Role of vascular calcification inhibitors in preventing vascular dysfunction and mortality in hemodialysis patients.

Cardiovascular events make up the primary cause of death in hemodialysis patients, and the risk for cardiovascular mortality is significantly increased by vascular calcification, a condition observed frequently in this patient population. The mechanisms underlying the pathogenesis of vascular calcification are complex, and many factors facilitate or hinder the development of calcification. In this review, we first summarize the main factors contributing to the pathogenesis of vascular calcification in patients with end-stage renal disease. We then explore the role of calcification inhibitors in the calcification process, as well as their effect on vascular dysfunction and mortality in hemodialysis patients.

Hormonal changes in hemodialysis patients: Novel risk factors for mortality?

Patients with end-stage renal disease undergoing dialysis commonly experience derangements in the hypothalamic-pituitary-gonadal axis together with alterations at the level of synthesis and clearance of many hormones. This hormonal imbalance, even if asymptomatic, has recently been associated with increased mortality in these patients. In this review, we summarize observational and mechanistic evidence linking hormonal alterations at the level of the thyroid and sex-hormone systems with this mortality risks.

Colchicine in Renal Medicine: New Virtues of an Ancient Friend.

Colchicine is a plant-derived alkaloid that disrupts the cell microtubule system and accumulates in neutrophils, inhibiting neutrophil adhesion and recruitment. Colchicine has been used extensively in the prevention and treatment of gouty arthritis attacks, familial Mediterranean fever attacks and resultant AA amyloidosis, and recurrent pericarditis. Colchicine also disrupts the intracellular traffic of additional inflammatory and fibrosis mediators. Renal fibrosis is the final common pathway of chronic renal disease. Colchicine had anti-fibrotic effects in experimental diabetic nephropathy, renal mass reduction, and cyclosporine nephrotoxicity among others and is undergoing clinical trials for non-diabetic metabolic syndrome and diabetic nephropathy. In this review, we summarize the anti-inflammatory and anti-fibrotic properties of colchicine in experimental and clinical studies in renal diseases or other fibrotic disease processes with renal consequences. We also discuss the potential future uses of colchicine in renal medicine and challenges faced with its use in patients with impaired kidney function.

Osteoprotegerin in Chronic Kidney Disease: Associations with Vascular Damage and Cardiovascular Events.

Vascular injury and dysfunction contribute to cardiovascular disease, the leading cause of death in patients with chronic kidney disease (CKD). Osteoprotegerin (OPG) is a soluble member of the tumor necrosis factor receptor superfamily that has been linked to atherogenesis and endothelial dysfunction. Elevated circulating OPG levels predict future cardiovascular events (CVE). Our aim was to evaluate the determinants of circulating OPG levels, to investigate the relationship between OPG and markers of vascular damage and to test whether OPG improves risk stratification for future CVE beyond traditional and renal-specific risk factors in a CKD population. 291 patients with CKD stage 1-5 not on dialysis were included in the study. In the multivariate analysis, OPG was a significant predictor for flow-mediated dilatation, but not for carotid intima media thickness levels. During follow-up (median 36 months, IQR = 32-42 months), 87 patients had CVE. In the Cox survival analysis, OPG levels were independently associated with CVE even after adjustment for traditional and renal-specific cardiovascular risk factors. The addition of OPG to a model based on commonly used cardiovascular factors significantly improved the reclassification abilities of the model for predicting CVE. We show for the first time that OPG improves risk stratification for CVE in a non-dialysis CKD population, above and beyond a model with established traditional and renal-specific cardiovascular risk factors, including estimated glomerular filtration rate and fibroblast growth factor 23.

The Prevalence of Fabry Disease in Patients with Chronic Kidney Disease in Turkey: The TURKFAB Study.

