Association of albuminuria and the metabolic syndrome

The relationship between triglyceride-glucose index and albuminuria in United States adults

Purpose

Triglyceride-glucose (TyG) index is a simple and reliable indicator of metabolic dysfunction. We aimed to investigate a possible relationship between TyG index and albuminuria in the United States adult population.

Methods

This cross-sectional study was conducted among adults with complete TyG index and urinary albumin/urinary creatinine (UACR) from 2011-2018 National Health and Nutrition Examination Survey (NHANES). The independent relationship between TyG index and albuminuria (UACR>30mg/g) was evaluated. TyG index was compared with insulin resistance represented by homeostatic model assessment of insulin resistance (HOMA-IR), and metabolic syndrome. Subgroup analysis was also performed.

Results

A total of 9872 participants were included in this study, and the average TyG index was 8.53 ± 0.01. The proportion of albuminuria gradually increased with the increase of TyG index quartile interval. Elevated TyG index was independently associated with albuminuria, and this association persisted after additional adjustments for HOMA-IR or dichotomous metabolic syndrome. The area under the ROC curve (AUC) of TyG index was larger than that of log (HOMA-IR). Subgroup analysis suggested that the relationship between TyG index and albuminuria is of greater concern in age<60, overweight/obese, diabetic, and metabolic syndrome patients.

Conclusion

The TyG index may be a potential epidemiological tool to quantify the role of metabolic dysfunction, rather than just insulin resistance, in albuminuria in the United States adult population. Further large-scale prospective studies are needed to confirm our findings.

Metabolic biomarkers and gallstone disease - a population-based study

OBJECTIVES

The objectives for this study were to examine the associations between metabolic biomarkers of obesity including insulin resistance, vascular dysfunction, systemic inflammation, genetic susceptibility and ultrasound proven gallstone disease or cholecystectomy in a population-based cross-sectional study.

MATERIAL AND METHODS

A total of 2650 participants were included, of whom 422 had gallstone disease. Associations between selected metabolic biomarkers and gallstone disease were estimated by multivariable logistic regression models and expressed as odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Gallstone disease was associated with fasting glucose (OR 1.14, 95% CI [1.05;1.24]), fasting insulin (OR 1.03, 95% CI [1.01;1.05]), homeostasis model assessment insulin resistance (OR 1.18, 95% CI [1.02;1.36]), the metabolic syndrome (OR 1.51, 95% CI [1.16;1.96]), white blood cell count (OR 1.07, 95% CI [1.00;1.15]) and C-reactive protein (OR 1.03, 95% CI [1.01;1.05]). A tendency towards an association for soluble urokinase plasminogen activator receptor was also found (OR 1.08, 95% CI [0.99;1.18]). The MC4R(rs17782313) (OR 1.27, 95% CI [1.02;1.58]), MAP2K5(rs2241423) (OR 1.80, 95% CI [1.04;3.41]), NRXN3(rs10146997) (OR 1.26, 95% CI [1.01;1.57]), HHEX(rs1111875) (OR 1.29, 95% CI [1.03;1.62]), FAIM2(rs7138803) (OR 0.66, 95% CI [0.48;0.91]), and apolipoprotein E4 allele (OR 0.76, 95% CI [0.59;0.98]) were associated with gallstone disease. Urinary albumin was not associated with gallstone disease. The association between BMI and gallstone disease was explained by insulin resistance.

CONCLUSIONS

Biomarkers of insulin resistance, systemic inflammation and genetic obesity or type 2 diabetes risk alleles seem to be associated with gallstone disease. Future studies should explore temporal associations and genetic associations in other populations in order to clarify targets for prevention or intervention.

Lung function and impaired kidney function in relation to metabolic syndrome

PURPOSE

This study aimed to assess the relationships between abnormal lung function and indicators of chronic kidney disease in relation to metabolic syndrome (MetS) by using data from the 2011-2013 Korea National Health and Nutrition Examination Survey.

METHODS

Using the data of 8551 Korean adults (3798 men, 4753 women, ≥40 years), lung function categories [obstructive lung disease (OLD), restrictive lung disease (RLD), and non-obstructive/non-restrictive lung disease (reference group)] were defined for each gender. Albuminuria and low estimated glomerular filtration rate (eGFR) were defined as urine albumin-to-creatinine ratio ≥30 mg/g and eGFR < 60 mL/min/1.73 m². Gender-specific logistic regression analysis was performed after adjusting for age, educational level, smoking, alcohol use, physical activity, and medication use for chronic diseases.

RESULTS

Compared to the reference group, low eGFR was associated with higher odds for RLD in men and RLD or OLD in women when they did not have MetS. In those with MetS, low eGFR was associated with higher odds for OLD in men and RLD or OLD in women. Albuminuria was associated with higher odds for RLD in men who did not have MetS, while it was associated with higher odds for RLD or OLD in men and women who had MetS.

CONCLUSIONS

Abnormal lung function was associated with increased odds for chronic kidney disease indicators, when combined with MetS in both gender. Even in those without MetS, RLD in men was associated with increased odds for low eGFR or albuminuria, while RLD or OLD in women was associated with increased odds for low eGFR.

