Effect of cholecalciferol on local arterial stiffness and endothelial dysfunction in children with chronic kidney disease

Changes in bone biomarkers in response to different dosing regimens of cholecalciferol supplementation in children with chronic kidney disease

BACKGROUND

The effect of different dosing regimens of cholecalciferol supplementation on bone biomarkers has not been studied in children with chronic kidney disease (CKD).

METHODS

This is a post hoc analysis of a multi-center randomized controlled trial which included children with CKD stages 2-4 with vitamin D deficiency (25-hydroxy vitamin D (25OHD) < 30 ng/ml) randomized 1:1:1 to receive an equivalent dose of oral cholecalciferol as daily, weekly or monthly treatment. Markers of bone formation (bone alkaline phosphatase (BAP), procollagen I N terminal peptide (PINP)), bone resorption (tartarate-resistant acid phosphatase 5b (TRAP), C terminal telopeptide (CTX)), and osteocyte markers (intact fibroblast growth factor 23 (iFGF23), sclerostin) and soluble klotho were measured at baseline and after 3 months of intensive replacement therapy. The change in biomarkers and ratio of markers of bone formation to resorption were compared between treatment arms. BAP and TRAP were expressed as age- and sex-specific z-scores.

RESULTS

25OHD levels increased with cholecalciferol supplementation, with 85% achieving normal levels. There was a significant increase in the BAP/TRAP ratio (p = 0.04), iFGF23 (p = 0.004), and klotho (p = 0.002) with cholecalciferol therapy, but this was comparable across all three therapy arms. The BAPz was significantly higher in the weekly arm (p = 0.01). The change in 25OHD (Δ25OHD) inversely correlated with ΔPTH (r =  - 0.4, p < 0.001).

CONCLUSIONS

Although cholecalciferol supplementation was associated with a significant increase in bone formation, the three dosing regimens of cholecalciferol supplementation have a comparable effect on the bone biomarker profile, suggesting that they can be used interchangeably to suit the patient's needs and optimize adherence to therapy. A higher resolution version of the Graphical abstract is available as Supplementary information.

A Retrospective Study on Vitamin D Status and Its Association With Cardiometabolic Risk Factors Among Children With Chronic Kidney Disease at King Abdulaziz University Hospital

BACKGROUND

Vitamin D deficiency is a significant global health issue. It is prevalent in chronic kidney disease (CKD) patients, which is an important cause of death among children. Many studies have found a link between low vitamin D status in CKD patients and cardiovascular disease (CVD) risk factors. However, there are no data on this relationship in children with CKD in Saudi Arabia.

AIMS

We aimed to demonstrate this association among children with CKD admitted to the King Abdulaziz University Hospital (KAUH) in Jeddah, Saudi Arabia.

MATERIALS AND METHODS

Data were collected between June and August 2020 from a convenience sample of pediatric patients.

RESULTS

In total, 153 pediatric patients with CKD stages 2-5 were admitted to the KAUH between 2010 and 2019, and 67.3% had CKD stage 5. Approximately 4.6% and 10.5% of the participants were overweight or obese, respectively. Patients who fell into the lower 25-hydroxyvitamin D (25[OH]D) tertile were older, had higher body mass index (BMI) values, and had higher blood pressure than those in the upper two tertiles; however, these differences were not statistically significant. There was a significant inverse association of 25(OH)D levels with BMI, blood pressure, and serum creatinine levels.

CONCLUSIONS

The results of this retrospective study suggest that patients with CKD and lower vitamin D levels have a higher BMI and blood pressure and are therefore at higher risk of developing CVD. Future prospective studies with a larger sample size are needed to confirm these findings. Randomized clinical trials are also needed to investigate the effect of sufficient vitamin D status on reducing CVD in patients with CKD.

Vitamin D and the Kidney: Two Players, One Console

Vitamin D belongs to the group of liposoluble steroids mainly involved in bone metabolism by modulating calcium and phosphorus absorption or reabsorption at various levels, as well as parathyroid hormone production. Recent evidence has shown the extra-bone effects of vitamin D, including glucose homeostasis, cardiovascular protection, and anti-inflammatory and antiproliferative effects. This narrative review provides an overall view of vitamin D’s role in different settings, with a special focus on chronic kidney disease and kidney transplant.

Effect of vitamin D supplementation on markers of cardiometabolic risk in children and adolescents: A meta-analysis of randomized clinical trials

BACKGROUND AND AIMS

An increasing attention to the effect of vitamin D supplementation on cardiometabolic risk markers in children and adolescents has been gained recently. However, the results are inconsistent. Therefore, we conducted a meta-analysis to examine the effect of vitamin D supplementation on cardiometabolic risk markers in children and adolescents.