BACKGROUND/AIMS: Fabry disease is a treatable cause of chronic kidney disease (CKD) characterized by a genetic deficiency of α-galactosidase A. European Renal Best Practice (ERBP) recommends screening for Fabry disease in CKD patients. However, this is based on expert opinion and there are no reports of the prevalence of Fabry disease in stage 1-5 CKD. Hence, we investigated the prevalence of Fabry disease in CKD patients not receiving renal replacement therapy. METHODS: This prospective study assessed α-galactosidase activity in dried blood spots in 313 stage 1-5 CKD patients, 167 males, between ages of 18-70 years whose etiology of CKD was unknown and were not receiving renal replacement therapy. The diagnosis was confirmed by GLA gene mutation analysis. RESULTS: Three (all males) of 313 CKD patients (0.95%) were diagnosed of Fabry disease, for a prevalence in males of 1.80%. Family screening identified 8 aditional Fabry patients with CKD. Of a total of 11 Fabry patients, 7 were male and started enzyme replacement therapy and 4 were female. The most frequent manifestations in male patients were fatigue (100%), tinnitus, vertigo, acroparesthesia, hypohidrosis, cornea verticillata and angiokeratoma (all 85%), heat intolerance (71%), and abdominal pain (57%). The most frequent manifestations in female patients were fatigue and cornea verticillata (50%), and tinnitus, vertigo and angiokeratoma (25%). Three patients had severe episodic abdominal pain attacks and proteinuria, and were misdiagnosed as familial Mediterranean fever. CONCLUSIONS: The prevalence of Fabry disease in selected CKD patients is in the range found among renal replacement therapy patients, but the disease is diagnosed at an earlier, treatable stage. These data support the ERBP recommendation to screen for Fabry disease in patients with CKD of unknown origin.

Vasopressin-related copeptin is a novel predictor of early endothelial dysfunction in patients with adult polycystic kidney disease.

BACKGROUND: In this study, we examined the relative usefulness of serum copeptin levels as a surrogate marker of vasopressin (AVP) in adult polycystic kidney disease (ADPKD) by correlating it with baseline and longitudinal changes in markers of both renal function and common CVD manifestations (hypertensive vascular disease, atherosclerosis and endothelial dysfunction) that accompany the progression of this disease. METHODS: We studied a cohort of young and otherwise healthy ADPKD patients (n = 235) and measured cardiovascular function using flow-mediation dilatation (FMD), carotid intima media thickness (cIMT) and pulse wave velocity (PWV), as well as serum copeptin (commercial ELISA, a stable marker of AVP activity). The same analyses were carried out at baseline and after 3 years of follow-up. RESULTS: At baseline, median eGFR was 69 mL/min./1.73 m2, mean FMD 6.9 ± 0.9%, cIMT 0.7 ± 0.1 mm, and PWV 8.1 ± 1.2 m/s. At follow-up, equivalent values were 65 (44-75) mL/min./1.73 m2, 5.8 ± 0.9%, 0.8 ± 0.1 mm. and 8.2 ± 1.3 m/s. with all changes statistically significant. Plasma copeptin also rose from 0.62 ± 0.12 to 0.94 ± 0.19 ng/mL and this change correlated with ΔeGFR (-0.33, p < 0.001), ΔFMD (0.599, p < 0.001), ΔcIMT (0.562, p < 0.001) and ΔPWV (0.27, p < 0.001) also after linear regression modeling to correct for confounders. Finally, ROC analysis was done for a high baseline copeptin with ΔeGFR [cut-off:≤59], ΔFMD [cut-off: ≤7.08], ΔcIMT [cut-off:>0.76], and ΔPWV [cut-off:≤7.80]. CONCLUSIONS: Vascular dysfunction as reflected by FMD and cIMT, but not PWV or an altered cardiac geometry, precede most other signs of disease in ADPKD but is predicted by elevated levels of the circulating AVP-marker copeptin.

Predictive Value of Atrial Electromechanical Delay on Long-Term Cardiovascular Outcomes in Hemodialysis Patients.