Clinical outcomes associated with albuminuria in central Australia: a cohort study

BACKGROUND

Chronic kidney disease (CKD) and end-stage-kidney disease (ESKD) continue to be under-diagnosed and a major burden for Aboriginal communities in central Australia. The aim of this study was to examine the risk of poor clinical outcomes associated with elevated albumin-to-creatinine ratio (ACR) among Aboriginal people in central Australia.

METHODS

Cox proportional hazards models were used to estimate the risk of end stage kidney disease (ESKD), dialysis, CVD (cardiovascular disease) and mortality associated with participants' baseline albuminuria reading from a 10-year cohort study of Aboriginal people (n = 623) from three communities in central Australia. Predictors of progression of albuminuria were also examined in the context of the Kidney Health Australia (KHA) Risk Matrix.

RESULTS

A baseline ACR level of ≥3.5 mg/mmol was associated with an almost 10-fold increased risk of ESKD (95%CI 2.07-43.8) and a 15-fold risk of dialysis (95%CI 1.89-121). Albuminuria ≥3.5 mg/mmol was also associated with a borderline 63 % increased risk of CVD (95%CI 0.98-2.71). No significant association was observed with mortality from all-causes or chronic disease. Diabetes and a waist-to-hip ratio ≥0.90 independently predicted a two-fold increased risk of a progression to higher ACR levels.

CONCLUSIONS

A single measure of moderately increased albuminuria was a strong predictor of renal failure in this population. A single spot urine ACR analysis in conjunction with the KHA Risk Matrix may be a useful and efficient strategy to screen for risk of CKD and progression to dialysis in remote communities. A focus on individuals with diabetes and/or central obesity for strategies to avoid increases in albuminuria may also prevent future CKD and CVD complications.

Association of Microalbuminuria with Metabolic Syndrome among Aged Population

Background. The impact of the various components of metabolic syndrome (MetS) on chronic kidney disease has been conflicting. We aim to investigate the association between MetS and microalbuminuria and identify the major contributing components of MetS that result in microalbuminuria in the Chinese aged population. Methods. A total of 674 adults aged 55–98 years (males: 266; mean age: 66.5 ± 7.5 years) were studied. MetS was defined by the 2004 Chinese Diabetes Society criteria and microalbuminuria by urine albumin-creatinine ratio (UACR) ≥3 mg/mmoL. Results. The prevalence of microalbuminuria was gradually increased with increasing number of MetS components (P < 0.05). In multivariate regression, after adjusting for age and sex, MetS was the strongest correlate of microalbuminuria (OR = 1.781, 95% CI = 1.226–2.587; P < 0.05) followed by the fasting plasma glucose (FPG) (OR = 1.217, 95% CI = 1.044–1.092; P < 0.05), systolic blood pressure (SBP) (OR = 1.011, 95% CI = 1.107–1.338; P < 0.05), and high-density lipoprotein cholesterol (HDL-C) (OR = 0.576, 95% CI = 0.348–0.953; P < 0.05). Conclusions. MetS is independently associated with microalbuminuria in the Chinese aged population. Elevated FPG is the most predominant component of metabolic syndrome associated with microalbuminuria followed by elevated SBP and reduced HDL-C.

Race and the insulin resistance syndrome

Type 2 diabetes remains an important cause of morbidity and mortality. The metabolic syndrome affects 25% of the adult US population based on the Third Report of the Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults from the National Cholesterol Education Program. Knowledge on the impact of obesity on metabolic health parameters has increased greatly over the past decade. This review discusses the limitations of the National Cholesterol Education Program metabolic syndrome definition and the racial disparities in the clinical presentation of the insulin resistance syndrome. We also examine the current literature with particular emphasis on albuminuria, nonalcoholic fatty liver disease, and intramyocellular lipid content. This review explores potential environmental and genetic reasons for differences in the manifestation of insulin resistance across racial/ethnic groups and highlights several promising areas for further study.

Microalbuminuria in chronic obstructive pulmonary disease

BACKGROUND

Microalbuminuria is an important risk factor for cardiovascular diseases. Microalbuminuria may be seen due to hypoxemia in patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

In this study, we investigated prevalence and relationship of microalbuminuria with clinical and physiological parameters in patients with COPD.

METHOD

During the research, 66 consecutive patients with COPD and 40 cases smokers with normal spirometry were included. The urinary albumin creatinin ratio (UACR) was calculated according to previously described formula. The presence of microalbuminuria was defined as UACR being ≥20 in men and ≥30 in women. The severity index of chronic diseases was evaluated by using MCIRS.

RESULTS

The rate of presence of microalbuminuria and UACR were higher in patients with COPD than smokers with normal spirometry. Pearson correlation analysis showed a significant inverse relationship between UACR and PaO2, FEV1%, FVC%. On the other hand, there was a positive relationship between UACR and BODE index. There was a significant relationship between the presence of microalbuminuria with PaO2 and BODE index. In the linear regression model, there was a negative relationship between UARC and PaO2 yet there was a significantly positive relationship between UARC and MCIRS score, BODE index. In the logistic regression model, the presence of microalbuminuria showed significant associations with PaO2, BODE index.

CONCLUSION

Microalbuminuria may be seen in patients with COPD, depending on the severity of disease and hypoxemia. Microalbuminuria in patients with severe COPD should be examined in regular periods for risk of cardiovascular morbidity or mortality.

