Effect of paricalcitol on left ventricular mass and function in CKD--the OPERA trial

Association of 1,25 dihydroxyvitamin D with left ventricular hypertrophy and left ventricular diastolic dysfunction in patients with chronic kidney disease

Left ventricular hypertrophy (LVH) and left ventricular diastolic dysfunction (LVDD) are highly prevalent predictors of cardiovascular disease in individuals with chronic kidney disease (CKD). Vitamin D, particularly 25-hydroxyvitamin D [25(OH)D], deficiency has been reported to be associated with cardiac structure and function in CKD patients. In the current study, we investigated the association between 1,25-dihydroxyvitamin D [1,25(OH)2D], the active form of 25(OH)D, and LVH/LVDD in CKD patients. We enrolled 513 non-dialysis CKD patients. The presence of LVH and LVDD was determined using transthoracic echocardiography. In multivariable analysis, serum 1,25(OH)2D levels, but not serum 25(OH)D, were independently associated with LVH [odds ratio (OR): 0.90, 95% confidential interval (CI): 0.88-0.93, P < 0.001]. Additionally, age, systolic blood pressure, and intact parathyroid hormone levels were independently associated with LVH. Similarly, multivariable analysis demonstrated that serum 1,25(OH)2D levels, but not 25(OH)D levels, were independently associated with LVDD (OR: 0.88, 95% CI: 0.86-0.91, P < 0.001) with systolic blood pressure showing independent association with LVDD. The optimal cut-off values for serum 1,25(OH)2D levels for identifying LVH and LVDD were determined as ≤ 12.7 pg/dl and ≤ 18.1 pg/dl, respectively. Our findings suggest that serum 1,25(OH)2D levels have independent association with LVH and LVDD in CKD patients, underscoring their potential as biomarkers for these conditions in this patient population.

Vitamin D and cardiovascular diseases: A narrative review

Cardiovascular diseases (CVD) and vitamin D deficiency are becoming highly prevalent among general populations. Despite plausible biological mechanisms for the role of vitamin D in cardio-protection, a cause-and-effect relationship has not yet been established. The interest in vitamin D as a potential therapeutic target to attenuate cardiovascular risk has been raised. The question about the benefit of vitamin D supplementation for cardiovascular outcomes cannot be answered certainly for the moment. The association between hypovitaminosis D and CVD has been proven by some studies while other studies deny any such link. The present narrative review gives a comprehensive overview of studies on the potential impact of hypovitaminosis D on CVD. The potential role of vitamin D supplementation in the management of CVD is also evaluated. Particular emphasis is paid to those studies that achieve a high level of scientific evidence.

SNF472: a novel therapeutic agent for vascular calcification and calciphylaxis

Vascular calcification is a common complication in patients with chronic kidney disease (CKD) and is strongly associated with an increased risk of cardiovascular events and all-cause mortality. Calciphylaxis is a specific and life-threatening manifestation of vascular calcifications that usually affects individuals with advanced kidney function impairment or those undergoing dialysis. Currently, the treatment of vascular calcification and calciphylaxis in CKD lacks approved treatments and focuses on controlling risk factors. SNF472, the intravenous formulation of myo-inositol hexaphosphate, is a novel vascular calcification inhibitor currently undergoing phase 3 clinical trials, demonstrating its ability to directly inhibit the formation of calcium and phosphorus crystals, thereby blocking the production and deposition of ectopic calcium. The efficacy and safety of SNF472 in inhibiting vascular calcification have been confirmed in recent clinical studies. This review summarizes the results of studies related to SNF472 to provide a comprehensive overview of its mechanism of action, efficacy, safety, and ongoing clinical studies.

Epimeric vitamin D and cardiovascular structure and function in advanced CKD and after kidney transplantation

BACKGROUND

25-hydroxyvitamin D can undergo C-3 epimerization to produce 3-epi-25(OH)D3. 3-epi-25(OH)D3 levels decline in chronic kidney disease (CKD), but its role in regulating the cardiovascular system is unknown. Herein, we examined the relationship between 3-epi-25(OH)D3, and cardiovascular functional and structural endpoints in patients with CKD.

METHODS

We examined n = 165 patients with advanced CKD from the Cardiopulmonary Exercise Testing in Renal Failure and After Kidney Transplantation (CAPER) study cohort, including those who underwent kidney transplant (KTR, n = 76) and waitlisted patients who did not (NTWC, n = 89). All patients underwent cardiopulmonary exercise testing and echocardiography at baseline, 2 months and 12 months. Serum 3-epi-25(OH)D3 was analyzed by liquid chromatography-tandem mass spectrometry.

RESULTS

Patients were stratified into quartiles of baseline 3-epi-25(OH)D3 (Q1: <0.4 ng/mL, n = 51; Q2: 0.4 ng/mL, n = 26; Q3: 0.5-0.7 ng/mL, n = 47; Q4: ≥0.8 ng/mL, n = 41). Patients in Q1 exhibited lower peak oxygen uptake [VO2Peak = 18.4 (16.2-20.8) mL/min/kg] compared with Q4 [20.8 (18.6-23.2) mL/min/kg; P = .009]. Linear mixed regression model showed that 3-epi-25(OH)D3 levels increased in KTR [from 0.47 (0.30) ng/mL to 0.90 (0.45) ng/mL] and declined in NTWC [from 0.61 (0.32) ng/mL to 0.45 (0.29) ng/mL; P < .001]. Serum 3-epi-25(OH)D3 was associated with VO2Peak longitudinally in both groups [KTR: β (standard error) = 2.53 (0.56), P < .001; NTWC: 2.73 (0.70), P < .001], but was not with left ventricular mass or arterial stiffness. Non-epimeric 25(OH)D3, 24,25(OH)2D3 and the 25(OH)D3:24,25(OH)2D3 ratio were not associated with any cardiovascular outcome (all P > .05).

CONCLUSIONS

Changes in 3-epi-25(OH)D3 levels may regulate cardiovascular functional capacity in patients with advanced CKD.

Vitamin D Supplementation and Cardiovascular Disease Risks in More Than 134000 Individuals in 29 Randomized Clinical Trials and 157000 Individuals in 30 Prospective Cohort Studies: An Updated Systematic Review and Meta-analysis

BACKGROUND

According to the findings from observational studies and clinical trials assessing the effect of vitamin D supplements on cardiovascular diseases (CVDs), there are still contradictory results. This systematic review aimed to assess the effect of vitamin D supplements on CVDs considering cohort studies and clinical trials. Study Design: A systematic review.

METHODS

MEDLINE/PubMed, Science Direct, Embase, and Cochrane Library databases were reviewed by two reviewers independently until 2022. The study effect is risk ratio (RR) and 95% confidence interval (CI) according to Mantel Haenszel's random-effects model. Then, Stata version 14 was used for statistical analysis.

RESULTS

In clinical trial studies, the incidence of CVDs among the vitamin D-consuming group was not significantly different from that in the placebo group (RR: 0.99, 95% CI: 0.95-1.03; P=0.77; I 2=0%). CVD mortality was also not significantly different between the two groups (RR: 0.97, 95% CI: 0.90-1.05; P=0.72; I2=0%). In cohort studies, circulating 25 (OH) D increased the risk of CVD incidence by 31% (RR: 1.31, 95% CI: 1.19-1.45) and CVD mortality by 37% (RR: 1.37, 95% CI: 1.17-1.61).

CONCLUSION

According to current evidence from clinical trials, vitamin D supplementation should not be recommended for CVD prevention. However, there is a direct association between vitamin D deficiency and the incidence of CVDs as well as its mortality. According to the results of clinical trial studies carrying higher levels of scientific evidence, it can be concluded that vitamin D supplementation does not exert a significant effect on the incidence, mortality, and reduction of CVDs.

Paricalcitol and Extended-Release Calcifediol for Treatment of Secondary Hyperparathyroidism in Non-Dialysis Chronic Kidney Disease: Results From a Network Meta-Analysis

CONTEXT

Secondary hyperparathyroidism (SHPT) is a complication of chronic kidney disease (CKD) affecting mineral and bone metabolism and characterized by excessive parathyroid hormone (PTH) production and parathyroid hyperplasia.

OBJECTIVE

The objective of this analysis was to compare the efficacy and adverse effects of extended-release calcifediol (ERC) and paricalcitol (PCT) by assessing their effect on the biomarkers PTH, calcium, and phosphate in patients with non-dialysis CKD (ND-CKD).

METHODS

A systematic literature research was performed in PubMed to identify randomized control trials (RCTs). Quality assessment was done with the GRADE method. The effects of ERC vs PCT were compared using random effects in a frequentist setting.

RESULTS

Nine RCTs comprising 1426 patients were included in the analyses. The analyses were performed on 2 overlapping networks, due to nonreporting of outcomes in some of the included studies. No head-to-head trials were identified. No statistically significant differences in PTH reduction were found between PCT and ERC. Treatment with PCT showed statistically significant increases in calcium compared with ERC (0.2 mg/dL increase; 95% CI, -0.37 to -0.05 mg/dL). No differences in effects on phosphate were observed.

CONCLUSION

This network meta-analysis showed that ERC is comparable in lowering PTH levels vs PCT. ERC displayed avoidance of potentially clinically relevant increases in serum calcium, offering an effective and well-tolerated treatment option for the management of SHPT in patients with ND-CKD.

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.

