Impact of Vitamin D on the Cardiovascular System in Advanced Chronic Kidney Disease (CKD) and Dialysis Patients

Joint and independent associations of dietary vitamin intake and prevalence of cardiovascular disease in chronic kidney disease subjects: a cross-sectional analysis

Background

Currently, the joint and independent effects of intake of multiple dietary vitamins (including vitamin A, B1, B2, B6, B12, C, D, E, and K) on the prevalence of cardiovascular disease (CVD) in the chronic kidney disease (CKD) population are unclear, so this study was conducted to investigate mainly this point.

Methods

We collected National Health and Nutrition Examination Survey (NHANES) data from 2011 to 2016. We performed weighted multivariate logistic regression models to analyze the association of single dietary vitamins intake with CVD. Additionally, we examined the co-exposure of nine dietary vitamins, defined as their concurrent intake, and evaluated the potential additive or interactive effects of co-exposure of nine dietary vitamins on CVD risk in CKD patients using Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression.

Results

Finally, 2,203 CKD participants (weighted n = 27,120,429) were included, and 622 had CVD, with a CVD prevalence of 28.2%. In the fully adjusted model, by comparing the third tertile with the first tertile, the adjusted OR [T3 vs. T1] for the effect of vitamin B6 on CVD prevalence was 0.67 (95% CI, 0.51-0.89, p-value = 0.01), while that of vitamin E was 0.61 (95% CI, 0.42-0.87, p-value = 0.01). In the WQS model, the intake of nine dietary vitamins was negatively correlated with CVD prevalence (OR: 0.81, 95% CI: 0.70-0.93, p-value = 0.004). In the BKMR model, when the concentration was between the 25th and 75th percentiles, there was an overall negative correlation between the total intake of nine dietary vitamins and CVD prevalence.

Conclusion

High intakes of vitamin B6 and vitamin E were associated with low CVD risk in CKD patients, respectively. Additionally, nine dietary vitamins (vitamins A, B1, B2, B6, B12, C, D, E, and K) co-exposure were inversely correlated with the CVD prevalence in the CKD populations.

Association of Ankle-Brachial Index with Quality of Life and Survival Outcomes in Hemodialysis Patients

Background/Objectives: Ankle-brachial index (ABI) is frequently measured in hemodialysis patients due to their high cardiovascular risk, while its potential role as a screening tool for assessing overall physical function and health-related quality of life (QOL) remains unclear. This study aimed to evaluate the association of the ABI with QOL and survival in hemodialysis patients. Methods: This study included 346 hemodialysis patients, categorized into two groups based on their ABI (≤0.9 vs. >0.9). Clinical parameters, QOL (measured using SF-36 and KDQOL questionnaires), and survival outcomes were analyzed. Results: There were 66 (19.1%) patients with an ABI ≤ 0.9 in this study population. Patients with an ABI ≤ 0.9 exhibited significantly older ages, longer dialysis durations, higher prevalence of diabetes mellites and cardiovascular disease, elevated N-terminal pro-brain natriuretic peptide levels, and higher calcitriol use but lower phase angle, skeletal muscle mass index values, health-related QOL domains, and several kidney disease-specific QOL domains compared to those with an ABI > 0.9. Kaplan-Meier analysis revealed significantly higher cumulative mortality in the ABI ≤ 0.9 group (6.6 vs. 2.5 per 100 patient-years, p < 0.001). Conclusions: A low ABI is significantly associated with decreased QOL and higher mortality risk in hemodialysis patients. While traditionally used for PAD screening, the ABI may serve as a practical tool for predicting QOL decline and survival outcomes. Interestingly, the ABI was also linked to muscle attenuation and volume overload. ABI assessment could aid in early risk stratification and guide multidisciplinary interventions, including exercise programs, nutritional support, and cardiovascular risk management, to improve patient care and outcomes.

Vitamin D status and intermediate vascular and bone outcomes in chronic kidney disease: a secondary post hoc analysis of IMPROVE-CKD

BACKGROUND AND AIMS

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD) and has been associated with abnormalities of mineral metabolism and vascular calcification. Vitamin D influences parathyroid hormone values and calcium and phosphate metabolism, and may play a role in vascular function and bone health. We aimed to test our hypothesis that vitamin D deficiency is associated with arterial stiffness, aortic calcification and lower bone mineral density (BMD) in patients with CKD.