Long term metabolic syndrome induced by a high fat high fructose diet leads to minimal renal injury in C57BL/6 mice

Metabolic syndrome can induce chronic kidney disease in humans. Genetically engineered mice on a C57BL/6 background are highly used for mechanistic studies. Although it has been shown that metabolic syndrome induces cardiovascular lesions in C57BL/6 mice, in depth renal phenotyping has never been performed. Therefore in this study we characterized renal function and injury in C57BL/6 mice with long-term metabolic syndrome induced by a high fat and fructose diet (HFFD). C57BL/6 mice received an 8 months HFFD diet enriched with fat (45% energy from fat) and drinking water enriched with fructose (30%). Body weight, food/water consumption, energy intake, fat/lean mass ratio, plasma glucose, HDL, LDL, triglycerides and cholesterol levels were monitored. At 3, 6 and 8 months, renal function was determined by inulin clearance and measure of albuminuria. At sacrifice, kidneys and liver were collected. Metabolic syndrome in C57BL/6 mice fed a HFFD was observed as early 4 weeks with development of type 2 diabetes at 8 weeks after initiation of diet. However, detailed analysis of kidney structure and function showed only minimal renal injury after 8 months of HFFD. HFFD induced moderate glomerular hyperfiltration (436,4 µL/min vs 289,8 µL/min; p-value=0.0418) together with a 2-fold increase in albuminuria only after 8 months of HFFD. This was accompanied by a 2-fold increase in renal inflammation (p-value=0.0217) but without renal fibrosis or mesangial matrix expansion. In addition, electron microscopy did not show alterations in glomeruli such as basal membrane thickening and foot process effacement. Finally, comparison of the urinary peptidome of these mice with the urinary peptidome from humans with diabetic nephropathy also suggested absence of diabetic nephropathy in this model. This study provides evidence that the HFFD C57BL/6 model is not the optimal model to study the effects of metabolic syndrome on the development of diabetic kidney disease.

Metabolic syndrome is independently associated with microalbuminuria in type 2 diabetes

We opted in this study to evaluate the association between metabolic syndrome (MetS) and microalbuminuria in type 2 diabetes. A total of 800 adults (344 males; age 54.8 +/- 9.6 years) with type 2 diabetes were studied. MetS was defined by the International Diabetes Federation criteria and microalbuminuria by urinary albumin excretion between 30 and 299 mg/day on at least two of three occasions. Patients with macroalbuminuria and those with poor renal function were not included. Microalbuminuria was present in 237 (29.6%) patients with MetS and increased in prevalence with increasing numbers of metabolic abnormalities (P < 0.001). The normo- and micro-albuminuric groups were not significantly different in age, sex, and renal function. However, MetS was significantly more common among patients with (90.3%) than those without (76.6%) microalbuminuria (P < 0.01). In multivariate regression, MetS was the strongest correlate of microalbuminuria (OR = 3.31, 95% CI = 1.91-5.75; P < 0.01). In conclusion, MetS is independently associated with microalbuminuria in type 2 diabetes.

Metabolic syndrome and chronic kidney disease

The prevalence of metabolic syndrome (MetS) is increasing worldwide in both developing and developed countries. Experimental and clinical studies have revealed that MetS plays an important role in the development of chronic kidney disease (CKD), which leads to end-stage renal disease. Emerging evidence also suggests that CKD may actually cause MetS since the kidney is an important organ of glucose and lipid homeostasis. Although multiple mechanisms have been shown to be involved in the pathogenesis of MetS, insulin resistance appears to be a central pathophysiological factor contributing to MetS. In this review we will discuss the association of MetS with insulin resistance and CKD, and the renal pathophysiological changes associated with MetS.

Blood pressure, atherosclerosis, and albuminuria in 10,113 participants in the atherosclerosis risk in communities study

BACKGROUND

Albuminuria predicts cardiovascular risk, but its function as a marker of endothelial damage and atherosclerosis is uncertain, as is the complex relationship with hypertension and diabetes.

OBJECTIVE

To determine whether hypertension contributes to albuminuria across levels of atherosclerosis and type 2 diabetes.

METHODS

Cross-sectional associations of cardiovascular risk factors and albuminuria were examined in 10,113 middle-aged participants in the atherosclerosis risk in communities study divided into four subgroups: type 2 diabetes with marked atherosclerosis, type 2 diabetes without marked atherosclerosis, without diabetes with marked atherosclerosis, and without diabetes without marked atherosclerosis. Marked atherosclerosis was defined as high levels of carotid atherosclerosis or prevalent coronary heart disease.

RESULTS

Hyperglycemia and hypertriglyceridemia were associated with albuminuria, but only among patients with type 2 diabetes. In multivariate models, increasing blood pressure levels (but not albuminuria) were significantly associated (P-trend <0.001) with carotid atherosclerosis when stratified by prevalent coronary heart disease. Excluding individuals on hypertension medication, higher blood pressure was associated with albuminuria in all groups (P-trend<0.05). The association was strong even for high-normal blood pressure among individuals without diabetes without marked atherosclerosis (odds ratio 2.7, 95% confidence interval 1.6-4.6) and patients with type 2 diabetes with marked atherosclerosis (12.0, 1.3-108.2).

CONCLUSION

Blood pressure, even at high-normal levels, is consistently associated with albuminuria across categories of type 2 diabetes and atherosclerosis. Our results suggest that the effects of blood pressure on albuminuria are not solely mediated through generalized vascular damage, as represented by degree of atherosclerosis.