Vitamin D Metabolites and Risk of Cardiovascular Disease in Chronic Kidney Disease: The CRIC Study

Background The ratio of 24,25-dihydroxyvitamin D3/25-hydroxyvitamin D3 (vitamin D metabolite ratio [VDMR]) may reflect functional vitamin D activity. We examined associations of the VDMR, 25-hydroxyvitamin D (25[OH]D), and 1,25-dihydroxyvitamin D (1,25[OH]2D) with cardiovascular disease (CVD) in patients with chronic kidney disease. Methods and Results This study included longitudinal and cross-sectional analyses of 1786 participants from the CRIC (Chronic Renal Insufficiency Cohort) Study. Serum 24,25-dihydroxyvitamin D3, 25(OH)D, and 1,25(OH)2D were measured by liquid chromatography-tandem mass spectrometry 1 year after enrollment. The primary outcome was composite CVD (heart failure, myocardial infarction, stroke, and peripheral arterial disease). We used Cox regression with regression-calibrated weights to test associations of the VDMR, 25(OH)D, and 1,25(OH)2D with incident CVD. We examined cross-sectional associations of these metabolites with left ventricular mass index using linear regression. Analytic models adjusted for demographics, comorbidity, medications, estimated glomerular filtration rate, and proteinuria. The cohort was 42% non-Hispanic White race and ethnicity, 42% non-Hispanic Black race and ethnicity, and 12% Hispanic ethnicity. Mean age was 59 years, and 43% were women. Among 1066 participants without prevalent CVD, there were 298 composite first CVD events over a mean follow-up of 8.6 years. Lower VDMR and 1,25(OH)2D were associated with incident CVD before, but not after, adjustment for estimated glomerular filtration rate and proteinuria (hazard ratio, 1.11 per 1 SD lower VDMR [95% CI, 0.95-1.31]). Only 25(OH)D was associated with left ventricular mass index after full covariate adjustment (0.6 g/m2.7 per 10 ng/mL lower [95% CI, 0.0-1.3]). Conclusions Despite modest associations of 25(OH)D with left ventricular mass index, 25(OH)D, the VDMR, and 1,25(OH)2D were not associated with incident CVD in chronic kidney disease.

Effect of active vitamin-D on left ventricular mass index: Results of a randomized controlled trial in type 2 diabetes and chronic kidney disease

BACKGROUND

Active vitamin-D deficiency is a potential modifiable risk factor for increased ventricular mass. We explored the effects of active vitamin-D (calcitriol) treatment on left ventricular mass in patients with type-2 diabetes (T2D) and chronic kidney disease (CKD).

METHODS

We performed a 48-week duration single center randomized double-blind parallel group trial examining the impact of calcitriol, 0.5 mcg once daily, as compared to placebo on a primary endpoint of change from baseline in left ventricular mass index (LVMI) measured by magnetic resonance imaging . Patients with T2D, CKD stage-3 and raised left ventricular mass on stable renin angiotensin aldosterone system blockade, who all had elevated intact parathyroid hormone were eligible. Secondary endpoints included interstitial myocardial fibrosis, assessed with cardiac magnetic resonance imaging. In total, 45 (male 73%) patients with T2D and stage-3 CKD were studied (calcitriol n = 19, placebo n = 26).

RESULTS

Following 48-weeks calcitriol treatment, the median difference and the (95% CI) of LVMI between the 2 treatment arms was 1.84 (-1.28, 4.96), similar between the 2 groups studied. Intact parathyroid hormone fell only in the calcitriol group from 142 pg/mL (80-293) to 76 pg/mL (41-204)(median, interquartile range, P= .04). No significant differences were observed in interstitial myocardial fibrosis or other secondary endpoints.

CONCLUSIONS

The study did not provide evidence that treatment with calcitriol as compared to placebo might improve LVMI in patients with T2D, mild left ventricular hypertrophy and stable CKD. Our data does not support the routine use of active vitamin-D for LVMI regression and cardiovascular protection in patients with T2D and stage-3 CKD.

Nutrition Management for Chronic Kidney Disease: Differences and Special Needs for Children and Adults

Common goals of nutritional therapy across the spectrum of pediatric and adult chronic kidney disease (CKD) include maintaining normal body mass and composition and reducing associated morbidity and mortality. Adult nephrologists caring for children and adolescents may be challenged by the existing complexities in identifying and interpreting the nutritional status and growth in children. Pediatric nephrologists may face situations that call for a sound knowledge of assessing nutritional status and providing nutrition therapy for adolescents and young adults. One important additional nutrition goal in children is to achieve normal growth and development. Children are growing and therefore need more calories and nutrients than just maintaining their body weight and composition. Lack of weight and height gain actually is considered failure to thrive in children. Some fundamental differences in approaches to nutritional therapy in CKD are necessitated based on the etiology of CKD. A large proportion of adults with CKD are diabetics, so the approach would be a low-carbohydrate diet. Children with CKD, especially young ones, often are anorexic, so calorie supplements that could include quite a lot of carbohydrates often are prescribed. More adults with CKD have hypertension and atherosclerotic comorbidities, which result in recommendations for low-salt and low-fat diets. Children with CKD often have salt and electrolyte wasting disease states and would require normal- or even high-salt diets, and fats often are included in supplements to bolster calorie intake. Low-protein diets often are recommended in adults with predialysis CKD to slow disease progression. Children are growing and have a higher protein daily requirement. Low-protein diets have not been found to be efficacious in children with CKD, in achieving normal growth, or in slowing disease progression. Adult nephrologists caring for children and adolescents may be challenged by the existing complexities in identifying and interpreting nutritional status and growth in children. Pediatric nephrologists may face situations that call for a sound knowledge of assessing nutritional status and providing nutrition therapy for adolescents and young adults. This article discusses the differences in the assessment of nutritional status between children and adults, as well as provides a comprehensive approach to nutritional management for CKD across the age spectrum. Semin Nephrol 43:x-xx © 2023 Elsevier Inc. All rights reserved.

The effects of vitamin D on all-cause mortality in different diseases: an evidence-map and umbrella review of 116 randomized controlled trials

Purpose

To conduct a solid evidence by synthesizing meta-analyses and updated RCTs about the effects of vitamin D on all-cause mortality in different health conditions.

Methods

Data sources: Pubmed, Embase, Web of Science, the Cochrane Library, Google Scholar from inception until 25th April, 2022. Study selection: English-language, meta-analyses and updated RCTs assessing the relationships between vitamin D and all-cause mortality. Data synthesis: Information of study characteristics, mortality, supplementation were extracted, estimating with fixed-effects model. A Measurement Tool to Assess Systematic Reviews, Grading of Recommendations Assessment, Development and Evaluation, and funnel plot was used to assess risk of bias. Main outcomes: All-cause mortality, cancer mortality, cardiovascular disease mortality.

Results

In total of 27 meta-analyses and 19 updated RCTs were selected, with a total of 116 RCTs and 149, 865 participants. Evidence confirms that vitamin D reduces respiratory cancer mortality (RR, 0.56 [95%CI, 0.33 to 0.96]). All-cause mortality is decreased in patients with COVID-19 (RR, 0.54[95%CI, 0.33 to 0.88]) and liver diseases (RR, 0.64 [95%CI, 0.50 to 0.81]), especially in liver cirrhosis (RR, 0.63 [95%CI, 0.50 to 0.81]). As for other health conditions, such as the general health, chronic kidney disease, critical illness, cardiovascular diseases, musculoskeletal diseases, sepsis, type 2 diabetes, no significant association was found between vitamin D and all-cause mortality.

Conclusions

Vitamin D may reduce respiratory cancer mortality in respiratory cancer patients and all-cause mortality in COVID-19 and liver disorders' patients. No benefits showed in all-cause mortality after vitamin D intervention among other health conditions. The hypothesis of reduced mortality with vitamin D still requires exploration.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=252921, identifier: CRD42021252921.

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).

Vitamin D and Chronic Kidney Disease Association with Mineral and Bone Disorder: An Appraisal of Tangled Guidelines

Chronic kidney disease (CKD) is a highly prevalent condition worldwide in which the kidneys lose many abilities, such as the regulation of vitamin D (VD) metabolism. Moreover, people with CKD are at a higher risk of multifactorial VD deficiency, which has been extensively associated with poor outcomes, including bone disease, cardiovascular disease, and higher mortality. Evidence is abundant in terms of the association of negative outcomes with low levels of VD, but recent studies have lowered previous high expectations regarding the beneficial effects of VD supplementation in the general population. Although controversies still exist, the diagnosis and treatment of VD have not been excluded from nephrology guidelines, and much data still supports VD supplementation in CKD patients. In this narrative review, we briefly summarize evolving controversies and useful clinical approaches, underscoring that the adverse effects of VD derivatives must be balanced against the need for effective prevention of progressive and severe secondary hyperparathyroidism. Guidelines vary, but there seems to be general agreement that VD deficiency should be avoided in CKD patients, and it is likely that one should not wait until severe SHPT is present before cautiously starting VD derivatives. Furthermore, it is emphasized that the goal should not be the complete normalization of parathyroid hormone (PTH) levels. New developments may help us to better define optimal VD and PTH at different CKD stages, but large trials are still needed to confirm that VD and precise control of these and other CKD-MBD biomarkers are unequivocally related to improved hard outcomes in this population.