METHODS

A cross-sectional analysis was performed using baseline data from the IMpact of Phosphate Reduction On Vascular Endpoints in CKD (IMPROVE-CKD) study cohort. Clinical and laboratory parameters were compared between those with and without vitamin D deficiency, defined as 25-hydroxyvitamin D (25(OH)D) <50 nmol/L. Univariable and multivariable linear regression analyses were performed to assess associations between serum 25(OH)D levels and pulse wave velocity (PWV), augmentation index (AIx), abdominal aortic calcification (measured by the Agatston score) and lumbar spine BMD.

RESULTS

Baseline 25(OHD) values were available in 208 out of 278 IMPROVE-CKD study participants, with a mean value of 70.1 ± 30.7 nmol/L. Of these, 57 (27%) patients had vitamin D deficiency. Those with 25(OH)D deficiency were more likely to have diabetes (56% vs 38%), cardiovascular disease (54% vs 36%) and lower serum calcium (2.29 ± 0.13 vs 2.34 ± 0.13 mmol/L). On univariable and multivariable regression analyses, baseline 25(OH)D values were not associated with PWV, the AIx, Agatston score or BMD.

CONCLUSION

Baseline 25(OH)D levels were not associated with intermediate markers of vascular function and BMD in patients with CKD stages 3b and 4.

Hyperparathyroidism and Peripheral Arterial Disease

Primary hyperparathyroidism (PHPT) is presented in various forms, including classic PHPT, characterised by increased parathyroid hormone (PTH) secretion, normohormonal PHPT, and normocalcaemic PHPT. Secondary hyperparathyroidism is characterised by increased PTH secretion triggered by factors such as vitamin D deficiency and kidney failure. This review aims to discuss the involvement of hyperparathyroidism (HPT) in atherosclerosis, including peripheral arterial disease (PAD). The increased level of PTH is involved in developing subclinical and overt vascular diseases, encompassing endothelial dysfunction, vascular stiffness, hypertension, and coronary and peripheral arterial diseases. It has been consistently associated with an augmented risk of cardiovascular morbidity and mortality, independent of classical risk factors for atherosclerosis. Chronic hypercalcemia associated with increased levels of PTH contributes to the development of calcification of vessel walls and atherosclerotic plaques. Vascular calcification can occur in the intima or media of the arterial wall and is associated with stiffness of peripheral arteries, which the formation of atherosclerotic plaques and narrowing of the vessel lumen can follow. For treating hyperparathyroidism, particularly SHPT, calcimimetics, novel phosphorus binders and novel vitamin D receptor activators are used. However, they are ineffective in severe PHPT. Therefore, parathyroidectomy remains the primary therapeutic option of PHPT.

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.

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.

Insulin Resistance and Vitamin D Deficiency: A Link Beyond the Appearances

Vitamin D is a steroid hormone that plays a key role in the regulation of body homeostasis, including cardiovascular function. Although the chronic deficiency of vitamin D is associated with cardiovascular risk factors, as well as with an adverse prognosis, randomized controlled trials have failed in demonstrating that dietary vitamin D supplementation could ameliorate the prognosis of patients with cardiovascular diseases, and suggested that vitamin D deficiency is the expression of the effects of other determinants of cardiovascular risk. Thus, the supplementation of vitamin D is not sufficient to improve the cardiovascular risk profile and prognosis. Insulin resistance is a complex phenomenon that plays a key role in the pathogenesis of conventional cardiovascular risk factors. Interestingly, defects of vitamin D and insulin resistance have a superimposable epidemiological distribution. According to the common view, Insulin resistance is considered the direct or indirect consequence of vitamin D deficiency. However, it is also reasonable to speculate that the deficit or the impaired action of vitamin D, in some circumstances, could be the result of the same pathogenic mechanisms responsible of insulin resistance development. In this case, vitamin D deficiency could be considered an epiphenomenon of insulin resistance. Insulin resistance is a reversible condition, being possibly ameliorated by physical activity and hypocaloric diets. Notably, both physical exercise and energy-restricted dietary regimens are associated with an increase of vitamin D levels. These findings indicate that improving insulin resistance condition is a necessary step to ameliorate vitamin D supplementation-based strategies in cardiovascular prevention.

