Vitamin D status and mortality in chronic kidney disease

Association of serum 25-hydroxyvitamin D with cardiovascular mortality and kidney outcome in patients with early stages of CKD

PURPOSE

While serum 25-hydroxyvitamin D (25[OH]D) deficiency is prevalent in chronic kidney disease (CKD), the effects of 25(OH)D deficiency on cardiovascular mortality and kidney outcomes in patients with early-stage CKD remain incompletely understood.

METHODS

This multicenter retrospective cohort study included adult patients with stages 1-3 CKD from 19 medical centers across China between January 2000 and May 2021. The primary outcome was cardiovascular mortality. The secondary study outcome included CKD progression (defined as a sustained > 40% eGFR decrease from baseline or progress to end-stage kidney disease), and annual percentage change of eGFR.

RESULTS

Of 9229 adults with stages 1-3 CKD, 27.0% and 38.9% had severe (< 10 ng/mL) and moderate (10 to < 20 ng/mL) serum 25(OH)D deficiency, respectively. Compared with patients having 25(OH)D ≥ 20 ng/mL, a significantly higher risk of cardiovascular mortality (hazard ratio [HR] 1.90, 95% CI 1.37-2.63), CKD progression (HR 2.20, 95% CI 1.68-2.88), and a steeper annual decline in eGFR (estimate - 7.87%; 95% CI - 10.24% to - 5.51% per year) was found in those with serum 25(OH)D < 10 ng/mL. Similar results were obtained in subgroups and by sensitivity analyses.

CONCLUSIONS

25(OH)D deficiency is associated with increased risks of cardiovascular mortality and CKD progression in patients with early-stage CKD. Studies are needed to determine whether early intervention for 25(OH)D deficiency could improve the prognosis of patients with early-stage CKD.

Associations between serum 25-hydroxyvitamin D and prognosis of chronic kidney disease: a prospective cohort study

BACKGROUND AND OBJECTIVES

25-hydroxyvitamin D [25(OH)D] deficiency is prevalent in patients with chronic kidney disease (CKD), the associations between serum 25(OH)D levels and mortality in patients with CKD remain unclear, and this study aimed to explore these associations further.

METHODS

4989 participants with CKD were enrolled in the study, and the Cox regression model was used to assess the effects of serum 25(OH)D concentrations on mortality risk. A restricted cubic spline model was used to explore the dose-response relationships, and threshold effect analysis was performed based on inflection points identified by a two-piecewise linear regression model. In addition, subgroup and sensitivity analyses were employed.

RESULTS

1255 participants died during a mean follow-up period of 70 months. Compared with the 25(OH)D-deficient group, the fully adjusted hazard ratios and 95% confidence intervals for the 25(OH)D-adequate group were 0.631 (0.545, 0.730) for all-cause mortality, 0.569 (0.435, 0.743) for cardiovascular mortality, 0.637 (0.461, 0.878) for hypertension mortality, and cancer mortality was 0.596 (0.426, 0.834). The inflection points of serum 25(OH)D concentration affecting all-cause and cardiovascular mortality were 89 nmol/L, and 107 nmol/L, respectively. Subgroup analyses and interaction tests suggested that the effects varied across populations. The results of sensitivity analyses indicated a reliable correlation.

CONCLUSION

We found an association between serum 25(OH)D concentrations and the prognosis of patients with CKD as a reliable predictor of early intervention and intensive care.

L-shaped association of serum 25-hydroxyvitamin D with all-cause and cardiovascular mortality in older people with chronic kidney disease: results from the NHANES database prospective cohort study

BACKGROUND

This study was conducted to assess the association of serum 25-hydroxyvitamin D [25(OH)D] concentrations with all-cause and cardiovascular disease (CVD) mortality in older people with chronic kidney disease (CKD) in the United States.

METHODS

We identified 3230 CKD participants aged ≥ 60 years from the National Health and Nutrition Examination Survey (2001-2018). CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m². Mortality outcomes were determined by linkage to National Death Index (NDI) records through December 31, 2019. Restricted cubic spline based on Cox regression models were utilized to elucidate the nonlinear relationship between serum 25(OH)D concentrations and mortality in patients with CKD.

RESULTS

During median 74 months of follow-up, 1615 all-cause death and 580 CVD death were recorded. We found an L-shaped association between serum 25(OH)D concentrations and all-cause and CVD mortality, reaching a plateau at 90 nmol/L. Accordingly, per one-unit increment in natural log-transformed 25(OH)D was associated with a 32% and 33% reduced risk of all-cause mortality (hazard ratio [HR] 0.68; 95%CI, 0.56 to 0.83) and CV mortality (HR 0.69; 95%CI, 0.49 to 0.97) in participants with serum 25(OH)D < 90 nmol/L, but no considerable difference was observed in participants with serum 25(OH)D ≥ 90 nmol/L. Compared with those in the deficiency group (< 50 nmol/L), insufficient (50 to < 75 nmol/L) and sufficient group (≥ 75 nmol/L) were significantly associated with lower all-cause mortality (HR,0.83; 95%CI, 0.71 to 0.97 and HR, 0.75; 95%CI, 0.64 to 0.89) and CV mortality (HR,0.87; 95%CI, 0.68 to 1.10 and HR, 0.77; 95%CI, 0.59 to < 1.0), respectively.

CONCLUSION

An L-shaped relationship between serum 25(OH)D levels with all-cause and CVD mortality was observed in elderly CKD patients in the United States. A 25(OH)D concentration of 90 nmol/L may be the target to reduce the risk of premature death.

Effects of 25-Hydroxyvitamin D Levels on Renal Function: A Bidirectional Mendelian Randomization Study

CONTEXT

Observational studies investigating the role of vitamin D in renal function have yielded inconsistent results.

OBJECTIVE

We tested whether 25-hydroxyvitamin D (25[OH]D) serum levels are associated with renal function, and inversely, whether altered renal function causes changes in 25(OH)D, using Mendelian randomization (MR).

METHODS

In this two-sample MR study, we used single nucleotide polymorphisms (SNP) associated with 25(OH)D in 443 734 Europeans and evaluated their effects on estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN), chronic kidney disease (CKD) risk and progression in genome-wide association studies totaling over 1 million Europeans. To control for pleiotropy, we also used SNPs solely in DHCR7, CYP2R1, and GC, all genes with known roles in vitamin D metabolism. We performed a reverse MR, using SNPs for the above indices of renal function to study causal effects on 25(OH)D levels.

RESULTS

We did not find robust evidence supporting effects of 25(OH)D on eGFR, BUN, and CKD or its progression. Our inverse variance weighted MR demonstrated a 0.56 decrease in standardized log-transformed 25(OH)D (95% CI -0.73, -0.41; P = 2.89 × 10-12) per unit increase in log-transformed eGFR. Increased BUN was associated with increased 25(OH)D (β = 0.25, 95% CI 0.15, 0.36; P = 4.12 × 10-6 per unit increase in log-transformed BUN). Finally, genetically predicted CKD conferred a 0.05 increase in standardized log-transformed 25(OH)D level (95% CI 0.04, 0.06; P = 1.06 × 10-13). Other MR methods confirmed the findings of the main analyses.

CONCLUSION

Genetically predicted CKD, increased BUN, and decreased eGFR are associated with increased 25(OH)D levels, but we found no causal effect of 25(OH)D on renal function in Europeans.

Vitamin D level, pain severity and quality of life among hemodialysis patients: a cross-sectional study

This cross-sectional study aims to find the prevalence of chronic pain and its correlation with the quality of life and vitamin D levels among hemodialysis patients in Palestine. We used the brief pain inventory, the medical outcomes study 36-item short-form health survey, and Serum 25-hydroxyvitamin D to assess chronic pain, quality of life, and vitamin D levels, respectively. The study included 200 patients, 38.1% (95% confidence interval 31.3-45.4%) of whom had chronic pain, and 77.7% (95% confidence interval 71.0-83.4%) had deficient Vitamin D levels. Quality of life scores were generally low, with the lowest in role emotional and physical functioning. Sex, comorbidities, and vitamin D level significantly correlate with pain severity. Employment, number of comorbidities, pain severity, and albumin level are significantly associated with the Physical component of quality of life. On the other hand, employment and pain severity are significantly related to the mental component of quality of life. In conclusion, low vitamin D levels, chronic pain, and low quality of life scores are common among hemodialysis patients. In addition, vitamin D is negatively correlated with pain severity. Therefore, healthcare workers should assess and manage hemodialysis patients' chronic pain to improve their quality of life and reduce suffering.

Detection of factors affecting kidney function using machine learning methods

Due to the increasing prevalence of chronic kidney disease and its high mortality rate, study of risk factors affecting the progression of the disease is of great importance. Here in this work, we aim to develop a framework for using machine learning methods to identify factors affecting kidney function. To this end classification methods are trained to predict the serum creatinine level based on numerical values of other blood test parameters in one of the three classes representing different ranges of the variable values. Models are trained using the data from blood test results of healthy and patient subjects including 46 different blood test parameters. The best developed models are random forest and LightGBM. Interpretation of the resulting model reveals a direct relationship between vitamin D and blood creatinine level. The detected analogy between these two parameters is reliable, regarding the relatively high predictive accuracy of the random forest model reaching the AUC of 0.90 and the accuracy of 0.74. Moreover, in this paper we develop a Bayesian network to infer the direct relationships between blood test parameters which have consistent results with the classification models. The proposed framework uses an inclusive set of advanced imputation methods to deal with the main challenge of working with electronic health data, missing values. Hence it can be applied to similar clinical studies to investigate and discover the relationships between the factors under study.

