Improvement of mineral and bone metabolism markers is associated with better survival in haemodialysis patients: the COSMOS study

Dietary nutrient intake and nutritional status in maintenance hemodialysis patients: a multicenter cross-sectional survey

PURPOSE

To investigate the dietary nutrient intake of Maintenance hemodialysis (MHD) patients, identify influencing factors, and explore the correlation between dietary nutrient intake and nutritional and disease control indicators.

METHODS

This was a multicenter cross-sectional study. A dietary survey was conducted using a three-day dietary record method, and a self-designed diet management software was utilized to calculate the daily intake of dietary nutrients. The nutritional status and disease control indicators were assessed using subjective global assessment, handgrip strength, blood test indexes, and dialysis adequacy.

RESULTS

A total of 382 MHD patients were included in this study. Among them, 225 (58.9%) and 233 (61.0%) patients' protein and energy intake did not meet the recommendations outlined in the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative Clinical Practice Guideline for Nutrition in Chronic Kidney Disease (2020 update). The average protein and energy intake for these patients were 0.99 ± 0.32 g/kg/d and 29.06 ± 7.79 kcal/kg/d, respectively. Multiple linear regression analysis showed that comorbidity-diabetes had a negative influence on normalized daily energy intake (nDEI = DEI / ideal body weight) (B = -2.880, p = 0.001) and normalized daily protein intake (nDPI = DPI / ideal body weight) (B = -0.109, p = 0.001). Pearson correlation analysis revealed that dietary DPI (r = -0.109, p < 0.05), DEI (r = -0.226, p < 0.05) and phosphorus (r = -0.195, p < 0.001) intake were statistically correlated to Kt/V; dietary nDPI (r = 0.101, p < 0.05) and sodium (r = -0.144, p < 0.001) intake were statistically correlated to serum urea nitrogen; dietary DPI (r = 0.200, p < 0.001), DEI (r = 0.241, p < 0.001), potassium (r = 0.129, p < 0.05), phosphorus (r = 0.199, p < 0.001), and fiber (r = 0.157, p < 0.001) intake were statistically correlated to serum creatinine; dietary phosphorus (r = 0.117, p < 0.05) and fiber (r = 0.142, p < 0.001) intake were statistically correlated to serum phosphorus; dietary nDPI (r = 0.125, p < 0.05), DPI (r = 0.135, p < 0.05), nDEI (r = 0.116, p < 0.05), DEI (r = 0.125, p < 0.05), potassium (r = 0.148, p < 0.001), and phosphorus (r = 0.156, p < 0.001) intake were statistically correlated to subjective global assessment scores; dietary nDPI (r = 0.215, p < 0.001), DPI (r = 0.341, p < 0.001), nDEI (r = 0.142, p < 0.05), DEI (r = 0.241, p < 0.001), potassium (r = 0.166, p < 0.05), phosphorus (r = 0.258, p < 0.001), and fiber (r = 0.252, p < 0.001) intake were statistically correlated to handgrip strength in males; dietary fiber (r = 0.190, p < 0.05) intake was statistically correlated to handgrip strength in females.

CONCLUSIONS

The dietary nutrient intake of MHD patients need improvement. Inadequate dietary nutrient intake among MHD patients could have a detrimental effect on their blood test indexes and overall nutritional status. It is crucial to address and optimize the dietary intake of nutrients in this patient population to enhance their health outcomes and well-being.

Education and cooking methods in the management of calcium and PTH serum levels in patients on hemodialysis: a randomized controlled study

BACKGROUND

Chronic kidney disease associated mineral bone disorder (CKD-MBD) is one of the major causes of excess morbidity and mortality in hemodialysis patients. The purpose of this study was to investigate whether education about dietary intakes and specific food processing methods affect serum calcium and PTH concentrations in hemodialysis patients.

METHODS

Forty-seven hemodialysis patients were randomly divided into a control and an intervention group. All participants were on individualized phosphate binder therapy. Both groups received education on dietary intake by a trained dietitian. The intervention group received additional education on specific preparation methods of different foodstuffs and consumed two hospital meals prepared according to these methods during hemodialysis. Serum calcium and PTH levels, and vitamin D analog therapy dosage were periodically monitored during the 1-year study period.

RESULTS

At the baseline of the study, there were no differences between control and intervention groups in serum calcium (p = 0.078), serum PTH (p = 0.670), and vitamin D analog therapy dosage (p = 0.184). At the end of the study, serum calcium was better regulated in the intervention group, resulting in a significant difference between the study groups (p = 0.013). This was also confirmed by serum PTH levels in the intervention group, which remained stable until the end of the study (p = 0.110).

DISCUSSION

Additional education on specific food processing techniques may result in improved management of serum calcium and PTH levels, which could ultimately provide better control of secondary hyperparathyroidism in hemodialysis patients.

Chest X-ray Findings and Prognostic Factors in Survival Analysis in Peritoneal Dialysis and Hemodialysis Patients: A Retrospective Cross-Sectional Study

Background and Objectives: This study aims to analyze survival in peritoneal and hemodialysis patients using chest radiography and biochemical parameters, determine common dialysis etiologies and causes of death, reveal prognostic factors, and contribute to clinical practice. Materials and Methods: A retrospective cross-sectional study was conducted with data from 33 peritoneal dialysis and 37 hemodialysis patients collected between October 2018 and February 2020. Survival and mortality were retrospectively tracked over 70 months (October 2018-June 2024). Chest X-ray measurements (cardiothoracic index, pulmonary vascular pedicle width, right pulmonary artery diameter, diaphragmatic height) and biochemical parameters (urea, albumin, creatinine, parathormone, ferritin, hemoglobin, arterial blood gas, potassium) were analyzed for their impact on survival. Statistical analyses included descriptive statistics, chi-square test, Fisher's exact test, Bayesian analysis, McNemar test, Kaplan-Meier survival analysis, Cox regression, Bayesian correlation test, linear regression analysis (scatter plot), and ROC analysis. SPSS 20.0 was used for data analysis, with p < 0.05 considered statistically significant. Results: Hypertension, type 2 diabetes, and urogenital disorders were the main dialysis etiologies. Peritonitis (38.5%) and cardiovascular diseases (47.4%) were the leading causes of death in peritoneal and hemodialysis patients, respectively. Significant chest X-ray differences included pulmonary vascular pedicle width and pulmonary artery diameter in hemodialysis and diaphragm height in peritoneal dialysis. Kaplan-Meier showed no survival difference between methods. Cox regression identified age, intact parathormone levels, iPTH/PVPW ratio, and clinical status as survival and mortality factors. The iPTH/PVPW ratio cut-off for mortality prediction was ≤6.8. Conclusions: Age, intact parathormone levels, pulmonary vascular pedicle width, and clinical status significantly impact survival in dialysis patients. Management of hypertension and diabetes, management and follow-up of urogenital disorders, infection control, patient education, and regular cardiovascular check-ups may improve survival rates. Additionally, the iPTH/PVPW ratio can predict mortality risk.

Assessment of the Correlation Between Serum Phosphate Level and Muscle Strength as Measured by Handgrip Strength in Patients Treated With Hemodialysis

Background

Sarcopenia, commonly observed in patients treated with hemodialysis, correlates with low serum phosphate levels. Although normophosphatemia is desired, dietary phosphate restriction is difficult to achieve and may result in undesirable protein restriction.

Objective

We aimed to evaluate whether hyperphosphatemia is associated with higher muscle strength in patients receiving hemodialysis treatment.

Design

A single-center prospective observational study.

Setting

Ambulatory prevalent patients undergoing hemodialysis treatments in a dialysis unit of a tertiary hospital.

Patients

Participants included prevalent patients treated with hemodialysis. All patients were above 18 years. Only patients with residual kidney function below 200 mL/24 hours were included to avoid bias.

Measurements

Muscle strength was measured by handgrip strength (HGS). Each patient repeated 3 measurements, and the highest value was recorded. Handgrip strength cutoffs for low muscle strength were defined as <27 kg in men and <16 kg in women. Biochemical parameters, including serum phosphate level, were driven from routine monthly blood tests. Hyperphosphatemia was defined as serum phosphate above 4.5 mg/dL.

Methods

Handgrip strength results were compared to nutritional, anthropometric, and biochemical parameters-in particular phosphate level. Long-term mortality was recorded.

Results

Seventy-four patients were included in the final analysis. Handgrip strength was abnormally low in 33 patients (44.5%). Patients with abnormal HGS were older and more likely to have diabetes mellitus and lower albumin and creatinine levels. There was no correlation between HGS and phosphate level (r = 0.008, P = .945). On multivariable analysis, predictors of higher HGS were body mass index and creatinine. Diabetes mellitus and female sex predicted lower HGS. Hyperphosphatemia correlated with protein catabolic rate, blood urea nitrogen, and creatinine. On multivariable analysis, predictors of hyperphosphatemia were higher creatinine level, normal albumin level, and heart failure. During mean follow-up time of 7.66 ± 3.9 months, 11 patients died. Mortality was significantly higher in patients with abnormally low HGS compared with normal HGS (odds ratio = 9.32, P = .02).

Limitations

A single-center study. All measurements were performed at one time point without repeated assessments. Direct dietary intake, degree of physical activity, and medication compliance were not assessed.

Conclusion

Hyperphosphatemia correlated with increased protein intake as assessed by protein catabolic rate in patients treated with hemodialysis; however, neither correlated with higher muscle strength as measured by HGS.Trial registration: MOH 202125213.

The effect of parathyroid hormone lowering by etelcalcetide therapy on calcification propensity and calciprotein particles in hemodialysis patients

Background

This study investigated whether parathyroid hormone (PTH) lowering with etelcalcetide, and the consequent effects on mineral and bone metabolism, could improve serum calcification propensity (T50 time) and decrease calciprotein particle (CPP) load in hemodialysis patients with secondary hyperparathyroidism.

Methods

In this single-arm, prospective, dose-escalation proof-of-principle study, hemodialysis patients received etelcalcetide at 2.5 mg/dialysis session with increments of 2.5 mg every 4 weeks to a maximum dose of 15 mg three times a week or until a pre-specified safety endpoint was reached, followed by an 8-week wash-out phase.

