Insulin resistance and the metabolic syndrome are associated with arterial stiffness in patients with chronic kidney disease

The association between Hba1c and arterial stiffness among non-diabetic patients with chronic kidney disease

Background

Cardiovascular events are seen more frequently after the age of 60 and they are a significant cause of morbidity and mortality. Arterial stiffness is a property that can be expressed by pulse wave velocity and this value is assumed to be a predictor of cardiovascular events. Patients with chronic kidney disease and dysregulated blood sugar have increased atherosclerosis and arterial stiffness, but the relationship between physiological levels of Hba1c and arterial stiffness is less clear in chronic kidney disease patients without diabetes mellitus.

Objectives

Here, we aimed to investigate the degree of arterial stiffness among non-diabetic, non-dialysis dependent chronic kidney disease patients with physiological HbA1c levels.

Methods

We enrolled 51 patients who were followed up at Ege University Hospital Nephrology Department between February and June 2015. Non-diabetic, non-dialysis dependent chronic kidney disease patients were included in the study. Blood pressure and pulse wave velocity were measured with an applanation tonometry device (Sphygmocor Vx Software Atcor Medical, Australia). Correlations between pulse wave velocity and the aforementioned parameters were investigated (see below).

Results

We detected a significant correlation between pulse wave velocity and systolic blood pressure (p=0.0001) and Hba1c (p=0.044) separately. There was an inverse correlation with creatinine clearance (p=0.04). We also detected a significant correlation with serum phosphorus level (p=0.0077) and furosemide use (p=0.014). No correlations were found among the other parameters.

Conclusions

Arterial stiffness is an important predictor of cardiovascular events and measuring it is an inexpensive method for estimating morbidity and mortality. Our study supports the importance of measuring arterial stiffness and of controlling blood glucose levels, even at physiological Hba1c values, especially for chronic kidney disease patients.

Insulin resistance and vascular dysfunction in chronic kidney disease: mechanisms and therapeutic interventions

Insulin resistance (IR) is a novel cardiovascular risk factor that has been implicated in the pathogenesis of cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). Beyond its metabolic effects, insulin can potentially mediate the increased risk for CVD through its vasoactive properties. This review examines key clinical data and potential mechanisms linking IR and cardiovascular risk in CKD. While lifestyle interventions and pharmacotherapies with known insulin-sensitizing properties are promising therapeutic targets to reduce the CVD burden in this population, clinical trial data on the effect of insulin sensitization on vascular function in CKD are either lacking or conflicting and are limited by small sample size and short duration of intervention. Affirming the role of IR in lowering CVD risk in CKD will require prospective randomized controlled studies with sufficient sample size and hard clinical outcomes. Future research efforts should be directed at assessing the efficacy, safety and mechanisms by which novel insulin sensitizers such as bile acid sequestrant, selective and dual peroxisome proliferator-activated receptor modulators and modulators of gut microbiota and uraemic toxins alter vascular function in patients with CKD.

Insulin resistance in chronic kidney disease: a systematic review

Insulin resistance (IR) is an early metabolic alteration in chronic kidney disease (CKD) patients, being apparent when the glomerular filtration rate is still within the normal range and becoming almost universal in those who reach the end stage of kidney failure. The skeletal muscle represents the primary site of IR in CKD, and alterations at sites beyond the insulin receptor are recognized as the main defect underlying IR in this condition. Estimates of IR based on fasting insulin concentration are easier and faster but may not be adequate in patients with CKD because renal insufficiency reduces insulin catabolism. The hyperinsulinemic euglycemic clamp is the gold standard for the assessment of insulin sensitivity because this technique allows a direct measure of skeletal muscle sensitivity to insulin. The etiology of IR in CKD is multifactorial in nature and may be secondary to disturbances that are prominent in renal diseases, including physical inactivity, chronic inflammation, oxidative stress, vitamin D deficiency, metabolic acidosis, anemia, adipokine derangement, and altered gut microbiome. IR contributes to the progression of renal disease by worsening renal hemodynamics by various mechanisms, including activation of the sympathetic nervous system, sodium retention, and downregulation of the natriuretic peptide system. IR has been solidly associated with intermediate mechanisms leading to cardiovascular (CV) disease in CKD including left ventricular hypertrophy, vascular dysfunction, and atherosclerosis. However, it remains unclear whether IR is an independent predictor of mortality and CV complications in CKD. Because IR is a modifiable risk factor and its reduction may lower CV morbidity and mortality, unveiling the molecular mechanisms responsible for the pathogenesis of CKD-related insulin resistance is of importance for the identification of novel therapeutic targets aimed at reducing the high CV risk of this condition.