Cardiovascular risk factors in Australian indigenous and non-indigenous children: a population-based study

AIM

Indigenous people have a two- to tenfold increased risk of premature death from cardiovascular disease. We aimed to determine whether some key risk factors for cardiovascular disease occur more commonly in Aboriginal than non-Aboriginal Australian children.

METHODS

Children were enrolled from primary schools throughout New South Wales, the state with the highest number of Aboriginal people. Associations between ethnicity, gender, birthweight, socio-demographic status and hypertension, obesity, baseline and persistent albuminuria were determined.

RESULTS

A total of 2266 children (55% Aboriginal) were enrolled. Mean age was 8.9 years (+/-3.8 years). Obesity (body mass index >or=2 standard deviations) was detected in 7.1%, systolic hypertension (blood pressure >90th percentile) in 7.2%, diastolic hypertension in 5.9%, baseline albuminuria (albumin : creatinine >or=3.4 mg/mmol) in 7.3% and persistent albuminuria in 1.5% with no differences between Aboriginal and non-Aboriginal children. Hypertension was less common with increasing social disadvantage (trend P < 0.02). Increasing body mass index standard deviation was strongly associated with systolic and diastolic hypertension (both P < 0.0001).

CONCLUSIONS

Many risk factors for cardiovascular disease are already common in young children but not more prevalent in Aboriginal than in non-Aboriginal children. In all children, overweight and obesity have the strongest association with hypertension, but social disadvantage appears protective for hypertension. Our findings suggest that risk for cardiovascular health disparities seen in indigenous adults manifests beyond childhood and that a window of opportunity exists to prevent some of these outcomes.

Renal manifestations of metabolic syndrome in type 2 diabetes

AIM

The association between metabolic syndrome (MS) and renal outcomes in diabetic patients remains unclear. We conducted a cross-sectional study to assess the association between MS and albuminuria and decreased glomerular filtration rate (GFR) in type 2 diabetic patients.

METHODS

We studied a total of 1003 adult Japanese patients with type 2 diabetes, 582 men, with a mean (+/-S.D.) age of 62+/-12 years. Patients with macroalbuminuria, defined as a urinary albumin-to-creatinine ratio (ACR) > or =300 mg/g Cr, and those with renal insufficiency, defined as serum creatinine > or =2.0 mg/dl, were excluded. MS was assessed according to Japanese definition proposed in 2005. Microalbuminuria and decreased GFR were defined as ACR of 30-299 mg/g Cr and estimated GFR <60 ml/min/1.73 m(2), respectively.

RESULTS

The prevalence of microalbuminuria was significantly higher in patients with MS than those without. In contrast, the prevalence of decreased GFR was comparable between patients with and without MS. Waist circumference was selected as a significant variable in the logistic regression analysis for microalbuminuria.

CONCLUSION

Microalbuminuria, but not decreased GFR, is independently associated with MS and solely with increased waist circumference in Japanese patients with type 2 diabetes.

Microalbuminuria and the metabolic syndrome and its components in the Chinese population

BACKGROUND

Microalbuminuria and the metabolic syndrome (MetS) have both been linked to chronic kidney disease and cardiovascular disease. This study investigated the association between urinary albumin-to-creatinine ratio (ACR) and MetS and its components.

MATERIALS AND METHODS

A total of 2311 subjects aged 40 years and over were recruited in 2004 in a metropolitan city in Taiwan. The biochemical indices, such as fasting glucose levels, urinary albumin, urinary creatinine and anthropometric indices, were measured. We defined microalbuminuria as a urinary ACR ranging from 30 to 300 mg g(-1) creatinine. MetS was defined using the American Heart Association and the National Heart, Lung and Blood Institute (AHA/NHLBI) and the International Diabetes Federation (IDF) definitions. The relationship between MetS and microalbuminuria was examined using multiple logistical regression analysis.

RESULTS

Subjects with microalbuminuria had higher age, body mass index (BMI), waist circumference, blood pressure, fasting plasma glucose, triglycerides, total cholesterol (TCHOL)/high-density lipoprotein cholesterol (HDL-C) ratio, prevalence of diabetes mellitus and hypertension and lower HDL-C than subjects with normoalbuminuria. After adjusting for age and BMI, microalbuminuria was associated with the individual components of MetS, except in central obesity in women and elevated fasting glucose in men. After adjusting for age, BMI, smoking and alcohol consumption status, multiple logistical regressions revealed that microalbuminuria is strongly associated with MetS in both genders and according to both definitions. The odds ratio of having MetS using the AHA/NHLBI and IDF definition was 1.76 (1.16-2.67) and 1.73 (1.06-2.83) in men and 2.19 (1.38-3.50) and 2.09 (1.24-3.51) in women, respectively.

CONCLUSIONS

Microalbuminuria was strongly associated with MetS and its components. There is an increased likelihood of having MetS if subjects have microalbuminuria.