Results

Out of 36 patients recruited (81% male, 62 ± 13 years), 16 patients completed the study per protocol with a mean maximum tolerated dose of etelcalcetide of 9.5 ± 2.9 mg/dialysis session. With escalating doses of etelcalcetide, PTH and serum calcium levels significantly decreased (P < 0.0001). While there was no significant change in T50 times or serum phosphate levels, etelcalcetide did yield significant and consistent reductions in serum levels of endogenous calciprotein monomers [-35.4 (-44.4 to -26.5)%, P < 0.0001], primary [-22.4 (-34.5 to -10.3)%, P < 0.01] and secondary CPP [-29.1 (-45.7 to -12.4)%, P < 0.01], an effect that was reversed after therapy withdrawal. Serum levels of osteoclastic markers significantly decreased with escalating doses of etelcalcetide, while levels of the osteoblastic marker remained stable.

Conclusions

Lowering of PTH with etelcalcetide did not result in statistically significant changes in T50. By contrast, homogenous reductions in serum levels of calciprotein monomers, primary and secondary CPP were observed.

The Relationship of Fetuin-A with Coronary Calcification, Carotid Atherosclerosis, and Mortality Risk in Non-Dialysis Chronic Kidney Disease

Objective

This study investigated the relationship of fetuin-A with coronary calcification, carotid atherosclerosis, and mortality risk in non-dialysis chronic kidney disease (CKD).

Methods

The study included 135 adult patients with CKD at stages 3-5, who were divided into coronary artery calcification (CAC) and non-CAC groups. We excluded current smokers and individuals with diabetes mellitus, inflammatory conditions, liver diseases, acute kidney failure, chronic hemodialysis, and cancer. We conducted kidney function tests, complete blood counts, and measured serum levels of fetuin-A, tumor necrosis factor-alpha (TNF-α), high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), total cholesterol (TC), total triglycerides (TG), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Cardiac spiral computed tomography was used to calculate the CAC score, employing the Agatston method. Carotid ultrasonography was performed to assess carotid intima-media thickness (CIMT) and to detect the presence of plaques.

Results

CAC patients had considerably higher levels of TNF-α (p<0.001), IL-6 (p<0.001), hs-CRP (p=0.006), TC, TG, parathyroid hormone (PTH) (p<0.001) and phosphorus (p<0.001) than non-CAC patients. They also had significantly lower levels of fetuin-A (p<0.001). Fetuin-A was considerably lower in CKD subgroups as CKD progressed. Fetuin-A (p=0.046), age (p=0.009), TNF-α (p=0.027), IL-6 (p=0.005), TG (p=0.002), PTH (p=0.002), and phosphorus (p=0.004) were significant predictors of CAC. CAC and fetuin-A were strong predictors of all-cause mortality and cardiovascular (CV) mortality. Fetuin-A was a significant predictor of CIMT (p=0.045).

Conclusion

Fetuin-A reliably predicted CAC and CIMT. Fetuin-A and CAC emerged as significant risk factors for all-cause and CV mortality in non-dialysis CKD.

Effectiveness of calcimimetics on fractures in dialysis patients with secondary hyperparathyroidism: meta-analysis of randomized trials

INTRODUCTION

This study aimed to assess the effectiveness of calcimimetics in reducing the risk of fractures in dialysis patients with secondary hyperparathyroidism (SHPT).

MATERIAL AND METHODS

A comprehensive literature search was conducted using PubMed, Embase, and Cochrane Library for articles published through December 9, 2023. The quality of each trial was evaluated using the Cochrane Collaboration tool. Meta-analysis was performed using a random-effects model, and effect measures across studies were synthesized. The risk ratio (RR) and 95% confidence interval (CI) were used to quantify the risk of fracture.

RESULTS

We identified seven studies involving 6481 dialysis patients with SHPT. The administration of calcimimetics reduced fracture incidence compared to placebo or conventional treatment (RR: 0.50, 95% CI 0.29-0.88, p = 0.02). Calcimimetics demonstrated a low number needed to treat (NNT) to prevent an incident fracture (NNT: 47).

CONCLUSION

The use of calcimimetics offers a significant benefit in reducing the risk of fractures in patients undergoing dialysis with SHPT.

Alkaline Phosphatase and Parathyroid Hormone Levels: International Variation and Associations With Clinical Outcomes in the DOPPS

Introduction

Secondary hyperparathyroidism (SHPT) increases the risk of fractures and cardiovascular (CV) disease in patients on hemodialysis (HD). The relationship between parathyroid hormone (PTH) and outcomes has been inconsistent, possibly due to variable bone responsiveness to PTH. The KDIGO guideline suggests monitoring total alkaline phosphatase (ALP), but the role of ALP versus PTH in the management of mineral and bone disorder (MBD) is not clear.

Methods

The analysis included 28,888 patients on HD in 9 countries in Dialysis Outcomes and Practice Patterns Study (DOPPS) phase 3 to 7 (2005-2021). The primary exposures of interest were normalized ALP and PTH, which are raw values divided by facility upper normal limit, measured at study enrollment. Cox models were used to estimate hazard ratios of all-cause or CV mortality and any or hip fracture adjusted for potential confounders. Linear mixed models, adjusted for potential confounders, were employed to investigate the relationship between normalized ALP levels and patient characteristics.

Results

Normalized PTH showed a J-shaped association with all-cause or CV mortality, and a weak linear association with fracture. In contrast, normalized ALP showed a strong association with all outcomes. Factors associated with higher ALP levels after controlling for PTH included Black race, longer dialysis vintage, diabetes mellitus, hypocalcemia, hypophosphatemia, elevated C-reactive protein (CRP), and the use of cinacalcet.

Conclusion

Total ALP is a more robust exposure of adverse outcomes than PTH in patients on HD. PTH responsiveness is affected by race, primary renal disease, comorbidities, and mineral metabolism and therapy. Our results indicate that it may be useful to evaluate target organ response, rather than PTH alone when considering the consequences of (SHPT).

Longer serum phosphorus time in range associated with lower mortality risk among peritoneal dialysis patients: a multicenter retrospective cohort study

BACKGROUND

Relationship between serum phosphorus time in range and mortality risk in peritoneal dialysis (PD) patients remains uncertain. We aimed to evaluate the association between serum phosphorus time in range and all-cause mortality in Chinese PD population.

METHODS

This was a multicenter, retrospective, cohort study of 1,915 patients collected from January 2008 to October 2020 in 4 Chinese centers. Serum phosphorus time in range was estimated as the months during the first year that a patient's serum phosphorus level was within the target range (defined as 1.13-1.78 mmol/L). The primary outcome was all-cause mortality. The secondary outcomes were cardiovascular (CV) mortality and PD withdrawal. Cox proportional hazards regression model with comprehensive adjustments was used to assess the association.

RESULTS

The primary outcome occurred in 249 (13.0%) PD patients over a median follow-up of 28 months. Overall, the serum phosphorus time in range was negatively associated with all-cause mortality (per 3-month increments, adjusted HR [aHR], 0.83; 95%CI: 0.75-0.92), CV mortality (per 3-month increments, aHR, 0.87; 95%CI: 0.77-0.99), and PD withdrawal (per 3-month increments, aHR, 0.89; 95%CI: 0.83-0.95). Competing-risk model showed that the relationship of serum phosphorus time in range with all-cause mortality remained stable. None of the variables including demographics, history of diabetes and CV disease, as well as several PD-related and clinical indicators modified this association.

CONCLUSIONS

PD patients with longer serum phosphorus time in range in the first year was negatively associated with all-cause mortality and CV mortality. Our findings highlight the importance of maintaining serum phosphorus levels within 1.13-1.78 mmol/L for PD patients.

Serum phosphate is associated with increased risk of bone fragility fractures in haemodialysis patients

BACKGROUND

Bone fragility fractures are associated with high morbidity and mortality. This study analysed the association between the current biochemical parameters of chronic kidney disease-mineral and bone disorders (CKD-MBD) and bone fragility fractures in the COSMOS (Current management Of Secondary hyperparathyroidism: a Multicentre Observational Study) project.

METHODS

COSMOS is a 3-year, multicentre, open cohort, prospective, observational study carried out in 6797 haemodialysis patients (227 centres from 20 European countries). The association of bone fragility fractures (outcome) with serum calcium, phosphate and parathyroid hormone (PTH) (exposure), was assessed using standard Cox proportional hazards regression and Cox proportional hazards regression for recurrent events. Additional analyses were performed considering all-cause mortality as a competitive event for bone fragility fracture occurrence. Multivariable models were used in all strategies, with the fully adjusted model including a total of 24 variables.

RESULTS

During a median follow-up of 24 months, 252 (4%) patients experienced at least one bone fragility fracture (incident bone fragility fracture rate 28.5 per 1000 patient-years). In the fractured and non-fractured patients, the percentage of men was 43.7% and 61.4%, mean age 68.1 and 63.8 years and a haemodialysis vintage of 55.9 and 38.3 months, respectively. Baseline serum phosphate >6.1 mg/dL (reference value 4.3-6.1 mg/dL) was significantly associated with a higher bone fragility fracture risk in both regression models {hazard ratio (HR) 1.53 [95% confidence interval (CI) 1.10-2.13] and HR 1.44 (95% CI 1.02-2.05)}. The significant association persisted after competitive risk analysis [subHR 1.42 (95% CI 1.02-1.98)] but the finding was not confirmed when serum phosphate was considered as a continuous variable. Baseline serum calcium showed no association with bone fragility fracture risk in any regression model. Baseline serum PTH >800 pg/mL was significantly associated with a higher bone fragility fracture risk in both regression models, but the association disappeared after a competitive risk analysis.

CONCLUSIONS

Hyperphosphatemia was independently and consistently associated with an increased bone fracture risk, suggesting serum phosphate could be a novel risk factor for bone fractures in haemodialysis patients.