METHODS AND RESULTS

Eligible randomized controlled trials (RCTs) were identified by searching PubMed, EMBASE and Web of Science. The results of this study are synthetized and reported in accordance with the PRISMA statement. GRADE system was used to assess the certainty of evidence. A total of 9 RCTs were identified and included in the meta-analysis. We found that vitamin D supplementation did not affect the changes of cardiometabolic risk markers including high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG), body mass index (BMI), waist circumferences, systolic blood pressure (SDP) and diastolic blood pressure (DBP). However, vitamin D supplementation showed a beneficial effect on fasting glucose (MD, -1.54 mg/dl, 95% CI -2.98 to -0.10) and TG (MD, -24.76 mg/dl, 95% CI -37.66 to -11.86) in the sub-group analysis of total vitamin D supplementation ≥ 200,000 IU.

CONCLUSIONS

Vitamin D supplementation appeared to have a beneficial effect on reducing fasting glucose and TG level when total vitamin D supplementation ≥200,000 IU but not HDL-C, LDL-C TC, blood pressure and waist circumferences levels in children and adolescents. Further studies are needed to address this issue.

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.

Implications of oxidative stress in chronic kidney disease: a review on current concepts and therapies

Moderate levels of endogenous reactive oxygen species (ROS) are important for various cellular activities, but high levels lead to toxicity and are associated with various diseases. Levels of ROS are maintained as a balance between oxidants and antioxidants. Accumulating data suggest that oxidative stress is a major factor in deterioration of renal function. In this review, we highlight the possible mechanism by which oxidative stress can lead to chronic kidney disease (CKD). This review also describes therapies that counter the effect of oxidative stress in CKD patients. Numerous factors such as upregulation of genes involved in oxidative phosphorylation and ROS generation, chronic inflammation, vitamin D deficiency, and a compromised antioxidant defense mechanism system cause progressive detrimental effects on renal function that eventually lead to loss of kidney function. Patients with renal dysfunction are highly susceptible to oxidative stress, as risk factors such as diabetes, renal hypertension, dietary restrictions, hemodialysis, and old age predispose them to increased levels of ROS. Biomolecular adducts (DNA, proteins, and lipids) formed due to reaction with ROS can be used to determine oxidative stress levels. Based on the strong correlation between oxidative stress and CKD, reversal of oxidative stress is being explored as a major therapeutic option. Xanthine oxidase inhibitors, dietary antioxidants, and other agents that scavenge free radicals are gaining interest as treatment modalities in CKD patients.

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.

Vitamin D and Stroke: Effects on Incidence, Severity, and Outcome and the Potential Benefits of Supplementation

Vitamin D serum level has been positively associated with improved cardiovascular health, especially with reduction of stroke risk. This systemic review summarizes and synthesizes findings from studies relevant to the relationship between vitamin D and stroke risk, severity, and outcome; potential mechanisms explaining such a relationship; and outcomes from vitamin D supplementation. The literature shows that vitamin D deficiency is a significant risk factor for ischemic stroke, with sun exposure, sex, age, race, diabetes, and genetics playing a role as well. Stroke severity and short- and long-term outcomes also worsen with vitamin D deficiency. The neuroprotective mechanisms by which vitamin D operates to mitigate stroke onset and outcomes have yet to be fully studied, but researchers have proposed several pathways, including promotion of certain neuroprotective growth factors, reduction of arterial pressure through vasodilation, and inhibition of reactive oxygen species. There is some evidence that vitamin D supplementation could lower stroke risk and improve recovery, though outcomes can also be negligible or negative. Although results are mixed and the limitations of vitamin D supplementation merit some caution, vitamin D overall plays a significant role in stroke health. Future research should further develop understanding of the neuroprotective mechanisms of vitamin D and study how supplementation could be administered effectively in stroke treatment.