Differential impacts of adiponectin on low-grade albuminuria between obese and nonobese persons without diabetes

The goal of this study was to examine the association between adiponectin and low-grade albuminuria in nondiabetic persons and whether it differed between obese and nonobese individuals. Urinary albumin excretion (UAE) was assessed by overnight collection in 157 participants. Overall, as anticipated, 24-hour systolic blood pressure and fasting glucose levels were independent determinants of UAE (beta=0.254 and 0.176, respectively, P<.05). In obese persons (body mass index [BMI] >/=25 kg/m(2); n=63), adiponectin value was a significant negative determinant of UAE (beta=-0.256, P<.05) independent of blood pressure and glucose levels, whereas in nonobese participants (n=94) it was not. In an analysis of BMI and the median value of adiponectin (9.9 microg/mL), UAE was found to be significantly higher in obese persons with low adiponectin levels than in obese persons with high adiponectin levels (9.20 vs 5.11 microg/min; P<.05), even after adjustment for age, sex, blood pressure level, and glucose level. There was an inverse association between adiponectin and low-grade albuminuria in obese nondiabetic persons.

Mechanisms of the components of the metabolic syndrome that predispose to diabetes and atherosclerotic CVD

The metabolic syndrome represents a summation of obesity-driven risk factors for atherosclerotic CVD and type 2 diabetes. Definitions of the syndrome vary but in general agree closely in identifying subjects. The relationships between the metabolic syndrome and atherosclerotic CVD and diabetes also vary, with relative risks of approximately 1.5-3.0 and approximately 3.0-5.0 respectively. Insulin resistance appears to explain much of the pathophysiology of the syndrome. Both increased fatty acid flux and an excess of circulating pro-inflammatory cytokines are likely mediators. With increased waist circumference, increases in fatty acid delivery to the liver result in higher rates of hepatic glucose production and increases in the secretion of apoB-containing lipoproteins. Concomitant changes in HDL ensue, including a replacement of the cholesterol content with TAG, an accelerated clearance from the plasma and thus a reduced number of HDL particles. Typically also present are increases in small dense LDL. Hypertension in part relates to the insulin resistance, but may involve other mechanisms. Impaired fasting glucose often relates to defects in insulin secretion in addition to insulin resistance, and probably more than any other component of the syndrome predicts the increased incidence of type 2 diabetes. Although not included in the diagnostic criteria, increases in pro-inflammatory cytokines and pro-thrombotic factors, in addition to decreases in plasma adiponectin, may also contribute to the increased incidence of atherosclerotic CVD and diabetes. In general, the greater the number of metabolic syndrome components, the greater the risk for these outcomes. The cytokines and pro-thrombotic factors also appear to contribute.

Investigation of microalbuminuria in nondiabetic, normotensive obese women

AIM

To investigate if obesity which is not accompanied by diabetes and/or hypertension is associated with microalbuminuria in female patients.

MATERIALS AND METHODS

A total of 77 obese female patients from the Outpatient Clinic of Endocrinology of Istanbul University Cerrahpasa Medical Faculty and 30 age-matched, lean, healthy women were enrolled in the study. Patients with accompanying diabetes mellitus, hypertension, obesity associated with any endocrine abnormality, hepatic or renal disease, fever, infectious disease, malignancy were excluded. Weight, height, body-mass index (BMI), waist circumference, waist/hip ratio (WHR) and systolic and diastolic blood pressures were recorded. Albumin excretion in 24-hour urine samples (UAE) were measured using SYNCHRON LX System with MA Microalbumin kit in two separate 24-hour urine samples from every patient. Statistical analysis was performed using t-test and Pearson's correlation in SPSS 12.0 for Windows Program.

RESULTS

The median albumin excretion in 24-hour urine sample was similar in obese and control groups (12.01 +/- 10.69 mg/day vs 9.35 +/- 4.09 mg/day; p= 0.211). There were no correlations between the albumin excretion in 24 hour urine samples and BMI, waist circumference, WHR, systolic or diastolic blood pressure.

CONCLUSION

Diabetes mellitus and hypertension are known to be associated with microalbuminuria. In our study, microalbuminuria was not detected in obese women without diabetes and/or hypertension and UAE was similar in obese and lean women.

Intracranial atherosclerotic stroke: specific focus on the metabolic syndrome and inflammation

Stroke is the second leading cause of mortality world-wide and is well suited for prevention because it has a high prevalence, high burden of economic cost, well-defined modifiable risk factors, and effective prevention measures. Atherosclerosis is one of the major mechanisms of ischemic stroke, but the apparent differences in risk factors for intra- and extracranial atherosclerosis are unclear and the mechanisms that underlie strokes in patients with intracranial atherosclerosis are not well known. Consequently, patients with intracranial stenosis receive the same treatment as those with carotid -atherosclerosis. Several novel substances have emerged recently as risk factors for atherosclerosis. Specifically, it has recently been suggested that both the metabolic syndrome, which refers to a constellation of metabolic risk factors that are linked to insulin resistance, and vascular inflammation are associated with increased risk of coronary heart disease and stroke. The results of the studies reviewed here suggest that these factors play a differential role in the development of atherosclerotic stroke between the intra- and extracranial arterial systems.

Can PPARgamma agonists have a role in the management of obesity-related hypertension?