Neck Circumference as a Predictive Indicator of CKD for High Cardiovascular Risk Patients

Background. Neck circumference (NC) is an anthropometric measure of obesity for upper subcutaneous adipose tissue distribution which is associated with cardiometabolic risk. This study investigated whether NC is associated with indicators of chronic kidney disease (CKD) for high cardiometabolic risk patients. Methods. A total of 177 consecutive patients who underwent the outpatient departments of cardiology were prospectively enrolled in the study. The patients were aged >20 years with normal renal function or with stages 1–4 CKD. A linear regression was performed using the Enter method to present an unadjusted R², standardized coefficients, and standard error, and the Durbin-Watson test was used to assess residual independence. Results. Most anthropometric measurements from patients aged ≧65 were lower than those from patients aged <65, except for women's waist circumference (WC) and waist hip ratio. Female NC obtained the highest R² values for 24 hr CCR, uric acid, microalbuminuria, hsCRP, triglycerides, and HDL compared to BMI, WC, and hip circumference. The significances of female NC with 24 hr CCR and uric acid were improved after adjusted age and serum creatinine. Conclusions. NC is associated with indicators of CKD for high cardiometabolic risk patients and can be routinely measured as easy as WC in the future.

Modifiable risk factors for increased arterial stiffness in outpatient nephrology

Arterial stiffness, as measured by pulse wave velocity (PWV), is an independent predictor of cardiovascular events and mortality. Arterial stiffness increases with age. However, modifiable risk factors such as smoking, BP and salt intake also impact on PWV. The finding of modifiable risk factors may lead to the identification of treatable factors, and, thus, is of interest to practicing nephrologist. We have now studied the prevalence and correlates of arterial stiffness, assessed by PWV, in 191 patients from nephrology outpatient clinics in order to identify modifiable risk factors for arterial stiffness that may in the future guide therapeutic decision-making. PWV was above normal levels for age in 85/191 (44.5%) patients. Multivariate analysis showed that advanced age, systolic BP, diabetes mellitus, serum uric acid and calcium polystyrene sulfonate therapy or calcium-containing medication were independent predictors of PWV. A new parameter, Delta above upper limit of normal PWV (Delta PWV) was defined to decrease the weight of age on PWV values. Delta PWV was calculated as (measured PWV) - (upper limit of the age-adjusted PWV values for the general population). Mean±SD Delta PWV was 0.76±1.60 m/sec. In multivariate analysis, systolic blood pressure, active smoking and calcium polystyrene sulfonate therapy remained independent predictors of higher delta PWV, while age, urinary potassium and beta blocker therapy were independent predictors of lower delta PWV. In conclusion, arterial stiffness was frequent in nephrology outpatients. Systolic blood pressure, smoking, serum uric acid, calcium-containing medications, potassium metabolism and non-use of beta blockers are modifiable factors associated with increased arterial stiffness in Nephrology outpatients.

Fenofibrate increases serum creatinine in a patient with familial nephropathy associated to hyperuricemia

BACKGROUND

Kidney function progressively deteriorates in patients with familial juvenile hyperuricemiac nephropathy (FJHN, OMIN 162000) and chronic renal disease is commonly associated to dyslipidemia. We report for the first time abrupt renal insufficiency in a patient with FJHN and hypertrygliceridemia following fenofibrate administration.

CASE REPORT

A 53-year-old man was diagnosed clinically with FJHN at age 24 years which was subsequently confirmed by genotypic analysis of the UMOD gene at age 40 years. His mother and two brothers suffered the disease. At that time, renal size and function were normal, as was his blood pressure and serum lipids. At age 34 years, serum urate was 8.5 mg/dL and creatinine 1.7 mg/dL (GFR, 58 mL/min/1.73 m2). He was treated with allopurinol, losartan, and lovastatin. Serum TG levels ranged between 150 and 250 mg/dL. At age 52 years, serum urate was 4.1 mg/dL, creatinine 3.2 mg/dL, LDLc 99 mg/dL (atorvastatin 40 mg/d), and TG 275 mg/dL. Fenofibrate (160 mg/d) was added. One month later, serum creatinine increased to 4.2 mg/dL and TG decreased to 125 mg/dL. He did not complain of muscle pain, weakness, or changes in urinary frequency or color and rabdomyolysis was discarded. Fenofibrate was withheld and three months later serum creatinine decreased to baseline levels (3.2 mg/dL) and TG increased to 197 mg/dL.