Vitamin D and cardiovascular disease in chronic kidney disease

Chronic kidney disease (CKD) is considered an independent risk factor for cardiovascular disease, with increased cardiovascular morbidity and mortality seen even in the early stages of CKD. Several studies have shown a high prevalence of vitamin D deficiency in individuals with CKD. Low vitamin D levels upregulate the renin-angiotensin-aldosterone system (RAAS), cause endothelial dysfunction, and increase inflammation. Epidemiological studies show an association between vitamin D deficiency and risk factors for cardiovascular disease, but a causal relationship has not been established. The high cardiovascular morbidity and mortality associated with CKD in adults requires therapies to decrease this elevated risk. However, results from several meta-analyses and randomized clinical trials in adults have not shown convincing evidence for the use of vitamin D therapy in improving cardiovascular outcomes. Lack of high-quality evidence from randomized clinical trials in children regarding the effectiveness and long-term safety of vitamin D treatment precludes any recommendations on its use to mitigate the cardiovascular burden of CKD.

Effect of atorvastatin on dyslipidemia and carotid intima-media thickness in children with refractory nephrotic syndrome: a randomized controlled trial

BACKGROUND

Dyslipidemia is an important cardiovascular risk factor in steroid-resistant nephrotic syndrome (SRNS). Efficacy of statins for treatment of hyperlipidemia in children with SRNS is unclear.

METHODS

This prospective, randomized, double-blind, placebo-controlled, parallel-group clinical trial enrolled 30 patients with SRNS, aged 5-18 years, with serum low-density lipoprotein cholesterol (LDL-C) levels between 130 and 300 mg/dl, to receive a fixed dose of atorvastatin (n = 15, 10 mg/d) or placebo (n = 15) by block randomization in a 1:1 ratio. Primary outcome was change in serum LDL-C at 12 months. Change in levels of other lipid fractions, carotid intima-media thickness (cIMT), flow-mediated dilation (FMD) of the brachial artery, and adverse events were also evaluated.

RESULTS

At the end of 12 months, atorvastatin was not superior to placebo in reducing plasma LDL-C levels, median percentage reduction 15.8% and 9.5% respectively, in atorvastatin and placebo arms (n = 14 in each; P = 0.40). Apolipoprotein B levels significantly declined with atorvastatin in modified intention-to-treat analysis (P = 0.01) but not in the per-protocol analysis. There was no significant effect on other lipid fractions, cIMT and FMD. Adverse events were similar between groups. Change in serum albumin was negatively associated with change in serum LDL-C, very low-density lipoprotein cholesterol, total cholesterol, triglyceride, and apolipoprotein B (P < 0.001), irrespective of receiving atorvastatin, age, gender, body mass index, and serum creatinine.

CONCLUSIONS

Atorvastatin, administered at a fixed daily dose of 10 mg, was not beneficial in lowering lipid levels in children with SRNS; rise in serum albumin was associated with improvement in dyslipidemia.

Improvements in peripheral vascular function with vitamin D treatment in deficient adolescents with type 1 diabetes

BACKGROUND

Vitamin D (VitD) deficiency is prevalent in adolescents with type 1 diabetes (T1D) and is associated with diabetes-related vascular complications in adulthood. The objective of this clinical trial was to assess VitD treatment on endothelial function (EF) and markers of renal inflammation, in this patient group.

METHODS

Adolescents with T1D with suboptimal levels of VitD (<37.5 nmol/L) were treated for 12 to 24 weeks with a VitD analog (VitD₃ ) at doses of 1000 or 2000 IU daily. The primary end-point assessed the change in reactive hyperemia index (lnRHI), a measure of EF. Secondary end-points included changes in blood pressure, lipid profile, HbA1c and albumin creatinine ratio (ACR). Urinary cytokine/chemokine inflammatory profile was also assessed in a subset of subjects posttreatment.

RESULTS

Two hundred and seventy-one subjects were screened for VitD status and 31 VitD deficient subjects with a mean age of 15.7 ± 1.4 years were enrolled and completed the study. Mean 25-OH-VitD levels significantly increased (33.0 ± 12.8 vs 67.0 ± 23.2 nmol/L, P < .01) with a significant improvement in EF following VitD supplementation (lnRHI 0.58 ± 0.20 vs 0.68 ± 0.21, P = .03). VitD supplementation did not significantly impact systolic blood pressure/diastolic blood pressure (SBP/DBP), lipids, HbA1c and ACR and no adverse effects were seen. Several urinary inflammatory cytokines/chemokines: MCP-3 (P < .01), epidermal growth factor (EGF) (P < .01) tumor necrosis factor β (TNFβ) (P = .01), interleukin-10 (IL-10) (P = .01), also significantly decreased post-VitD-treatment.

CONCLUSIONS

Treatment with VitD was associated with an improvement in EF and reduced expression of urinary inflammatory markers in adolescents with T1D. This data is suggestive of an additional benefit of VitD supplementation on early markers of microvascular complications.