Peroxisome proliferator-activated receptors (PPAR) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. PPARgamma is the most extensively studied amongst the three subtypes (alpha, delta and gamma). This receptor is a key modulator of lipid and glucose homeostasis and is predominantly expressed in adipose tissue. Expression of PPARgamma is also found in non-adipose tissues including heart, kidney, spleen, and interestingly, in all relevant components of the vasculature: endothelial and smooth muscle cells. These receptors may therefore also play a role in the regulation of vascular tone and blood pressure. Genetic variants of PPARgamma have also been associated with features of the metabolic syndrome, including obesity and increased blood pressure. The discovery of synthetic ligands for PPARgamma, the Thiazolidinediones (TZDs) has greatly enhanced our understanding of their ligand dependent activation and more importantly their role in vascular pathobiology. Approximately 10 years ago, serendipitous animal experiments demonstrated that despite causing sodium retention, the TZDs actually lowered blood pressure. This review will highlight the role of TZDs in various models of hypertension and discuss their potential role in the management of obesity-related hypertension.

Microalbuminuria as a marker of cardiovascular risk in patients with type 2 diabetes

Diabetes is a major risk factor for coronary artery disease and most patients with diabetes die of cardiovascular complications. Reduction of cardiovascular risk is therefore a high priority in the management of patients with diabetes. Microalbuminuria is an important predictor of cardiovascular events and forms one of the components of the insulin resistance/metabolic syndrome, which confers a particularly high risk of cardiovascular death. The currently available glucose-lowering agents vary considerably in their ability to reduce microalbuminuria. The sulfonylureas and metformin appear to have little effect on microalbuminuria expressed as urinary albumin/creatinine ratio, while the thiazolidinediones have unique effects on this risk factor, in parallel with their effects on insulin resistance. In two 1-year European multicenter, randomized, double-blind monotherapy trials (n=2444), pioglitazone produced similar reductions in urinary albumin/creatinine ratio to gliclazide and greater reductions than metformin (P<0.001). Similarly, two further 1-year European multicenter, randomized, double-blind trials assessed the effects of add-on therapy (n=1269) on urinary albumin/creatinine ratio. In the first study, urinary albumin/creatinine ratio was reduced by pioglitazone add-on to sulfonylurea (-15%), but was largely unaffected by metformin add-on to sulfonylurea (2%; P<0.05). In the second, urinary albumin/creatinine ratio was also reduced by pioglitazone add-on to metformin (-10%), but increased by gliclazide add-on to metformin (6%, P<0.05). The results of these studies indicated that compared with metformin or gliclazide, pioglitazone may provide therapeutic benefits, over and above those due to improved glycemic control. These include significant reductions in urinary albumin/creatinine ratio, a known cardiovascular risk marker.

The metabolic syndrome

The metabolic syndrome is a multifaceted clinical entity resulting from the interaction of genetic, hormonal, and lifestyle factors. Over the past two decades, the number of people diagnosed with the syndrome has steadily increased and is associated with the global epidemic of obesity and diabetes. The metabolic syndrome is characterized by the clustering of disorders which includes high blood pressure, high (pro)insulin concentrations, excess body weight with central obesity, and an altered lipid profile (dyslipidaemia) that increase the likelihood to develop micro- and macrovascular complications, including coronary heart disease or stroke. Each of these disorders is by itself a risk factor for other diseases including diabetes mellitus. In combination, morbidity and mortality are dramatically increased. Because the defining thresholds for establishing the diagnosis of the metabolic syndrome are controversial, the NCEP: ATP III and the WHO have made specific suggestions. The current definitions of the metabolic syndrome can be used as predictors of vascular complications. Risk assessment and subsequent selection of probands for intervention, such as weight reduction and increased physical activity are recommended for the clinical management of the metabolic syndrome.

Kidney disease among the Zuni Indians: The Zuni Kidney Project

BACKGROUND

There is an epidemic of kidney disease among the Zuni Indians. In collaboration with health care providers and research institutions, the Zuni Pueblo established the Zuni Kidney Project to reduce the burden of kidney disease.

METHODS

The Zuni Kidney Project conducted a population-based, cross-sectional survey to estimate the prevalence of albuminuria, hematuria, and related risk factors. Neighborhood household clusters served as the sampling frame. Participants completed a questionnaire, donated blood and urine samples, and had blood pressure, height, and weight measured. This survey provided the foundation for ongoing studies to identify genetic and environmental risk factors for disease susceptibility and progression.

RESULTS

Age and gender distributions among survey participants were similar to those in the eligible Zuni population. Prevalence of incipient albuminuria (IA) (0.03< or = urine albumin:creatinine ratio, UACR <0.3) and overt albuminuria (OA) (UACR < 0.3) were higher among diabetics [IA 34.3% (28.3, 40.4%); OA 18.6% (13.7, 23.6%)] than nondiabetics [IA 11.1% (9.3, 12.8%); OA 1.7% (1.0, 2.5%)]. Nondiabetics comprised 58.6% (52.2, 65.0%) and 30.9% (19.9, 41.9%) of participants with IA and OA, respectively. The prevalence of hematuria was higher among diabetics [> or = trace 47.0% (40.7, 53.4); > or =50 red blood cell/microL 25.8% (20.3, 31.4%)] than nondiabetics [> or = trace 31.1% (28.5, 33.7%); > or =50 red blood cell/microL 16.6% (14.5, 18.7%)]. Hypertension was associated with albuminuria among diabetic and nondiabetic participants. Hypercholesterolemia was associated with albuminuria among nondiabetic participants. Diabetes and alcohol use were associated with hematuria.

CONCLUSION

The high prevalences of albuminuria among nondiabetics and of hematuria among diabetics and nondiabetics are consistent with high rates of nondiabetic kidney disease among Zuni Indians with and without diabetes.