BACKGROUND: Atrial electromechanical delay (AEMD) times were considered independent predictors of cardiovascular morbidity among the general population. We aimed at evaluating AEMD times and other risk factors associated with 2-year combined cardiovascular (CV) events in HD patients. MATERIAL AND METHODS: Sixty hemodialysis (HD) and 44 healthy individuals were enrolled in this prospective study. Echocardiography was performed before the mid-week dialysis session for HD patients. Data were expressed as mean ± SD. Spearman test was used to assess linear associations. Survival was examined with the Kaplan-Meier method. Multivariate Cox regression analysis was used to determine the predictors of combined CV events in this cohort. RESULTS: At the beginning of the study, left intra-atrial-AEMD times were significantly longer in HD patients compared to the left intra-atrial-AEMD times in healthy individuals. After 24 months, 41 patients were still on HD treatment and 19 (31.6%) had died. Serum triglyceride, total cholesterol and albumin were found to be higher and C-reactive protein (CRP) levels, left intra-atrial EMD time (LIAT) and interatrial EMD times were found to be lower in survived HD patients. With the cut-off median values of 3.5 g/dl for albumin, 0.87 mg/dl for CRP, 157 mg/dl for total cholesterol and 151 mg/dl for triglyceride, the Kaplan-Meier curves demonstrated significant differences in terms of all-cause mortality. We also demonstrated the Kaplan-Meier survival curves of HD patients according to tertile values of LIAT. Cox regression analysis revealed that increased CRP and higher LIAT were found to be independent predictors of combined CV events. CONCLUSIONS: Increased LIAT and inflammation were found to be closely associated with 2 years combined CV events and all-cause mortality in HD patients.

The role of plasma triglyceride/high-density lipoprotein cholesterol ratio to predict cardiovascular outcomes in chronic kidney disease.

BACKGROUND: Cardiovascular disease (CVD) risk is substantially increased in subjects with chronic kidney disease (CKD). The Triglycerides (TG) to High-Density Lipoprotein Cholesterol (HDL-C) ratio is an indirect measure of insulin resistance and an independent predictor of cardiovascular risk. No study to date has been performed to evaluate whether the TG/HDL-C ratio predicts CVD risk in patients with CKD. METHODS: A total of 197 patients (age 53±12 years) with CKD Stages 1 to 5, were enrolled in this longitudinal, observational, retrospective study. TG/HDL-C ratio, HOMA-IR indexes, serum asymmetric dimethyl arginine (ADMA), high sensitivity C-reactive protein (CRP), parathyroid hormone (PTH), calcium, phosphorous, estimated glomerular filtration rate (eGFR), and albumin levels were measured. Flow mediated vasodilatation (FMD) of the brachial artery was assessed by using high-resolution ultrasonography. RESULTS: A total of 11 cardiovascular (CV) deaths and 43 nonfatal CV events were registered in a mean follow-up period of 30 (range 9 to 35) months. Subjects with TG/HDL-C ratios above the median values (>3.29) had significantly higher plasma ADMA, PTH, and phosphorous levels (p=0.04, p=0.02, p=0.01 respectively) and lower eGFR and FMD values (p=0.03, p<0.001 respectively). The TG/HDL-C ratio was an independent determinant of FMD (ß=-0.25 p=0.02) along with TG, HDL-C, hsCRP, serum albumin, phosphate levels, systolic blood pressure, PTH, eGFR and the presence of diabetes mellitus. The TG/HDL-C ratio was also a significant independent determinant of cardiovascular outcomes [HR: 1.36 (1.11-1.67) (p=0.003)] along with plasma ADMA levels [HR: 1.31 (1.13-1.52) (p<0.001)] and a history of diabetes mellitus [HR: 4.82 (2.80-8.37) (p<0.001)]. CONCLUSION: This study demonstrates that the elevated TG/HDL-C ratio predicts poor CVD outcome in subjects with CKD. Being a simple, inexpensive, and reproducible marker of CVD risk, the TG/HDL-C ratio may emerge as a novel and reliable indicator among the many well-established markers of CVD risk in CKD. SYSTEMATIC REVIEW REGISTRATION: Clinical trial registration number and date: NCT02113462 / 10-04-2014.