Hypocalcemia and cardiovascular mortality in cinacalcet users

BACKGROUND

Calcimimetics are widely used in hemodialysis patients and influence serum calcium levels. Although the Kidney Disease: Improving Global Outcomes guidelines argued that low calcium levels induced by calcimimetics may be harmless, large observational studies investigating the association between hypocalcemia and mortality are scarce. We investigated the association between serum calcium levels and cardiovascular mortality in calcimimetics users using the nationwide Japanese registry for dialysis patients.

METHODS

In this 9-year prospective cohort study, the baseline data were collected at the end of 2009. We enrolled patients on maintenance hemodialysis or hemodiafiltration. We employed three models (baseline, time-dependent and time-averaged) to conduct Cox proportional hazard regression analyses.

RESULTS

Cinacalcet was prescribed to 12.7% (N = 22 853) at baseline. The median observation period was 98 (interquartile range 40-108) months and 108 (interquartile range 59-108) months in the whole cohort (N = 180 136) and in cinacalcet users, respectively. Three-quarters of survivors at the end of 2019 had continued calcimimetic therapy for 10 years, corresponding to a mean annual dropout rate of 2.9%. Hypocalcemia was not associated with cardiovascular mortality in the baseline or time-averaged model. In the time-dependent model, however, the lowest calcium decile (corrected calcium <8.4 mg/dL) was significantly associated with higher cardiovascular mortality than the reference (corrected calcium 8.7-8.9 mg/dL) in both cinacalcet users and all patients [hazard ratio (95% confidence interval) 1.32 (1.00, 1.75) and 1.15 (1.05, 1.26), respectively]. Hypocalcemia was especially associated with sudden death and death due to hemorrhagic stroke, heart failure and ischemic heart disease. Higher rate of fatal and non-fatal cardiovascular events was observed in hypocalcemic patients regardless of cinacalcet usage.

CONCLUSIONS

Our findings suggest that transient hypocalcemia was associated with an increased risk of cardiovascular death independent of cinacalcet usage. We should pay attention to hypocalcemia transiently induced by cinacalcet.

Dietary knowledge-attitude-practice status in hemodialysis patients: a latent profile analysis

BACKGROUND

Hemodialysis patients require a reasonable dietary intake to manage their disease progression effectively. However, there is limited research on these patients' overall dietary knowledge, attitude, and practice (KAP) status. This study aimed to investigate the dietary KAP status and latent profiles in hemodialysis patients and identify sociodemographic and disease-related factors associated with these profiles and dietary practice.

METHODS

A multicenter cross-sectional study involving 425 hemodialysis patients was conducted. A dietary KAP questionnaire in hemodialysis patients was used to evaluate the dietary KAP of the patients. A structural equation model was employed to analyze the correlations between dietary knowledge, attitude, and practice. Multiple linear regression analysis was used to identify factors associated with dietary practice scores. Latent profile analysis was conducted to determine the latent profiles of dietary KAP, and binary logistic regression was used to explore the sociodemographic and disease-related characteristics associated with each KAP profile in hemodialysis patients.

RESULTS

The normalized average scores for dietary knowledge, attitude, and practice in hemodialysis patients were 0.58, 0.82, and 0.58, respectively. The structural equation model revealed significant positive correlations between dietary knowledge and attitude, and attitude and practice. Attitude played an indirect effect between knowledge and practice. Gender, cerebrovascular disease, and dietary attitude scores were identified as independent influencing factors for dietary practice scores. Two dietary KAP profiles were developed: a profile with general knowledge and attitude but low practice (40.2%) and a profile with general knowledge and attitude and high practice (59.8%). Binary logistic regression analysis indicated gender and monthly income per household significantly predicted membership in each KAP profile.

CONCLUSIONS

The dietary practice of hemodialysis patients requires improvement. It is necessary to develop more individualized dietary interventions for these patients. Further exploration is needed to understand the motivation of patients to change their dietary behavior.

Multi-trait Analysis of GWAS for circulating FGF23 Identifies Novel Network Interactions Between HRG-HMGB1 and Cardiac Disease in CKD

Background

Genome-wide association studies (GWAS) have identified numerous genetic loci associated with mineral metabolism (MM) markers but have exclusively focused on single-trait analysis. In this study, we performed a multi-trait analysis of GWAS (MTAG) of MM, exploring overlapping genetic architecture between traits, to identify novel genetic associations for fibroblast growth factor 23 (FGF23).

Methods

We applied MTAG to genetic variants common to GWAS of 5 genetically correlated MM markers (calcium, phosphorus, FGF23, 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH)) in European-ancestry subjects. We integrated information from UKBioBank GWAS for blood levels for phosphate, 25(OH)D and calcium (n=366,484), and CHARGE GWAS for PTH (n=29,155) and FGF23 (n=16,624). We then used functional genomics to model interactive and dynamic networks to identify novel associations between genetic traits and circulating FGF23.

Results

MTAG increased the effective sample size for all MM markers to n=50,325 for FGF23. After clumping, MTAG identified independent genome-wide significant SNPs for all traits, including 62 loci for FGF23. Many of these loci have not been previously reported in single-trait analyses. Through functional genomics we identified Histidine-rich glycoprotein (HRG) and high mobility group box 1(HMGB1) genes as master regulators of downstream canonical pathways associated with FGF23. HRG-HMGB1 network interactions were also highly enriched in left ventricular heart tissue of a cohort of deceased hemodialysis patients.

Conclusion

Our findings highlight the importance of MTAG analysis of MM markers to boost the number of genome-wide significant loci for FGF23 to identify novel genetic traits. Functional genomics revealed novel networks that inform unique cellular functions and identified HRG-HMGB1 as key master regulators of FGF23 and cardiovascular disease in CKD. Future studies will provide a deeper understanding of genetic signatures associated with FGF23 and its role in health and disease.

Recommended calcium intake in adults and children with chronic kidney disease-a European consensus statement

Mineral and bone disorders (MBD) are common in patients with chronic kidney disease (CKD), contributing to significant morbidity and mortality. For several decades, the first-line approach to controlling hyperparathyroidism in CKD was by exogenous calcium loading. Since the turn of the millennium, however, a growing awareness of vascular calcification risk has led to a paradigm shift in management and a move away from calcium-based phosphate binders. As a consequence, contemporary CKD patients may be at risk of a negative calcium balance, which, in turn, may compromise bone health, contributing to renal bone disease and increased fracture risk. A calcium intake below a certain threshold may be as problematic as a high intake, worsening the MBD syndrome of CKD, but is not addressed in current clinical practice guidelines. The CKD-MBD and European Renal Nutrition working groups of the European Renal Association (ERA), together with the CKD-MBD and Dialysis working groups of the European Society for Pediatric Nephrology (ESPN), developed key evidence points and clinical practice points on calcium management in children and adults with CKD across stages of disease. These were reviewed by a Delphi panel consisting of ERA and ESPN working groups members. The main clinical practice points include a suggested total calcium intake from diet and medications of 800-1000 mg/day and not exceeding 1500 mg/day to maintain a neutral calcium balance in adults with CKD. In children with CKD, total calcium intake should be kept within the age-appropriate normal range. These statements provide information and may assist in decision-making, but in the absence of high-level evidence must be carefully considered and adapted to individual patient needs.

Clinical Implication of Consistently Strict Phosphate Control for Coronary and Valvular Calcification in Incident Patients Undergoing Hemodialysis

AIMS

Serum phosphate control is crucial for the progression of vascular and valvular calcifications. Strict phosphate control is recently suggested; however, there is a lack of convincing evidence. Therefore, we explored the effects of strict phosphate control on vascular and valvular calcifications in incident patients undergoing hemodialysis.

METHODS

A total of 64 patients undergoing hemodialysis from our previous randomized controlled trial were included in this study. Coronary artery calcification score (CACS) and cardiac valvular calcification score (CVCS) were evaluated using computed tomography and ultrasound cardiography at baseline and 18 months after the initiation of hemodialysis. The absolute changes in CACS (ΔCACS) and CVCS (ΔCVCS) and the percent change in CACS (%ΔCACS) and CVCS (%ΔCVCS) were calculated. Serum phosphate level was measured at 6, 12, and 18 months after the initiation of hemodialysis. Moreover, phosphate control status was evaluated using the area under the curve (AUC) by the amount of time spent with a serum phosphate level of ≥ 4.5 mg/dL and the extent to which this threshold exceeded over the observation period.

RESULTS

ΔCACS, %ΔCACS, ΔCVCS, and %ΔCVCS were significantly lower in the low AUC group than in the high AUC group. ΔCACS and %ΔCACS were also significantly lower. ΔCVCS and %ΔCVCS tended to be lower in patients whose serum phosphate level never exceeded 4.5 mg/dL than in those whose serum phosphate level continuously exceeded 4.5 mg/dL. AUC significantly correlated with ΔCACS and ΔCVCS.

CONCLUSION

Consistently strict phosphate control may slow the progression of coronary and valvular calcifications in incident patients undergoing hemodialysis.

Changes in Bone Quality after Treatment with Etelcalcetide

INTRODUCTION

Secondary hyperparathyroidism is associated with osteoporosis and fractures. Etelcalcetide is an intravenous calcimimetic for the control of hyperparathyroidism in patients on hemodialysis. Effects of etelcalcetide on the skeleton are unknown.

METHODS

In a single-arm, open-label, 36-week prospective trial, we hypothesized that etelcalcetide improves bone quality and strength without damaging bone-tissue quality. Participants were 18 years or older, on hemodialysis ≥1 year, without calcimimetic exposure within 12 weeks of enrollment. We measured pretreatment and post-treatment areal bone mineral density by dual-energy X-ray absorptiometry, central skeleton trabecular microarchitecture by trabecular bone score, and peripheral skeleton volumetric bone density, geometry, microarchitecture, and estimated strength by high-resolution peripheral quantitative computed tomography. Bone-tissue quality was assessed using quadruple-label bone biopsy in a subset of patients. Paired t tests were used in our analysis.