Greater adherence to the dietary approaches to stop hypertension dietary pattern is associated with preserved muscle strength in patients with autosomal dominant polycystic kidney disease: a single-center cross-sectional study

The present study aimed to determine whether certain diets lower the risk of low muscle strength in patients with autosomal dominant polycystic kidney disease (ADPKD). In this cross-sectional study, outpatient ADPKD patients were enrolled from a tertiary care hospital. Muscle strength was assessed on the basis of handgrip strength (HGS), and dietary pattern indices were calculated using dietary intake data. Among the 68 participants included in this study, 19 (27.9%) had low HGS. Cystatin C concentrations were significantly higher in all participants, and in women in the low compared to the normal HGS group in the unadjusted analyses (P = 0.004). Among analyzed dietary pattern indices, the Dietary Approaches to Stop Hypertension (DASH) score was lower, for all participants and men, in the low compared to the normal HGS group (P < 0.05). Especially, the component score for whole grains of the DASH score was significantly lower in men in the low compared to the normal HGS group in unadjusted analyses. The DASH score was positively correlated with HGS in men (r = 0.387, P = 0.046). In addition, logistic regression analysis showed that the DASH score was negatively associated with low HGS, for all participants (odds ratio = 0.851, P = 0.049) and men (odds ratio = 0.716, P = 0.043), after adjusting for age, sex, and body weight. These findings suggest that the DASH dietary pattern may promote the preservation of muscle strength in ADPKD patients. The DASH diet can be considered as a nutritional strategy to maintain muscle strength and prevent sarcopenia in ADPKD patients.

MicroRNA-122 contributes to lipopolysaccharide-induced acute kidney injury via down-regulating the vitamin D receptor in the kidney

BACKGROUND

Our previous studies showed that vitamin D receptor (VDR) depletion promotes lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice, and renal VDR is down-regulated in AKI, but the mechanism of VDR down-regulation is unclear.

METHODS

Nutritional vitamin D deficiency was induced by feeding mice a vitamin D-deficient (VD-D) diet. Mice were injected intraperitoneally with LPS (20 mg/kg) to establish LPS-induced AKI. Levels of VDR and miR-122 were measured both in vivo and in vitro. The associations between VDR and miR-122 were analysed by dual-luciferase reporter assays.

RESULTS

Compared with vitamin D-sufficient (VD-S) mice, VD-D mice developed more severe renal injury following LPS challenge. LPS induced a dramatic decrease in VDR expression and marked induction of miR-122 both in vivo and in vitro. Furthermore, miR-122 hairpin inhibitor alleviated LPS-induced VDR down-regulation whereas miR-122 mimic directly suppressed VDR expression in HK-2 cells. In luciferase reporter assays, miR-122 mimic was able to suppress luciferase activity in 293T cells co-transfected with a luciferase reporter that contains a putative miR-122 target site from 3'UTR of the VDR transcript, but not when this site was mutated. Moreover, miR-122 mimic significantly blocked paricalcitol-induced luciferase activity in 293T cells co-transfected with a VDRE-driven luciferase reporter, whereas miR-122 hairpin inhibitor enhanced paricalcitol's activity to suppress PUMA and caspase 3 activation induced by LPS in HK-2 cells.

CONCLUSIONS

Collectively, these studies provide evidence that miR-122 directly targets VDR in renal tubular cells, which strongly suggest that miR-122 up-regulation in the kidney under LPS challenge contributes to kidney injury by down-regulating VDR expression.

Hepcidin, iron indices and bone mineral metabolism in non-dialysis chronic kidney disease

BACKGROUND

Few studies have examined the association between hepcidin, iron indices and bone mineral metabolism in non-dialysis chronic kidney disease (CKD) patients.

METHODS

We reviewed the data of 2238 patients from a large-scale multicenter prospective Korean study (2011-16) and excluded 214 patients with missing data on markers and related medications of iron and bone mineral metabolism, hemoglobin, blood pressure and causes of CKD. Multivariate linear regression analysis was used to identify the association between iron and bone mineral metabolism.

RESULTS

The proportion of CKD Stages 1-5 were 16.2, 18.7, 37.1, 21.6 and 6.4%, respectively. Per each 10% increase in transferrin saturation (TSAT), there was a 0.013 mmol/L decrease in phosphorus [95% confidence interval (CI) -0.021 to -0.004; P = 0.003] and a 0.022 nmol/L increase in logarithmic 25-hydroxyvitamin D (Ln-25OHD) levels (95% CI 0.005-0.040; P = 0.019). A 1 pmol/L increase in Ln-ferritin was associated with a 0.080 ng/L decrease in Ln-intact parathyroid hormone (Ln-iPTH; 95% CI -0.122 to -0.039; P < 0.001). Meanwhile, beta (95% CI) per 1 unit increase in phosphorus, Ln-25OHD and Ln-iPTH for the square root of the serum hepcidin were 0.594 (0.257-0.932; P = 0.001), -0.270 (-0.431 to -0.108; P = 0.001) and 0.115 (0.004-0.226; P = 0.042), respectively. In subgroup analysis, the relationship between phosphorus, 25OHD and hepcidin was strongest in the positive-inflammation group.

CONCLUSIONS

Markers of bone mineral metabolism and iron status, including hepcidin, were closely correlated to each other. Potential mechanisms of the relationship warrant further studies.

Combined Treatment with Omega-3 Fatty Acid and Cholecalciferol Increases 1,25-Dihydroxyvitamin D Levels by Modulating Dysregulation of Vitamin D Metabolism in 5/6 Nephrectomy Rats

The protein 1α-hydroxylase (CYP27B1) was expressed in liver and omega-3 fatty acid (FA) elevated 1,25-dihydroxyvitamin D [1,25(OH)₂D] levels in dialysis patients. The aim of this study was to determine whether omega-3 FA and cholecalciferol have effects on vitamin D metabolism related to CYP27B1 and 24-hydroxylase (CYP24) activities in the kidney and liver of 5/6 nephrectomy (Nx) rats. Male Sprague–Dawley rats were divided into the following groups: sham control, 5/6 Nx, 5/6 Nx treated with cholecalciferol, 5/6 Nx treated with omega-3 FA, and 5/6 Nx treated with cholecalciferol/omega-3 FA. CYP27B1 and CYP24 expression were measured in the liver and kidney. Further, 1,25(OH)₂D and 25-hydroxyvitamin D [25(OH)D] levels were measured in serum. Among Nx groups, 1,25(OH)₂D and 25(OH)D levels were lowest in the 5/6 Nx group. CYP24 expression was increased in the kidney of the 5/6 Nx rat model, which was found to be reversed by omega-3 FA or cholecalciferol/omega-3 FA supplementation. Decreased CYP27B1 expression was observed in the liver of the 5/6 Nx rats and its expression was recovered by supplementation with cholecalciferol/omega-3 FA. In conclusion, omega-3 FA and cholecalciferol may synergistically increase 1,25(OH)₂D levels by inhibiting CYP24 expression in the kidney and liver and activating CYP27B1 expression in the liver of 5/6 Nx rats.

Assessment of kidney function and associated risk factors among type 2 diabetic patients

AIM

diabetic patients are required for continuous monitoring programs hence continuous assessment of kidney function parameters is crucial. So, we aimed to determine the prevalence of Chronic Kidney Disease (CKD) and abnormal renal parameters, with poorly controlled type 2 diabetes mellitus pateints MATERIALS AND METHODS: A cross-sectional study was carried out at private health care centre. A total of 300 diabetic patients aged 18 years and above attended the clinic from February 2018 to Dec 2018 were included. Socio-demographic, clinical, and laboratory data were obtained from the medical records of patients. Statistical analysis was carried out using (SPSS, version 23).

RESULTS

out of the 300 diabetes patients recruited 42% of patients with type 2 diabetes had abnormal Creatinine Serum levels and 22.3% had abnormal glomerular filtration rate (GFR). Abnormal albumin urine levels were found in 28.3% and 11.3% had abnormal creatinine in urine. Abnormal Albumin: Creatinine Ratios (Alb/Cr), were found in 23%. Of the total, 77% (n = 231) had normal Alb: Cr Ratio, 20% had risk of nephropathy and 9% had nephropathy.

CONCLUSION

Current study revealed a high prevalence of abnormal renal parameters in patients with type 2 diabetes Mellitus. This necessitates the need for early and universal screening of renal functions. There is also an urgent demand for measures that target tight glycaemic, Vitamin D level and life style modifications is also required to all diabetic patients to achieve target value of HbA1C ≤ 7.

Seasonal variation of serum 25-hydroxyvitamin D and parameters of bone and mineral disorder in dialysis patients

BACKGROUND

Vitamin D deficiency is common among dialysis patients and may impact blood concentrations of calcium, phosphorus, intact parathyroid hormone (iPTH), and alkaline phosphatase (ALP). Seasonal variation of serum 25-hydroxyvitamin D [25(OH)D] concentrations has been well established for the general population; however, less is known about circannual variation in 25(OH)D as well as other parameters of mineral and bone disorder among dialysis patients.

METHOD

Based on 57,500 serum 25(OH)D measurements collected over two years from January 2009 to December 2010 among 25,025 dialysis patients, we evaluated the circannual variations in serum concentrations of 25(OH)D, calcium, phosphorus, iPTH, and ALP by a linear regression model with a cosinor function for the time period (month). We adjusted for potential confounders including case-mix variables, and ultraviolet index.

RESULTS

Serum 25(OH)D concentrations showed significant circannual variation and mean serum 25(OH)D was 3.2 ng/mL higher in summer than in winter. Furthermore, 25(OH)D concentration increased steadily by 1.3 ng/mL per year. While serum calcium concentrations showed statistically significant but clinically negligible seasonal variation (0.02 mg/dL in peak-trough difference), serum phosphorus did not follow such a pattern. Serum iPTH concentrations also showed a modest seasonal variation with 9% higher values in winter than in summer. Concordantly, ALP concentrations in the winter were 2% higher than in the summer time. Seasonal variation of 25(OH)D was greater in male (vs. female), African-American (vs. non-African-American), and younger (vs. older) dialysis patients.