Effect of a high vs. standard dose of vitamin D3 supplementation on bone metabolism and kidney function in children with chronic kidney disease

We investigated the effects of high- vs. standard-dose vitamin D supplementation on kidney function and bone metabolism in children with chronic kidney disease (CKD). Children were randomized to receive one of two formulations: 75 participants received 2,000 IU/D of oral supplementation of vitamin D, while 75 participants received 400 IU/d for a minimum of 4 months. We investigated the effects of vitamin D supplementation on kidney-related indicators and bone metabolism-related indicators at different doses. A total of 158 participants were screened, among whom 150 met the inclusion criteria. The indicators of chronic kidney disease such as eGFR and serum uric acid were negatively correlated with the 25(OH)D level and BMD. Serum 25(OH)D and osteocalcin levels were positively correlated with spine BMD. The standard dose of vitamin D can improve the serum uric acid level, but high doses of vitamin D supplementation had no significant effect on the serum uric acid level. High doses of vitamin D supplementation can also improve the alkaline phosphatase level. When comparing the results of different doses of vitamin D supplementation, it was found that high-dose vitamin D supplementation did not improve bone density in the spine and femur neck relative to the standard dose of vitamin D but improved hypocalcemia and N-terminal propeptide of the human procollagen type I (PINP) level. Among the children with clinical kidney disease, high-dose vitamin D treatment for 4 months resulted in statistically significant improvement in kidney function but no significant difference in bone metabolism compared with the standard-dose vitamin D treatment.

Effect of vitamin D receptor activators on serum Klotho levels in 3b–4 stages chronic кidney disease patients: a prospective randomized study

Background. High risk of cardiovascular events is among leading problems in chronic kidney disease (CKD). Serum Klotho is supposed to be cardio- and nephroprotective; modification of its levels may be important in CKD. Aim. To evaluate the impact of vitamin D receptor activators (VDRA) on Klotho serum levels in CKD 3b4 stages patients. Materials and methods. Study included 90 CKD 3b4 stages patients who had elevated serum levels of parathyroid hormone (PTH). From them, 47 patients (group 1) started to treat with the selective VDRA (zemplar 1 mcg/day), and 43 patients (group 2) started to treat with non-selective VDRA (alfacalcidol 0.25 mcg/day). At baseline and after 12 months we conducted routine examination, serum Klotho measurement, and broad cardiovascular examination. Results. The patients who managed to maintain a target serum PTH level, had higher Klotho serum level (p=0.037) at the end of the study. Patients who used selective VDRA significantly more often reached the target PTH level (p=0.032), had higher serum Klotho levels (p=0.037), and glomerular filtration rate (eGFR) level (p=0.048) than patients who used non-selective VDRA. In addition, patients treated with alfacalcidol more than 6 months, more often had hypercalcemia (p=0.047) and hyperphosphatemia (p=0.035). Group 2 showed higher: pulse wave velocity (p=0.051), left ventricular myocardial mass index (p=0.033), and more advanced heart valve calcification (p=0.038). Conclusion. Successful parathyroid hormone level control with vitamin D receptor activators was associated with higher serum Klotho, selective agents having shown greater effect. Long-term treatment with selective vitamin D receptor activators may contribute to cardiovascular calcification prevention by modifying Klotho levels.

The effect of vitamin D on fibroblast growth factor 23: a systematic review and meta-analysis of randomized controlled trials

The phosphaturic hormone fibroblast growth factor 23 (FGF23) is a risk marker of cardiovascular and all-cause mortality. We therefore aimed to synthesize the evidence for the effect of vitamin D administration on circulating FGF23 concentrations. We performed a systematic review and meta-analysis of randomized, placebo-controlled trials (RCTs) in several databases from inception to January 2020. A total of 73 records were identified for full-text review, and 21 articles with 23 studies were included in the final analysis. The selected studies included 1925 participants with 8-156 weeks of follow-up. The weighted mean difference in FGF23 in the vitamin D versus placebo group was +21 pg/ml (95% CI: 13-28 pg/ml; P < 0.001) with considerable heterogeneity among studies (I2 = 99%). The FGF23 increment was higher in patients with end-stage kidney/heart failure than in other individuals (+300 pg/ml [95% CI: 41-558 pg/ml] vs. +20 pg/ml [95% CI: 12-28 pg/ml], Pinteraction = 0.03), and if baseline 25-hydroxyvitamin D concentrations were <50 nmol/l instead of ≥50 nmol/l (+34 pg/ml [95% CI: 18-51 pg/ml] vs. +9 pg/ml [95% CI: 3-14 pg/ml]; Pinteraction = 0.002). Moreover, the FGF23 increment was influenced by vitamin D dose/type (vitamin D dose equivalent ≤ 2000 IU/day: +2 pg/ml [95% CI: 0-3 pg/ml]; vitamin D dose equivalent > 2000 IU/day: +18 pg/ml [95% CI: 6-30 pg/ml]; administration of activated vitamin D: +67 pg/ml [95% CI: 16-117 pg/ml]; Pinteraction = 0.001). Results were not significantly influenced by study duration (Pinteraction = 0.14), age class (Pinteraction = 0.09), or assay provider (Pinteraction = 0.11). In conclusion, this meta-analysis of RCTs demonstrates that vitamin D administration of >2000 IU/d vitamin D or activated vitamin D significantly increased concentrations of the cardiovascular risk marker FGF23, especially in patients with end-stage kidney/heart failure.