Thiazolidinediones-benefits on microvascular complications of type 2 diabetes

Type 2 diabetes is associated with serious microvascular complications, such as nephropathy, retinopathy, and neuropathy, which have a significant impact on patients' quality of life, morbidity, and mortality. Type 2 diabetes management strategies to reduce the risk of microvascular complications include treatment of hyperglycaemia, hypertension, and other vascular risk factors. The importance of glycaemic control in reducing the risk of microvascular complications of diabetes is well established. However, many antihyperglycaemic therapies fail to provide adequate glycaemic control and do not prevent complications in the long term. The thiazolidinediones (TZDs) are a class of agents that provide sustained glycaemic control, mediated primarily by reductions in insulin resistance. Evidence reviewed suggests that the TZDs may have the potential to reduce microvascular complications through benefits that go beyond glycaemic control. Insulin resistance underlies a range of metabolic abnormalities, collectively known as the metabolic syndrome (MS), which are cardiovascular (CV) risk factors. Components include visceral obesity, hyperglycaemia, hypertension, dyslipidaemia, low-grade inflammation and microalbuminuria (an early manifestation of target organ damage). Reducing insulin resistance, therefore, has the potential to reduce both microvascular and macrovascular complications.

The metabolic syndrome

The metabolic syndrome is a common metabolic disorder that results from the increasing prevalence of obesity. The disorder is defined in various ways, but in the near future a new definition(s) will be applicable worldwide. The pathophysiology seems to be largely attributable to insulin resistance with excessive flux of fatty acids implicated. A proinflammatory state probably contributes to the syndrome. The increased risk for type 2 diabetes and cardiovascular disease demands therapeutic attention for those at high risk. The fundamental approach is weight reduction and increased physical activity; however, drug treatment could be appropriate for diabetes and cardiovascular disease risk reduction.

Impact of statins in microalbuminuric subjects with the metabolic syndrome: a substudy of the PREVEND Intervention Trial

AIMS

Microalbuminuria frequently clusters with the metabolic syndrome and may identify subjects at increased coronary risk. Statin treatment may reduce the incidence of major adverse cardiac events in subjects with the metabolic syndrome, but evidence is limited. We evaluated the impact of pravastatin treatment on the incidence of major adverse cardiac events in microalbuminuric subjects with the metabolic syndrome.

METHODS AND RESULTS

This substudy of the PREVEND Intervention Trial (a randomized, placebo-controlled trial with a 2x2 factorial design) included 864 microalbuminuric subjects, who were randomized to fosinopril 20 mg or matching placebo and pravastatin 40 mg or matching placebo (mean follow-up 46 months). The metabolic syndrome was defined according to the NCEP ATPIII-report. Subjects with or without the metabolic syndrome were characterized by a higher age, male sex, and increased albuminuria. The incidence of major adverse cardiac events in subjects with the metabolic syndrome [9.1%; 95% confidence interval (CI) 6.0-13.0%] was increased vs. those without [3.6%; 95% CI 2.3-5.5%; P=0.007). Pravastatin treatment lowered the incidence of major adverse cardiac events in subjects with the metabolic syndrome after adjustment for age and sex (hazard ratio=0.39; 95% CI 0.17-0.89; P=0.025).

CONCLUSION

This study supports the use of statins in microalbuminuric subjects with the metabolic syndrome to reduce the incidence of major adverse cardiac events.

Renal disease in cardiovascular disorders: an underrecognized problem

Chronic renal disease is generally appreciated as a major and rapidly growing health problem. In the United States alone, as many as 19.5 million people may have markers of early renal disease, and more than 660,000 people are expected to require renal replacement therapy by the year 2010. By contrast, the presence and pathological role of renal disease in patients with cardiovascular disease are somewhat underrecognized. Evidence now shows that even minor impairments in renal function, as indicated by measures including glomerular filtration rate and microalbuminuria, are common in cardiovascular disease states and predictive of cardiovascular events. Indeed, microalbuminuria may be a marker of systemic vascular disease rather than kidney dysfunction alone. In patients with hypertension, diabetes, metabolic syndrome, acute coronary syndromes, and stroke, markers of renal disease have proved to be at least as predictive of morbidity and mortality as conventional risk factors. Yet, chart reviews in a variety of clinical settings reflect poor recognition and management of renal disease in at-risk patients. Models for renal protection are based on the control of risk factors, particularly blood pressure, that are associated with renal and cardiovascular outcomes. Screening protocols for markers of renal disease should recognize the potential inaccuracy of serum creatinine concentrations and the preferability of glomerular filtration rate estimates that take age and gender into account. Pilot programs for screening high-risk populations have shown efficacy in detecting renal disease.

Is the effect of antihypertensive drugs on platelet aggregability and fibrinolysis clinically relevant?