CONCLUSION

Serum 25(OH)D and iPTH concentrations show seasonal variation among dialysis patients while the variation in other parameters of mineral and bone disorder was clinically irrelevant, if any. Serum 25(OH)D also showed a gradual increase over time. Clinicians and researchers should be aware of these changes when interpreting laboratory results in dialysis patients.

Free 25-Vitamin D Is Correlated with Cardiovascular Events in Prevalent Hemodialysis Patients but Not with Markers of Renal Mineral Bone Disease

Free vitamin D is the biologically active form of vitamin D. Vitamin D deficiency is associated with cardiovascular disease, the most common cause of mortality in hemodialysis patients. The goal of our current study was to investigate the relation between blood concentrations of free 25-hydroxyvitamin D with cardiovascular events in end-stage chronic kidney disease patients on hemodialysis, because this is unknown so far. We measured free vitamin D levels in 117 stable consecutive prevalent patients in September as a surrogate of vitamin D exposure during the past 6 months, and recorded the number of cardiovascular events during the previous 6 months defined as hospitalization due to heart failure, episodes of acute coronary syndrome, and stroke. Fourteen events occurred during the observation period. In patients without any cardiovascular events the free vitamin D levels were significantly higher as compared to those with cardiovascular events (patients without events: 5.68 [4.37–9.27] pg/mL; patients with events: 4.74 [3.46–5.37] pg/mL, p = 0.015). This finding remained stable after multiple regression analysis considering confounding factors such as age, time on dialysis, preexisting diabetes, hypertension, and coronary heart disease. In conclusion, our study shows that free vitamin D serum concentrations are independently associated with major cardiovascular events in chronic kidney disease patients on dialysis.

Association between serum 25-hydroxyvitamin D and diabetic kidney disease in Chinese patients with type 2 diabetes

Objective

The objective was to assess the association between 25-hydroxyvitamin D (25OHD) level and diabetic kidney disease (DKD) in Chinese patients with type 2 diabetes.

Methods

Data pertaining to 351 in-patients with type 2 diabetes were collected. Subjects were classified into three groups based on the level of urinary albumin-to-creatinine ratio (UACR). UACR < 30 mg/g was defined as normoalbuminuria, while UACR levels of 30–300 mg/g and ≥ 300 mg/g were defined as microalbuminuria and macroalbuminuria, respectively. Serum 25OHD and other clinical characteristics among various UACR groups were compared. The relationship between albuminuiria and 25OHD was analyzed.

Results

The prevalence of 25OHD insufficiency in the microalbuminuria group was significantly higher than that in the normoalbuminuria group (25.1% vs. 19.6%; P < 0.05); patients with macroalbuminuria had the highest prevalence of 25OHD deficiency (37.8%; P < 0.01 versus normoalbuminuria). Logistic regression analyses demonstrated that low 25OHD levels were associated with DKD [odds ratio (OR) = 1.51, 95% confidence interval (CI) 1.16–1.97). The association was more robust after adjusting for sex, hypertension, increased systolic blood pressure, glycemic status, and hyperuricemia (OR = 1.62, 95% CI 1.19–2.20).

Conclusions

The prevalence of vitamin D insufficiency/deficiency in patients with albuminuria was overtly higher than that in patients without albuminuria among Chinese adults with type 2 diabetes. Vitamin D insufficiency/deficiency was independently associated with DKD in type 2 diabetes.

Placebo-controlled, randomized clinical trial of high-dose cholecalciferol in renal dialysis patients: effect on muscle strength and quality of life

BACKGROUND

The importance of vitamin D sufficiency in deficient dialysis patients is uncertain. This study aimed to determine if high-dose cholecalciferol for 1-year affected symptoms, muscle strength, blood pressure (BP), cardiac ischaemia, parathyroid hormone, calcium or phosphate.

METHODS

This was a randomized, double-blind, placebo-controlled trial with 1-year follow-up that enrolled dialysis patients with 25-hydroxy-vitamin D [25(OH)D] concentration <50 nmol/L. Consenting patients were randomized to 50 000 U/week oral cholecalciferol or matching placebo. Dosage was adjusted at 3- and 6-month study visits, targeting a 25(OH)D concentration >80 nmol/L. The primary objectives were to assess the effect of supplementation on renal-specific symptoms and on hand-grip strength. Symptoms were assessed using the Kidney Disease Quality of Life Short Form and muscle strength with a hand grip-strength dynamometer. Hypothesis testing was by two-group t-test and Wilcoxon rank-sum on an intention-to-treat basis.

RESULTS

In all, 68 participants were randomized and received study medication. Median 12-month plasma 25(OH)D concentration was 119 nmol/L and 37 nmol/L in the cholecalciferol and placebo groups, respectively. There was no statistical difference in primary outcomes at 12 months. Mean symptom scores at 12 months were two lower in the cholecalciferol group (95% confidence interval -10 to 6) and geometric mean grip-strength was 27 kg in both groups. Symptoms, strength, BP, plasma mineral bone parameters and adverse events were not different between the groups at follow-up.

CONCLUSIONS

High-dose cholecalciferol in a deficient dialysis population had no effect on muscle strength or symptoms but appears safe.

The impact of sunlight exposure on mortality of patients with end stage renal disease

Recent data suggest that reduced sunlight exposure is associated with increased mortality in the general population. To date, the association between sunlight exposure and mortality in dialysis patients has not been examined. Among 134,478 dialysis patients in the Korean end-stage renal disease (ESRD) cohort from 2001 to 2014, 31,291 patients were enrolled from seven metropolitan cities, and data were analyzed using bi-directional case-crossover design. We examined the association between short-term sunlight exposure and mortality in ESRD patients. We adjusted for temperature, humidity, and daily concentrations of nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), carbon monoxide (CO), and particle matter (PM₁₀) as confounders. The characteristics of the study population included age (65.6 ± 12.26 (mean ± standard deviation [SD]) years), sex (male, 59.96%; female, 41.04%), comorbidity (diabetes, 53.58%; hypertension, 40.5%), and kidney dialysis type (hemodialysis, 73.02%; peritoneal dialysis, 26.98%). The mean ± SD follow-up time was 4.68 ± 4.37 years. The daily sunlight exposure was significantly decreased in the case group compared with the control group (P = 0.004). Sunlight exposure was associated with all-cause death overall (ORs [95% CI]: 0.99 [0.98-0.99], P = 0.042) in a fully adjusted model. Patients with diabetes (ORs [95% CI]: 0.98 [0.97-0.99], P = 0.016) or aged higher than 75 years (ORs [95% CI]; 0.97 [0.96-0.99], P = 0.020) had higher risks of mortality than patients without diabetes or aged below 75 years, respectively. These findings suggest that sunlight exposure is inversely correlated with all-cause mortality in dialysis patients.

The Effect of Long-Term Cholecalciferol Supplementation on Vascular Calcification in Chronic Kidney Disease Patients With Hypovitaminosis D

OBJECTIVE

The role of vitamin D supplementation on vascular calcification (VC) in patients with chronic kidney disease (CKD) is controversial. The objective of this study was to evaluate the effects of long-term cholecalciferol supplementation on VC in nondialysis patients with CKD stages 3-4 with hypovitaminosis D.

DESIGN AND METHODS

Eighty patients aged 18-85 years with creatinine clearance between 15 and 60 mL/min/1.73 m² and serum 25(OH)D level < 30 ng/mL were enrolled in a 18-month prospective study. Individuals with vitamin D insufficiency (25-hydroxyvitamin D [25(OH)D] level between 16 and 29 ng/mL) were included in a randomized, double-blind, two-arm study to receive cholecalciferol or placebo. Patients with vitamin D deficiency [25(OH)D < 15 ng/mL] were included in an observational study and mandatorily received cholecalciferol. The coronary artery calcium score was obtained by multislice computed tomography at baseline and the 18th month.

RESULTS

During the study, VC did not change in the treated insufficient group (418 [81-611] to 364 [232-817] AU, P = 0.25) but increased in the placebo group (118 [37-421] to 199 [49-490] AU, P = 0.01). The calcium score change was inversely correlated with 25(OH)D change (r = -0.45; P = 0.037) in the treated insufficient group but not in the placebo group. Renal function did not change in the insufficient, treated, and placebo groups. In multivariate analysis, there was no difference in VC progression between the treated and placebo insufficient groups (interaction P = 0.92). In the deficient group, VC progressed (265 [84-733] to 333 [157-745] AU; P = 0.006) and renal function declined (33 [26-43] to 23 [17-49] mL/min/1.73 m²; P = 0.04). The calcium score change was inversely correlated with cholecalciferol cumulative doses (r = -0.41; P = 0.048) and kidney function change (r = -0.43; P = 0.033) but not with 25(OH)D change (r = -0.08; P = 0.69).

CONCLUSION

Vitamin D supplementation did not attenuate VC progression in CKD patients with hypovitaminosis D.

CONCLUSION

Vitamin D supplementation did not attenuate VC progression in CKD patients with hypovitaminosis D.

Factors associated with survival in dogs with chronic kidney disease

Background: Chronic kidney disease (CKD) is associated with morbidity and mortality in dogs. Plasma fibroblast growth factor‐23 (FGF‐23) concentration is an independent predictor of CKD progression and survival in cats and people with CKD.

Objectives: To investigate the relationship among FGF‐23, parathyroid hormone (PTH), vitamin D metabolites, and other clinical variables with survival time in dogs with CKD.

Animals: Twenty‐seven azotemic CKD dogs.