The 1,24,25(OH)3D3 metabolite in clinical and experimental CKD: Impact of calcitriol treatment

Calcitriol, and other vitamin D receptor activators, remain a primary treatment for elevated parathyroid hormone levels in patients with end stage kidney disease. The objective of this study was to assess the 24-hydroxylation-mediated metabolism of 25(OH)D₃ and 1,25(OH)₂D₃ in rats with experimental kidney disease treated with calcitriol and in a cross-sectional analysis of patients requiring hemodialysis. Methods: Animals were stratified by creatinine into a time control group or calcitriol (20 ng/kg/day) for 3 weeks following CKD induction using a dietary adenine model (0.25% adenine). Hemodialysis patients were recruited and demographic data including calcitriol prescription was obtained by chart review and participant interview. Vitamin D metabolites were assessed using LC-MS/MS. In the rat model, 1,25(OH)₂D₃ levels increased substantially in calcitriol-treated rats yet there was no increase in its primary metabolite: 1,24,25(OH)₂D₃. A lower ratio of 1,24,25(OH)₂D₃:1,25(OH)₂D₃ (1,25-VMR) was associated with increased calcium levels in calcitriol treated rats. In hemodialysis patients (N = 86), the level of 1,25(OH)₂D₃ was substantially higher in calcitriol-treated patients yet there was no difference between groups in 1,24,25(OH)₃D₃, resulting in a marked decrease in the 1,25-VMR in calcitriol treated patients. In hemodialysis patients treated with calcitriol, 1,25(OH)₂D₃ and a lower ratio between 1,24,25(OH)₃D₃ and 1,25(OH)₂D₃ were associated with higher serum calcium levels. Impaired metabolism of exogenous calcitriol may contribute to the adverse effects associated with this treatment. A better understanding of the uniquely dysfunctional catabolic vitamin D profile in CKD may guide more effective treatment strategies.

Effects of Vitamin D3 Supplementation on Cardiovascular and Cancer Outcomes by eGFR in VITAL

Background

Reduced 25-hydroxyvitamin D (25[OH]D) metabolism and secondary hyperparathyroidism are common with lower estimated glomerular filtration rate (eGFR) and may contribute to cardiovascular disease and cancer risk.

Methods

We assessed for heterogeneity by baseline eGFR of the effects of vitamin D3 on cardiovascular and cancer outcomes in the Vitamin D and Omega-3 Trial (VITAL). Participants were randomized to 2000 IU vitamin D3 and/or 1 g Ω-3 fatty acids daily using a placebo-controlled, two-by-two factorial design (5.3 years follow-up). Primary study end points were incident major cardiovascular events and invasive cancer. Changes in serum 25(OH)D and parathyroid hormone (PTH) were examined.

Results

Baseline eGFR was available for 15,917 participants. Participants' mean age was 68 years, and 51% were women. Vitamin D3 resulted in higher serum 25(OH)D compared with placebo (difference in change 12.5 ng/ml; 95% CI, 12 to 13.1 ng/ml), without heterogeneity by eGFR (P interaction, continuous eGFR=0.2). Difference in change in PTH between vitamin D3 and placebo was larger with lower eGFR (P interaction=0.05): -6.9 (95% CI, -10.5 to -3.4), -5.8 (95% CI, -8.3 to -3.4), -4 (95% CI, -5.9 to -2.2), and -3.8 (95% CI, -5.6 to -2) pg/ml for eGFR <60, 60-74, 75-89, and ≥90 ml/min per 1.73 m2, respectively. Effects of vitamin D3 supplementation on cardiovascular events (P interaction=0.61) and cancer (P interaction=0.89) did not differ by eGFR: HR=1.14 (95% CI, 0.73 to 1.79), HR=1.06 (95% CI, 0.75 to 1.5), HR=0.92 (95% CI, 0.67 to 1.25), and HR=0.92 (95% CI, 0.66 to 1.27) across eGFR categories for cardiovascular events and HR=1.63 (95% CI, 1.03 to 2.58), HR=0.85 (95% CI, 0.64 to 1.11), HR=0.84 (95% CI, 0.68 to 1.03), and 1.11 (95% CI, 0.92 to 1.35) for cancer, respectively.

Conclusions

We observed no significant heterogeneity by baseline eGFR in the effects of vitamin D3 supplementation versus placebo on cardiovascular or cancer outcomes, despite effects on 25(OH)D and PTH concentrations.

Real-world assessment: effectiveness and safety of extended-release calcifediol and other vitamin D therapies for secondary hyperparathyroidism in CKD patients

Introduction

Extended-release calcifediol (ERC), active vitamin D hormones and analogs (AVD) and nutritional vitamin D (NVD) are commonly used therapies for treating secondary hyperparathyroidism (SHPT) in adults with stage 3–4 chronic kidney disease (CKD) and vitamin D insufficiency (VDI). Their effectiveness for increasing serum total 25-hydroxyvitamin D (25D) and reducing elevated plasma parathyroid hormone (PTH), the latter of which is associated with increased morbidity and mortality, has varied across controlled clinical trials. This study aimed to assess real-world experience of ERC and other vitamin D therapies in reducing PTH and increasing 25D.

Methods

Medical records of 376 adult patients with stage 3–4 CKD and a history of SHPT and VDI from 15 United States (US) nephrology clinics were reviewed for up to 1 year pre- and post-ERC, NVD or AVD initiation. Key study variables included patient demographics, concomitant usage of medications and laboratory data. The mean age of the study population was 69.5 years, with gender and racial distributions representative of the US CKD population. Enrolled patients were grouped by treatment into three cohorts: ERC (n = 174), AVD (n = 55) and NVD (n = 147), and mean baseline levels were similar for serum 25D (18.8–23.5 ng/mL), calcium (Ca: 9.1–9.3 mg/dL), phosphorus (P: 3.7–3.8 mg/dL) and estimated glomerular filtration rate (eGFR: 30.3–35.7 mL/min/1.73m²). Mean baseline PTH was 181.4 pg/mL for the ERC cohort versus 156.9 for the AVD cohort and 134.8 pg/mL (p < 0.001) for the NVD cohort. Mean follow-up during treatment ranged from 20.0 to 28.8 weeks.

Results

Serum 25D rose in all cohorts (p < 0.001) during treatment. ERC yielded the highest increase (p < 0.001) of 23.7 ± 1.6 ng/mL versus 9.7 ± 1.5 and 5.5 ± 1.3 ng/mL for NVD and AVD, respectively. PTH declined with ERC treatment by 34.1 ± 6.6 pg/mL (p < 0.001) but remained unchanged in the other two cohorts. Serum Ca increased 0.2 ± 0.1 pg/mL (p < 0.001) with AVD but remained otherwise stable. Serum alkaline phosphatase remained unchanged.

Conclusions

Real-world clinical effectiveness and safety varied across the therapies under investigation, but only ERC effectively raised mean 25D (to well above 30 ng/mL) and reduced mean PTH levels without causing hypercalcemia.

Mineral Bone Disorders in Kidney Disease Patients: The Ever-Current Topic

Chronic kidney disease (CKD) is a complex and multifactorial disease, and one of the most prevalent worldwide. Chronic kidney disease–mineral bone disorders (CKD–MBD) with biochemical and hormonal alterations are part of the complications associated with the progression of CKD. Pathophysiology of CKD–MBD focused on abnormalities in serum levels of several biomarkers (such as FGF-23, klotho, phosphate, calcium, vitamin D, and PTH) which are discussed in this review. We therefore examine the prognostic association between CKD–MBD and the increased risk for cardiovascular events, mortality, and CKD progression to end-stage kidney disease (ESKD). Lastly, we present specific treatments acting on CKD to prevent and treat the complications associated with secondary hyperparathyroidism (SHPT): control of hyperphosphatemia (with dietary restriction, intestinal phosphate binders, and adequate dialysis), the use of calcimimetic agents, vitamin D, and analogues, and the use of bisphosphonates or denosumab in patients with osteoporosis.

Mechanism of calcitriol regulating parathyroid cells in secondary hyperparathyroidism

A common consequence of chronic renal disease is secondary hyperparathyroidism (SHPT) and is closely related to the mortality and morbidity of uremia patients. Secondary hyperparathyroidism (SHPT) is caused by excessive PTH production and release, as well as parathyroid enlargement. At present, the mechanism of cell proliferation in secondary hyperparathyroidism (SHPT) is not completely clear. Decreased expression of the vitamin D receptor (VDR) and calcium-sensing receptor (CaSR), and 1,25(OH)2D3 insufficiency all lead to a decrease in cell proliferation suppression, and activation of multiple pathways is also involved in cell proliferation in renal hyperparathyroidism. The interaction between the parathormone (PTH) and parathyroid hyperplasia and 1,25(OH)2D3 has received considerable attention. 1,25(OH)2D3 is commonly applied in the therapy of renal hyperparathyroidism. It regulates the production of parathormone (PTH) and parathyroid cell proliferation through transcription and post-transcription mechanisms. This article reviews the role of 1,25(OH)2D3 in parathyroid cells in secondary hyperparathyroidism and its current understanding and potential molecular mechanism.