RESULTS

Twenty-two participants were enrolled; 13 completed follow-up (mean±SD age 51±14 years, 53% male, and 15% White). Five underwent bone biopsy (mean±SD age 52±16 years and 80% female). Over 36 weeks, parathyroid hormone levels declined 67%±9% ( P < 0.001); areal bone mineral density at the spine, femoral neck, and total hip increased 3%±1%, 7%±2%, and 3%±1%, respectively ( P < 0.05); spine trabecular bone score increased 10%±2% ( P < 0.001); and radius stiffness and failure load trended to a 7%±4% ( P = 0.05) and 6%±4% increase ( P = 0.06), respectively. Bone biopsy demonstrated a decreased bone formation rate (mean difference -25±4 µ m 3 / µ m 2 per year; P < 0.01).

CONCLUSIONS

Treatment with etelcalcetide for 36 weeks was associated with improvements in central skeleton areal bone mineral density and trabecular quality and lowered bone turnover without affecting bone material properties.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

The Effect of Etelcalcetide on CKD-MBD (Parsabiv-MBD), NCT03960437.

Association between CKD-MBD and mortality in older patients with advanced CKD-results from the EQUAL study

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication of CKD; it is associated with higher mortality in dialysis patients, while its impact in non-dialysis patients remains mostly unknown. We investigated the associations between parathyroid hormone (PTH), phosphate and calcium (and their interactions), and all-cause, cardiovascular (CV) and non-CV mortality in older non-dialysis patients with advanced CKD.

METHODS

We used data from the European Quality study, which includes patients aged ≥65 years with estimated glomerular filtration rate ≤20 mL/min/1.73 m2 from six European countries. Sequentially adjusted Cox models were used to assess the association between baseline and time-dependent CKD-MBD biomarkers and all-cause, CV and non-CV mortality. Effect modification between biomarkers was also assessed.

RESULTS

In 1294 patients, the prevalence of CKD-MBD at baseline was 94%. Both PTH [adjusted hazard ratio (aHR) 1.12, 95% confidence interval (CI) 1.03-1.23, P = .01] and phosphate (aHR 1.35, 95% CI 1.00-1.84, P = .05), but not calcium (aHR 1.11, 95% CI 0.57-2.17, P = .76), were associated with all-cause mortality. Calcium was not independently associated with mortality, but modified the effect of phosphate, with the highest mortality risk found in patients with both hypercalcemia and hyperphosphatemia. PTH level was associated with CV mortality, but not with non-CV mortality, whereas phosphate was associated with both CV and non-CV mortality in most models.

CONCLUSIONS

CKD-MBD is very common in older non-dialysis patients with advanced CKD. PTH and phosphate are independently associated with all-cause mortality in this population. While PTH level is only associated with CV mortality, phosphate seems to be associated with both CV and non-CV mortality.

Mineral and bone metabolism markers and mortality in diabetic patients on haemodialysis

BACKGROUND

Diabetic patients on haemodialysis have a higher risk of mortality than non-diabetic patients. The aim of this COSMOS (Current management of secondary hyperparathyroidism: a multicentre observational study) analysis was to assess whether bone and mineral laboratory values [calcium, phosphorus and parathyroid hormone (PTH)] contribute to this risk.

METHODS

COSMOS is a multicentre, open-cohort, 3-year prospective study, which includes 6797 patients from 227 randomly selected dialysis centres in 20 European countries. The association between mortality and calcium, phosphate or PTH was assessed using Cox proportional hazard regression models using both penalized splines smoothing and categorization according to KDIGO guidelines. The effect modification of the association between the relative risk of mortality and serum calcium, phosphate or PTH by diabetes was assessed.

RESULTS

There was a statistically significant effect modification of the association between the relative risk of mortality and serum PTH by diabetes (P = .011). The slope of the curve of the association between increasing values of PTH and relative risk of mortality was steeper for diabetic compared with non-diabetic patients, mainly for high levels of PTH. In addition, high serum PTH (>9 times the normal values) was significantly associated with a higher relative risk of mortality in diabetic patients but not in non-diabetic patients [1.53 (95% confidence interval 1.07-2.19) and 1.17 (95% confidence interval 0.91-1.52)]. No significant effect modification of the association between the relative risk of mortality and serum calcium or phosphate by diabetes was found (P = .2 and P = .059, respectively).

CONCLUSION

The results show a different association of PTH with the relative risk of mortality in diabetic and non-diabetic patients. These findings could have relevant implications for the diagnosis and treatment of chronic kidney disease-mineral and bone disorders.

Intact FGF23 predicts serum phosphate improvement after combined nicotinamide and phosphate binder treatment in hemodialysis patients

Background

Hyperphosphatemia is associated with increased mortality and cardiovascular morbidity of end-stage kidney failure (ESKF) patients. Managing serum phosphate in ESKF patients is challenging and mostly based on limiting intestinal phosphate absorption with low phosphate diets and phosphate binders (PB). In a multi-centric, double-blinded, placebo-controlled study cohort of maintenance hemodialysis patients with hyperphosphatemia, we demonstrated the efficacy of nicotinamide modified release (NAMR) formulation treatment in addition to standard PB therapy in decreasing serum phosphate. Here we aimed to assess the relationship between phosphate, FGF23, inflammation and iron metabolism in this cohort.

Methods

We measured the plasma concentrations of intact fibroblast growth factor 23 (iFGF23) and selected proinflammatory cytokines at baseline and Week 12 after initiating treatment.

Results

We observed a strong correlation between iFGF23 and cFGF23 (C-terminal fragment plus iFGF23). We identified iFGF23 as a better predictor of changes in serum phosphate induced by NAMR and PB treatment compared with cFGF23. Recursive partitioning revealed at baseline and Week 12, that iFGF23 and cFGF23 together with T50 propensity were the most important predictors of serum phosphate, whereas intact parathyroid hormone (iPTH) played a minor role in this model. Furthermore, we found serum phosphate and iPTH as the best predictors of iFGF23 and cFGF23. Sex, age, body mass index, and markers of inflammation and iron metabolism had only a minor impact in predicting FGF23.

Conclusion

Lowering serum phosphate in ESKF patients may depend highly on iFGF23 which is correlated to cFGF23 levels. Serum phosphate was the most important predictor of plasma FGF23 in this ESKF cohort.

Role of Chronic Kidney Disease (CKD)-Mineral and Bone Disorder (MBD) in the Pathogenesis of Cardiovascular Disease in CKD

Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD). Multiple factors account for the increased incidence of cardiovascular morbidity and mortality in patients with CKD. Traditional risk factors for atherosclerosis and arteriosclerosis, including age, hypertension, dyslipidemia, diabetes mellitus, and smoking, are also risk factors for CKD. Non-traditional risk factors specific for CKD are also involved in CVD pathogenesis in patients with CKD. Recently, CKD-mineral and bone disorder (CKD-MBD) has emerged as a key player in CVD pathogenesis in the context of CKD. CKD-MBD manifests as hypocalcemia and hyperphosphatemia in the later stages of CKD; however, it initially develops much earlier in disease course. The initial step in CKD-MBD involves decreased phosphate excretion in the urine, followed by increased circulating concentrations of fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH), which increase urinary phosphate excretion. Simultaneously, the serum calcitriol concentration decreases as a result of FGF23 elevation. Importantly, FGF23 and PTH cause left ventricular hypertrophy, arrhythmia, and cardiovascular calcification. More recently, calciprotein particles, which are nanoparticles composed of calcium, phosphate, and fetuin-A, among other components, have been reported to cause inflammation, cardiovascular calcification, and other clinically relevant outcomes. CKD-MBD has become one of the critical therapeutic targets for the prevention of cardiovascular events and is another link between cardiology and nephrology. In this review, we describe the role of CKD-MBD in the pathogenesis of cardiovascular disorders and present the current treatment strategies for CKD-MBD.

Improved β2-Microglobulin and Phosphorous Removal with Expanded Hemodialysis and Online Hemodiafiltration versus High-Flux Hemodialysis: A Cross-Over Randomized Clinical Trial

INTRODUCTION

Expanded hemodialysis (HDx) is expected to provide enhanced permeability of medium-sized molecules, selective solute retention, and better internal retrofiltration. The primary objective of this study was to compare the efficiency for removal of β2-microglobulin with 3 different extracorporeal therapies (ETs): high-flux hemodialysis (HF), online hemodiafiltration (OL-HDF), and HDx. The secondary objective was to evaluate the efficiency of removal of other uremic toxins, including urea, phosphate, CRP, IL-6, IL-10, TNF-⍺, indoxyl sulfate, and p-cresol.

METHODS

This single-center, randomized, and cross-over study was performed. Patients were randomized to determine the initial modality of treatment, each period lasted 4 weeks and between one modality and another, there was a washout period of 1 week. Reduction ratios (RRs) of different-size molecules and albumin were calculated for the different ET.

RESULTS

Twenty-two patients were included, β2-microglobulin RR was greater during both OL-HDF and HDx as compared to HF (RR 62% vs. 73% vs. 27%, respectively, p = <0.0001), and there was no significant difference between HDx and OL-HDF (p = 0.09). A decrease in serum phosphate levels was observed in the HDx and OL-HDF periods, contrary to an increase in HF (-0.79 mg/dL vs. -1.02 mg/dL vs. + 0.11 mg/dL, respectively, p = <0.0001). There was no difference in RRs of other molecules (BUN, CRP, IL-6, IL-10, TNF-⍺, indoxyl sulfate, and p-Cresol). There was no decrease in serum albumin in any ET.

CONCLUSION

HDx provides enhanced removal of β2-microglobulin and phosphate as compared to HF, and similar efficacy as with OL-HDF. HDx should be considered an alternative to chronic convective therapies.