Methods: Dogs were recruited prospectively into the study and followed until death or study conclusion. Dogs were International Renal Interest Society (IRIS) staged into stage 2 (n = 9), stage 3 (n = 12), and stage 4 (n = 6) CKD. Survival times were calculated from the date of study inclusion. Univariable Cox regression was used to assess variables associated with survival including body condition score (BCS), muscle condition score, hematocrit, creatinine, CKD stage, serum phosphorus, urine protein:creatinine ratio (UPC), calcium phosphorus product (CaPP), PTH, 25‐hydroxyvitamin D, 1,25‐‐dihydroxyvitamin D, and FGF‐23 concentrations.

Results: Significant hazard ratios (hazard ratio; 95% confidence interval; P value) were as follows: BCS < 4/9 (1.579; 1.003‐2.282; P = .05), muscle atrophy (2.334; 1.352‐4.030; P = .01), increased creatinine (1.383; 1.16‐1.64; .01), hyperphosphatemia (3.20; 1.357‐7.548; P = .005), increased UPC (3.191; 1.310‐7.773; P = .01), increased CaPP (4.092; 1.771‐9.454; P = .003), and increased FGF‐23 (2.609; 1.090‐6.240; P = .05). Survival times for each IRIS CKD stage were significantly different (P = .01).

Conclusions and Clinical Importance: Multiple variables, including FGF‐23, were associated with duration of survival in CKD dogs. FGF‐23 could be a prognostic marker in dogs with CKD.

Vitamin D deficiency and infection risk in kidney transplant recipients: A single-center cohort study

BACKGROUND

Recent studies have reported an increased susceptibility to infection among vitamin D-deficient kidney transplant (KT) recipients, although methodological concerns remain.

METHODS

Serum 25-hydroxyvitamin D (25(OH)D) levels were measured in 246 KT recipients at post-transplant months 1, 3, 6 and 12. Vitamin D status was analysed in terms of deficiency (Endocrine Society [<20 ng/mL] and Institute of Medicine [IoM, <12 ng/mL] criteria) and as a continuous variable. Cox models for overall, bacterial and opportunistic infection were adjusted for nutritional status and immunosuppression-related covariates.

RESULTS

Median serum 25(OH)D increased from month 1 (10.5 ng/mL) to month 6 (16.3 ng/mL; P-value = 0.001). Prevalence of vitamin D deficiency at month 1 ranged from 87.0% to 61.0% (depending on the diagnostic criteria) and significantly decreased over the next months. After adjustment for age and nutritional status, vitamin D deficiency (serum 25(OH)D < 12 ng/mL) at month 1 was an independent risk factor for overall (hazard ratio [HR]: 1.70; 95% confidence interval [CI]: 1.08-2.69; P-value = 0.023) and opportunistic infection (HR: 4.05; 95% CI: 1.57-10.46; P-value = 0.004), but not for bacterial infection. A protective effect for overall (adjusted HR: 0.76; 95% CI: 0.63-0.93; P-value = 0.007) and opportunistic infection (adjusted HR: 0.62; 95% CI: 0.45-0.86; P-value = 0.004) was observed when 25(OH)D levels were analyzed per one-quartile increases.

CONCLUSIONS

Vitamin D status influences the risk of infection among KT recipients, with the association being particularly evident for opportunistic events and mainly restricted to the early post-transplant period.

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.

Randomized Controlled Trial for the Effect of Vitamin D Supplementation on Vascular Stiffness in CKD

BACKGROUND AND OBJECTIVES

Vitamin D is implicated in vascular health in CKD. This study compared placebo, calcifediol, and calcitriol treatment with changes in vascular stiffness, BP, proteinuria, mineral metabolism parameters, C-reactive protein, and fibroblast growth factor 23 in patients with stable CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a double-blind, randomized controlled trial in out-patient CKD clinics in Vancouver, Canada, from February of 2011 to August of 2014, enrolling 119 patients with an eGFR of 15-45 ml/min per 1.73 m2. Change in pulse wave velocity (PWV) was measured after 6 months of treatment with a fixed dose of oral calcifediol (5000 IU 25-hydroxyvitamin D3), calcitriol (0.5 µg 1,25-dihydroxyvitamin D3), or placebo, thrice weekly.

RESULTS

Eighty-seven participants were evaluated. Mean age was 66 years, 71% were men, 40% were diabetic, and mean baseline PWV was 11.5 m/s (SD=3.9 m/s). After 6 months, the PWV decreased in the calcifediol group (mean change, -1.1; 95% confidence interval [95% CI], -2.2 to 0.1 m/s), remained unchanged in the calcitriol group (mean change, 0.2; 95% CI, -0.9 to 1.4 m/s), and increased in the placebo group (mean change, 1.1; 95% CI, -0.1 to 2.2 m/s). The overall P value for between-arm changes was 0.03. Absolute PWV change was significantly different between groups (P=0.04): the combined vitamin D treatment group saw decreased PWV (mean change, -0.4; 95% CI, -1.2 to 0.4 m/s) whereas the placebo group saw increased PWV (mean change, +1.1; 95% CI, -0.1 to 2.2 m/s). The treatment group demonstrated significantly decreased serum parathyroid hormone (mean difference, -0.5; 95% CI, -0.7 to -0.3 ln[pg/ml]; P<0.001) and increased calcium (mean difference, 0.4; 95% CI, -0.1 to 0.7 mg/dl; P=0.02). In observational analysis, participants in the highest 25-hydroxyvitamin D tertile at trial end had significant decreases in PWV (mean change, -1.0; 95% CI, -2.0 to 0.0 m/s) compared with the middle and lowest tertiles (P<0.01). Side effects were minor and rare.

CONCLUSIONS

Six months of supplemental vitamin D analogs at fixed doses may achieve a reduction of PWV in patients with advanced CKD. Because the treatment effect was attenuated when baseline PWV was included as a covariate, these findings should be replicated in larger populations and further studied.

Vitamin D status and all-cause mortality in patients with chronic kidney disease: A systematic review and dose-response meta-analysis

CONTEXT

Prevalence of vitamin D deficiency is high in patients with chronic kidney disease. Less attention has been paid to measurement and correction of serum level of 25(OH)D in these patients.

OBJECTIVE

We examined the association between different levels of serum 25(OH)D and risk of all-cause mortality in patients with chronic kidney disease.

DATA SOURCES

Systematic search were done using MedLine and EMBASE from inception up to November 2016. Reference lists of all relevant articles and reviews also were searched.

STUDY SELECTION

Prospective or retrospective cohort studies that reported risk estimates of all-cause mortality for three or more categories of serum 25(OH)D in patients with chronic kidney disease were selected. Studies that reported results as continuously also were included. Two independent investigators screened and selected the articles. Of 1281 identified studies, 13 prospective cohorts, two retrospective cohorts and one nested case-control study with 17053 patients and 7517 incident death were included.

DATA EXTRACTION

Two independent authors extracted data from included studies. Any discrepancies were resolved through consensus.

DATA SYNTHESIS

Reported risk estimates were combined using a random-effects model. Summary risk estimates of all-cause mortality were1.63 (95%CI: 1.32, 1.94) for severe deficiency (<10 ng/ml), 1.22 (95%CI: 1.09, 1.35) for mild deficiency (10-20 ng/ml) and 1.12 (95%CI: 1.06, 1.18) for insufficiency (20-30 ng/ml). Results were more evident in dialysis dependent patients. 10 ng/ml increment in serum 25(OH)D was associated with 21% reduction in the risk of overall mortality (RR: 0.79, 95%CI: 0.70, 0.87).Lower risk of all-cause mortality was observed at serum 25(OH)D about 25 to 30 ng/ml. Dialysis treatment was one of the sources of variation between studies.

CONCLUSIONS

Higher levels of serum 25(OH) D were associated with lower risk of all-cause mortality in patients with chronic kidney disease, but concerning serum levels more than 35 ng/mL we have no conclusive evidence.

Vitamin D prohormone in the treatment of secondary hyperparathyroidism in patients with chronic kidney disease

Secondary hyperparathyroidism (sHPT) represents the adaptive and very often, finally, maladaptive response of the organism to control the disturbed homeostasis of calcium, phosphorus, and vitamin D metabolism caused by declining renal function in chronic kidney disease (CKD). sHPT leads to cardiovascular and extravascular calcifications and is directly linked to an increased risk of cardiovascular morbidity and mortality as well as excess all-cause mortality. Vitamin D plays an important role in the development of sHPT. CKD patients are characterized by a high prevalence of hypovitaminosis D. Supplementation with both vitamin D prohormones cholecalciferol and ergocalciferol enables the achievement and maintenance of a normal vitamin D status when given in adequate doses over an appropriate treatment period. In patients with earlier stages of CKD, sHPT is influenced by and can be successfully treated with vitamin D prohormone supplementation, whereas in patients with very late stages of CKD and those requiring dialysis, treatment with prohormones seems to be of limited efficacy. This review gives an overview of the pathogenesis of sHPT, summarizes vitamin D metabolism, and discusses the existing literature regarding the role of vitamin D prohormone in the treatment of sHPT in patients with CKD.

Secondary Hyperparthyroidism: Pathogenesis, Diagnosis, Preventive and Therapeutic Strategies

Uremic secondary hyperparathyroidism is a multifactorial and complex disease often present in advanced stages of chronic kidney disease. The accumulation of phosphate, the increased FGF23 levels, the reduction in active vitamin D production, and the tendency to hypocalcemia are persistent stimuli for the development and progression of parathyroid hyperplasia with increased secretion of PTH. Parathyroid proliferation may become nodular mainly in cases of advanced hyperparathyroidism. The alterations in the regulation of mineral metabolism, the development of bone disease and extraosseous calcifications are essential components of chronic kidney disease-mineral and bone disorder and have been associated with negative outcomes. The management of hyperparathyroidism includes the correction of vitamin D deficiency and control of serum phosphorus and PTH without inducing hypercalcemia. An update of the leading therapeutic tools available for the prevention and clinical management of secondary hyperparathyroidism, its diagnosis, and the main mechanisms and factors involved in the pathogenesis of the disease will be described in this review.