Adherence to the Mediterranean Diet Is Associated with a More Favorable Left Ventricular Geometry in Patients with End-Stage Kidney Disease

Introduction. The aim of the study was to examine the impact of adherence to a Mediterranean-style diet (MD) on left ventricular hypertrophy (LVH) and cardiac geometry in chronic kidney disease patients on dialysis (CKD-5D), given the high prevalence of cardiovascular morbidity in this population. Methods. n = 127 (77 men and 50 women) CKD-5D patients (69 on hemodialysis and 58 on peritoneal dialysis) with a mean age of 62 ± 15 years were studied. An MD adherence score (MDS) (range 0−55, 55 representing maximal adherence) was estimated with a validated method. Echocardiographic LVH was defined by LV mass index (LVMI) > 95 g/m2 in women and >115 g/m2 in men. Based on LVMI and relative wall thickness (RWT), four LV geometric patterns were defined: normal (normal LVMI and RWT), concentric remodeling (normal LVMI and increased RWT > 0.42), eccentric LVH (increased LVMI and normal RWT), and concentric LVH (increased LVMI and RWT). Results. Patients with LVH (n = 81) as compared to patients with no LVH (n = 46) were older in age (66 ± 13 vs. 55 ± 16 years; p < 0.001) had lower MDS (24 ± 2.7 vs. 25 ± 4.3; p < 0.05) and higher malnutrition-inflammation score (5.0 ± 2.7 vs. 3.9 ± 1.9; p < 0.05), body mass index (27.5 ± 4.9 vs. 24.1 ± 3.5 kg/m2; p < 0.001), prevalence of diabetes (79% vs. 20%; p < 0.05), coronary artery disease (78% vs. 20%; p < 0.05) and peripheral vascular disease (78% vs. 20%; p < 0.01). In a multivariate logistic regression analysis adjusted for all factors mentioned above, each 1-point greater MDS was associated with 18% lower odds of having LVH (OR = 0.82, 95% CI: 0.69−0.98; p < 0.05). MDS was inversely related to LVMI (r = −0.273; p = 0.02), and in a multiple linear regression model (where LVMI was analyzed as a continuous variable), MDS emerged as a significant (Β = −2.217; p < 0.01) independent predictor of LVH. Considering LV geometry, there was a progressive decrease in MDS from the normal group (25.0 ± 3.7) to concentric remodeling (25.8 ± 3.0), eccentric (24.0 ± 2.8), and then concentric (23.6 ± 2.7) group (p < 0.05 for the trend). Conclusions. The greater adherence to an MD is associated with lesser LVH, an important cardiovascular disease risk factor; MD preserves normal cardiac geometry and may confer protection against future cardiac dysfunction in dialysis patients.

Effects of alfacalcidol on cardiovascular outcomes according to alkaline phosphatase levels in the J-DAVID trial

In the Japan Dialysis Active Vitamin D (J-DAVID) trial, oral alfacalcidol numerically, but not significantly, increased the risk of cardiovascular events among patients undergoing hemodialysis. Because the cardiovascular effect of alfacalcidol could be modulated by bone turnover status, this post-hoc analysis of the J-DAVID examined how alkaline phosphatase (ALP), a more precise marker of bone turnover than parathyroid hormone (PTH), modifies the impact of alfacalcidol. The J-DAVID was a 48-month, open-label, randomized controlled trial comparing oral alfacalcidol with no vitamin D receptor activators use in terms of cardiovascular events among 976 hemodialysis patients without secondary hyperparathyroidism. This post-hoc analysis included 959 patients with available data on baseline ALP. The median [25–75th percentile] baseline ALP level was 234 [183–296] U/L. In a Cox proportional hazards model, ALP did not significantly modify the effect of alfacalcidol on the rate of cardiovascular events or all-cause death (P for effect modification = 0.54 and 0.74, respectively). The effect of alfacalcidol on time-series changes in calcium, phosphate, and intact PTH were similar across ALP subgroups. In conclusion, oral alfacalcidol did not significantly affect cardiovascular outcomes irrespective of bone turnover status.

Vitamin D supplementation and risk of stroke: A meta-analysis of randomized controlled trials

Background

Previous observational studies have supported the hypothesis that vitamin D supplementation protects against stroke. However, several current intervention studies contradict this observation. Therefore, we conducted a meta-analysis to investigate further the association between vitamin D supplementation and the risk of stroke.

Methods

This meta-analysis was conducted in accordance with the PRISMA statement and included all the randomized controlled trials (RCTs) that analyzed the relationship between vitamin D supplementation and the risk of stroke. A literature search strategy was established, and the following Medical Search Terms (MeSH) were used: “vitamin D,” “Calcitriol,” “Calcifediol,” “Cholecalciferol,” “25-Hydroxyvitamin D 2,” “ergocalciferols,” “stroke,” and stroke-derived terms. We searched for articles published before January 2022 in several databases, namely, PubMed, Web of Science, EMBASE, and The Cochrane Library. We also reviewed references included in relevant published meta-analyses and searched the http://www.ClinicalTrials.gov website for additional RCTs. The Q test and I2 were utilized to assess the degree of heterogeneity among the studies. Review Manager 5.3 and STATA16.0 software programs were used to assess the literature quality and perform statistical analyses.

Results

In total, twenty-four RCTs (86,202 participants) were included. There was no statistical heterogeneity among the RCTs (I2 = 0.0%, P = 0.94) included in this meta-analysis. We determined that vitamin D supplementation was not associated with a reduced risk of stroke compared with the placebo (RR = 1.02, 95% CI: 0.93–1.13, P = 0.65). In total, 10 studies only included women, and 14 studies included women and men among the 24 RCTs. Therefore, we performed a subgroup analysis based on sex. After the subgroup analysis, the effect remained statistically insignificant (mixed-sex group: RR = 1.06, 95% CI: 0.93–1.22, P = 0.37, women group: RR = 0.98, 95% CI: 0.86–1.13, P = 0.80). The results were generally comparable, based on age, body mass index (BMI), follow-up period, baseline 25-hydroxyvitamin D (25(OH)D) levels, the designated endpoint, latitude, vitamin D dosage, type of vitamin D administered, and an absence or presence of concurrent calcium supplementation (P &gt; 0.05).

Conclusion

Our study revealed that additional vitamin D supplementation did not reduce the risk of stroke. Therefore, additional RCTs of similar design should not be encouraged to assess any association between vitamin D supplementation and reduced stroke risk.

Treatment of secondary hyperparathyroidism in non-dialysis CKD: an appraisal 2022s

The situation of secondary hyperparathyroidism (sHPT) in CKD patients not on dialysis (ND-CKD) is probably best characterised by the KDIGO CKD-MBD Update 2017 guideline 4.2.1 stating that the optimal PTH levels is not known in these stages. Furthermore, new caution became recommended with regard to the routine use of active vitamin D analogues in early CKD stages and moderate sHPT phenotypes, due to their potential risks for hypercalcaemia and hyperphosphataemia aggravation. Nevertheless, there is still a substantial clinical need to prevent the development of parathyroid gland autonomy with its associated consequences of bone and vascular damage including fracture risks and cardiovascular events. Therefore, we now attempt to review the current guideline-based and clinical practice management of sHPT in ND-CKD including their strengths and weaknesses, favouring individualised approaches respecting calcium and phosphate homeostasis. We further comment on extended-release calcifediol (ERC) as a new differential therapeutic option now also available in Europe, and on a potentially novel understanding of a required vitamin D saturation in more advanced CKD stages. There is no doubt, however, that knowledge gaps will remain in this issue unless powerful RCTs with hard and meaningful endpoints are performed.

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?

Vitamin D Analogues and Fracture Risk in Chronic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Vitamin D receptor agonists (VDRAs) are commonly prescribed in chronic kidney disease (CKD). However, their protective effects on bone remain controversial. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of VDRAs on fracture risk and bone mineral density (BMD) in adult patients with CKD. We searched MEDLINE, EMBASE, CENTRAL, ClinicalTrials.gov, and the WHO's International Clinical Trials Registry Platform databases from inception to June 19, 2021. We included RCTs comparing VDRAs, to placebo or another medication, in adults with CKD requiring or not dialysis. Conference abstracts and trials involving kidney transplant recipients and/or comparing VDRAs to antiresorptive or anabolic bone therapy were excluded. Primary outcome was fracture at any anatomical site. Secondary outcomes were BMD at femoral neck, lumbar spine, and/or total hip. Prespecified subgroup analyses were conducted according to baseline demographics, overall risk of bias, and follow-up time. From 6868 references retrieved, eight RCTs were eligible: five reported fracture, two reported BMD, and one reported both outcomes. As comparator, one study used no VDRAs, one used nutritional intervention and no medication, and six used placebo. In meta-analysis, VDRAs were not associated with a significant reduction in total fractures in overall (risk ratio = 0.79, 95% confidence interval 0.38-1.65, I2 = 0%, six trials, 1507 participants, 27 fractures) or in prespecified subgroup analyses. Three trials reported BMD at different sites and with different BMD measurements; thus, a meta-analysis could not be performed. Two RCTs were at high risk of bias, notably because of deviations from the intended interventions. As limitation, we have to mention the low total number of fractures included in our meta-analysis. In conclusion, current evidence from RCTs is insufficient to associate VDRAs with bone protection in CKD. Further large and long-term studies specifically designed to evaluate the efficacy of VDRAs on bone outcomes are thus required. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Interventions to Attenuate Vascular Calcification Progression in Chronic Kidney Disease: A Systematic Review of Clinical Trials

Background Vascular calcification is associated with cardiovascular morbidity and mortality in people with chronic kidney disease (CKD). Evidence-based interventions that may attenuate its progression in CKD remain uncertain.

Methods We conducted a systematic review of prospective clinical trials of interventions to attenuate vascular calcification in people with CKD, compare with placebo, another comparator, or standard of care. We included prospective clinical trials (randomized and nonrandomized) involving participants with stage 3-5D CKD or kidney transplant recipients; the outcome was vascular calcification measured using radiological methods. Quality of evidence was determined by the Cochrane risk of bias assessment tool and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) method.