Effect of high-dose oral cholecalciferol on cardiac mechanics in children with chronic kidney disease

Cardiovascular factors are an important cause of mortality in chronic kidney disease, and vitamin-D deficiency is common in this patient population. Therefore, we aimed to investigate the effect of oral cholecalciferol on cardiac mechanics in children with chronic kidney disease. A total of 41 children with chronic kidney disease - the patient group - and 24 healthy subjects - the control group - free of any underlying cardiac or renal disease with low 25-hydroxyvitamin-D3 levels were evaluated by conventional tissue Doppler imaging and two-dimensional speckle-tracking echocardiography, both at baseline and following Stoss vitamin-D supplementation. Left ventricular strain and strain rate values were compared between the study groups. Initial longitudinal and radial strain as well as strain rate values of the left ventricle were significantly lower in patients. After vitamin-D supplementation, these improved significantly in patients, whereas no significant change was observed in the control group. Our study showed that, although conventional and tissue Doppler imaging methods could not determine any effect, two-dimensional speckle-tracking echocardiography revealed the favourable effects of high-dose cholecalciferol on cardiac mechanics, implying the importance of vitamin-D supplementation in children with chronic kidney disease.

A Randomized Trial of Vitamin D Supplementation on Vascular Function in CKD

Vitamin D deficiency associates with mortality in patients with CKD, and vitamin D supplementation might mitigate cardiovascular disease risk in CKD. In this randomized, double-blind, placebo-controlled trial, we investigated the effect of cholecalciferol supplementation on vascular function in 120 patients of either sex, aged 18-70 years, with nondiabetic CKD stage 3-4 and vitamin D deficiency (serum 25-hydroxyvitamin D ≤20 ng/ml). We randomized patients using a 1:1 ratio to receive either two directly observed oral doses of cholecalciferol (300,000 IU) or matching placebo at baseline and 8 weeks. The primary outcome was change in endothelium-dependent brachial artery flow-mediated dilation at 16 weeks. Secondary outcome measures included changes in pulse wave velocity and circulating biomarkers. Cholecalciferol supplementation significantly increased endothelium-dependent brachial artery flow-mediated dilation at 16 weeks, whereas placebo did not (between-group difference in mean change: 5.49%; 95% confidence interval, 4.34% to 6.64%; P<0.001). Intervention also led to significant favorable changes in pulse wave velocity and circulating IL-6 levels. Thus, in nondiabetic patients with stage 3-4 CKD and vitamin D deficiency, vitamin D supplementation may improve vascular function. This study is registered with the Clinical Trials Registry of India (no.: CTRI/2013/05/003648).

Vitamin D in Chronic Kidney Disease and Dialysis Patients

Vitamin D deficiency (<20 ng/mL) and insufficiency (20–29 ng/mL) are common among patients with chronic kidney disease (CKD) or undergoing dialysis. In addition to nutritional and sunlight exposure deficits, factors that affect vitamin D deficiency include race, sex, age, obesity and impaired vitamin D synthesis and metabolism. Serum 1,25(OH)₂D levels also decrease progressively because of 25(OH)D deficiency, together with impaired availability of 25(OH)D by renal proximal tubular cells, high fibroblast growth factor (FGF)-23 and decreased functional renal tissue. As in the general population, this condition is associated with increased morbidity and poor outcomes. Together with the progressive decline of serum calcitriol, vitamin D deficiency leads to secondary hyperparathyroidism (SHPT) and its complications, tertiary hyperparathyroidism and hypercalcemia, which require surgical parathyroidectomy or calcimimetics. Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease Improving Global Outcomes (KDIGO) experts have recognized that vitamin D insufficiency and deficiency should be avoided in CKD and dialysis patients by using supplementation to prevent SHPT. Many vitamin D supplementation regimens using either ergocalciferol or cholecalciferol daily, weekly or monthly have been reported. The benefit of native vitamin D supplementation remains debatable because observational studies suggest that vitamin D receptor activator (VDRA) use is associated with better outcomes and it is more efficient for decreasing the serum parathormone (PTH) levels. Vitamin D has pleiotropic effects on the immune, cardiovascular and neurological systems and on antineoplastic activity. Extra-renal organs possess the enzymatic capacity to convert 25(OH)D to 1,25(OH)₂D. Despite many unanswered questions, much data support vitamin D use in renal patients. This article emphasizes the role of native vitamin D replacement during all-phases of CKD together with VDRA when SHPT persists.