Endocan and Circulating Progenitor Cells in Women with Systemic Sclerosis: Association with Inflammation and Pulmonary Hypertension

BACKGROUND

Systemic sclerosis (SSc) is characterized by early vasculopathy and fibrosis in the skin, lungs, and other tissues. Vascular manifestations of SSc include Raynaud's phenomenon, digital ulcers, and pulmonary artery hypertension (PAH). PAH is the second most common cause of mortality in SSc. Circulating CD34+ cells associated with cardiovascular health status in several conditions, including chronic immune-inflammatory disease. CD34+ cell numbers have been found inconstantly reduced in SSc. Endocan, a proteoglycan expressed by endothelial cells, was recently suggested as a marker of vascular stress. We tested the relationships among CD34+ cells, endocan, inflammatory markers, vitamin D levels, and clinical parameters in SSc patients with PAH.

METHODS

Standard echocardiography was performed. Vitamin D levels, CD34+ cells, inflammatory markers, endocan plasma levels were determined in 36 female SSc patients (24 diffuse/12 limited) and 36 matched controls (HC).

RESULTS

We found no difference in CD34+ and vitamin D levels in SSc as compared to controls; ESR, CRP, fibrinogen, endocan, sPAP were higher in SSc with respect to controls. We found a correlation between endocan and: CD34+ cells (r: -0.540, p = 0.002), pulmonary arterial pressure (sPAP) (r: 0.565, p < 0.001), tricuspid annular plane excursion (TAPSE) (r: -0.311, p < 0.01), and E/A ratio (r: -0.487, p < 0.001), but not with ejection fraction (r: -0.057, p = 0.785) in SSc. CD34+ cells correlate with fibrinogen (r: -0.619, p < 0.001), sPAP (r: -0.404, p = 0.011), E/A (r: 0.470, p < 0.005 in SSc.

CONCLUSION

CD34+ cell number was significantly correlated with endocan levels and with sPAP in SSc; endocan and CD34+ progenitor cells might be suggested as a potential marker of disease status.

Role of vitamin D in the pathogenesis of atheromatosis

BACKGROUND AND AIMS

Cardiovascular disease is the main cause of death worldwide, but the collective efforts to prevent this pathological condition are directed exclusively to individuals at higher risk due to hypercholesterolemia, hypertension, obesity, diabetes. Recently, vitamin D deficiency was identified as a risk factor for cardiovascular disease in healthy people, as it predisposes to different vascular dysfunctions that can result in plaque development and fragility. In this scenario, the fundamental aim of the study was to reproduce a disease model inducing vitamin D deficiency and atheromatosis in ApoE-/- mice and then to evaluate the impact of this vitamin D status on the onset/progression of atheromatosis, focusing on plaque formation and instability.

METHODS AND RESULTS

In our murine disease model, vitamin D deficiency was achieved by 3 weeks of vitamin D deficient diet along with intraperitoneal paricalcitol injections, while atheromatosis by western-type diet administration. Under these experimental conditions, vitamin D deficient mice developed more unstable atheromatous plaques with reduced or absent fibrotic cap. Since calcium and phosphorus metabolism and also cholesterol and triglycerides systemic concentration were not affected by vitamin D level, our results highlighted the role of vitamin D deficiency in the formation/instability of atheromatous plaque and, although further studies are needed, suggested a possible intervention with vitamin D to prevent or delay the atheromatous disease.