Results There were 77 trials (63 randomized) involving 6898 participants eligible for inclusion (median sample size, 50; median duration, 12 months); 58 involved participants on dialysis, 15 involved individuals with nondialysis CKD, and 4 involved kidney transplant recipients. Risk of bias was moderate over all. Trials involving magnesium and sodium thiosulfate consistently showed attenuation of vascular calcification. Trials involving intestinal phosphate binders, alterations in dialysate calcium concentration, vitamin K therapy, calcimimetics, and antiresorptive agents had conflicting or inconclusive outcomes. Trials involving vitamin D therapy and HMG-CoA reductase inhibitors did not demonstrate attenuation of vascular calcification. Mixed results were reported for single studies of exercise, vitamin E-coated or high-flux hemodialysis membranes, interdialytic sodium bicarbonate, SNF472, spironolactone, sotatercept, nicotinamide, and oral activated charcoal.

Conclusions Currently, there are insufficient or conflicting data regarding interventions evaluated in clinical trials for mitigation of vascular calcification in people with CKD. Therapy involving magnesium or sodium thiosulfate appears most promising, but evaluable studies were small and of short duration.

Cardiac valve calcification is associated with mortality in hemodialysis patients: a retrospective cohort study

Background

Cardiac valve calcification (CVC) is common in end-stage renal disease (ESRD). We investigated the effect of CVC on all-cause and cardiovascular (CV) mortality in maintenance hemodialysis (MHD) patients.

Methods

A retrospective cohort study was conducted on 434 hemodialysis patients who underwent echocardiography for qualitative assessment of valve calcification with complete follow-up data from January 1, 2014, to April 30, 2021. The baseline data between the CVC and non-CVC groups were compared. The Kaplan–Meier method was used to analyse all-cause and cardiovascular mortality. The association of CVC with all-cause and cardiovascular mortality was evaluated using multivariate Cox regression analysis.

Results

Overall, 27.2% of patients had mitral valve calcification (MVC), and 31.8% had aortic valve calcification (AVC) on echocardiography. Patients with CVC showed significantly higher all-cause (log-rank P < 0.001) and cardiovascular (log-rank P < 0.001) mortality rates than patients without CVC. In multivariate regression analyses, MVC (HR: 1.517, P = 0.010) and AVC (HR: 1.433, P = 0.028) were significant factors associated with all-cause mortality. MVC (HR: 2.340, P < 0.001) and AVC (HR: 2.410, P < 0.001) were also significant factors associated with cardiovascular mortality.

Conclusions

MVC and AVC increased the risk of all-cause and cardiovascular mortality in MHD patients. Regular follow-up with echocardiography could be a useful method for risk stratification in MHD patients.

Vitamin D receptor gene polymorphism predicts left ventricular hypertrophy in maintenance hemodialysis

Background

To verify that the single nucleotide polymorphisms (SNP) of vitamin D receptor (VDR) may lead to genetic susceptibility to left ventricular hypertrophy (LVH), the present study was designed to study four SNPs of VDR associated with LVH in maintenance hemodialysis (MHD) patients of Han nationality.

Methods

120 MHD patients were recruited at Department of Nephrology, Zhongnan Hospital of Wuhan University to analyze the expression of genotype, allele and haplotype of Fok I, Bsm I, Apa I and Taq I in blood samples, and to explore their correlation with blood biochemical indexes and ventricular remodeling.

Results

The results showed that the risks of CVD included gender, dialysis time, heart rate, SBP, glycated hemoglobin, calcium, iPTH and CRP concentration. Moreover, LAD, LVDd, LVDs, IVST and LVMI in B allele of Bsm I increased significantly. Fok I, Apa I and Taq I polymorphisms have no significant difference between MHD with LVH and without LVH. Further study showed that VDR expression level decreased significantly in MHD patients with LVH, and the B allele was positively correlated with VDR Expression.

Conclusion

VDR Bsm I gene polymorphism may predict cardiovascular disease risk of MDH patients, and provided theoretical basis for early detection and prevention of cardiovascular complications.

Characterization of Medication Trends for Chronic Kidney Disease: Mineral and Bone Disorder Treatment Using Electronic Health Record-Based Common Data Model

Chronic kidney disease–mineral bone disorder (CKD-MBD) is the most common complication in CKD patients. Although there is a consensus on treatment guidelines for CKD-MBD, it remains uncertain whether these treatment recommendations reflect actual practice. Therefore, the aim of this study was to investigate the CKD-MBD medication trend in real-world practice. This was a retrospective and observational study using a 12-year period database transformed into a common data model from three tertiary university hospitals. Study populations were subjects initially diagnosed as CKD. The date of diagnosis was designated as the index date. New patients were categorized year to year from 2008 to 2019 with a fixed observation period of 365 days to check the prescription of CKD-MBD medications including calcium-containing phosphate binder, noncalcium-containing phosphate binder, aluminium hydroxide, vitamin D receptor activator (VDRA), and cinacalcet. The numbers of CKD patients in the three hospitals were 7555, 2424, and 5351, respectively. The proportion for patients with CKD-MBD medication prescription decreased yearly regardless of hospital and CKD stage (p for trend < 0.05). The use of aluminium hydroxide disappeared steadily while the use of VDRA increased annually in all settings. Despite these changes in prescription patterns, the mean value for CKD-MBD-related serologic markers was almost within target range. The proportion of the population within the target value was not significantly changed. Irrespective of hospital and CKD stage, similar trends of prescription for CKD-MBD medications were observed in real-world practice. Further research with a distributed network study may be helpful to understand medication trends in CKD-MBD treatment.

Relationship between selection of dosage forms of vitamin D receptor activators and short-term survival of patients on hemodialysis

BACKGROUND

The benefits of vitamin D receptor activators (VDRAs) for patients with chronic kidney disease are well recognized. However, the optimal criteria for patient selection, dosage forms, and duration providing the highest benefit and the least potential risk remain to be confirmed.

MATERIALS AND METHODS

The study population was derived from the Aichi Cohort Study of Prognosis in Patients Newly Initiated into Dialysis, a multicenter prospective cohort study of 1520 incident dialysis patients. According to the VDRA usage status in March 2015 (interim report), the 967 patients surviving after March 2015 were classified into three groups: without VDRA (NV, n = 177), oral VDRA (OV, n = 447), and intravenous VDRA (IV, n = 343). Mortality rates were compared using the log-rank test, and factors contributing to all-cause mortality were examined using both univariate and multivariate Cox proportional hazard regression analyses.

RESULTS

There were 104 deaths (NV, n = 27; OV, n = 53; IV, n = 24) during the follow-up period (1360 days, median), and significant differences in cumulative survival rates were observed between the three groups (p = 0.010). Moreover, lower all-cause mortality was associated with IV versus NV (hazard ratio, 0.46 [95% confidence interval 0.24-0.89]; p = 0.020).

CONCLUSION

This study demonstrated the impact of the VDRA dosage form on the short-term survival of incident hemodialysis patients during the introduction period. Our results suggest that relatively early initiation of intravenous VDRA in patients beginning hemodialysis may have some clinical potential.

Real-World Assessment: Clinical Effectiveness and Safety of Extended-Release Calcifediol

INTRODUCTION

The safety and efficacy of extended-release calcifediol (ERC) as a treatment for secondary hyperparathyroidism (SHPT) in adults with stage 3 or 4 chronic kidney disease (CKD) and vitamin D insufficiency (VDI) has been demonstrated in prospective randomized clinical trials (RCTs). ERC (Rayaldee®) was approved by the Food and Drug Administration in 2016 on the basis of these prospective RCTs. The current retrospective study assessed the postlaunch data available with respect to ERC's efficacy and safety in increasing serum 25-hydroxyvitamin D (25D) and reducing parathyroid hormone (PTH) in the indicated population.

MATERIALS AND METHODS

Medical records of 174 patients who met study criteria from 15 geographically representative United States nephrology clinics were reviewed for 1 year before and after initiation of ERC treatment. Enrolled subjects had ages ≥18 years, stage 3 or 4 CKD, and a history of SHPT and VDI. Key study variables included patient demographics, medication usage, and laboratory results, including serial 25D and PTH determinations.

RESULTS

The enrolled subjects had a mean age of 69.0 years, gender and racial distributions representative of the indicated population, and were balanced for CKD stage. Most (98%) received 30 mcg of ERC/day during the course of treatment (mean follow-up: 24 weeks). Baseline 25D and PTH levels averaged 20.3 ± 0.7 (standard error) ng/mL and 181 ± 7.4 pg/mL, respectively. ERC treatment raised 25D by 23.7 ± 1.6 ng/mL (p < 0.001) and decreased PTH by 34.1 ± 6.6 pg/mL (p < 0.001) with nominal changes of 0.1 mg/dL (p > 0.05) in serum calcium (Ca) and phosphorus (P) levels.

DISCUSSION/CONCLUSION

Analysis of postlaunch data confirmed ERC's effectiveness in increasing serum 25D and reducing PTH levels without statistically significant or notable impact on serum Ca and P levels. A significant percentage of these subjects achieved 25D levels ≥30 mg/mL and PTH levels which decreased by at least 30% from baseline. Dose titration to 60 mcgs was rarely prescribed. Closer patient monitoring and appropriate dose titration may have led to a higher percentage of subjects achieving an increase in 25D levels to at least 50 ng/mL and a reduction in PTH levels of at least 30%.

Active vitamin D increases the risk of hypercalcaemia in non-dialysis chronic kidney disease patients with secondary hyperparathyroidism: a systematic review and meta-analysis

Background

This study evaluates the effects of active (1α-hydroxylated) vitamin D (AVD) therapy on hypercalcaemia in patients with non-dialysis chronic kidney disease (ND-CKD) and secondary hyperparathyroidism (SHPT).