Endothelial dysfunction, insulin resistance and inflammation in congenital hypogonadism, and the effect of testosterone replacement.

Patients with hypogonadism have poor cardiovascular and metabolic outcomes, and the effect of testosterone replacement therapy (TRT) is not clear. We investigated the presence of inflammation, insulin resistance and endothelial dysfunction in an unconfounded population of congenital hypogonadotrophic hypogonadism (CHH) and the effect of TRT on these subjects. A total of 60 patients with CHH (mean age 21.82±2.22 years) and 70 healthy control subjects (mean age 21.32±1.13 years) were enrolled. The demographic parameters, Asymmetric dimethylarginine (ADMA), TNF-like weak inducer of apoptosis (TWEAK), high sensitive C reactive protein (hs-CRP) and homeostatic model assessment of insulin resistance (HOMA-IR) levels were measured before and after TRT. The patients had higher Waist Circumferences (WC) (p=0.009), Diastolic Blood Pressures (p=0.02), Triglycerides (p=0.03), ADMA, insulin and HOMA-IR levels (p<0.001 for all) and lower TWEAK levels (p<0.001), compared to the healthy controls. After 5.56 ± 2.04 months of TRT, the patients had significantly elevated systolic blood pressures (p=0.01), body mass indexes and WC (p<0.001 and p=0.001 respectively) and decreased total and HDL cholesterol levels (p=0.032 and p<0.001 respectively). ADMA levels significantly increased (p=0.003), while the alterations in TWEAK, hsCRP and HOMA-IR were not significant. The results of the present study show that endothelial dysfunction, inflammation and insulin resistance are prevalent even in the very young subjects with CHH, who have no metabolic or cardiac problems at present. This increased cardiometabolic risk however, do not improve but even get worse after six months of TRT. Long term follow-up studies are warranted to investigate the unfavorable cardiometabolic effects of TRT.

Ramipril lowers plasma FGF-23 in patients with diabetic nephropathy.

BACKGROUND/AIMS: Ramipril attenuates renal Fibroblast growth factor-23 (FGF-23) expression, ameliorates proteinuria and normalizes serum phosphate in the diabetic Zucker rat with progressive renal disease suggesting that the renoprotective effect by this drug may be in part due to a FGF-23-lowering effect of angiotensin-converting enzyme (ACE) inhibition. METHODS: In this nonrandomized study, we tested whether ACE-inhibition reduces circulating FGF-23 in type-2 diabetics with stage-1 chronic kidney disease (CKD) and proteinuria. Intact FGF-23, the eGFR, proteinuria and the endothelium-dependent flow-mediated (FMD) response to ischemia and other parameters were measured at baseline and after 12-weeks of treatment with ramipril (n = 68) or amlodipine (n = 32). RESULTS: Blood Pressure (BP) fell to a similar extent (p < 0.001) in the two groups. However, 24 h proteinuria and the FMD improved more (both p < 0.01) in ramipril-treated patients than in amlodipine-treated patients. Changes in proteinuria (r = 0.47) and in FMD (r = -0.49) by ramipril were closely associated (p < 0.001) with simultaneous changes in FGF-23 and this link was confirmed in multiple regression analyses. In these analyses, the relationship between FMD and proteinuria changes attained statistical significance (p < 0.01) only in a model excluding FGF-23 suggesting that endothelial dysfunction and FGF-23 share a common pathway conducive to renal damage. CONCLUSION: Findings in this study contribute to generate the hypothesis that FGF-23 may be implicated in proteinuria and in endothelial dysfunction in diabetic nephropathy (clinicaltrials.gov (NCT01738945)).

Mitral annular calcification and the serum osteocalcin level in patients with chronic kidney disease.