Crosstalk between Vitamins A, B12, D, K, C, and E Status and Arterial Stiffness

Arterial stiffness is associated with cardiovascular risk, morbidity, and mortality. The present paper reviews the main vitamins related to arterial stiffness and enabling destiffening, their mechanisms of action, providing a brief description of the latest studies in the area, and their implications for primary cardiovascular prevention, clinical practice, and therapy. Despite inconsistent evidence for destiffening induced by vitamin supplementation in several randomized clinical trials, positive results were obtained in specific populations. The main mechanisms are related to antiatherogenic effects, improvement of endothelial function (vitamins A, C, D, and E) and metabolic profile (vitamins A, B12, C, D, and K), inhibition of the renin-angiotensin-aldosterone system (vitamin D), anti-inflammatory (vitamins A, D, E, and K) and antioxidant effects (vitamins A, C, and E), decrease of homocysteine level (vitamin B12), and reversing calcification of arteries (vitamin K). Vitamins A, B12, C, D, E, and K status is important in evaluating cardiovascular risk, and vitamin supplementation may be an effective, individualized, and inexpensive destiffening therapy.

A pilot validation study of crowdsourcing systematic reviews: update of a searchable database of pediatric clinical trials of high-dose vitamin D

BACKGROUND

Completing large systematic reviews and maintaining them up to date poses significant challenges. This is mainly due to the toll required of a small group of experts to screen and extract potentially eligible citations. Automated approaches have failed so far in providing an accessible and adaptable tool to the research community. Over the past decade, crowdsourcing has become attractive in the scientific field, and implementing it in citation screening could save the investigative team significant work and decrease the time to publication.

METHODS

Citations from the 2015 update of a pediatrics vitamin D systematic review were uploaded to an online platform designed for crowdsourcing the screening process (http://www.CHEORI.org/en/CrowdScreenOverview). Three sets of exclusion criteria were used for screening, with a review of abstracts at level one, and full-text eligibility determined through two screening stages. Two trained reviewers, who participated in the initial systematic review, established citation eligibility. In parallel, each citation received four independent assessments from an untrained crowd with a medical background. Citations were retained or excluded if they received three congruent assessments. Otherwise, they were reviewed by the principal investigator. Measured outcomes included sensitivity of the crowd to retain eligible studies, and potential work saved defined as citations sorted by the crowd (excluded or retained) without involvement of the principal investigator.

RESULTS

A total of 148 citations for screening were identified, of which 20 met eligibility criteria (true positives). The four reviewers from the crowd agreed completely on 63% (95% CI: 57-69%) of assessments, and achieved a sensitivity of 100% (95% CI: 88-100%) and a specificity of 99% (95% CI: 96-100%). Potential work saved to the research team was 84% (95% CI: 77-89%) at the abstract screening stage, and 73% (95% CI: 67-79%) through all three levels. In addition, different thresholds for citation retention and exclusion were assessed. With an algorithm favoring sensitivity (citation excluded only if all four reviewers agree), sensitivity was maintained at 100%, with a decrease of potential work saved to 66% (95% CI: 59-71%). In contrast, increasing the threshold required for retention (exclude all citations not obtaining 3/4 retain assessments) decreased sensitivity to 85% (95% CI: 65-96%), while improving potential workload saved to 92% (95% CI: 88-95%).

CONCLUSIONS

This study demonstrates the accuracy of crowdsourcing for systematic review citations screening, with retention of all eligible articles and a significant reduction in the work required from the investigative team. Together, these two findings suggest that crowdsourcing could represent a significant advancement in the area of systematic review. Future directions include further study to assess validity across medical fields and determination of the capacity of a non-medical crowd.

Vitamin D and cardiovascular disease: From atherosclerosis to myocardial infarction and stroke

There continues to be interest in understanding the role of vitamin D in the pathogenesis, epidemiology and prevention of cardiovascular disease (CVD). In fact vitamin D deficiency has been associated to an increased risk of developing CVD given to the relationship between low vitamin D levels and obesity, diabetes mellitus, dyslipidaemia, endothelial dysfunction and hypertension. However, although vitamin D has been identified as a potentially important marker of CVD, the mechanisms through which vitamin D deficiency leads from endothelial dysfunction to myocardial infarction and stroke are not fully understood. Thus, the goal of this review is to provide an updated review of the literature on the basic science of how vitamin D may affect the cardiovascular system and in particular to analyze the role that vitamin D may have in the whole dynamic process from the initiation of endothelial dysfunction to the development of myocardial infarction and stroke.