Methods

A systematic search of the PubMed, Embase and Cochrane Library databases (up to 14 May 2020) was performed to identify randomized, placebo-controlled trials of single-agent, oral AVD therapies in adults with ND-CKD and SHPT. Only studies with ≥30 participants per arm and ≥6 weeks in duration were eligible. The outcome of interest was the number of subjects with an episode of hypercalcaemia. A meta-analysis of eligible studies was conducted using Comprehensive Meta-Analysis software (version 3.0).

Results

Six studies (five evaluating paricalcitol, one evaluating alfacalcidol) involving 799 patients were identified. Treatment durations ranged from 16 weeks to 2 years. The weekly doses of paricalcitol administered were 7 (three studies) and 14 µg (two studies); the weekly dose of alfacalcidol was 1.75–7.0 µg. Across all studies, rates of hypercalcaemia were 1.1–43.3% with AVD versus 0–3.4% with placebo. Meta-analysis of the six studies showed that AVD was associated with a 6.6-fold greater probability of hypercalcaemia versus placebo (odds ratio: 6.63, 95% confidence interval: 2.37, 18.55; P < 0.001). Two separate sensitivity analyses (one excluded a study identified as having a high risk of bias; the second excluded two studies that accounted for a large proportion of observed hypercalcaemia events) indicated the primary meta-analysis findings were robust.

Conclusions

Compared with placebo, AVD significantly increased the risk of hypercalcaemia among ND-CKD patients with SHPT.

Impact of nutritional vitamin D supplementation on parathyroid hormone and 25-hydroxyvitamin D levels in non-dialysis chronic kidney disease: a meta-analysis

Background

Secondary hyperparathyroidism (SHPT) is a common and major complication in chronic kidney disease (CKD), reflecting the increase of parathyroid hormone (PTH) in response to reduced vitamin D signalling and hypocalcaemia. This meta-analysis evaluated the impact of nutritional vitamin D (NVD) (cholecalciferol or ergocalciferol) on SHPT-related biomarkers.

Methods

A systematic literature search was performed in PubMed to identify relevant randomized control trials to be included in the meta-analysis. Fixed- and random-effects models were used to pool study-level results. Effects were studied within NVD study arms and relative to control groups (placebo/no treatment); the former in order to identify the effect of actively altering biomarkers levels.

Results

Reductions in PTH from supplementation with NVD were small when observed within the NVD study arms (pooled reduction: 10.5 pg/mL) and larger when compared with placebo/no treatment (pooled reduction: 49.7 pg/mL). NVD supplementation increased levels of 25-hydroxyvitamin D [25(OH)D] in both analyses (increase within NVD study arm: 20.6 ng/mL, increase versus placebo/no treatment: 26.9 ng/mL). While small and statistically non-significant changes in phosphate and fibroblast growth factor 23 were observed, NVD supplementation caused calcium levels to increase when compared with placebo/no treatment (increase: 0.23 mg/dL).

Conclusions

Our results suggest that supplementation with NVD can be used to increase 25(OH)D to a certain extent, while the potential of NVD to actively reduce PTH in non-dialysis-CKD patients with SHPT is limited.

Key metalloproteinase-mediated pathways in the kidney

Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases (ADAMs) belong to the metzincin family of zinc-containing multidomain molecules, and can act as soluble or membrane-bound proteases. These enzymes inactivate or activate other soluble or membrane-expressed mediator molecules, which enables them to control developmental processes, tissue remodelling, inflammatory responses and proliferative signalling pathways. The dysregulation of MMPs and ADAMs has long been recognized in acute kidney injury and in chronic kidney disease, and genetic targeting of selected MMPs and ADAMs in different mouse models of kidney disease showed that they can have detrimental and protective roles. In particular, MMP-2, MMP-7, MMP-9, ADAM10 and ADAM17 have been shown to have a mainly profibrotic effect and might therefore represent therapeutic targets. Each of these proteases has been associated with a different profibrotic pathway that involves tissue remodelling, Wnt-β-catenin signalling, stem cell factor-c-kit signalling, IL-6 trans-signalling or epidermal growth factor receptor (EGFR) signalling. Broad-spectrum metalloproteinase inhibitors have been used to treat fibrotic kidney diseases experimentally but more targeted approaches have since been developed, including inhibitory antibodies, to avoid the toxic side effects initially observed with broad-spectrum inhibitors. These advances not only provide a solid foundation for additional preclinical studies but also encourage further translation into clinical research.

Vitamin D Supplementation for Patients with Chronic Kidney Disease: A Systematic Review and Meta-analyses of Trials Investigating the Response to Supplementation and an Overview of Guidelines

A large proportion of patients with chronic kidney disease (CKD) are vitamin D deficient (plasma 25-hydroxyvitamin D (25(OH)D) < 25 or 30 nmol/L per UK and US population guidelines) and this contributes to the development of CKD-mineral bone disease (CKD-MBD). Gaps in the evidence-base for the management of vitamin D status in relation to CKD-MBD are hindering the formulation of comprehensive guidelines. We conducted a systemic review of 22 RCTs with different forms of vitamin D or analogues with CKD-MBD related outcomes and meta-analyses for parathyroid hormone (PTH). We provide a comprehensive overview of current guidelines for the management of vitamin D status for pre-dialysis CKD patients. Vitamin D supplementation had an inconsistent effect on PTH concentrations and meta-analysis showed non- significant reduction (P = 0.08) whereas calcifediol, calcitriol and paricalcitol consistently reduced PTH. An increase in Fibroblast Growth Factor 23 (FGF23) with analogue administration was found in all 3 studies reporting FGF23, but was unaltered in 4 studies with vitamin D or calcifediol. Few RCTS reported markers of bone metabolism and variations in the range of markers prevented direct comparisons. Guidelines for CKD stages G1-G3a follow general population recommendations. For the correction of deficiency general or CKD-specific patient guidelines provide recommendations. Calcitriol or analogues administration is restricted to stages G3b-G5 and depends on patient characteristics. In conclusion, the effect of vitamin D supplementation in CKD patients was inconsistent between studies. Calcifediol and analogues consistently suppressed PTH, but the increase in FGF23 with calcitriol analogues warrants caution.

Association between Vitamin D and Risk of Stroke: A PRISMA-Compliant Systematic Review and Meta-Analysis

BACKGROUND

Previous studies have shown inconsistent results for associations between vitamin D and risk of stroke. We gathered the existing published articles and conducted this meta-analysis with the aim to explore the association between vitamin D and risk of stroke.

METHODS

We searched for articles exploring the association between vitamin D and risk of stroke and published before April 2021 in the following databases: PubMed, Web of Science, MEDLINE, EMBASE, and Google Scholar. All statistical analyses were made using STATA 12.0 software. Q test and I2 were applied to examine heterogeneities between studies.

RESULTS

For the association between serum levels of 25(OH) vitamin D and risks of stroke, the present analysis included 20 cohort studies (including 213,276 participants) and a case-control analysis (including 13,642 participants). Additionally, the analysis included 15 studies (including 41,146 participants given vitamin D supplementation and 41,163 participants given placebo) to evaluate the influence of vitamin D supplementation on risk of stroke. Higher circulating levels of 25(OH) vitamin D were associated with a reduced risk of stroke (odds ratio/relative risk = 0.78, 95% confidence interval [CI]: 0.70-0.86, I2 = 41.5%, p = 0.025). However, the present analysis showed that vitamin D supplementation did not influence the risk of stroke (hazard ratio = 1.05, 95% CI: 0.96-1.14, I2 = 2.3%, p = 0.425).

CONCLUSIONS

Our analysis indicated that lower circulating level of vitamin D was associated with an elevated risk of stroke, but extra supplement of vitamin D failed to show benefit in decreasing the risk of stroke. Further research and study are also needed to show the role of vitamin D in relation to stroke.

Impact of vitamin D on cardiac structure and function in chronic kidney disease patients with hypovitaminosis D: a randomized controlled trial and meta-analysis

AIMS

Vitamin D deficiency is associated with cardiovascular events in chronic kidney disease (CKD) yet the impact of supplementation is controversial. Previous active vitamin D supplementation studies did not show improvement in cardiac structure or function but the effect of native vitamin D supplementation in CKD patients with low vitamin D levels is unknown. We have addressed this question via both a randomized double-blind prospective study and a meta-analysis of three randomized placebo-controlled studies.

METHODS AND RESULTS

We conducted a randomized double-blind, placebo-controlled trial of vitamin D supplementation in stable, non-diabetic, CKD three to four patients with circulating vitamin D <75nmol/L, who were receiving treatment with ACEi or ARB and had high-normal left ventricular (LV) mass. Patients were randomized to receive six directly observed doses of 100 000 IU cholecalciferol (n = 25) or matched placebo (n = 23). The primary endpoint was changed in LV mass index (LVMI) over 52 weeks, as assessed by cardiac magnetic resonance imaging. Secondary endpoints included changes in LV ejection fraction (LVEF); LV and right ventricular volumes and left and right atrial area. Vitamin D concentration increased with the administration of cholecalciferol. The change in LVMI with cholecalciferol [median (inter-quartile range), -0.25 g (-7.20 to 5.30)] was no different from placebo [-4.30 g (9.70 to 2.60)]. There was no difference in changes of LVEF; LV and right ventricular volumes and left and right atrial area. The meta-analysis of three 52-week, randomized placebo-controlled studies using active/native vitamin D supplementation showed no differences in LVMI measurements.