OBJECTIVE: To determine the relationships between inflammatory mediators, mitral annular calcification (MAC), and osteocalcin in patients with chronic kidney disease (CKD). MATERIALS AND METHODS: Echocardiographic data for 60 patients diagnosed as CKD were retrospectively evaluated. The patients were divided into 2 groups; patients with MAC (MAC+ group) and patients without MAC (MAC- group). The relationships between biochemical markers-including osteocalcin-and MAC were evaluated. RESULTS: The study included 19 female and 41 male patients. In all, 29 patients were MAC+ and 31 were MAC-. High-sensitive C-reactive protein (hsCRP) and osteocalcin levels were significantly higher in the MAC+ group (p < 0.05). The eGFR was lower, serum calcitonin (we could not obtain calcitonin data for 15 patients), Ca, PO4, CaxPO4, the erythrocyte sedimentation rate, red cell distribution width, the neutrophil/Lymphocyte rate, and PTH were higher in the MAC+ group; however, the differences between the groups were not significant (p > 0.05). The mitral E/A ratio, mitral peak Ea velocity, tricuspid E/A ratio, hsCRP, and the osteocalcin level were strongly correlated with MAC. Multivariate logistic regression analysis showed that only the osteocalcin level and mitral E/A ratio were independent variables, each with an independent effect on MAC. CONCLUSION: CKD patients in the MAC+ group had higher osteocalcin levels than those in the MAC- group, and left ventricular diastolic dysfunction was more common in the MAC+ group.

A link between the intrarenal renin angiotensin system and hypertension in autosomal dominant polycystic kidney disease.

BACKGROUND/AIMS: Early onset of hypertension and its consequences account for the great majority of deaths in patients with autosomal dominant polycystic kidney disease (ADPKD). Renin-angiotensin system (RAS) components have been shown in ADPKD kidneys independent of systemic RAS. Thus, we examined the urinary angiotensinogen (UAGT) levels as a biomarker of intrarenal RAS status in ADPKD patients with/without hypertension and healthy subjects. METHODS: Eighty-four ADPKD patients (43 with hypertension and 41 without hypertension) and 40 healthy controls were studied cross-sectionally. Patients with glomerular filtration rate <60 ml/min were excluded from the study. Hypertension was diagnosed with ambulatory blood pressure monitoring. Urinary and plasma concentration of angiotensinogen, spot urine microprotein and creatinine (UCre) levels were recorded for each participant. RESULTS: UAGT/UCre levels were higher in hypertensive ADPKD patients (23.7 ± 8.4) compared with normotensive ADPKD patients (16.6 ± 5.2) and healthy controls (6.9 ± 3.3; p < 0.001). In univariate analysis, UAGT correlated with systolic blood pressure, diastolic blood pressure (DBP) and proteinuria. The independence of these correlations was analyzed in a regression model, and UAGT was shown to be significantly predicted by proteinuria and DBP. CONCLUSION: Intrarenal RAS activation which is monitored by UAGT levels clinically may be a harbinger of hypertension and kidney disease in ADPKD patients.

Longitudinal analysis of vascular function and biomarkers of metabolic bone disorders before and after renal transplantation.

BACKGROUND/AIMS: The role of chronic kidney disease-mineral bone disorder (CKD-MBD) reversibility in the amelioration of vascular function and in the reduction of the risk for cardiovascular events after renal transplantation is still unknown. METHODS: We investigated the longitudinal relationship between the main biomarkers of CKD-MBD and the evolution of vascular function [flow-mediated dilatation (FMD)] after transplantation in a series of 161 patients with kidney failure maintained on chronic dialysis (5D-CKD). RESULTS: Before transplantation, FMD in patients was markedly lower (-40%, p < 0.001) than in well-matched healthy subjects and increased by 27% after transplantation (p = 0.001). Fibroblast growth factor 23 (FGF23), 25-hydroxy-vitamin D (25OHVD) and serum phosphate (p < 0.01) were independently associated with simultaneous changes in FMD. Changes in classical risk factors and in risk factors related to CKD like the glomerular filtration rate, serum albumin, C-reactive protein and insulin resistance failed to independently explain the variability in FMD changes after transplantation. CONCLUSION: Endothelium-dependent vasodilatation improves after kidney transplantation, which is parallel to the dramatic fall in FGF23, the reduction in serum phosphorus and the increase in 25OHVD levels. If these associations are causal, a part of decline in cardiovascular risk after transplantation is related to partial resolution of CKD-MBD.