Dysfunctional immunometabolic effects of vitamin D deficiency, increased cardiometabolic risk. Potential epidemiological alert in America?

Vitamin D deficiency is a serious public health problem worldwide that affects not only skeletal health, but also a wide range of acute and chronic diseases. However, there is still skepticism because of the lack of randomized, controlled trials to support association studies on the benefits of vitamin D for non-skeletal health. This review was based on articles published during the 1980-2015 obtained from the Cochrane Central Register of controlled trials, MEDLINE and PubMed, and focuses on recent challenges with regard to the definition of vitamin D deficiency and how to achieve optimal serum 25-hydroxyvitamin D levels from dietary sources, supplements, and sun exposure. The effect of vitamin D on epigenetic fetal programming and regulation of genes that may potentially explain why vitamin D could have such lifelong comprehensive health benefits is reviewed. Optimization of vitamin D levels in children and adults around the world has potential benefits to improve skeletal health and to reduce the risk of chronic diseases, including some types of cancer, autoimmune diseases, infectious diseases, type 2 diabetes mellitus, and severe cardiovascular disorders such as atherothrombosis, neurocognitive disorders, and mortality.

Cholecalciferol v. ergocalciferol for 25-hydroxyvitamin D (25(OH)D) repletion in chronic kidney disease: a randomised clinical trial

Patients with chronic kidney disease (CKD) demonstrate complex mineral metabolism derangements and a high prevalence of vitamin D deficiency. However, the optimal method of 25-hydroxyvitamin D (25(OH)D) repletion is unknown, and trials analysing the comparative efficacy of cholecalciferol and ergocalciferol in this population are lacking. We conducted a randomised clinical trial of cholecalciferol 1250μg (50 000 IU) weekly v. ergocalciferol 1250μg (50 000 IU) weekly for 12 weeks in forty-four non-dialysis-dependent patients with stage 3-5 CKD. The primary outcome was change in total 25(OH)D from baseline to week 12 (immediately after therapy). Secondary analyses included the change in 1,25-dihydroxyvitamin D (1,25(OH)2D), parathyroid hormone (PTH), D2 and D3 sub-fractions of 25(OH)D and 1,25(OH)2D and total 25(OH)D from baseline to week 18 (6 weeks after therapy). Cholecalciferol therapy yielded a greater change in total 25(OH)D (45·0 (sd 16·5) ng/ml) v. ergocalciferol (30·7 (sd 15·3) ng/ml) from baseline to week 12 (P<0·01); this observation partially resulted from a substantial reduction in the 25(OH)D3 sub-fraction with ergocalciferol. However, following cessation of therapy, no statistical difference was observed for total 25(OH)D change from baseline to week 18 between cholecalciferol and ergocalciferol groups (22·4 (sd 12·7) v. 17·6 (sd 8·9) ng/ml, respectively; P=0·17). We observed no significant difference between these therapies with regard to changes in serum PTH or 1,25(OH)2D. Therapy with cholecalciferol, compared with ergocalciferol, is more effective at raising serum 25(OH)D in non-dialysis-dependent CKD patients while active therapy is ongoing. However, levels of 25(OH)D declined substantially in both arms following cessation of therapy, suggesting the need for maintenance therapy to sustain levels.

Beneficial Effects of UV-Radiation: Vitamin D and beyond

Aside from its well-known effects on bone and mineral metabolism, vitamin D may also play an important role in extra-skeletal processes like immunologic diseases, cancer, or cardiovascular diseases. Even though meta-analyses showed that vitamin D supplementation reduces fractures, falls, and overall mortality, its potential benefits did not find universal acclaim. Several health care authorities published Recommended Dietary Allowances (RDAs) for vitamin D, most of them ranging from 600 to 800 international units (IU) per day, corresponding to a serum level of 25-hydroxyvitamin D of at least 20 ng/mL (50 nmol/L). However, studies conducted in the general population revealed a much lower overall intake of vitamin D than the proposed RDAs. Thus, strategies to increase the vitamin D intake in the general population, e.g., food fortification or vitamin D supplementation, are needed to match the existing evidence and recommendations. Therefore, several currently ongoing projects aim to investigate the effect of vitamin D supplementation in the general population and try to establish food-based solutions to improve vitamin D status.

What is the optimal level of vitamin D in non-dialysis chronic kidney disease population?

AIM

To evaluate thresholds for serum 25(OH)D concentrations in relation to death, kidney progression and hospitalization in non-dialysis chronic kidney disease (CKD) population.

METHODS

Four hundred and seventy non-dialysis 3-5 stage CKD patients participating in OSERCE-2 study, a prospective, multicenter, cohort study, were prospectively evaluated and categorized into 3 groups according to 25(OH)D levels at enrollment (less than 20 ng/mL, between 20 and 29 ng/mL, and at or above 30 ng/mL), considering 25(OH)D between 20 and 29 ng/mL as reference group. Association between 25(OH)D levels and death (primary outcome), and time to first hospitalization and renal progression (secondary outcomes) over a 3-year follow-up, were assessed by Kaplan-Meier survival curves and Cox-proportional hazard models. To identify 25(OH)D levels at highest risk for outcomes, receiver operating characteristic (ROC) curves were performed.

RESULTS

Over 29 ± 12 mo of follow-up, 46 (10%) patients dead, 156 (33%) showed kidney progression, and 126 (27%) were hospitalized. After multivariate adjustment, 25(OH)D < 20 ng/mL was an independent predictor of all-cause mortality (HR = 2.33; 95%CI: 1.10-4.91; P = 0.027) and kidney progression (HR = 2.46; 95%CI: 1.63-3.71; P < 0.001), whereas the group with 25(OH)D at or above 30 ng/mL did not have a different hazard for outcomes from the reference group. Hospitalization outcomes were predicted by 25(OH) levels (HR = 0.98; 95%CI: 0.96-1.00; P = 0.027) in the unadjusted Cox proportional hazards model, but not after multivariate adjusting. ROC curves identified 25(OH)D levels at highest risk for death, kidney progression, and hospitalization, at 17.4 ng/mL [area under the curve (AUC) = 0.60; 95%CI: 0.52-0.69; P = 0.027], 18.6 ng/mL (AUC = 0.65; 95%CI: 0.60-0.71; P < 0.001), and 19.0 ng/mL (AUC = 0.56; 95%CI: 0.50-0.62; P = 0.048), respectively.

CONCLUSION

25(OH)D < 20 ng/mL was an independent predictor of death and progression in patients with stage 3-5 CKD, with no additional benefits when patients reached the levels at or above 30 ng/mL suggested as optimal by CKD guidelines.

Inflammation, vitamin D and dendritic cell precursors in chronic kidney disease

Decreased blood dendritic cell precursors (DCP) count is linked with atherosclerotic disease, while reduction of circulating DCP is also seen in patients with chronic kidney disease (CKD). As poor vitamin D status could be linked to a compromised innate immune response, we hypothesized that vitamin D status might be involved in the decrease in circulating DCP in CKD. Moreover, the potential role of inflammation was considered. Circulating myeloid (mDCP), plasmacytoid (pDCP) and total DCP (tDCP) were analysed using flow cytometry in 287 patients with CKD stage 3. Serum 25(OH)D and 1,25(OH)2D levels were measured using enzyme-linked immunosorbent assays (ELISA), interleukin (IL)-6, IL-10 and tumour necrosis factor (TNF)-α using cytometric bead array, C-reactive protein (CRP) using a high-sensitivity (hs) ELISA. Contrary to our hypothesis, there was no association between vitamin D levels and DCP, although their number was decreased significantly in CKD (P < 0·001). Instead, mDCP (r = -0·211) and tDCP (r = -0·188,) were associated slightly negatively with hsCRP but positively with the estimated glomerular filtration rate (eGFR, r = 0·314 for tDCP). According to multivariate linear regression, only higher hsCRP concentration and the presence of diabetes mellitus had a significant negative influence on DCP count (P < 0·03, respectively) but not vitamin D, age and eGFR. A significant impact of vitamin D on the reduction of circulating DCP in CKD 3 patients can be neglected. Instead, inflammation as a common phenomenon in CKD and diabetes mellitus had the main influence on the decrease in DCP. Thus, a potential role for DCP as a sensitive marker of inflammation and cardiovascular risk should be elucidated in future studies.

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

BACKGROUND

As cardiovascular factors are the leading cause of mortality in chronic kidney disease (CKD) and as vitamin D deficiency is prevalent in this population, we aimed to examine the effect of oral cholecalciferol on cardiac parameters and biomarkers for endothelial cell activation in children with CKD.

METHODS

Forty-one children with CKD and 24 healthy subjects free of any underlying cardiac or renal disease with low 25-hydroxyvitamin D3 (25OHD) levels were evaluated using echocardiography basally and following Stoss vitamin D supplementation. The local vascular stiffness and endothelial dysfunction markers were compared among the groups.

RESULTS

Initial flow-mediated dilatation (FMD) measurements were lower and local arterial stiffness was significantly higher in patients. After vitamin D supplementation, these improved significantly in patients, while no significant change was observed for the healthy group. Homocysteine showed inverse correlation with baseline vitamin D level in CKD children and von Willebrand factor emerged as an independent risk factor for FMD impairment.

CONCLUSIONS

Our interventional study revealed the favorable effects of high-dose cholecalciferol on cardiovascular and endothelial parameters, implying the importance of vitamin D supplementation in children with CKD.