Sodium Thiosulfate for Calciphylaxis Treatment in Patients on Peritoneal Dialysis: A Systematic Review

Limited data are available on the utilization of sodium thiosulfate (STS) treatment for calciphylaxis in peritoneal dialysis (PD) patients, while it is well-studied in hemodialysis (HD) patients. A systematic literature search was conducted using Ovid MEDLINE, EBM Reviews-Cochrane Central Register of Controlled Trials, and EBM Reviews-Cochrane Database of Systematic Reviews to identify reported cases of PD patients with calciphylaxis who received STS. The search covered the inception of the databases through August 2022. Across 19 articles, this review identified 30 PD patients with calciphylaxis who received STS. These included 15 case reports, 2 case series, and 2 cohort studies. The administration routes and doses varied depending on the study. For intravenous (IV) administration (n = 18), STS doses ranged from 3.2 g twice daily to 25 g three times weekly for 5 weeks to 8 months. Outcomes included 44% of patients experiencing successful wound healing, 6% discontinuing STS due to adverse effects, 67% transitioning to HD, and 50% dying from calciphylaxis complications. For intraperitoneal (IP) administration (n = 5), STS doses ranged from 12.5 to 25 g three to four times weekly for 12 h to 3 months. Results showed 80% of patients achieving successful wound healing, 80% discontinuing STS due to adverse effects, 40% transitioning to HD, and 20% dying from IP STS-related chemical peritonitis. In cases where patients switched from IV to IP STS (n = 3), doses ranged from 12.5 to 25 g two to three times weekly for 2.5 to 5 months. Among them, 67% experienced successful wound healing, while 33% died from sepsis. Two cases utilized oral STS at a dose of 1500 mg twice daily for 6 and 11 months, resulting in successful wound healing without adverse effects or need for HD. However, one patient (50%) died due to small bowel obstruction. This systematic review provides an overview of STS treatment for PD patients with calciphylaxis. Although successful treatment cases exist, adverse effects were significant. Further research, including larger clinical studies and pharmacokinetic data, is necessary to establish the optimal route, dose, and efficacy of STS in PD patients.

Effect of dialytic phosphate reduction rate on mortality in maintenance hemodialysis patients: a matched case-control study

BACKGROUND

Phosphates, similar to urea, are small molecular substances that can be cleared during dialysis. Dialytic phosphate reduction rate (PRR) may, to some extent, be related to the relative amount of phosphates cleared during dialysis. However, few studies have evaluated the associations between PRR and mortality in maintenance hemodialysis (MHD) patients. In this study, we investigated the association between PRR and clinical outcomes in MHD patients.

METHODS

This was a retrospective, matched case-control study. Data were collected from the Beijing Hemodialysis Quality Control and Improvement Center. Patients were divided into four groups according to PRR quartile. Age, sex, and diabetes were matched between the groups. The primary outcome was all-cause death, and the secondary outcome was cardiocerebrovascular death.

RESULTS

The study cohort comprised 4063 patients who were divided into four groups according to the PRR quartile: group PRR₁ (< 48.35%), group PRR₂ (48.35% - 54.14%), group PRR₃ (54.14% - 59.14%), and group PRR₄ (≥ 59.14%). We enrolled 2172 patients (543 in each study group) by case-control matching. The all-cause death rates were as follows: group PRR₁: 22.5% (122/543), group PRR₂: 20.1% (109/543), group PRR₃: 19.3% (105/543), and group PRR₄: 19.3% (105/543). No significant differences in all-cause and cardiocerebrovascular death rates according to the Kaplan-Meier survival curves were found between the groups (log-rank test, P > 0.05). Multivariable Cox regression analysis revealed no significant differences in all-cause and cardiocerebrovascular death rates between the four groups (P = 0.461; adjusted hazard ratio, 0.99; 95% confidence interval, 0.97 - 1.02 versus P = 0.068; adjusted hazard ratio, 0.99; 95% confidence interval, 0.97 - 1.00, respectively).

CONCLUSIONS

Dialytic PRR was not significantly associated with all-cause death and cardiocerebrovascular death in MHD patients.

Recommendations of the Spanish Society of Nephrology for the management of mineral and bone metabolism disorders in patients with chronic kidney disease: 2021 (SEN-MM)

As in 2011, when the Spanish Society of Nephrology (SEN) published the Spanish adaptation to the Kidney Disease: Improving Global Outcomes (KDIGO) universal Guideline on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), this document contains an update and an adaptation of the 2017 KDIGO guidelines to our setting. In this field, as in many other areas of nephrology, it has been impossible to irrefutably answer many questions, which remain pending. However, there is no doubt that the close relationship between the CKD-MBD/cardiovascular disease/morbidity and mortality complex and new randomised clinical trials in some areas and the development of new drugs have yielded significant advances in this field and created the need for this update. We would therefore highlight the slight divergences that we propose in the ideal objectives for biochemical abnormalities in the CKD-MBD complex compared to the KDIGO suggestions (for example, in relation to parathyroid hormone or phosphate), the role of native vitamin D and analogues in the control of secondary hyperparathyroidism and the contribution of new phosphate binders and calcimimetics. Attention should also be drawn to the adoption of important new developments in the diagnosis of bone abnormalities in patients with kidney disease and to the need to be more proactive in treating them. In any event, the current speed at which innovations are taking place, while perhaps slower than we might like, globally drives the need for more frequent updates (for example, through Nefrología al día).

The 'Phosphorus Week': involvement of Spanish nephrologists in the control of phosphorus blood levels

BACKGROUND

The adequate control of phosphorus levels is a major concern for professionals involved in the care of patients with chronic kidney disease (CKD), since high phosphorus levels are directly related to an increase in mortality.

OBJECTIVES

To know the perception and involvement of Spanish nephrologists on the control of phosphorus levels, the so-called 'Phosphorus Week' was organized (November 13-17, 2017).

METHODS

All members of the Spanish Society of Nephrology were invited to participate in an online survey, which included questions on aspects related to phosphorus control in patients with advanced CKD (aCKD) (glomerular filtration rate <30 ml/min/1, 73 m2) and in the different modalities of renal replacement therapies [peritoneal dialysis (PD), hemodialysis (HD) and renal transplantation (KT)].

RESULTS

72 data entries were obtained in the survey with an inclusion of 7463 patients. Of them, 35.4% were on HD, 34.8% were KT, 24.2% had aCKD and 5.5% were on PD. The serum phosphorus level target for the four groups of patients was 4.5 mg/dl, with minimal variations depending on the area of ​​the national territory. The patients with better control of phosphataemia were patients with KT (93.3% had phosphorus values ​​<4.5 mg/dl), followed by patients with aCKD (65.6% with phosphorus <4.5 mg/dl). Only 53.6% of the patients on HD and 39.4% of those on PD reached the phosphorus goal <4.5 mg/dl. The group of patients on dialysis was the one in whom phosphorus binders prescribed the most (73.5% and 75.6% in HD and PD, respectively), being less frequent in patients with patients with aCKD (39.9%) and only 4.5 % in KT.

CONCLUSIONS

The objectives of the Spanish nephrologists are in line with those recommended by the national and international clinical guidelines; however, there is still a wide room for improvement to achieve these goals, especially in HD and PD patients.

Investigation on maintenance hemodialysis patients with mineral and bone disorder in Anhui province, China

BACKGROUND

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a common comorbidity in patients with CKD. The study aims to describe the control rates of serum-corrected calcium (Ca), phosphate (P) and intact parathyroid hormone (iPTH) and its risk factors among maintenance hemodialysis (MHD) patients in Anhui Province of China.

METHODS

The study was conducted in 27 hemodialysis centers of Anhui Province between January 1st 2020 and December 31th 2020. Chi-square test was used to compare the control rates of serum-corrected Ca, P and iPTH between the present study and DOPPS 4 or Anhui Province in 2014. Binary logistic regression analysis was used to explore the risk factors of the control rates of serum-corrected Ca, P and iPTH.

RESULTS

A total of 3 025 MHD patients were recruited in this study, with a mean age of 54.8 (SD: 12.8) years, and 60.1% were males. According to the Chinese Diagnosis and Treatment Guidelines for CKD-MBD, the control rates of serum-corrected Ca, P and iPTH in the present study were 57.9%, 20.0% and 56.0%, respectively. Based on KDOQI guidelines (2003), the control rates of the above indicators were 43.1%, 35.3% and 22.3%, respectively. The control rates of serum-corrected Ca, P and iPTH in this study were lower than those of DOPPS 4 (P < 0.001). Compared to the results of Anhui Province in 2014, the control rate of corrected Ca was higher (P < 0.001) and the control rate of iPTH was lower (P = 0.005). Age, residential area, BMI, dialysis vintage, albumin and hemoglobin levels were factors of serum-corrected Ca, P and iPTH not within target range.

CONCLUSION

The control rates of serum-corrected Ca, P and iPTH in MHD patients in Anhui Province are relatively low. Monitoring and management should be strengthened to improve the prognosis of patients undergoing dialysis.

Target phosphate and calcium levels in patients undergoing hemodialysis: a post-hoc analysis of the LANDMARK study

BACKGROUND

It is necessary to re-examine the optimal phosphate (P) and calcium (Ca) target values in the contemporary management of chronic kidney disease-mineral and bone disorder to reduce the risks of cardiovascular events in patients receiving hemodialysis.

METHODS

We performed a post-hoc analysis of the LANDMARK study. The outcomes were defined as cardiovascular events and all-cause death. Data from 2135 patients receiving hemodialysis at risk of vascular calcification were analyzed using a time-dependent Cox proportional hazard model adjusted for background factors.

RESULTS

On the hazard ratio (HR) curve, the ranges where the lower 95% confidence interval (CI) were below the minimum of HR (= 1.00) were as follows: P = 3.5-5.5 mg/dL; albumin-adjusted Ca < 9.1 mg/dL for cardiovascular events; and P = 3.6-5.3 mg/dL; albumin-adjusted Ca < 9.1 mg/dL for all-cause mortality. In stratified analysis, the HRs for cardiovascular events in P < 3.5 mg/dL and P ≥ 5.5 mg/dL were similar to that of P = 3.5-5.5 mg/dL (P ≥ 0.05), and albumin-adjusted Ca ≥ 9.1 mg/dL had higher HR than values < 9.1 mg/dL [1.30 (95% CI 1.00-1.68; P = 0.046)]. For all-cause mortality, the HR in P < 3.6 mg/dL was higher than that in P = 3.6-5.3 mg/dL [1.76 (95% CI 1.25-2.48; P = 0.001)], while the HRs between P ≥ 5.3 mg/dL and P = 3.6-5.3 mg/dL as well as those between albumin-adjusted Ca ≥ 9.1 and < 9.1 mg/dL were not significantly different (P ≥ 0.05).