CONCLUSION

Vitamin D supplementation does not have beneficial effects on LV mass in CKD patients.

Effects of calcitriol and paricalcitol on renal fibrosis in CKD

BACKGROUND

In chronic kidney disease, the activation of the renin-angiotensin-aldosterone system (RAAS) and renal inflammation stimulates renal fibrosis and the progression to end-stage renal disease. The low levels of vitamin D receptor (VDR) and its activators (VDRAs) contribute to worsen secondary hyperparathyroidism and renal fibrosis.

METHODS

The 7/8 nephrectomy model of experimental chronic renal failure (CRF) was used to examine the anti-fibrotic effects of treatment with two VDRAs, paricalcitol and calcitriol, at equivalent doses (3/1 dose ratio) during 4 weeks.

RESULTS

CRF increased the activation of the RAAS, renal inflammation and interstitial fibrosis. Paricalcitol treatment reduced renal collagen I and renal interstitial fibrosis by decreasing the activation of the RAAS through renal changes in renin, angiotensin receptor 1 (ATR1) and ATR2 mRNAs levels and renal inflammation by decreasing renal inflammatory leucocytes (CD45), a desintegrin and metaloproteinase mRNA, transforming growth factor beta mRNA and protein, and maintaining E-cadherin mRNA levels. Calcitriol showed similar trends without significant changes in most of these biomarkers.

CONCLUSIONS

Paricalcitol effectively attenuated the renal interstitial fibrosis induced by CRF through a combination of inhibitory actions on the RAAS, inflammation and epithelial/mesenchymal transition.

Where are we now? Emerging opportunities and challenges in the management of secondary hyperparathyroidism in patients with non-dialysis chronic kidney disease

Abstract

Rising levels of parathyroid hormone (PTH) are common in patients with chronic kidney disease (CKD) not on dialysis and are associated with an elevated risk of morbidity (including progression to dialysis) and mortality. However, there are several challenges for the clinical management of secondary hyperparathyroidism (SHPT) in this population. While no recognised target level for PTH currently exists, it is accepted that patients with non-dialysis CKD should receive early and regular monitoring of PTH from CKD stage G3a. However, studies indicate that adherence to monitoring recommendations in non-dialysis CKD may be suboptimal. SHPT is linked to vitamin D [25(OH)D] insufficiency in non-dialysis CKD, and correction of low 25(OH)D levels is a recognised management approach. A second challenge is that target 25(OH)D levels are unclear in this population, with recent evidence suggesting that the level of 25(OH)D above which suppression of PTH progressively diminishes may be considerably higher than that recommended for the general population. Few therapeutic agents are licensed for use in non-dialysis CKD patients with SHPT and optimal management remains controversial. Novel approaches include the development of calcifediol in an extended-release formulation, which has been shown to increase 25(OH)D gradually and provide a physiologically-regulated increase in 1,25(OH)₂D that can reliably lower PTH in CKD stage G3–G4 without clinically meaningful increases in serum calcium and phosphate levels. Additional studies would be beneficial to assess the comparative effects of available treatments, and to more clearly elucidate the overall benefits of lowering PTH in non-dialysis CKD, particularly in terms of hard clinical outcomes.

Graphic abstract

Current treatment options for secondary hyperparathyroidism in patients with stage 3 to 4 chronic kidney disease and vitamin D deficiency

Introduction: Secondary hyperparathyroidism (SHPT) represents a complication of chronic kidney disease (CKD). Vitamin D system is altered since early CKD, and vitamin D deficiency is an established trigger of SHPT. Although untreated SHPT may degenerate into tertiary hyperparathyroidism with detrimental consequences in advanced CKD, best treatments for counteracting SHPT from stage 3 CKD are still debated. Enthusiasm on prescription of vitamin D receptor activators (VDRA) in non-dialysis renal patients, has been mitigated by the risk of low bone turnover and positive calcium-phosphate balance. Nutritional vitamin D is now suggested as first-line therapy to treat SHPT with low 25(OH)D insufficiency. However, no high-grade evidence supports the best choice between ergocalciferol, cholecalciferol, and calcifediol (in its immediate or extended-release formulation).Areas covered: The review discusses available data on safety and efficacy of nutritional vitamin D, VDRA and nutritional therapy in replenishing 25(OH)D deficiency and counteracting SHPT in non-dialysis CKD patients.Expert opinion: Best treatment for low 25(OH)D and SHPT remains unknown, due to incomplete understanding of the best homeostatic, as mutable, adaptation of mineral metabolism to CKD progression. Nutritional vitamin D and nutritional therapy appear safest interventions, whenever contextualized with single-patient characteristics. VDRA should be restricted to uncontrolled SHPT by first-line therapy.

Clinical Approach to Vascular Calcification in Patients With Non-dialysis Dependent Chronic Kidney Disease: Mineral-Bone Disorder-Related Aspects

Chronic kidney disease (CKD) is associated with a very high morbimortality, mainly from cardiovascular origin, and CKD is currently considered in the high- or very high risk- cardiovascular risk category. CKD-mineral and bone disorders (CKD-MBDs), including vascular and/or valvular calcifications, are also associated with these poor outcomes. Vascular calcification (VC) is very prevalent (both intimal and medial), even in non-dialysis dependent patients, with a greater severity and more rapid progression. Simple X-ray based-scores such as Adragão's (AS) are useful prognostic tools and AS (even AS based on hand-X-ray only) may be superior to the classic Kauppila's score when evaluating non-dialysis CKD patients. Thus, in this mini-review, we briefly review CKD-MBD-related aspects of VC and its complex pathophysiology including the vast array of contributors and inhibitors. Furthermore, although VC is a surrogate marker and is not yet considered a treatment target, we consider that the presence of VC may be relevant in guiding therapeutic interventions, unless all patients are treated with the mindset of reducing the incidence or progression of VC with the currently available armamentarium. Avoiding phosphate loading, restricting calcium-based phosphate binders and high doses of vitamin D, and avoiding normalizing (within the normal limits for the assay) parathyroid hormone levels seem logical approaches. The availability of new drugs and future studies, including patients in early stages of CKD, may lead to significant improvements not only in patient risk stratification but also in attenuating the accelerated progression of VC in CKD.

Active vitamin D is cardioprotective in experimental uraemia but not in children with CKD Stages 3-5

BACKGROUND

Uraemic cardiac remodelling is associated with vitamin D and Klotho deficiency, elevated fibroblast growth factor 23 (FGF23) and activation of the renin-angiotensin system (RAS). The cardioprotective properties of active vitamin D analogues in this setting are unclear.

METHODS

In rats with 5/6 nephrectomy (5/6Nx) treated with calcitriol, the cardiac phenotype and local RAS activation were investigated compared with controls. A nested case-control study was performed within the Cardiovascular Comorbidity in Children with Chronic Kidney Disease (4C) study, including children with chronic kidney disease (CKD) Stages 3-5 [estimated glomerular filtration rate (eGFR) 25 mL/min/1.73 m2] treated with and without active vitamin D. Echocardiograms, plasma FGF23 and soluble Klotho (sKlotho) were assessed at baseline and after 9 months.

RESULTS

In rats with 5/6Nx, left ventricular (LV) hypertrophy, LV fibrosis and upregulated cardiac RAS were dose-dependently attenuated by calcitriol. Calcitriol further stimulated FGF23 synthesis in bone but not in the heart, and normalized suppressed renal Klotho expression. In the 4C study cohort, treatment over a mean period of 9 months with active vitamin D was associated with increased FGF23 and phosphate and decreased sKlotho and eGFR compared with vitamin D naïve controls, whereas LV mass index did not differ between groups.

CONCLUSIONS

Active vitamin D ameliorates cardiac remodelling and normalizes renal Klotho expression in 5/6Nx rats but does not improve the cardiac phenotype in children with CKD Stages 3-5. This discrepancy may be due to further enhancement of circulating FGF23 and faster progression of CKD associated with reduced sKlotho and higher serum phosphate in vitamin D-treated patients.

Vitamin D Effects on Bone Homeostasis and Cardiovascular System in Patients with Chronic Kidney Disease and Renal Transplant Recipients

Poor vitamin D status is common in patients with impaired renal function and represents one main component of the complex scenario of chronic kidney disease-mineral and bone disorder (CKD-MBD). Therapeutic and dietary efforts to limit the consequences of uremia-associated vitamin D deficiency are a current hot topic for researchers and clinicians in the nephrology area. Evidence indicates that the low levels of vitamin D in patients with CKD stage above 4 (GFR < 15 mL/min) have a multifactorial origin, mainly related to uremic malnutrition, namely impaired gastrointestinal absorption, dietary restrictions (low-protein and low-phosphate diets), and proteinuria. This condition is further worsened by the compromised response of CKD patients to high-dose cholecalciferol supplementation due to the defective activation of renal hydroxylation of vitamin D. Currently, the literature lacks large and interventional studies on the so-called non-calcemic activities of vitamin D and, above all, the modulation of renal and cardiovascular functions and immune response. Here, we review the current state of the art of the benefits of supplementation with native vitamin D in various clinical settings of nephrological interest: CKD, dialysis, and renal transplant, with a special focus on the effects on bone homeostasis and cardiovascular outcomes.