Race, Mineral Homeostasis and Mortality in Patients with End-Stage Renal Disease on Dialysis

BACKGROUND

Abnormalities in mineral homeostasis are ubiquitous in patients on dialysis, and influenced by race. In this study, we determine the race-specific relationship between mineral parameters and mortality in patients initiating hemodialysis.

METHODS

We measured the levels of fibroblast growth factor 23 (FGF23) and 25-hydroxyvitamin D (25 D) in 184 African American and 327 non-African American hemodialysis patients who enrolled between 1995 and 1998 in the Choices for Healthy Outcomes in Caring for ESRD Study. Serum calcium, phosphorus, parathyroid hormone (PTH) and total alkaline phosphatase levels were averaged from clinical measurements during the first 4.5 months of dialysis. We evaluated the associated prospective risk of mortality using multivariable Cox proportional hazards models stratified by race.

RESULTS

PTH and total alkaline phosphatase levels were higher, whereas calcium, phosphorus, FGF23 and 25 D levels were lower in African Americans compared to those of non-African Americans. Higher serum phosphorus and FGF23 levels were associated with greater mortality risk overall; however, phosphorus was only associated with risk among African Americans (HR 5.38, 95% CI 2.14-13.55 for quartile 4 vs. 1), but not among non-African Americans (p-interaction = 0.04). FGF23 was associated with mortality in both groups, but more strongly in African Americans (HR 3.91, 95% CI 1.74-8.82 for quartiles 4 vs. 1; p-interaction = 0.09). Serum calcium, PTH, and 25 D levels were not consistently associated with mortality. The lowest and highest quartiles of total alkaline phosphatase were associated with higher mortality risk, but this did not differ by race (p-interaction = 0.97).

CONCLUSIONS

Aberrant phosphorus homeostasis, reflected by higher phosphorus and FGF23, may be a risk factor for mortality in patients initiating hemodialysis, particularly among African Americans.

Vitamin d in the patients with chronic kidney disease: when, to whom and in which form

Alteration in vitamin D metabolism has a central role in the pathogenesis of secondary hyperparathyroidism (SHPT) and is also associated with increased cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). For more than sixty years, vitamin D, nutritional vitamin D (ergocalciferol, cholecalciferol or calcifediol) and nonselective vitamin D receptor (VDR) activators (calcitriol, alfacalcidol) have been used in the prevention and treatment of SHPT. In the last twenty years, selective VDR activators (paricalcitol, maxacalcitol) have been used to target SHPT. However, there are many open questions regarding use of nutritional vitamin D or VDR activators. The K/DOQI and KDIGO guidelines recommended testing for vitamin D insufficiency and deficiency in patients with CKD, but there is no consensus on the definition of vitamin D insufficiency in CKD. There are a many open questions, for example, regarding the optimal nutritional vitamin D type and the dose and co-administration of nutritional vitamin and VDR activators. Therapy with VDRAs is required in the majority of patients with CKD, particularly in dialysis patients. However, when to start with VDRAs is not so apparent. Is PTH level the only indication of when to start therapy? Although VDRAs are very effective in lowering PTH levels and bone metabolism the effect of patients mortality is not so straightforward. Despite many unanswered questions, there is a large body of experimental and clinical data to support vitamin D use in patients with CKD. To obtain answers to the open questions, we need more randomized controlled trials.

The effects of omega-3 fatty acid on vitamin D activation in hemodialysis patients: a pilot study

The high incidence of cardiovascular disease and vitamin D deficiency in chronic kidney disease patients is well known. Vitamin D activation by omega-3 fatty acid (FA) supplementation may explain the cardioprotective effects exerted by omega-3 FA. We hypothesized that omega-3 FA and 25-hydroxyvitamin D (25(OH)D) supplementation may increase 1,25-dihydroxyvitamin D (1,25(OH)₂D) levels compared to 25(OH)D supplementation alone in hemodialysis (HD) patients that have insufficient or deficient 25(OH)D levels. We enrolled patients that were treated for at least six months with 25(OH)D < 30 ng/mL (NCT01596842). Patients were randomized to treatment for 12 weeks with cholecalciferol supplemented with omega-3 FA or a placebo. Levels of 25(OH)D and 1,25(OH)₂D were measured after 12 weeks. The erythrocyte membrane FA contents were also measured. Levels of 25(OH)D were increased in both groups at 12 weeks compared to baseline. The 1,25(OH)₂D levels at 12 weeks compared to baseline showed a tendency to increase in the omega-3 FA group. The oleic acid and monounsaturated FA content decreased, while the omega-3 index increased in the omega-3 FA group. Omega-3 FA supplementation may be partly associated with vitamin D activation, although increased 25(OH)D levels caused by short-term cholecalciferol supplementation were not associated with vitamin D activation in HD patients.

The relationship between ultraviolet light exposure and mortality in dialysis patients

BACKGROUND

Emerging data suggest that reduced exposure to ultraviolet (UV) radiation is associated with increased mortality in the general population. To date, the association between UV exposure and mortality in dialysis patients has not been examined.

METHODS

We examined the association between UV index, a proxy of UV exposure, and all-cause mortality among 47,286 US dialysis patients (entry period 2001-2006, with follow-up through 2009) from a large national dialysis organization using multivariable Cox regression. The UV index was ascertained by linking individual patients' residential zip codes to National Oceanic and Atmospheric Administration data, and was categorized as low (0-<3), moderate (3-<5), moderate-high (5-<6), high (6-<7), and very-high (≥7). In secondary analyses, we examined the UV index-mortality association within subgroups of age (<65 vs. ≥65 years old), sex, and race (white vs. non-white).

RESULTS

The study population's mean ± SD age was 60 ± 16 and included 46% women and 56% diabetics. Compared to patients residing in moderate-high UV index regions, those residing in high and very-high UV index regions had a lower mortality risk: adjusted HRs 0.84 (95% CI) 0.81-0.88 and 0.83 (95% CI) 0.75-0.91, respectively. A similar inverse association between UV index and mortality was observed across all subgroups, although there was more pronounced reduction in mortality among whites vs. non-whites.

CONCLUSION

These data suggest that dialysis patients residing in higher UV index regions have lower all-cause mortality compared to those living in moderate-high UV regions. Further studies are needed to determine the mechanisms underlying the UV index-mortality association.

Low-dose cholecalciferol supplementation and dual vitamin D therapy in haemodialysis patients

BACKGROUND

Traditionally, secondary hyperparathyroidism (SHPT) due to low calcitriol synthesis in failing kidneys has been treated with synthetic vitamin D receptor (VDR) activators. Recently, also the importance of low native vitamin D status beyond the issue of SHPT has been recognized in these patients. The aim of this work was to evaluate the effect of cholecalciferol supplementation in haemodialysis patients with low vitamin D serum levels. Another aim was to evaluate dual vitamin D therapy (cholecalciferol supplementation plus paricalcitol) in haemodialysis patients with vitamin D deficiency and concomitant SHPT.

METHODS

Ninety clinically stable maintenance haemodialysis patients were included. Supervised cholecalciferol supplementation was administered due to low vitamin D status. Patients with SHPT were also treated with synthetic VDR activator. Two pre hoc subgroups for statistical analysis were formed: patients treated solely with cholecalciferol (N=34; 5,000 IU once weekly) and patients treated with a combination of cholecalciferol (identical dose, i.e. 5,000 IU/week) plus paricalcitol (N=34, median dose 10 μg/week). Follow-up visit was scheduled 15 weeks later. Serum concentrations of calcidiol (25-D), parathyroid hormone (PTH) and beta-cross laps (CTX) were assessed at baseline and at follow-up. Serum calcium, phosphate and alkaline phosphatase (ALP) were monitored monthly. Only non-calcium gastrointestinal phosphate binders were administered. Dialysate calcium was 1.5 mmol/L in all patients, and no oral calcium-containing preparations were prescribed. Depending on data distribution, parametric or nonparametric statistical methods were used for comparison within each group (i.e. baseline vs. follow-up data) as well as between groups.

RESULTS

In the whole group of 90 patients, mean baseline 25-D serum level was 20.3 (standard deviation 8.7) nmol/L, and it increased to 66.8 (19) nmol/L (p<0.0001) after supplementation. In both preformed subgroups, the effect of vitamin D supplementation was almost identical. In cholecalciferol monotherapy, 25-D levels increased from 18.4 (8.2) to 68.6 (21.2) and in dual vitamin D therapy from 18.4 (5.0) to 67.6 (17.7) nmol/L (both p<0.0001). In addition, both treatment modalities decreased serum PTH levels importantly: from 21.7 (interquartile range 17.3; 35.4) to 18.1 pmol/L (15.3; 24.7) in monotherapy (p=0.05) and from 38.6 (31.8; 53.3) to 33.9 pmol/L (26.1; 47.5) in dual vitamin D therapy (p=0.01). Serum calcium, phosphate, ALP and CTX did not change. We have not observed any episode of hypercalcemia in any subject during the whole period of follow-up. At baseline, slightly lower 25-D levels were observed in diabetic than in non-diabetic patients. This difference disappeared after substitution. Vitamin D status and its changes were not related to the patient's age.

CONCLUSION

Low 25-D levels were very common in haemodialysis patients. They were safely and effectively corrected with supervised low-dose cholecalciferol supplementation. In patients with higher baseline PTH levels, dual vitamin D therapy (cholecalciferol plus paricalcitol) was safely and effectively used.

The influence of vitamin D analogs on calcification modulators, N-terminal pro-B-type natriuretic peptide and inflammatory markers in hemodialysis patients: a randomized crossover study

Background

The risk of cardiovascular disease is tremendously high in dialysis patients. Dialysis patients treated with vitamin D analogs show decreased cardiovascular morbidity and mortality compared with untreated patients. We examined the influence of two common vitamin D analogs, alfacalcidol and paricalcitol, on important cardiovascular biomarkers in hemodialysis patients. Anti-inflammatory effects and the influence on regulators of vascular calcification as well as markers of heart failure were examined.