CONCLUSIONS

Managing albumin-adjusted Ca < 9.1 mg/dL may reduce the cardiovascular risk among patients undergoing hemodialysis. Hypophosphatemia < 3.6 mg/dL may be associated with mortality.

Mineral and bone disorder and longterm survival in a chronic kidney disease grade 3b-4cohort

Mineral and bone disorder biomarkers 'normal ranges' are controversial. The aim of the study was to evaluate the association between serum calcium (Ca), phosphate (P), intact parathyroid hormone (iPTH), and 25(OH) vitamin D levels and mortality risk, in a chronic kidney disease (CKD) grade (G) 3b-4 cohort. The Uruguayan National Renal Healthcare Program (NRHP-UY) CKD patients' cohort, included between 1 October 2004 and 1 March 2020 and followed-up until 1 March 2021, was analyzed with the Ethics Committee approval. A total of 6473 patients were analyzed: 56% men, median age 73 (65-79) years, 55% on CKD G3b. At the end of the follow-up, 2459 (37.7%) patients had died (6.4/100 patient-year). There were iPTH data on 2013 patients (younger, with lower estimated glomerular filtration rate (eGFR) and lesser comorbidities). By bivariate Cox analysis the lowest death risk was observed with mean Ca between 9.01 and 10.25 mg/dl, P between 2.76 and 4.0 mg/dl, iPTH ≤ 105 pg/ml, and 25(OH) vitamin D >10 ng/ml. The multivariate Cox regression mortality risk adjusted to age, sex, CKD etiology, diabetes, smoking, cardiovascular comorbidity, blood pressure, proteinuria, eGFR, renin-angiotensin system blockers and vitamin D treatments, serum Ca, P, iPTH, and 25(OH) vitamin D (n = 964) showed that a higher mortality risk was associated with p > 4.00 mg/dl (HR 1.668, CI 95%: 1.201-2.317), iPTH >105 pg/ml (HR 1.386, CI 95%: 1.012-1.989), and 25(OH) vitamin D ≤ 10 ng/ml (HR 1.958, CI 95%: 1.238-3.098) and a lower mortality risk with 1,25(OH)2 vitamin D treatment (HR 0.639, CI 95%: 0.451-0.906). These data may contribute to the precise G3b-4 CKD-MBD biomarkers levels definition.

Nutrition and quality of life in chronic kidney disease patients: a practical approach for salt restriction

The clinical practice guidelines (CPGs) for nutrition in chronic kidney disease (CKD) were updated after 20 years from the previous guidelines by the Kidney Disease Outcomes Quality Initiative (KDOQI). During this period, the severity of CKD was defined by eGFR and albuminuria by the organization Kidney Disease: Improving Global Outcomes (KDIGO). Main risk factors for CKD such as hypertension, hyperlipidemia, obesity, metabolic syndrome, and diabetes mellitus are closely related to lifestyle. Nutritional management is important to prevent and retard the progression of CKD. Members of the International Society of Renal Nutrition and Metabolism (ISRNM) reviewed the KDOQI CPG draft. ISRNM is an international scientific society comprising members of multiple subspecialties. ISRNM proposed the medical term protein-energy wasting (PEW), which is a keyword in renal nutrition. The prevalence of PEW among dialysis patients is high. The success of dietary therapy depends on adherence to the diet. It has to be palatable, otherwise eating habits will not change. To prevent the development and progression of CKD and PEW, regular consultation with an expert dietitian is required, especially regarding salt and protein restriction. Our cluster-randomized trial showed that intervention by a dietician was effective at retarding the progression of stage 3 CKD. In this review, I focus on salt (sodium) restriction and introduce tips for salt restriction and Japanese kidney-friendly recipes. Due to the lack of randomized controlled trials, nutritional management of CKD inevitably relies on expert opinion. In this regard, well-designed observational studies are needed. Too strict salt restriction may decrease quality of life and result in PEW.

Safety and effectiveness of sucroferric oxyhydroxide in Spanish patients on dialysis: sub-analysis of the VERIFIE study

BACKGROUND AND AIMS

In this study, we show the results of the subset of Spanish patients of the VERIFIE study, the first post-marketing study assessing the long-term safety and effectiveness of sucroferric oxyhydroxide (SFOH) in patients with hyperphosphatemia undergoing dialysis during clinical practice.

PATIENTS AND METHODS

Patients undergoing hemodialysis and peritoneal dialysis with indication of SFOH treatment were included. Follow-up duration was 12-36 months after SFOH initiation. Primary safety variables were the incidence of adverse drug reactions (ADRs), medical events of special interest (MESIs), and variations in iron-related parameters. SFOH effectiveness was evaluated by the change in serum phosphorus levels.

RESULTS

A total of 286 patients were recruited and data from 282 were analyzed. Among those 282 patients, 161 (57.1%) withdrew the study prematurely and 52.5% received concomitant treatment with other phosphate binders. ADRs were observed in 35.1% of patients, the most common of which were gastrointestinal disorders (77.1%) and mild/moderate in severity (83.7%). MESIs were reported in 14.2% of patients, and 93.7% were mild/moderate. An increase in ferritin (386.66ng/mL vs 447.55ng/mL; p=0.0013) and transferrin saturation (28.07% vs 30.34%; p=0.043) was observed from baseline to the last visit (p=0.0013). Serum phosphorus levels progressively decreased from 5.69mg/dL at baseline to 4.84mg/dL at the last visit (p<0.0001), increasing by 32.2% the proportion of patients who achieved serum phosphorus levels ≤5.5mg/dL, with a mean daily SFOH dose of 1.98 pills/day.

CONCLUSIONS

SFOH showed a favorable effectiveness profile, a similar safety profile to that observed in the international study with most adverse events of mild/moderate severity, and a low daily pill burden in Spanish patients in dialysis.

Phosphate Frustration: Treatment Options to Complement Current Therapies

Hyperphosphatemia eventually develops in almost all patients with advanced chronic kidney disease and is associated with negative clinical outcomes. Thus, guidelines recommend targeting treatment to normal phosphate levels in patients with chronic kidney disease. Despite low phosphorus diets, clearance by dialysis, and phosphate binder use, many patients with chronic kidney disease on dialysis are unable to consistently achieve and maintain serum phosphate concentrations <5.5 mg/dL. A chart audit of patients on dialysis receiving phosphate binders showed that 74 to 86% were unable to consistently achieve serum phosphate ≤5.5 mg/dL over 6 months. Furthermore, although there is evidence that serum phosphate concentrations <4.5 mg/dL are associated with improved survival and cardiovascular outcomes, real-world phosphate control data suggest achieving and maintaining this goal for most patients would be extremely challenging, if not near impossible, using current therapies. As phosphate binders can only remove approximately 300 mg of the 2,500 mg or more daily dietary phosphate intake, therapeutic innovations are necessary to improve phosphate management. We present treatment options to complement current therapies including tenapanor, a novel sodium/hydrogen exchanger isoform 3 inhibitor that blocks the dominant paracellular phosphate absorption pathway and has been shown to reduce phosphate levels in several clinical trials.

Associations of time-dependent changes in phosphorus levels with cardiovascular diseases in patients undergoing hemodialysis: Results from the Japan Dialysis Active Vitamin D (J-DAVID) randomized clinical trial

Background

While the risk of exceeding the standard range of phosphorus levels has been investigated, the impact of the degree of fluctuations has not been investigated.

Methods

Data were derived from the Japan Dialysis Active Vitamin D trial, a 4-year prospective, randomized study involving 976 patients without secondary hyperparathyroidism undergoing hemodialysis in Japan. Laboratory data were collected every six months, and the primary outcome was the time to the occurrence of cardiovascular events. The effect of time-dependent changes in phosphorus levels was assessed using a time-varying Cox proportional hazard regression model.

Results

The median serum phosphorus levels at baseline and at the final observation were 4.70 [3.90–5.30] and 5.00 [4.20–5.80] mg/dL, respectively. Over each six-month period, phosphorus changes ranged from -7.1 to +6.7 mg/dL, with a median value of -0.1 to +0.3 mg/dL. During follow-up, composite cardiovascular events occurred in 103 of 964 patients. Although the p-value for the interaction between serum phosphorus level fluctuations and baseline phosphorus levels was insignificant, the following trends were observed. First, patients with relatively high initial phosphorus levels over a six-month period showed a trend towards a higher hazard with greater changes in the phosphorus level over the six-month period. Second, it was suggested that oral VDRAs could contribute to the relationship between fluctuating phosphorus levels and cardiovascular events.

Conclusions

Our results suggest the importance of maintaining stable phosphorus levels, not only in the normal range but also without fluctuations in the risk of cardiovascular events, among patients without secondary hyperparathyroidism undergoing maintenance hemodialysis.

Vitamin D and Secondary Hyperparathyroidism in Chronic Kidney Disease: A Critical Appraisal of the Past, Present, and the Future

The association between vitamin D deficiency and especially critical shortage of active vitamin D (1,25-dihydroxyvitamin D, calcitriol) with the development of secondary hyperparathyroidism (sHPT) is a well-known fact in patients with chronic kidney disease (CKD). The association between sHPT and important clinical outcomes, such as kidney disease progression, fractures, cardiovascular events, and mortality, has turned the prevention and the control of HPT into a core issue of patients with CKD and on dialysis. However, vitamin D therapy entails the risk of unwanted side effects, such as hypercalcemia and hyperphosphatemia. This review summarizes the developments of vitamin D therapies in CKD patients of the last decades, from calcitriol substitution to extended-release calcifediol. In view of the study situation for vitamin D insufficiency and sHPT in CKD patients, we conclude that the nephrology community has to solve three core issues: (1) What is the optimal parathyroid hormone (PTH) target level for CKD and dialysis patients? (2) What is the optimal vitamin D level to support optimal PTH titration? (3) How can sHPT treatment support reduction in the occurrence of hard renal and cardiovascular events in CKD and dialysis patients?