CONCLUSIONS

The data obtained open the question about the potential role of the vitamins in the pharmacological treatments of cardiovascular disorders as coadjutant of the primary drugs used for these pathologies.

In vitro anti-inflammatory effects of vitamin D supplementation may be blurred in hemodialysis patients

OBJECTIVES

This study aimed to evaluate the potential anti-inflammatory effects of vitamin D supplementation under uremic conditions, both in vivo and in vitro, and its effects on the parameters of mineral metabolism.

METHODS

Thirty-two hemodialysis patients were randomly assigned to receive placebo (N=14) or cholecalciferol (N=18) for six months. Serum levels of calcium, phosphate, total alkaline phosphatase, intact parathyroid hormone (iPTH), and vitamin D were measured at baseline and after three and six months. The levels of fibroblast growth factor-23 (FGF-23), interleukin-1β (IL-1β), and high-sensitivity C-reactive protein (hs-CRP) were also measured at baseline and at six months. Human monocytes were used for in vitro experiments and treated with cholecalciferol (150 nM) and uremic serum. Cell viability, reactive oxygen species (ROS) production, and cathelicidin (CAMP) expression were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, dichloro-dihydro-fluorescein diacetate assay, and real time-quantitative polymerase chain reaction, respectively.

RESULTS

Both patient groups were clinically and biochemically similar at baseline. After six months, the levels of vitamin D and iPTH were higher and lower, respectively, in the cholecalciferol group than in the placebo group (p<0.05). There was no significant difference between the parameters of mineral metabolism, such as IL-1β and hs-CRP levels, in both groups. Treatment with uremic serum lowered the monocyte viability (p<0.0001) and increased ROS production (p<0.01) and CAMP expression (p<0.05); these effects were counterbalanced by cholecalciferol treatment (p<0.05).

CONCLUSIONS

Thus, cholecalciferol supplementation is an efficient strategy to ameliorate hypovitaminosis D in hemodialysis patients, but its beneficial effects on the control of secondary hyperparathyroidism are relatively unclear. Even though cholecalciferol exhibited anti-inflammatory effects in vitro, its short-term supplementation was not effective in improving the inflammatory profile of patients on hemodialysis, as indicated by the IL-1β and hs-CRP levels.

Correlation Between 25-Hydroxyvitamin D Level and Cardiac Diastolic Dysfunction in Chinese Adults with Early-Onset Type 2 Diabetes Mellitus: A Cross-Sectional Study

PURPOSE

Chinese adults with early-onset type 2 diabetes mellitus have impaired diastolic function. This study aims to analyse the association between serum vitamin D levels and cardiac diastolic dysfunction in Chinese adults with early-onset type 2 diabetes mellitus.

PATIENTS AND METHODS

We enrolled Chinese adults with early-onset type 2 diabetes mellitus in this study. These patients were divided into two groups: those with diastolic dysfunction and those without diastolic dysfunction. We then compared the levels of serum 25-hydroxyvitamin D [25-(OH)D] between the two groups. The correlation between diastolic function and 25-(OH)D was evaluated by Pearson correlation analysis. Finally, binary logistic regression was used to analyse the relationship between the decrease in diastolic function and 25-(OH)D and other indexes in Chinese adults with early-onset type 2 diabetes mellitus.

RESULTS

The level of 25-(OH)D in patients with early-onset type 2 diabetes mellitus complicated with cardiac diastolic dysfunction was significantly lower than that in patients without cardiac diastolic dysfunction (P<0.01). The degree of liver fibrosis in adult patients with early-onset type 2 diabetes mellitus complicated with diastolic dysfunction was significantly higher than that in adult patients without diastolic dysfunction (P<0.01). Moreover, decreased 25-(OH)D levels were associated with decreased diastolic function in adults with early-onset type 2 diabetes.

CONCLUSION

25-(OH)-D was identified as an independent predictor of decreased diastolic function in adults with early-onset type 2 diabetes. The serum 25-(OH)D level in adults with early-onset type 2 diabetes was significantly reduced. 25-(OH)D influences the reduction in diastolic function in adults with early-onset type 2 diabetes and can be used as a predictor of decreased diastolic function in such patients.