Serum uric acid levels and endothelial dysfunction in patients with autosomal dominant polycystic kidney disease.

BACKGROUND/AIMS: Patients with autosomal dominant polycystic kidney disease (ADPKD) exhibit endothelial dysfunction (ED) despite normal levels of renal function. Hyperuricemia occurs in these patients and has been postulated to affect ED through the generation of oxidative stress. We therefore investigated the prevalence of ED and its association with serum uric acid levels in early-stage ADPKD. METHODS: A cross-sectional design was used for the assessment of prevalent patients with early-stage (normal renal function) ADPKD (n = 91) from two academic medical centers. ED was assessed using ischemia-induced forearm flow-mediated vasodilation (FMD). Serum uric acid levels were evaluated using an Olympus AU2700 autoanalyzer. RESULTS: ADPKD patients with higher serum uric acid levels had a higher asymmetric dimethylarginine (ADMA) level (1.19 ± 0.2 vs. 1.47 ± 0.3, p < 0.001) and lower FMD rates (8.1 ± 1.3 vs. 6.8 ± 0.7, p < 0.001). In multiple regression analysis for predictors of cohort FMD, uric acid (ß = -0.32, p < 0.001), ADMA (ß = -0.36, p < 0.001), high-sensitivity C reactive protein (CRP; ß = -0.32, p < 0.001) and estimated glomerular filtration rate (eGFR; ß = 0.33, p < 0.001) all predicted FMD. CONCLUSIONS: In early-stage ADPKD patients, uric acid levels, serum ADMA and eGFR all independently predict ED in a similar manner. Future studies are needed to investigate the causes of elevated serum uric acid, ADMA and CRP in these patients.

The role of platelet activation in determining response to therapy in patients with primary nephrotic syndrome.

To test the role of platelet activation in the prognosis of nephrotic syndrome (NS), we evaluated the mean platelet volume (MPV) in patients with NS undergoing treatment. In this prospective, multicenter clinical study 156 patients with primary NS under treatment were assigned and followed for one year. Patients were divided into three groups for complete remission, partial remission, and resistance. Biochemical parameters, estimated glomerular filtration rate, proteinuria level, and MPV levels were compared at baseline and 12 months after treatment. MPV, proteinuria, total cholesterol, triglyceride, LDL cholesterol, HDL cholesterol, total protein, albumin, and hs-CRP levels significantly decreased in partial and complete remission group after 12 months compared to the baseline (p < 0.05). However, MPV levels significantly increased and only LDL cholesterol significantly decreased in the resistance group (p < 0.05). Univariate analyses demonstrated that ΔMPV was significantly associated with Δproteinuria (r = 0.41, p < 0.001), Δhs-CRP (r = 0.39, p < 0.001), and ΔAlbumin (r = -0.30, p < 0.001). We found that ΔAlbumin (ß = -0.33, p < 0.001), ΔTotal cholesterol (ß = -0.20, p = 0.011), and Δhs-CRP (ß = 0.19, p = 0.018) were statistically significant predictors of the Δproteinuria in multiple regression analysis. In subjects with primary NS, MPV is associated with the prognosis or the disease. This study provides the background for longer trials and the role of platelet activation in NS.

Neutrophil to lymphocyte ratio independently predicts cardiovascular events in patients with chronic kidney disease.