Modified-release nicotinamide for the treatment of hyperphosphataemia in haemodialysis patients: 52-week efficacy and safety results of the phase III randomised controlled NOPHOS trial

BACKGROUND

We previously reported that modified-release nicotinamide (NAMR) was superior to placebo in reducing serum phosphate concentrations over 12 weeks in a large cohort of haemodialysis patients with hyperphosphataemia. Here, we report outcomes after 52 weeks of treatment.

METHODS

NOPHOS was a phase III, international, randomised, controlled, double-blind trial in parallel group design. NAMR (250-1500 mg/d) was investigated in comparison to placebo as an add-on therapy to an individual therapy with approved phosphate binders.

RESULTS

In the intention-to-treat population (NAMR: N = 539, placebo: N = 183), serum phosphate was significantly lower in the NAMR group compared to the placebo group at W24 (5.40 ± 1.55 mg/dl vs. 5.79 ± 1.37 mg/dl,  P < 0.001) with a mean difference of -0.39 mg/dl [95% CI -0.66, -0.13], but was comparable between the groups at W52 (mean difference -0.08 [95% CI -0.36, 0.20]). In the completer population (N = 358), statistical significance in favour of NAMR was reached at W24 and W52. The treatment effect was reduced in patients with high baseline serum intact parathyroid hormone (iPTH) compared to patients with low baseline serum iPTH. Compliant patients in the NAMR group had a more pronounced and sustained reduction in serum phosphate than non-compliant patients. NAMR treatment was associated with a significantly increased risk of thrombocytopenia, pruritus, anaemia, and diarrhoea. Herpes zoster occurred exclusively in patients randomised to NAMR.

CONCLUSIONS

NAMR combined with phosphate binders significantly reduced serum phosphate over the first 24 weeks of treatment, but the treatment effect was not maintained up to W52. Non-compliance may have contributed to reduced long-term efficacy. Several newly identified safety signals warrant further evaluation.

A retrospective observational study of patients on maintenance hemodialysis receiving parathyroidectomy by ultrasonic scalpel

Background

Secondary hyperparathyroidism (SHPT) remains a common complication in many patients on maintenance hemodialysis. Kidney Disease Improve Global Outcomes (KDIGO) 2017 guidelines suggest that parathyroidectomy (PTX) should be performed in severe SHPT patients with chronic kidney disease stage 3a-stage 5D. In the present study, we observed the efficacy of ultrasonic scalpel for PTX in SHPT patients on maintenance hemodialysis.

Methods

A total of 74 patients on maintenance hemodialysis who underwent PTX (34 with traditional electrocautery and 40 with an ultrasonic scalpel) were observed between August 2020 and August 2021 at Xiangyang Central Hospital (Hubei University of Arts and Science). Baseline demographic and clinic characteristics were collected pre- and post-PTX. Moreover, the postoperative complications and operation time were assessed between the two groups.

Results

The univariate analysis showed that there was no statistical significance in weight, dialysis duration, serum potassium, serum calcium, serum magnesium, alkaline phosphate, triglyceride, and intact parathyroid hormone (iPTH) before and after PTX between the two groups (P > 0.05). The operation time in the ultrasonic scalpel group was significantly decreased compared with the traditional electrocautery group (P < 0.05). Compared with the traditional electrocautery group, the drainage amount was significantly reduced in the ultrasonic scalpel group, and the number of days with drain and postoperative hospital stay were also remarkably decreased (P < 0.05).

Conclusions

The use of ultrasonic scalpel significantly reduced the operation time and postoperative hospital stay in patients on maintenance hemodialysis undergoing PTX.

Optimal targets of chronic kidney disease-mineral and bone disorder markers for Chinese patients with maintenance peritoneal dialysis: a single-center retrospective cohort study

Background

The chronic kidney disease-mineral and bone disorder（CKD-MBD) is known to be associated with increased mortality in dialysis patients, but whether current global guidelines for CKD-MBD, which were primarily developed from hemodialysis, are suitable for peritoneal dialysis (PD) patients practice require further investigation.

Methods

This is a single-center retrospective cohort study. In total 491 prevalent PD patients (median follow-ups: 34 months) from Peking Union Medical College Hospital (PUMCH) from January 2004 to December 2017 were included and followed until 30 June 2018. In the first dialysis year, the average levels of serum calcium, albumin-corrected calcium (CorCa), phosphorus, and parathyroid hormone (PTH) levels were the interested predictors in Cox proportional regression model.

Results

Of these PD patients (age 58 ± 17 years), 52% were male and 36% had diabetic nephropathy. In Cox regression over first-year mean parameters, PTH <100 pg/mL (HR = 1.97, 95% CI 1.32 to 2.94, p < 0.001) and ≥300 pg/mL (HR = 2.24, 95% CI 1.32 to 3.81, p = 0.003) were associated with increased all-cause mortality than that of PTH 100–200 pg/mL. Patients with albumin-corrected serum calcium level < 2.13 mmol/L also had higher risk of death than patients with level of 2.13 to 2.38 mmol/L (HR = 2.06, 95% CI 1.06 to 4.01, p = 0.02). Serum phosphorus ≥1.45 mmol/L were associated with increased all-cause mortality. However, lacking of data on 25-hydroxy vitamin D, alkaline phosphatase, and activated vitamin-D are limitations of our analysis.

Conclusions

As one of the largest PD cohort study focusing on CKD-MBD, we demonstrated that the level of CKD-MBD markers in the first PD year are independent predictors of all-cause mortality. PTH 100–300 pg/mL might be the best target for Chinese PD patients.

Sucroferric oxyhydroxide for hyperphosphatemia: a review of real-world evidence

Hyperphosphatemia is a common complication in dialysis-dependent patients with chronic kidney disease. Most dialysis-dependent patients need oral phosphate binder therapy to control serum phosphorus concentrations. Most phosphate binders have a high daily pill burden, which may reduce treatment adherence and impair phosphorus control. Sucroferric oxyhydroxide is a potent iron-based phosphate binder approved for use in dialysis-dependent patients in 2013. A randomized controlled trial of sucroferric oxyhydroxide demonstrated its efficacy for reduction of serum phosphorus with a lower pill burden than sevelamer carbonate. Clinical trials carefully select patients, monitor adherence, and routinely titrate medications to a protocol-defined goal. Consequently, trials may not reflect real-world use of medications. Since its approval, we and others have performed retrospective and prospective analyses of sucroferric oxyhydroxide in real-world clinical practice in > 6400 hemodialysis and approximately 500 peritoneal dialysis patients in the USA and Europe. Consistent with the clinical trial data, real-world observational studies have demonstrated that sucroferric oxyhydroxide can effectively reduce serum phosphorus with a lower daily pill burden than most other phosphate binders. These studies have also shown sucroferric oxyhydroxide provides effective serum phosphorus control in different treatment settings, including as monotherapy in phosphate binder-naïve patients, in patients switching from other phosphate binders, or when used in combination with other phosphate binders. These observational studies indicate a favorable safety and tolerability profile, and minimal, if any, systemic iron absorption. This article reviews the key results from these observational studies of sucroferric oxyhydroxide and evaluates its role in the management of hyperphosphatemia in clinical practice.

Non-classical Vitamin D Actions for Renal Protection

Chronic Kidney Disease (CKD), a disorder that affects 11% of the world's population, is characterized by an acceleration in skeletal, immune, renal, and cardiovascular aging that increases the risk of cardiovascular mortality by 10- to 20-fold, compared to that in individuals with normal renal function. For more than two decades, the progressive impairment in renal capacity to maintain normal circulating levels of the hormonal form of vitamin D (1,25-dihydroxyvitamin D or calcitriol) was considered the main contributor to the reduced survival of CKD patients. Accordingly, calcitriol administration was the treatment of choice to attenuate the progression of secondary hyperparathyroidism (SHPT) and its adverse impact on bone health and vascular calcification. The development of calcitriol analogs, designed to mitigate the resistance to calcitriol suppression of PTH associated with CKD progression, demonstrated survival benefits unrelated to the control of SHPT or skeletal health. The exhaustive search for the pathophysiology behind survival benefits associated with active vitamin D analogs has identified novel anti-inflammatory, anti-hypertensive, anti-aging actions of the vitamin D endocrine system. A major paradigm shift regarding the use of calcitriol or active vitamin D analogs to improve survival in CKD patients emerged upon demonstration of a high prevalence of vitamin D (not calcitriol) deficiency at all stages of CKD and, more significantly, that maintaining serum levels of the calcitriol precursor, 25(OH)vitamin D, above 23 ng/ml delayed CKD progression. The cause of vitamin D deficiency in CKD, however, is unclear since vitamin D bioactivation to 25(OH)D occurs mostly at the liver. Importantly, neither calcitriol nor its analogs can correct vitamin D deficiency. The goals of this chapter are to present our current understanding of the pathogenesis of vitamin D deficiency in CKD and of the causal link between defective vitamin D bioactivation to calcitriol and the onset of molecular pathways that promote CKD progression independently of the degree of SHPT. An understanding of these mechanisms will highlight the need for identification of novel sensitive biomarkers to assess the efficacy of interventions with vitamin D and/or calcitriol(analogs) to ameliorate CKD progression in a PTH-independent manner.

The Impact of Protein Type on Phosphorus Intake, Serum Phosphate Concentrations, and Nutrition Status in Adults with Chronic Kidney Disease: A Critical Review

Lower phosphorus intake to prevent hyperphosphatemia for those with chronic kidney disease (CKD) is often recommended. Plant proteins are frequently restricted for their high phosphorus content despite having lower bioavailability. To summarize the evidence on protein type and dietary phosphorus intake, serum phosphate concentrations, and nutritional adequacy in adults with CKD, a search in MEDLINE via Ovid was conducted. Citation lists were reviewed to identify any additional articles. Sixteen articles were included-7 intervention (n = 290) and 9 observational (n = 4933). All intervention trials reported high-plant-protein diets provided adequate protein and adhered to low phosphorus diet guidelines. All intervention trials reported higher plant-protein intake was associated with lower serum phosphate; however, only 2 achieved statistical significance. For observational studies, 2 reported that higher proportions of plant to animal protein resulted in lower phosphorus intake but equivalent serum phosphate concentrations. Two reported that plant protein and animal protein had equivalent correlation values to phosphorus intake and no correlation to serum phosphate concentrations. One trial reported lower total phosphorus and protein intake among those who consumed more plant proteins but did not examine serum concentrations. Four reported lower serum phosphate concentrations among those who consumed more plant proteins but did not report dietary phosphorus intake. Of the observational studies that reported on protein intake, all reported lower protein intake among those with higher versus lower plant-protein intake. BMI tended to be lower among those consuming more plant protein. There was not a consistent relation between protein type and albumin concentrations. Routine restriction of plant-protein foods to prevent hyperphosphatemia in CKD would likely benefit from re-evaluation, as evidence does not suggest that higher plant-protein intake leads to higher serum phosphate concentrations or worse nutritional status, although longer-duration intervention trials with larger sample sizes appear to be warranted.