The relationship between circulating vitamin D3 and subclinical atherosclerosis in an elderly Asian population

The current evidence regarding the association between vitamin D deficiency and cardiovascular diseases/metabolic disorders is contradictory and inconclusive. In this large-scale observational study, we investigated the relationship between the serum 25-hydroxy vitamin D3 [25(OH)D] concentration and subclinical atherosclerosis in an elderly Asian population. In the I-Lan longitudinal study (ILAS), 1798 elderly, aged 50 and older, were enrolled. For each subject, serum 25-hydroxy vitamin D3 [25(OH)D] concentration and demographic data were recorded. The participants were divided into two groups according to their serum 25(OH)D level (sufficient, > 20 ng/mL and deficient, ≤ 20 ng/mL). Carotid intima-media thickness (cIMT) was measured at bilateral common carotid arteries. Subclinical atherosclerosis was defined as a mean cIMT > 0.81 mm. The mean subject age was 64 ± 9 years old, and 604 (33.6%) were identified as having serum 25(OH)D level ≤ 20 ng/mL. Subjects with serum 25(OH)D level ≤ 20 ng/mL were younger, more likely to be female and smoker, and had a higher incidence of hypertension, dyslipidemia, and metabolic syndrome, compared to those with serum 25(OH)D level > 20 ng/mL. Additionally, patients with serum 25(OH)D level ≤ 20 ng/mL were associated with a lower risk of subclinical atherosclerosis (crude OR: 0.63, 95% CI 0.50–0.81, p < 0.001), according to univariate analysis. However, after adjusting for gender and age, serum 25(OH)D level ≤ 20 ng/mL was not a significant risk factor for subclinical atherosclerosis. Serum 25(OH)D level ≤ 20 ng/mL was not an independent risk factor for subclinical atherosclerosis in this large elderly Asian population. Association observed in the univariate analysis may be confounded by gender or comorbidities.

Cardiac Remodeling in Chronic Kidney Disease

Cardiac remodeling occurs frequently in chronic kidney disease patients and affects quality of life and survival. Current treatment options are highly inadequate. As kidney function declines, numerous metabolic pathways are disturbed. Kidney and heart functions are highly connected by organ crosstalk. Among others, altered volume and pressure status, ischemia, accelerated atherosclerosis and arteriosclerosis, disturbed mineral metabolism, renal anemia, activation of the renin-angiotensin system, uremic toxins, oxidative stress and upregulation of cytokines stress the sensitive interplay between different cardiac cell types. The fatal consequences are left-ventricular hypertrophy, fibrosis and capillary rarefaction, which lead to systolic and/or diastolic left-ventricular failure. Furthermore, fibrosis triggers electric instability and sudden cardiac death. This review focuses on established and potential pathophysiological cardiorenal crosstalk mechanisms that drive uremia-induced senescence and disease progression, including potential known targets and animal models that might help us to better understand the disease and to identify novel therapeutics.

Effectiveness of Native Vitamin D Therapy in Patients with Chronic Kidney Disease Stage 3 and Hypovitaminosis D in Colombia, South America

Introduction: In a high percentage of patients with chronic kidney disease (CKD) low levels of vitamin D are detected. The purpose of this study was to evaluate if the native vitamin D therapy (cholecalciferol) in the patients with stage 3 and hypovitaminosis D allows to modify markers of bone and mineral metabolism once normal serum levels have been achieved.

MATERIALS AND METHODS

From an initial base of 297 patients with CKD and hypovitaminosis D, those with normal or high levels of PTH were chosen for therapy with native vitamin D. The initial administered dose was 1000 IU/day, with adjustments every 4 months of 1000 IU (maximum 4000 IU/day, according to RDA and IOM), until achieving serum levels of 25 hydroxyvitamin D greater than 30 ng/mL and lower than 80 ng/mL. The variables calcium, phosphorus, intact parathormone (iPTH), creatinine and glomerular filtration rate (GFR) were also evaluated every 4 months.

RESULTS

The total number of patients included in this study was 170. Seventy-three patients were excluded along the follow-up: 17 non-responders (never achieved the projected serum levels of vitamin D), and 56 for not completing one year of follow-up. A total of 97 patients were finally included. In 82 patients, follow-up was achieved for 12 months (G1) and in 38 patients for 24 months (G2). In 15 patients despite achieving satisfactory levels of vitamin D at 12 months, it was not possible to obtain adequate levels of iPTH for their GFR according to K/DOQI 2003 guidelines and they were called refractory to therapy (G3). In both groups 1 and 2, a non-significant tendency to increase calcium and serum phosphorus was observed. iPTH decreased significantly at 12 and 24 months follow-up. In group 3, we opted at 12 months for conversion to calcitriol, with a significant reduction in iPTH values. In this group, the initial value of GFR was close to 30 mL/min, and its fall in time more significant than the other two groups to CKD stage 4.