CONCLUSION

To our knowledge, this is the first patient with FJHN in whom fenofibrate administration was associated to a further impairment in renal function not attributable to rabdomyolysis.

The relationships between visit-to-visit blood pressure variability and renal and endothelial function in chronic kidney disease

Visit-to-visit blood pressure variability has been shown to be an independent risk factor for cardiovascular diseases. High visit-to-visit blood pressure variability and endothelial dysfunction are observed in patients with chronic kidney disease. It is therefore assumed that high variability in visit-to-visit blood pressure measurements may be associated with endothelial dysfunction in these patients. The present study investigated the associations between visit-to-visit blood pressure variability and renal and endothelial function in patients with chronic kidney disease. We analyzed 150 consecutive patients with predialysis chronic kidney disease who visited our outpatient clinic from January 2006 to December 2010. The study examined the relationships between variability in visit-to-visit systolic blood pressure levels or mean systolic blood pressure (M SBP) and estimated glomerular filtration rate (eGFR) and flow-mediated dilation, an index of endothelial function. Variability in visit-to-visit systolic blood pressure showed a significant negative association with eGFR, independent of age, hemoglobin A1c, low-density lipoprotein (LDL) cholesterol and uric acid, whereas M SBP did not. Similarly, variability in SBP showed a significant negative association with flow-mediated dilation, independent of age, eGFR, HbA1c, LDL cholesterol and M SBP. These data indicate that variability in visit-to-visit blood pressure measurements is associated with impaired renal and endothelial function in patients with chronic kidney disease. This finding suggests that reducing blood pressure fluctuations might have beneficial effects in patients with chronic kidney disease, although this point needs to be addressed by future studies.

Relationship between chronic kidney disease and metabolic syndrome: current perspectives

Both metabolic syndrome (MetS) and chronic kidney disease (CKD) are increasing in incidence and lead to significant cardiovascular morbidity and mortality. The relationship between these two entities is complex. Individual components of the MetS are known risk factors for incident kidney disease, but it is not clear how the clustering of these components is linked to the development and progression of kidney disease. Cross-sectional studies show an association of the MetS and prevalent CKD; however, one cannot draw conclusions as to which came first - the MetS or the kidney disease. Observational studies suggest a relationship between MetS and incident CKD, but they also demonstrate the development of MetS in patients with established CKD. These observations suggest a bidirectional relationship. A better understanding of the relationship between components of the MetS and whether and how these components contribute to progression of CKD and incident cardiovascular disease could inform more effective prevention strategies.

Influence of metabolic syndrome and its components on subclinical organ damage in hypertensive perimenopausal women

PURPOSE

We investigated the association between metabolic syndrome (MS), its components and the presence of subclinical organ damage in hypertensive perimenopausal women.

PATIENTS/METHODS

152 women with newly diagnosed, untreated arterial hypertension (mean age 51.0 ± 3.5 years) were included in the study. In all subjects anthropometrical measurements, 24-hr blood pressure monitoring, echocardiographic examination, and carotid ultrasound were performed. Carotid-femoral pulse wave velocity (PWV) was measured to obtain data on vascular compliance. As the index of early kidney damage both glomerular filtration rate was calculated and albumin/creatinine ratio in the urine sample was measured. A fasting blood sample was taken to measure glucose and lipid concentration.

RESULTS

MS was found in 41% of patients. Patients with MS exhibited elevated left ventricular mass index (LVMI 84.7 vs. 78.8 g/m(2.7), p=0.03), higher intima-media thickness (IMT 0.67 vs. 0.62 mm, p=0.003), greater prevalence of LV hypertrophy (30% vs. 13%, p=0.01), and carotid plaques (24% vs. 15%, p=0.01). The multivariate regression analysis revealed that components of MS (systolic blood pressure and waist circumference) are stronger predictors of LVM than MS itself. The relationship between MS and LVMI lost its significance when BMI was included in the model, and remained significant for IMT.

CONCLUSION

In hypertensive perimenopausal women components of MS are stronger predictors of subclinical organ damage than MS itself. Left ventricular mass and hypertrophy are more strongly correlated with increasing body weight than with the presence of MS. MS, independently of BMI, influences the level of subclinical atherosclerosis in the study group.