoclast activity, and it plays an important role in bone metabolism. In hemodialysis (HD) patients, the relationship between OPG and bone mineral density (BMD) is important, but remains unclear yet. The study objective was to assess the OPG role related to uremic osteoporosis in HD patients.

METHODS

This cross-sectional study has been realized on a cohort of 63 chronic HD patients.

INCLUSION CRITERIA

elderly prevalent HD patients with an age over 55 years old.

EXCLUSION CRITERIA

previous bone disease or previous renal transplant; neoplasia; parathyroidectomy, hormone replacement therapy. The data regarding demographical and clinical characteristics, including treatments for mineral and cardiovascular complications, were recorded. Serum OPG and mineral markers levels were measured. BMD was assessed by calcaneus quantitative ultrasound; it measured broadband ultrasound attenuation, speed of sound (SOS) and stiffness index (STI).

RESULTS

The high OPG levels were associated with higher bone mineral density (OPG-SOS P = 0.003; R = 0.37; OPG-STI P = 0.03; R = 0.28). Malnutrition, anemia and advanced age correlated with bone demineralization. Males had higher bone density parameters than females. In patients treated with vitamin D (P = 0.005), the BMD was increased comparing to patients without these treatments.

CONCLUSIONS

OPG levels had directly correlated with bone mineral density parameters. Our study further confirms the critical role of OPG in the pathogenesis of uremic osteoporosis in ESRD. Whether the increased circulant OPG protect against bone loss in patients undergoing HD remains to be established.

Mineral and bone disorders, morbidity and mortality in end-stage renal failure patients on chronic dialysis

BACKGROUND AND AIM

In spite of numerous interventions, the control of mineral disturbances remains poor in end-stage renal failure (ESRF) patients. Chronic kidney disease - mineral and bone disorders (CKD-MBD) represent an important cause of mortality and morbidity. The aim of this study is to analyze the relationship between mineral and bone disorders (MBD) and their components impact on all-cause mortality and cardiovascular (CDV) mortality and morbidity in chronic dialysis patients.

METHODS

This prospective study was carried out in a cohort of 92 randomly selected patients with ESRF treated with hemodialysis (HD) and peritoneal dialysis (PD). The data regarding demographic and clinical characteristics were recorded, including vascular disease (coronary, cerebral, peripheral). The follow-up lasted 40 months and the final evaluation included the number and causes of deaths, CDV events and disease. Serum Ca, P, ALP, iPTH, albumin, cholesterol, urea and creatinine levels were measured. The plain radiographic films of hands and pelvis evaluated all bone abnormalities suggestive of renal osteodystrophy (ROD) and peripheral vascular calcification (VC).

RESULTS

All-cause annual mortality represented 9.25% in HD and 9.09% in PD patients. The CDV mortality represented almost 44% in HD patients and 66% in PD patients from all deaths. There was a high prevalence of CDV diseases and events. High and low serum P levels were associated with a worse survival rate. Hypercalcaemia was associated with high risk for CDV events in HD patients. In PD patients, the relationship between increased ALP levels and all-cause mortality was significant. Other mineral markers were not predictive of the outcome in the studied patients. In the HD patients the severity of VC was associated with all-cause and CDV mortality, and with CDV events. Male gender, hypercholesterolemia, decreased URR, albumin and creatinine were identified as risk factors for all-cause mortality. The diabetics had higher death rates. Low dialysis efficacy represented a risk factor for mortality and CDV diseases and events. In PD patients, low albumin induced a higher death rate. In PD patients the death rate was similar to HD patients.

CONCLUSION

All-cause mortality was higher than in general population, but lower than the chronic dialysis patients' mortality reported in other studies. The death rates in HD and PD patients were similar. VC and serum P levels influenced the outcome in the HD patients - increased the risk for all-cause and CDV mortality, but also for CDV events. ALP levels influenced outcome in PD patients. There were no significant differences between HD and PD patients regarding outcome.