Methods

In 57 chronic hemodialysis patients enrolled in a randomized crossover trial comparing paricalcitol and alfacalcidol, we examined the changes in osteoprotegerin, fetuin-A, NT-proBNP, hs-Crp, IL-6 and TNF-α, during 16 weeks of treatment.

Results

NT-proBNP and osteoprotegerin increased comparably in the paricalcitol and alfacalcidol-treated groups. Fetuin-A increased significantly in the alfacalcidol-treated group compared with the paricalcitol-treated group (difference 32.84 μmol/l (95% C.I.; range 0.21–67.47)) during the first treatment period. No difference was found between the groups during the second treatment period, and IL-6, TNF-α and hs-Crp were unchanged in both treatment groups.

Conclusions

Paricalcitol and alfacalcidol modulate regulators of vascular calcification. Alfacalcidol may increase the level of the calcification inhibitor fetuin-A. We did not find any anti-inflammatory effect or difference in changes of NT-proBNP.

Trial registry

ClinicalTrials.gov NCT00469599 May 3 2007.

Vitamin D and inflammatory diseases

Beyond its critical function in calcium homeostasis, vitamin D has recently been found to play an important role in the modulation of the immune/inflammation system via regulating the production of inflammatory cytokines and inhibiting the proliferation of proinflammatory cells, both of which are crucial for the pathogenesis of inflammatory diseases. Several studies have associated lower vitamin D status with increased risk and unfavorable outcome of acute infections. Vitamin D supplementation bolsters clinical responses to acute infection. Moreover, chronic inflammatory diseases, such as atherosclerosis-related cardiovascular disease, asthma, inflammatory bowel disease, chronic kidney disease, nonalcoholic fatty liver disease, and others, tend to have lower vitamin D status, which may play a pleiotropic role in the pathogenesis of the diseases. In this article, we review recent epidemiological and interventional studies of vitamin D in various inflammatory diseases. The potential mechanisms of vitamin D in regulating immune/inflammatory responses in inflammatory diseases are also discussed.

Impact of vitamin D supplementation on arterial vasomotion, stiffness and endothelial biomarkers in chronic kidney disease patients

Background

Cardiovascular events are frequent and vascular endothelial function is abnormal in patients with chronic kidney disease (CKD). We demonstrated endothelial dysfunction with vitamin D deficiency in CKD patients; however the impact of cholecalciferol supplementation on vascular stiffness and vasomotor function, endothelial and bone biomarkers in CKD patients with low 25-hydroxy vitamin D [25(OH)D] is unknown, which this study investigated.

Methods

We assessed non-diabetic patients with CKD stage 3/4, age 17–80 years and serum 25(OH)D <75 nmol/L. Brachial artery Flow Mediated Dilation (FMD), Pulse Wave Velocity (PWV), Augmentation Index (AI) and circulating blood biomarkers were evaluated at baseline and at 16 weeks. Oral 300,000 units cholecalciferol was administered at baseline and 8-weeks.

Results

Clinical characteristics of 26 patients were: age 50±14 (mean±1SD) years, eGFR 41±11 ml/min/1.73 m², males 73%, dyslipidaemia 36%, smokers 23% and hypertensives 87%.

At 16-week serum 25(OH)D and calcium increased (43±16 to 84±29 nmol/L, p<0.001 and 2.37±0.09 to 2.42±0.09 mmol/L; p = 0.004, respectively) and parathyroid hormone decreased (10.8±8.6 to 7.4±4.4; p = 0.001). FMD improved from 3.1±3.3% to 6.1±3.7%, p = 0.001.

Endothelial biomarker concentrations decreased: E-Selectin from 5666±2123 to 5256±2058 pg/mL; p = 0.032, ICAM-1, 3.45±0.01 to 3.10±1.04 ng/mL; p = 0.038 and VCAM-1, 54±33 to 42±33 ng/mL; p = 0.006. eGFR, BP, PWV, AI, hsCRP, von Willebrand factor and Fibroblast Growth Factor-23, remained unchanged.

Conclusion

This study demonstrates for the first time improvement of endothelial vasomotor and secretory functions with vitamin D in CKD patients without significant adverse effects on arterial stiffness, serum calcium or FGF-23.

Trial Registration

ClinicalTrials.gov NCT02005718

Vitamin D deficiency is associated with mortality and adverse vascular access outcomes in patients with end-stage renal disease

BACKGROUND

Plasma 25 hydroxycholecalciferol (vitamin D) deficiency has been associated with adverse cardiovascular outcomes in epidemiologic studies. Chronic kidney disease is associated with loss of 1α-hydroxylase and consequently vitamin D deficiency. We hypothesized that vitamin D deficiency was associated with increased mortality and increased vascular access failure in patients undergoing permanent vascular access for end-stage renal disease.

METHODS

This retrospective cohort study analyzed 128 patients undergoing permanent vascular access surgery between 2003 and 2012 for whom concurrent plasma vitamin D levels were also available. Levels were considered deficient at <20 ng/mL. Multivariable analysis was used to determine the association between vitamin D and mortality and vascular access outcomes.

RESULTS

The mean age was 66.7 years, 96.8% were male, 32.0% were African American, and 60.9% had diabetes mellitus. In the entire cohort, 55.5% were vitamin D-deficient, despite similar rates of repletion among the vitamin D-deficient and nondeficient groups. During a median follow-up of 2.73 years, there were 40 deaths (31%). Vitamin D-deficient patients tended to be younger (P = .01) and to have higher total cholesterol (P = .001) and lower albumin (P = .017) and calcium (P = .007) levels. Despite their younger age, mortality was significantly higher (P = .026) and vascular access failure was increased (P = .008) in the vitamin D-deficient group. Multivariate logistic regression analysis found vitamin D deficiency (odds ratio [OR], 3.64; 95% confidence interval [CI], 1.12-11.79; P = .031), hemodialysis through a central catheter (OR, 3.08; 95% CI, 1.04-9.12; P = .042), coronary artery disease (OR, 3.08; 95% CI, 1.06-8.94; P = .039), increased age (OR, 1.09; 95% CI, 1.03-1.15; P = .001), and albumin (OR, 0.27; 95% CI, 0.09-0.83; P = .023) remained independent predictors of mortality. Vitamin D deficiency (hazard ratio [HR], 2.34; 95% CI, 1.17-4.71; P = .02), a synthetic graft (HR, 3.50; 95% CI, 1.38-8.89; P = .009), and hyperlipidemia (HR, 0.42; 95% CI, 0.22-0.81; P = .01) were independent predictors of vascular access failure in a Cox proportional hazard model.

CONCLUSIONS

Vitamin D deficiency is highly prevalent in patients undergoing vascular access procedures. Patients who are deficient in vitamin D have worse survival and worse vascular access outcomes. Further study is warranted to assess whether aggressive vitamin D repletion will improve outcomes in this population.

Vitamin D and the cardiovascular system: an overview of the recent literature

Since the discovery that the enzyme catalyzing the synthesis of the most active natural vitamin D metabolite(calcitriol) and the vitamin D-specific receptor (VDR)were expressed in a wide range of tissues and organs, not only involved in the mineral metabolism (MM), there has been increasing interest on the putative ‘non classical’ roles of vitamin D metabolites, particularly on their possible effects on the cardiovascular (CV) system. These hypothetical CV effects of vitamin D gained particular interesting the nephrology field, given the high prevalence of CV disease in patients affected by either acute or chronic kidney diseases. However, notwithstanding a huge amount of experimental data suggesting a possible protective role of vitamin D on the CV system, the conclusions of two recent meta-analyses from the Cochrane group and a recent statement from the Institute of Medicine, based on a complete revision of the available data, concluded that there is no clear evidence for a role of vitamin D other than that strictly associated with bone health. However, a continuous and increasing flow of new studies still continues to add information on this topic. In the present review, we have tried to critically address the data added on this topicin the last 2 years, considering separately the experimental,observational, and intervention studies that have appeared in PubMed in the last 2 years, discussing the data providing proof, pro or contra, the involvement of vitamin D in CV disease, both in the absence or presence of kidney function impairment.

Association between vitamin D receptor activator and the risk of infection-related hospitalizations among incident hemodialysis patients: a nested case-control study

BACKGROUND

Patients suffering from chronic kidney disease are at greater risk of developing infection than the normal population, and infections are the second cause of mortality after cardiovascular complications in this population. Some reports suggest that the intake of active vitamin D might be beneficial to prevent infections. Therefore, we aimed to determine if the oral intake of vitamin D receptor activator (VDRA) is associated with a lower risk of infection-related hospitalization (IRH) among incident chronic hemodialysis patients.

METHODS

We conducted a nested case-control study in a cohort of 4933 patients initiating chronic hemodialysis between 1 January 2001 and 31 December 2007 in Quebec, Canada, using administrative databases. We identified cases of hospital admission indicating an infection as main diagnosis on the hospital's discharge sheet. Up to 10 controls were randomly selected for each case. Association between oral VDRA use and risk of IRH was estimated using conditional logistic regression.

RESULTS

We identified 1136 cases of IRH and 10396 controls during the study period. The intake of VDRA was not associated with the risk of being hospitalized due to an infection (odds ratio [OR], 1.07; 95% confidence interval [CI], 0.95-1.20). Using the prior 6-month cumulative dose of VDRA, we also found that a cumulative VDRA dose of less than 45 mcg (OR, 1.05; 95%CI, 0.92-1.19) or greater than 45 mcg (OR, 1.15; 95%CI, 0.96-1.36) was not associated with the IRH risk.