BACKGROUND: Increased inflammation is common in patients with chronic kidney disease (CKD) and is associated with increased adverse cardiovascular events (CVE). Neutrophil-to-lymphocyte ratio (NLR) was used to predict survival in patients with acute coronary syndrome. We aimed to evaluate predictive ability of NLR in CKD patients. METHODS: 225 subjects with stage 3-5 CKD were followed for a mean of 39 months. Fatal and nonfatal CVE were recorded during this period. NLR at baseline was determined from complete blood count differential. Endothelial dysfunction (flow-mediated dilation, FMD), hsCRP and insulin resistance were determined. We investigated if NLR could predict development of fatal and nonfatal CVE. We also looked at how NLR and its individual components change across CKD stages and whether NLR is related to CRP, insulin resistance and endothelial dysfunction. RESULTS: There were 70, 74 and 81 patients in groups of CKD stage-3, stage-4 and stage-5, respectively. Median NLR was 2.81. NLR showed a significant increase from stage 3 to stage 5. NLR was inversely associated with FMD independent of hsCRP. 14 fatal and 52 nonfatal CVE occurred during follow-up period. NLR could predict composite CVE independent of insulin resistance and hsCRP. Increased NLR over 2.81 was related to a significantly decreased survival time (log-rank Chi-square = 14.833, P < 0.0001). A cutoff value for NLR ≥3.76 could predict development of composite CVE with 80.3 % sensitivity and 91.8 % specificity. CONCLUSIONS: NLR is independently related to endothelial dysfunction and could predict composite cardiovascular endpoints independent of traditional confounding factors in patients with moderate to severe CKD.

FGF23: a mature renal and cardiovascular risk factor?

High FGF23 predicts renal function loss in chronic kidney disease (CKD) patients and graft failure in transplant patients. FGF23, parathyroid hormone and serum phosphate are all interrelated but among these CKD-MBD biomarkers only FGF23 is independently related with CKD progression. High FGF23 associates with endothelial dysfunction in CKD patients and in elderly individuals in the general population. Furthermore, independently of serum phosphate, high FGF23 associates with mortality and left ventricular hypertrophy in dialysis patients and with atherosclerosis in elderly individuals in the general population. FGF23 also predicts a high risk for death and cardiovascular events in predialysis CKD patients and in subjects with coronary artery disease. A recent trial in CKD patients showed that low phosphate intake associated with a phosphate binder produces a 35% decrease in plasma FGF23. Yet in this and in another trial testing several phosphate binders, FGF23 levels remained well beyond the upper limit of the normal range. Of note, in this latter study, calcification of the coronary arteries and abdominal aorta actually increased, rather than decreased, during treatment with these drugs in the face of evidence of negative phosphate balance and amelioration of hyperparathyroidism. Mechanistic studies are still needed before testing the hypothesis that FGF23 is implicated in a causal manner in cardiovascular and renal diseases. Given the modest effects of phosphate binders on serum FGF23 in CKD patients, pharmacologic interventions antagonizing the effects of this growth factor rather than phosphate-lowering interventions should be put in place to properly test this hypothesis in the clinical scenario in CKD.

Mean corpuscular volume is associated with endothelial dysfunction and predicts composite cardiovascular events in patients with chronic kidney disease.

AIM: Mean corpuscular volume (MCV) is a measure of size of red blood cells. Recently a few studies showed an association of macrocytosis with all-cause mortality. We aimed to assess the relationship of MCV with cardiovascular (CV) morbidity and mortality in patients with chronic kidney disease (CKD), and the effect of MCV on endothelial function. METHODS: This is an observational cohort study with a prospectively maintained cohort of patients with stage 1-5 CKD. Estimated glomerular filtration rate (eGFR), flow mediated dilatation (FMD) and laboratory values were measured at baseline. Multivariate linear and Cox regression analyses were used to predict independent associations of FMD and composite CV events, respectively. RESULTS: A total of 309 patients were included in the study. In contrast to anaemia MCV did not show a significant change among CKD groups. MCV was an independent predictor of FMD in addition to serum haemoglobin, CRP, diabetes, systolic blood pressure (SBP) and eGFR. Median MCV value was 85 fl. Kaplan-Meier analysis showed that at 38 months the survival rate was 97.6% in the group with MCV < 85 compared to 81.6% in the arm with MCV ≥ 85 (P < 0.001, log-rank test). Cox regression analysis showed MCV as a predictor of composite CV events independent of major confounding factors. CONCLUSION: This is the first study in the literature showing an independent association of MCV and FMD. Our results also determined MCV as an independent predictor of composite CV events independent of anaemia, inflammation, diabetes and eGFR in patients with CKD.