Novel Protein to Phosphorous Ratio Score Predicts Mortality in Hemodialysis Patients

OBJECTIVE

Lowering serum phosphorus in people on hemodialysis may improve their survival. However, prior studies have shown that restricting dietary protein intake, a major source of phosphorus, is associated with higher mortality. We hypothesized that a novel metric that incorporates both these values commensurately can improve survival prediction.

METHODS

We used serum phosphorous and normalized protein catabolic rate (nPCR), a surrogate of dietary protein intake, to form a new metric R that was used to examine the associations with mortality in 63,016 people on hemodialysis (HD) of one year after treatment initiation. Survival models were adjusted for case-mix, malnutrition-inflammation cachexia syndrome (MICS), and residual kidney function (RKF).

RESULTS

Individuals treated with hemodialysis were divided into five groups in accordance with R value. Group 1 included sick individuals with high phosphorous and low nPCR. Group 5 included individuals with low phosphorous and high nPCR. After 1-year follow-up, survival difference between the groups reflected R value, where an increase in R was associated with improved survival. The association of R with mortality was strengthened by adjustment in demographic variables and attenuated after adjustment to MICS. Mortality associations in accordance with R were not influenced by residual kidney function (RKF).

CONCLUSION

The novel protein to phosphorus ratio score R predicts mortality in people on dialysis, probably reflecting both nutrition and inflammation state independent of RKF. The metric enables better phosphorus monitoring, although adequate dietary protein intake is ensured and may improve the prediction of outcomes in the clinical setting.

The impact of CASR A990G polymorphism in response to cinacalcet treatment in hemodialysis patients with secondary hyperparathyroidism

The objective of this study was to determine the impact of calcium sensing receptor (CASR) A990G genetic polymorphism on parathyroid hormone (PTH) lowering response to cinacalcet treatment when controlling for significant influencing clinical factors. This retrospective study was conducted on 135 Thai hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT). CASR A990G genotypes were determined. The patients were identified as either G carriers (heterozygous or homozygous CASR 990G allele carriers) or noncarriers (homozygous CASR 990A carriers). Tested covariates were baseline PTH level (bPTH), baseline serum phosphate (bPhos), baseline serum calcium (bCa), baseline calcitriol equivalent dose (bCtriol), baseline ergocalciferol dose (bErgo), and age. The ANCOVA showed that intact PTH levels after 12 weeks of cinacalcet treatment (PTHw12) was significantly lower among G carriers compared with noncarriers after controlling for bPTH, bPhos, bCtriol, and bErgo (F(1, 127) = 15.472, p < 0.001), with the adjusted mean difference of 253.7 pg/mL. The logistic regression analysis revealed that the odds of a G carrier achieving 30% PTH reduction after 12-week cinacalcet treatment were 3.968 times greater than the odds for a noncarrier after adjusting for bPhos, bCtriol, and age. In conclusion, the CASR A990G polymorphism significantly influences cinacalcet response in HD patients with SHPT.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

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

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

Microwave ablation versus parathyroidectomy for severe secondary hyperparathyroidism in patients on hemodialysis: a retrospective multicenter study

BACKGROUND

Microwave ablation is effective for severe secondary hyperparathyroidism, but the difference in efficacy between microwave ablation and parathyroidectomy remains unclear. In this multicenter retrospective cohort study, we compared the long-term clinical efficacy of microwave ablation and parathyroidectomy for severe secondary hyperparathyroidism undergoing hemodialysis.

MATERIALS AND METHODS

The patients were divided into microwave ablation and parathyroidectomy groups. The primary endpoint was the proportion of patients with intact parathyroid hormone (iPTH) concentrations within the target range (100-600 pg/mL) during the efficacy assessment phase. The secondary endpoints were (i) differences in iPTH concentrations over time between the two groups, and (ii) decreases in iPTH concentrations over time in the two groups.

RESULTS

Microwave ablation was performed in 47/92 patients and parathyroidectomy in 45/92. Primary endpoint: iPTH concentrations within the target range were achieved during the efficacy assessment phase in 26/47 patients (55.3%) and in 14/45 (31.1%) patients in the microwave ablation and parathyroidectomy groups, respectively (p = .02). Secondary endpoints: (i) Mean iPTH concentrations during the efficacy assessment phase were significantly higher in the microwave ablation versus parathyroidectomy groups (649 ± 519 pg/mL versus 136 ± 228 pg/mL, respectively; p < .01). (ii) Mean decrease in iPTH concentration from baseline was 725 ± 605 pg/mL versus 1369 ± 478 pg/mL in the MWA versus parathyroidectomy groups, respectively (p < .01).

CONCLUSIONS

Ultrasound-guided percutaneous microwave ablation provides higher iPTH target-achieving rates than parathyroidectomy in patients with severe secondary hyperparathyroidism undergoing hemodialysis.

Phosphate Control: The Next Frontier in Dialysis Cardiovascular Mortality

BACKGROUND

Cardiovascular disease (CVD) is a major cause of death in patients with chronic kidney disease (CKD) on dialysis. Mortality rates are still unacceptably high even though they have fallen in the past 2 decades. Hyperphosphatemia (elevated serum phosphate levels) is seen in almost all patients with advanced CKD and is by far the largest remaining modifiable contributor to CKD mortality.

SUMMARY

Phosphate retention drives multiple physiological mechanisms linked to increased risk of CVD. Fibroblast growth factor 23 and parathyroid hormone (PTH) levels, both of which have been suggested to have direct pathogenic CV effects, increase in response to phosphate retention. Phosphate, calcium, and PTH levels are linked in a progressively worsening cycle. Maladaptive upregulation of phosphate absorption is also likely to occur further exacerbating hyperphosphatemia. Even higher phosphate levels within the normal range may be a risk factor for vascular calcification and, thus, CV morbidity and mortality. A greater degree of phosphate control is important to reduce the risk of CV morbidity and mortality. Improved phosphate control and regular monitoring of phosphate levels are guideline-recommended, established clinical practices. There are several challenges with the current phosphate management approaches in patients with CKD on dialysis. Dietary restriction of phosphate and thrice-weekly dialysis alone are insufficient/unreliable to reduce phosphate to <5.5 mg/dL. Even with the addition of phosphate binders, the only pharmacological treatment currently indicated for hyperphosphatemia, the majority of patients are unable to achieve and maintain phosphate levels <5.5 mg/dL (or more normal levels) [PhosLo® gelcaps (calcium acetate): 667 mg (prescribing information), 2011, VELPHORO®: (Sucroferric oxyhydroxide) (prescribing information), 2013, FOSRENAL®: (Lanthanum carbonate) (prescribing information), 2016, AURYXIA®: (Ferric citrate) tablets (prescribing information), 2017, RENVELA®: (Sevelamer carbonate) (prescribing information), 2020, RealWorld dynamix. Dialysis US: Spherix Global Insights, 2019]. Phosphate binders do not target the primary pathway of phosphate absorption (paracellular), have limited binding capacity, and bind nonspecifically [PhosLo® gelcaps (calcium acetate): 667 mg (prescribing information). 2013, VELPHORO®: (Sucroferric oxyhydroxide) (prescribing information), 2013, FOSRENAL®: (Lanthanum carbonate) (prescribing information), 2016, AURYXIA®: (Ferric citrate) tablets (prescribing information), 2017, RENVELA®: (Sevelamer carbonate) (prescribing information) 2020]. Key Messages: Despite current phosphate management strategies, most patients on dialysis are unable to consistently achieve target phosphate levels, indicating a need for therapeutic innovations [RealWorld dynamix. Dialysis US: Spherix Global Insights, 2019]. Given a growing evidence base that the dominant mechanism of phosphate absorption is the intestinal paracellular pathway, new therapies are investigating ways to reduce phosphate levels by blocking absorption through the paracellular pathway.

Serum phosphate and mortality in incident dialysis patients in Australia and New Zealand

AIM

Hyperphosphataemia is associated with increased adverse outcomes, including mortality. Re-examining this association using up-to-date data reflecting current and real-world practices, across different global regions and in both haemodialysis and peritoneal dialysis patients, is important.

METHODS

We describe the association between serum phosphate and all-cause and cardiovascular mortality in incident dialysis patients between 2008 and 2018 using the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. Time-dependent Cox proportionate hazards models were used. Models were adjusted for available covariates and fitted for the overall cohort, and also each dialysis modality.

RESULTS

31 989 patients were followed over 97 122 person-years at risk (mean age at first dialysis 61 years, 38% female, 67% haemodialysis). We observed a U-shaped association between serum phosphate and all-cause mortality. In the fully adjusted model, categories of serum phosphate above and below 1.25-1.99 mmol/L were associated with progressively higher risk, reaching a hazard ratio of 2.13 (95% CI 1.93-2.36, p < .001) for serum phosphate ≥2.75 mmol/L, and 1.56 (95% CI 1.44-1.69, p < .001) for serum phosphate <1.00 mmol/L. Low and high levels of serum phosphate were also associated with increased risk of cardiovascular mortality, however the association with high serum phosphate was more pronounced ("J-shaped relationship"). The associations were consistent across sub-analyses of patients receiving haemodialysis and peritoneal dialysis treatment.

CONCLUSION

In this large contemporary dialysis cohort, both high and low levels of serum phosphate were independently associated with increased risk of mortality. Future studies are required to determine whether treatment of abnormal serum phosphate levels improves mortality.