CONCLUSIONS

The oral intake of VDRA was not associated with the risk of IRH in incident hemodialysis patients.

Oral postdialysis cholecalciferol supplementation in patients on maintenance hemodialysis: a dose-response approach

The aim of the present study was to evaluate the dose of postdialysis cholecalciferol needed to maintain the 25-hydroxyvitamin D [25(OH)D] levels in the optimal range of 75–150 nmol/L. Twenty-six patients who had low baseline 25(OH)D levels (mean 27.5 ± 14.9 nmol/L) were studied. The 25(OH)D levels were measured every 2 months for one year. During the first two months, all the patients received 2000 IU of cholecalciferol after each hemodialysis (=6000 IU/wk). Thereafter, the dose was individualized and adapted every 2 months by administering 1 to 6 cholecalciferol tablets (2000 IU each) per week (total weekly dose = 2000–12000 IU/wk). During cholecalciferol supplementation, the 25(OH)D concentrations rapidly increased from baseline to 140.1 ± 28.3 nmol/L at month 6 and 95.6 ± 20.9 nmol/L at month 12. At month twelve, 86% of the patients had 25(OH)D levels within the target range with a mean dose of 5917 ± 4106 IU/wk of cholecalciferol; however, the amount needed to maintain these levels varied widely from 0 (n = 2) to 12000 IU/wk (n = 5). In conclusion, postdialysis cholecalciferol prescription is quite effective in correcting vitamin D deficiency/insufficiency, but the amount of cholecalciferol needed to maintain the 25(OH)D levels within the optimal range over the long-term varies widely among patients and must be individualized.

Circulating dendritic cell precursors in chronic kidney disease: a cross-sectional study

BACKGROUND

Dendritic cells (DC) are professional antigen-presenting cells in the immune system. They patrol the blood as circulating dendritic cell precursors (DCP). Decreased blood DCP count has been shown to be related to atherosclerotic plaque burden. Since chronic kidney disease (CKD) is associated with chronic inflammation and increased cardiovascular risk, the aim of our study was to investigate a potential effect of CKD on circulating DCP numbers especially in patients with a history of cardiovascular disease.

METHODS

The number of circulating myeloid (mDCP), plasmacytoid (pDCP), and total DCP (tDCP) was analysed by flow cytometry in 245 patients with CKD stage 3 (with and without known cardiovascular events) and 85 coronary healthy controls. In addition, data were compared with a historical group of 130 patients with known coronary artery disease (CAD).

RESULTS

Compared to controls, patients with CKD 3 revealed a significant decrease in circulating mDCP (-29%), pDCP (-43%), and tDCP (-38%) (P < 0.001, respectively). Compared with CAD-patients, the decrease in circulating DCP in CKD was comparable or even more pronounced indicating a potential role for DCP in cardiovascular risk potentiation due to CKD.

CONCLUSIONS

Based on previous findings in CAD, the marked decrease of DCP in CKD implicates a potential role for DCP as a mediator of cardiovascular disease. Whether DCP in CKD may act as new cardiovascular biomarkers needs to be established in future prospective trials.

The role of vitamin D deficiency in cardiovascular disease: where do we stand in 2013?

The high worldwide prevalence of vitamin D deficiency is largely the result of low sunlight exposure with subsequently limited cutaneous vitamin D production. Classic manifestations of vitamin D deficiency are linked to disturbances in bone and mineral metabolism, but the identification of the vitamin D receptor in almost every human cell suggests a broader role of vitamin D for overall and cardiovascular health. The various cardiovascular protective actions of vitamin D such as anti-diabetic and anti-hypertensive effects including renin suppression as well as protection against atherosclerosis and heart diseases are well defined in previous experimental studies. In line with this, large epidemiological studies have highlighted vitamin D deficiency as a marker of cardiovascular risk. However, randomized controlled trials (RCTs) on vitamin D have largely failed to show its beneficial effects on cardiovascular diseases and its conventional risk factors. While most prior vitamin D RCTs were not designed to assess cardiovascular outcomes, some large RCTs have been initiated to evaluate the efficacy of vitamin D supplementation on cardiovascular events in the general population. When considering the history of previous disappointing vitamin RCTs in general populations, more emphasis should be placed on RCTs among severely vitamin D-deficient populations who would most likely benefit from vitamin D treatment. At present, vitamin D deficiency can only be considered a cardiovascular risk marker, as vitamin D supplementation with doses recommended for osteoporosis treatment is neither proven to be beneficial nor harmful in cardiovascular diseases.

Vitamin D and cardiovascular disease

Vitamin D deficiency, as well as cardiovascular diseases (CVD) and related risk factors are highly prevalent worldwide and frequently co-occur. Vitamin D has long been known to be an essential part of bone metabolism, although recent evidence suggests that vitamin D plays a key role in the pathophysiology of other diseases, including CVD, as well. In this review, we aim to summarize the most recent data on the involvement of vitamin D deficiency in the development of major cardiovascular risk factors: hypertension, obesity and dyslipidemia, type 2 diabetes, chronic kidney disease and endothelial dysfunction. In addition, we outline the most recent observational, as well as interventional data on the influence of vitamin D on CVD. Since it is still an unresolved issue whether vitamin D deficiency is causally involved in the pathogenesis of CVD, data from randomized controlled trials (RCTs) designed to assess the impact of vitamin D supplementation on cardiovascular outcomes are awaited with anticipation. At present, we can only conclude that vitamin D deficiency is an independent cardiovascular risk factor, but whether vitamin D supplementation can significantly improve cardiovascular outcomes is still largely unknown.

Placental growth factor may predict increased left ventricular mass index in patients with mild to moderate chronic kidney disease--a prospective observational study

Background

Placental growth factor [PlGF) is a cardiovascular (CV) risk marker, which is related to left ventricle hypertrophy (LVH) in animal models. Currently there are no data available regarding the possible relationship of PlGF and the development of LVH or diastolic dysfunction in patients with chronic kidney disease (CKD) and the relationship of PlGF to other CV risk factors in CKD patients. The aim of our study was to determine the possible association of PlGF and several other CV risk markers to echocardiographic parameters in CKD population.

Methods

We prospectively examined selected laboratory (PlGF, fibroblast growth factor-23 -FGF23, vitamin D, parathyroid hormone, extracellular newly identified RAGE-binding protein - EN-RAGE, B-type natriuretic peptide - BNP) and echocardiographic parameters in 62 patients with CKD 2–4. Mean follow-up was 36 ±10 months. Laboratory and echocardiographic data were collected 2–3 times, at the shortest interval of 12 months apart. Multivariate regression analysis was used to detect independent correlations of variables.

Results

Increased left ventricular mass index (LVMI, g/m^2.7) was found in 29% patients with CKD 2–4, left ventricular (LV) diastolic dysfunction was detected in 74.1% patients (impaired LV relaxation in 43.5% patients and pseudonormal pattern in 30.6% patients). After 36 ± 10 months increased LVMI was found in 37.1% patients with CKD 2–4, LV diastolic dysfunction was detected in 75.8% patients (impaired LV relaxation in 43.5% patients and pseudonormal pattern in 32.3% patients). Following independent correlations were found: LVMI was related to PlGF, cholesterol, BNP, systolic blood pressure and serum creatinine. EN-RAGE correlated positively with left atrial diameter and inversely with E/A ratio. During the follow-up we found a significant increase in LVMI and left atrial diameter, whereas a significant decrease in LVEF was noted.

Conclusion

According to our data, PlGF is independently related to increased LV mass in CKD, whereas EN-RAGE is more likely related to diastolic dysfunction in this population.

Are low levels of 25-hydroxyvitamin D a risk factor for cardiovascular diseases or malignancies in renal transplantation?

BACKGROUND

Observational studies in healthy people suggest an inverse relationship between 25-hydroxy-vitamin D (25(OH)D levels) and cardiovascular diseases and malignancies. We performed an observational prospective study in renal transplant recipients to investigate the effects of vitamin D deficiency on cardiovascular and malignancy risks.

METHODS

From 389 renal transplant recipients, 331 with a functioning graft at 12 months were included in the study. Mineral metabolism parameters were measured at 1, 3, 4 and 12 months. Information regarding the cardiovascular events and malignancies were collected from an electronic database.

RESULTS

According to the 1-year mean of 25(OH)D levels, 75 recipients (22.7%) had a normal vitamin D status, 161 (48.6%) had insufficiency and 95 (28.7%) had deficiency in vitamin D levels. During the follow-up, 80 recipients presented at least one cardiovascular event. The total cardiovascular diseases included: 27 patients with coronary diseases, 25 with cardiac failure, 18 with arrhythmia, 11 with acute cerebrovascular events and 19 with peripheral vascular disease. Cardiovascular events were not associated with 25(OH)D levels or vitamin D status, and the 10-year cumulative incidence was 29.3% for normal vitamin D status and 31.6% for insufficiency and 51.9% for deficiency (P = 0.216). Furthermore, Cox univariate analysis showed no association between cardiovascular events and vitamin D levels or vitamin D status. In addition, 53 recipients presented at least one malignancy: 33 non-melanoma skin malignancies and 20 non-skin malignancies (5 prostate, 3 kidney and urinary tract, 2 colon, 2 lung, 2 lymphoma, 2 breast and 4 from other locations). The cumulative incidence of malignancies was 21.3% for normal vitamin D status, 22.7% for insufficiency and 16.7% for deficiency (P = 0.818).

CONCLUSIONS

Our data suggested that low vitamin D levels were not associated with an increased risk of cardiovascular diseases or malignancies. However, due to the small number of patients and events, the results should not be considered as definitive. Additional studies with a higher number of patients are required to elucidate the true impact of vitamin D status on cardiovascular and malignancy risks.