Comparison of calcium acetate and sevelamer on vascular function and fibroblast growth factor 23 in CKD patients: a randomized clinical trial.

BACKGROUND: Fibroblast growth factor 23 (FGF-23) is a marker of endothelial dysfunction and atherosclerotic complications in patients with chronic kidney disease (CKD). Because previous studies suggested that sevelamer may exert effects on FGF-23 level and endothelial function independently of its phosphate-lowering action, we tested the effect of sevelamer versus calcium acetate on vascular function and FGF-23 levels. STUDY DESIGN: Randomized prospective open-label trial. SETTING & PARTICIPANTS: Patients with stage 4 CKD with hyperphosphatemia (n = 100). INTERVENTION: An 8-week intervention with sevelamer (n = 47) and calcium acetate (n = 53). OUTCOMES: The primary study outcome was change in flow-mediated vasodilatation in the forearm. The secondary outcome was change in FGF-23 levels. RESULTS: Serum phosphate levels decreased in both treatment arms (P < 0.001), but more markedly in the sevelamer group (P < 0.001). Flow-mediated vasodilatation increased from 6.1% to 7.1% (P < 0.001) in sevelamer-treated patients, whereas it was unchanged in the calcium-acetate group (6.0% vs 6.0%). In a combined analysis, treatment-induced changes in flow-mediated vasodilatation were (P < 0.001) associated with simultaneous changes in FGF-23 levels (-27.1% [-33.2% to -8.8%] for the sevelamer group; 3.5% [-8.4% to 12.1%] for the calcium acetate group), as well as with C-reactive protein and fetuin A levels. These relationships were confirmed in multiple regression analysis adjusting for changes in serum phosphate levels and other factors. LIMITATIONS: Unblinded randomized controlled study that cannot establish mechanisms of effect. CONCLUSIONS: In hyperphosphatemic patients with stage 4 CKD, treatment with phosphate lowering induces measurable improvements in flow-mediated vasodilatation. Furthermore, independently of serum phosphate level, FGF-23 level changes induced by phosphate binders are associated with simultaneous changes in flow-mediated vasodilatation. These observations are compatible with the hypothesis that FGF-23 may contribute to vascular dysfunction in this population.

Serum uric acid independently predicts cardiovascular events in advanced nephropathy.

BACKGROUND: Chronic kidney disease (CKD) is associated with increased risk for cardiovascular (CV) disease and is also associated with elevated uric acid, which is emerging as a nontraditional CV risk factor. We therefore evaluated uric acid as a risk factor for CV disease in subjects presenting to nephrologists with CKD who were not on medications known to alter endothelial function. METHODS: 303 subjects with stage 3-5 CKD were followed for a mean of 39 months (range 6-46) and assessed for fatal and nonfatal CV events. Hyperuricemia was defined as uric acid >6.0 mg/dl for women and >7.0 mg/dl for men. In addition to other CV risk factors, endothelial function (flow-mediated dilatation), inflammatory markers (hsCRP), and insulin resistance (HOMA index and fasting insulin levels) were included in the analysis. We evaluated the association between uric acid and flow-mediated dilatation with linear regression. The impact of uric acid on composite CV events was assessed with Cox regression analysis. RESULTS: Of a total of 303 patients, 89 had normouricemia and 214 had hyperuricemia. Both fatal (32 of 214 vs. 1 of 89 subjects) and combined fatal and nonfatal (100 of 214 vs. 13 of 89 subjects) CV events were more common in subjects with hyperuricemia compared with normal uric acid levels, and this was independent of estimated glomerular filtration rate, traditional CV risk factors including diabetes, hypertension and BMI, and nontraditional risk factors (hsCRP and endothelial function). The 46-month survival rate was 98.7% in the group with low uric acid compared to 85.8% in patients with high uric acid (p = 0.002). CONCLUSIONS: Hyperuricemia is an independent risk factor for CV events in subjects presenting with CKD who are not on medications known to alter endothelial function.