Hypertension is associated with decreased fibrinolytic potential, mainly expressed as elevated plasma plasminogen activator inhibitor type 1 (PAI-1) levels, and increased platelet aggregability, which may account in part for the increased risk of atherosclerosis and its clinical complications in hypertensive patients. The effects of antihypertensive drugs on this prothrombotic state have been investigated and controversial findings have been reported, possibly because of differences in study designs, patients selected, and methodology used. Scarce and conflicting data exist about the effects of diuretics and beta-adrenoceptor antagonists on the fibrinolytic system, whereas ACE inhibitors have generally been reported to improve the fibrinolytic balance by decreasing plasma PAI-1 levels, calcium channel antagonists have been shown to increase tissue plasminogen activator (tPA) activity, and angiotensin II type 1 (AT(1)) receptor antagonists seem to exert neutral effects. beta-Adrenoceptor antagonists, calcium channel antagonists, and AT(1)-receptor antagonists have been reported to exert anti-aggregatory effects on platelets, while contrasting data exist about the influence of ACE inhibitors. Clinical implications of the changes induced by antihypertensive drugs on the fibrinolytic balance and platelet function are still debated. In particular, the question of whether these changes may translate into different degrees of cardiovascular protection in hypertensive patients remains unanswered. While awaiting more information from clinical trials, the choice of antihypertensive drugs, particularly in high-risk patients, should take into account effects beyond their BP-lowering efficacy. Selected agents should have a favorable, or at least neutral, impact on fibrinolytic function and platelet activity.

Interfaces between cardiovascular and kidney disease among Aboriginal Australians

Rates of kidney disease among several indigenous groups have been shown to be substantially higher than corresponding non-indigenous groups. This excess has been clearly shown among Aboriginal Australians with respect to both end-stage kidney disease and early kidney disease. Rates of cardiovascular disease among Aboriginal Australians are also very high, as are rates of diabetes, smoking, and possibly overweight and obesity. These factors have been traditionally linked with cardiovascular and renal disease as part of a broader "metabolic syndrome." However, the links and interfaces between cardiovascular and kidney disease in this environment extend beyond these "traditional" factors. The factors associated with atherosclerosis have expanded in recent years to include markers of inflammation, some infection, antioxidants, and other "non-traditional" risk factors. Given the high rates of acute infection and poor living conditions endured by many indigenous people, one might expect these "non-traditional" risk factors to be highly prevalent. In this review, we explore the relationships between markers of inflammation, some serological markers of infection, and other selected markers and both cardiovascular and renal disease. In doing so, we demonstrate links between kidney and cardiovascular disease at a number of levels, beyond the "traditional" cardiovascular/renal risk factors. Many of these factors are beyond the control of the individual or even community; addressing these issues a broader focus and biopsychosocial model.

Is there a rationale for angiotensin blockade in the management of obesity hypertension?

Obesity, currently affecting >20% of the adult population in most Western countries, is a major risk factor for the development of hypertension. Hypertension in obese patients is, in the majority of instances, further complicated by the concomitant presence of dyslipidemia and insulin resistance. The latter is reflected by derangement of glucose homeostasis, ranging from hyperinsulinemia to frank type 2 diabetes. Hypertension in obese patients is also associated with an increased risk for left ventricular hypertrophy, endothelial dysfunction, renal hyperfiltration, microalbuminuria, and elevated markers of inflammation. Sodium retention, volume expansion, and increased cardiac output are common findings in obese individuals. These changes are largely attributable to increased activity of the sympathetic nervous system and insufficient suppression of the renin-angiotensin system. Recent data show increased expression of angiotensin II-forming enzymes in adipose tissue, and increased activity of the renin-angiotensin system has recently been implicated in the development of insulin resistance and type 2 diabetes. Accordingly, antihypertensive agents that block the renin-angiotensin system might be a beneficial strategy for treatment of obesity-related hypertension. Both angiotensin-converting enzyme inhibitors and angiotensin type-1 receptor blockers have been associated with favorable metabolic properties and end-organ protection in addition to their antihypertensive effects. Data from ongoing large trials will provide an indication of the protective and preventive effects of these treatment strategies while offering insights into the mechanisms linking obesity, hypertension, and other facets of the metabolic syndrome.

Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure

The National High Blood Pressure Education Program presents the complete Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Like its predecessors, the purpose is to provide an evidence-based approach to the prevention and management of hypertension. The key messages of this report are these: in those older than age 50, systolic blood pressure (BP) of greater than 140 mm Hg is a more important cardiovascular disease (CVD) risk factor than diastolic BP; beginning at 115/75 mm Hg, CVD risk doubles for each increment of 20/10 mm Hg; those who are normotensive at 55 years of age will have a 90% lifetime risk of developing hypertension; prehypertensive individuals (systolic BP 120-139 mm Hg or diastolic BP 80-89 mm Hg) require health-promoting lifestyle modifications to prevent the progressive rise in blood pressure and CVD; for uncomplicated hypertension, thiazide diuretic should be used in drug treatment for most, either alone or combined with drugs from other classes; this report delineates specific high-risk conditions that are compelling indications for the use of other antihypertensive drug classes (angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, calcium channel blockers); two or more antihypertensive medications will be required to achieve goal BP (<140/90 mm Hg, or <130/80 mm Hg) for patients with diabetes and chronic kidney disease; for patients whose BP is more than 20 mm Hg above the systolic BP goal or more than 10 mm Hg above the diastolic BP goal, initiation of therapy using two agents, one of which usually will be a thiazide diuretic, should be considered; regardless of therapy or care, hypertension will be controlled only if patients are motivated to stay on their treatment plan. Positive experiences, trust in the clinician, and empathy improve patient motivation and satisfaction. This report serves as a guide, and the committee continues to recognize that the responsible physician's judgment remains paramount.