CONCLUSION

Cholecalciferol with adjustment in its dose, and obtaining normal serum levels is an excellent therapeutic alternative for the treatment of patients with CKD stage 3, and hypovitaminosis D. In the group of patients with GFR close to 30 mL/min, or lower values (stage 4), and with the presence of secondary hyperparathyroidism, the use of active form of vitamin D (calcitriol, paricalcitol) is recommended as the first therapeutic alternative.

Evolving concepts in the pathogenesis of uraemic cardiomyopathy

The term uraemic cardiomyopathy refers to the cardiac abnormalities that are seen in patients with chronic kidney disease (CKD). Historically, this term was used to describe a severe cardiomyopathy that was associated with end-stage renal disease and characterized by severe functional abnormalities that could be reversed following renal transplantation. In a modern context, uraemic cardiomyopathy describes the clinical phenotype of cardiac disease that accompanies CKD and is perhaps best characterized as diastolic dysfunction seen in conjunction with left ventricular hypertrophy and fibrosis. A multitude of factors may contribute to the pathogenesis of uraemic cardiomyopathy, and current treatments only modestly improve outcomes. In this Review, we focus on evolving concepts regarding the roles of fibroblast growth factor 23 (FGF23), inflammation and systemic oxidant stress and their interactions with more established mechanisms such as pressure and volume overload resulting from hypertension and anaemia, respectively, activation of the renin-angiotensin and sympathetic nervous systems, activation of the transforming growth factor-β (TGFβ) pathway, abnormal mineral metabolism and increased levels of endogenous cardiotonic steroids.

Nutritional vitamin D in CKD: Should we measure? Should we treat?

Vitamin Ddeficiency is frequently present in patients affected by chronic kidney disease (CKD). Experimental studies demonstrated that Vitamin D may play a role in the pathophysiology of diseases beyond mineral bone disorders in CKD (CKD-MBD). Unfortunately, the lack of large and interventional studies focused on the so called "non-classic" effects of 25(OH) Vitamin D supplementation in CKD patients, doesn't permit to conclude definitely about the beneficial effects of this supplementation in clinical practice. In conclusion, treatment of nutritional vitamin D deficiency in CKD may play a central role in both bone homeostasis and cardiovascular outcomes, but there is not clear evidence to support one formulation of nutritional vitamin D over another in CKD.

Association between VDR gene FokI polymorphism and renal function in patients with IgA nephropathy

Background

Studies have shown that the occurrence and development of IgA nephropathy (IgAN) are genetically susceptible, but the relationship between vitamin D receptor (VDR) gene polymorphisms and renal function in IgAN patients is unclear.

Methods

We investigated the relationship between VDR FokI (rs2228570) single nucleotide polymorphism (SNP) and renal function and related clinicopathologic parameters in IgAN patients. Clinical and pathological data of 282 IgAN patients treated at the First Affiliated Hospital of Guangxi Medical University were collected, and FokI genotypes were determined by PCR and direct sequencing. Patients were divided into the renal dysfunction group and normal renal function (control) group by estimated glomerular filtration rate (eGFR) and serum creatinine level.

Results

Frequencies of TT genotype and T allele in the renal dysfunction group were higher than those of the control group. Blood urea nitrogen, serum phosphorus (P), proportions of mesangial cell proliferation, interstitial fibrosis/tubular atrophy and crescents in T allele carriers were higher than those in non-T allele carriers, while eGFR and 25-Hydroxyvitamin D3 were lower in T allele carriers than non-T allele carriers. Multiple linear regression analysis showed that eGFR was affected by FokI genotypes in IgAN patients. Logistics regression analysis showed that middle and elderly age, elevated P, intact parathyroid hormone and TT genotype were independent risk factors for renal dysfunction in IgAN patients; the odds ratio of carrying the TT genotype was as high as 84.77 (P < 0.05 for all).

Conclusions

IgA nephropathy patients carrying the VDR FokI TT genotype have an increased risk of renal dysfunction. VDR FokI SNP is closely related to renal function, calcium-phosphate metabolism, and related pathological damage in IgAN patients.