Comparative Effects of Etelcalcetide and Maxacalcitol on Serum Calcification Propensity in Secondary Hyperparathyroidism: A Randomized Clinical Trial

BACKGROUND AND OBJECTIVES

Vitamin D receptor activators and calcimimetics (calcium-sensing receptor agonists) are two major options for medical treatment of secondary hyperparathyroidism. A higher serum calcification propensity (a shorter T₅₀ value) is a novel surrogate marker of calcification stress and mortality in patients with CKD. We tested a hypothesis that a calcimimetic agent etelcalcetide is more effective in increasing T₅₀ value than a vitamin D receptor activator maxacalcitol.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A randomized, multicenter, open-label, blinded end point trial with active control was conducted in patients with secondary hyperparathyroidism undergoing hemodialysis in Japan. Patients were randomly assigned to receive intravenous etelcalcetide 5 mg thrice weekly (etelcalcetide group) or intravenous maxacalcitol 5 or 10 µg thrice weekly (maxacalcitol group). The primary, secondary, and tertiary outcomes were changes in T₅₀ value, handgrip strength, and score of the Dementia Assessment Sheet for Community-Based Integrated Care System from baseline to 12 months, respectively.

RESULTS

In total, 425 patients from 23 dialysis centers were screened for eligibility, 326 patients were randomized (etelcalcetide, n=167; control, n=159), and 321 were included in the intention-to-treat analysis (median age, 66 years; 113 women [35%]). The median (interquartile range) of T₅₀ value was changed from 116 minutes (interquartile range, 90-151) to 131 minutes (interquartile range, 102-176) in the maxacalcitol group, whereas it was changed from 123 minutes (interquartile range, 98-174) to 166 minutes (interquartile range, 127-218) in the etelcalcetide group. The increase in T₅₀ value was significantly greater in the etelcalcetide group (difference in change, 20 minutes; 95% confidence interval, 7 to 34 minutes; P=0.004). No significant between-group difference was found in the change in handgrip strength or in the Dementia Assessment Sheet for Community-Based Integrated Care System score.

CONCLUSIONS

Etelcalcetide was more effective in increasing T₅₀ value than maxacalcitol among patients on hemodialysis with secondary hyperparathyroidism. There was no difference in handgrip strength or cognition between the two drugs.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

VICTORY; UMIN000030636 and jRCTs051180156.

Old and New Drugs for the Management of Bone Disorders in CKD

Disturbances in mineral and bone metabolism are common in patients with chronic kidney disease (CKD), especially those undergoing dialysis. Renal osteodystrophy, which describes an alteration of bone morphology, is an important component of this systemic disorder and may explain the elevated risk of fracture which adversely affects morbidity and mortality. The most common form of renal osteodystrophy is high-turnover bone disease (osteitis fibrosa), which is induced by secondary hyperparathyroidism (SHPT). During the past decade, there has been considerable advances in the management of SHPT, with the introduction of the calcimimetic agents, the optimized use of nutritional and active vitamin D, and the accumulated experience with surgical parathyroidectomy. Studies supported that these advances could translate into improvement of renal bone disease and fracture prevention, as well as decreasing the risk of cardiovascular events and mortality. In this review, we summarize the available clinical evidence on the effect of old and new drugs on bone disorders in patients with CKD.

Are Nutraceuticals Beneficial in Chronic Kidney Disease?

Chronic kidney disease (CKD) is a worldwide health problem in which prevalence is constantly rising. The pathophysiology of CKD is complicated and has not been fully resolved. However, elevated oxidative stress is considered to play a vital role in the development of this disease. CKD is also thought to be an inflammatory disorder in which uremic toxins participate in the development of the inflammatory milieu. A healthy, balanced diet supports the maintenance of a good health status as it helps to reduce the risk of the development of chronic diseases, including chronic kidney disease, diabetes mellitus, and hypertension. Numerous studies have demonstrated that functional molecules and nutrients, including fatty acids and fiber as well as nutraceuticals such as curcumin, steviol glycosides, and resveratrol not only exert beneficial effects on pro-inflammatory and anti-inflammatory pathways but also on gut mucosa. Nutraceuticals have attracted great interest recently due to their potential favorable physiological effects on the human body and their safety. This review presents some nutraceuticals in which consumption could exert a beneficial impact on the development and progression of renal disease as well cardiovascular disease.

Most exposed: the endothelium in chronic kidney disease

Accumulating evidence indicates that the pathological changes of the endothelium may contribute to the development of cardiovascular complications in chronic kidney disease (CKD). Non-traditional risk factors related to CKD are associated with the incidence of cardiovascular disease, but their role in uraemic endothelial dysfunction has often been disregarded. In this context, soluble α-Klotho and vitamin D are of importance to maintain endothelial integrity, but their concentrations decline in CKD, thereby contributing to the dysfunction of the endothelial lining. These hormonal disturbances are accompanied by an increment of circulating fibroblast growth factor-23 and phosphate, both exacerbating endothelial toxicities. Furthermore, impaired renal function leads to an increment of inflammatory mediators, reactive oxygen species and uraemic toxins that further aggravate the endothelial abnormalities and in turn also inhibit the regeneration of disrupted endothelial lining. Here, we highlight the distinct endothelial alterations mediated by the abovementioned non-traditional risk factors as demonstrated in experimental studies and connect these to pathological changes in CKD patients, which are driven by endothelial disturbances, other than atherosclerosis. In addition, we describe therapeutic strategies that may promote restoration of endothelial abnormalities by modulating imbalanced mineral homoeostasis and attenuate the impact of uraemic retention molecules, inflammatory mediators and reactive oxygen species. A clinical perspective on endothelial dysfunction in CKD may translate into reduced structural and functional abnormalities of the vessel wall in CKD, and ultimately improved cardiovascular disease.

The risk of medically uncontrolled secondary hyperparathyroidism depends on parathyroid hormone levels at haemodialysis initiation

BACKGROUND

Optimal parathyroid hormone (PTH) control during non-dialysis chronic kidney disease (ND-CKD) might decrease the subsequent risk of parathyroid hyperplasia and uncontrolled secondary hyperparathyroidism (SHPT) on dialysis. However, the evidence for recommending PTH targets and therapeutic strategies is weak for ND-CKD. We evaluated the patient characteristics, treatment patterns and PTH control over the first year of haemodialysis (HD) by PTH prior to HD initiation.

METHODS

We studied 5683 incident HD patients from 21 countries in Dialysis Outcomes and Practice Patterns Study Phases 4-6 (2009-18). We stratified by PTH measured immediately prior to HD initiation and reported the monthly prescription prevalence of active vitamin D and calcimimetics over the first year of HD and risk of PTH >600 pg/mL after 9-12 months on HD.

RESULTS

The 16% of patients with PTH >600 pg/mL prior to HD initiation were more likely to be prescribed active vitamin D and calcimimetics during the first year of HD. The prevalence of PTH >600 pg/mL 9-12 months after start of HD was greater for patients who initiated HD with PTH >600 (29%) versus 150-300 (7%) pg/mL (adjusted risk difference: 19%; 95% confidence interval : 15%, 23%). The patients with sustained PTH >600 pg/mL after 9-12 months on HD were younger, more likely to be black, and had higher serum phosphorus and estimated glomerular filtration rates at HD initiation.

CONCLUSIONS

Increased PTH before HD start predicted a higher PTH level 9-12 months later, despite greater use of active vitamin D and calcimimetics. More targeted PTH control during ND-CKD may influence outcomes during HD, raising the need for PTH target guidelines in these patients.

Differences in 25-Hydroxyvitamin D Clearance by eGFR and Race: A Pharmacokinetic Study

BACKGROUND

Conversion of 25-hydroxyvitamin D (25[OH]D) to the active form of vitamin D occurs primarily in the kidney. Observational studies suggest 25(OH)D clearance from the circulation differs by kidney function and race. However, these potential variations have not been tested using gold-standard methods.

METHODS

We administered intravenous, deuterated 25(OH)D3 (d-25[OH]D3) in a pharmacokinetic study of 87 adults, including 43 with normal eGFR (≥60 ml/min per 1.73 m2), 24 with nondialysis CKD (eGFR <60 ml/min per 1.73 m2), and 20 with ESKD treated with hemodialysis. We measured concentrations of d-25(OH)D3 and deuterated 24,25-dihydroxyvitamin D3 at 5 minutes and 4 hours after administration, and at 1, 4, 7, 14, 21, 28, 42, and 56 days postadministration. We calculated 25(OH)D clearance using noncompartmental analysis of d-25(OH)D3 concentrations over time. We remeasured 25(OH)D clearance in a subset of 18 participants after extended oral vitamin-D3 supplementation.

RESULTS

The mean age of the study cohort was 64 years; 41% were female, and 30% were Black. Mean 25(OH)D clearances were 360 ml/d, 313 ml/d, and 263 ml/d in participants with normal eGFR, CKD, and kidney failure, respectively (P=0.02). After adjustment for age, sex, race, and estimated blood volume, lower eGFR was associated with reduced 25(OH)D clearance (β=-17 ml/d per 10 ml/min per 1.73 m2 lower eGFR; 95% CI, -21 to -12). Black race was associated with higher 25(OH)D clearance in participants with normal eGFR, but not in those with CKD or kidney failure (P for interaction=0.05). Clearance of 25(OH)D before versus after vitamin-D3 supplementation did not differ.

CONCLUSIONS

Using direct pharmacokinetic measurements, we show that 25(OH)D clearance is reduced in CKD and may differ by race.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Clearance of 25-hydroxyvitamin D in Chronic Kidney Disease (CLEAR), NCT02937350; Clearance of 25-hydroxyvitamin D3 During Vitamin D3 Supplementation (CLEAR-PLUS), NCT03576716.