Atherosclerotic risk factors are increased in clinically healthy subjects with microalbuminuria

Cardiac risk assessment for end-stage renal disease patients on the renal transplant waiting list

Cardiovascular disease is a leading cause of morbidity and mortality and is becoming more prevalent as the population ages and risk factors increase. This is most apparent in the end-stage renal disease (ESRD) patient population. In part, this is due to cofactors such as diabetes and hypertension commonly predisposing to progressive renal disease, as well as being a direct consequence of having renal failure. Of all major organ failures, kidney failure is the most likely to be managed chronically using renal replacement therapy and, ultimately, transplant. However, lack of transplant organs and a large renal failure cohort means waiting lists are often quite long and may extend to 5-10 years. Due to the cardiac risk factors inherent in patients awaiting transplant, many succumb to cardiac issues while waiting and present an increased per-procedural cardiac risk that extends into the post-transplant period. We aim to review the epidemiology of coronary artery disease in this population and the etiology as it relates to ESRD and its associated co-factors. We also will review the current approaches, recommendations and evidence for management of these patients as it relates to transplant waiting lists before and after the surgery. Recommendations on how to best manage patients in this cohort revolve around the available evidence and are best customized to the institution and the structure of the program. It is not clear whether the revascularization of patients without symptoms and with a good functional status yields any improvement in outcomes. Therefore, each individual case should be considered based on the risk factors, symptoms and functional status, and approached as part of a multi-disciplinary assessment program.

Stepped-wedge cluster-randomised controlled trial to assess the cardiovascular health effects of a managed aquifer recharge initiative to reduce drinking water salinity in southwest coastal Bangladesh: study design and rationale

INTRODUCTION

Saltwater intrusion and salinisation have contributed to drinking water scarcity in many coastal regions globally, leading to dependence on alternative sources for water supply. In southwest coastal Bangladesh, communities have few options but to drink brackish groundwater which has been associated with high blood pressure among the adult population, and pre-eclampsia and gestational hypertension among pregnant women. Managed aquifer recharge (MAR), the purposeful recharge of surface water or rainwater to aquifers to bring hydrological equilibrium, is a potential solution for salinity problem in southwest coastal Bangladesh by creating a freshwater lens within the brackish aquifer. Our study aims to evaluate whether consumption of MAR water improves human health, particularly by reducing blood pressure among communities in coastal Bangladesh.

METHODS AND ANALYSIS

The study employs a stepped-wedge cluster-randomised controlled community trial design in 16 communities over five monthly visits. During each visit, we will collect data on participants' source of drinking and cooking water and measure the salinity level and electrical conductivity of household stored water. At each visit, we will also measure the blood pressure of participants ≥20 years of age and pregnant women and collect urine samples for urinary sodium and protein measurements. We will use generalised linear mixed models to determine the association of access to MAR water on blood pressure of the participants.

ETHICS AND DISSEMINATION

The study protocol has been reviewed and approved by the Institutional Review Boards of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b). Informed written consent will be taken from all the participants. This study is funded by Wellcome Trust, UK. The study findings will be disseminated to the government partners, at research conferences and in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02746003; Pre-results.

The metabolic syndrome: an emerging risk state for cardiovascular disease

The common clustering of glucose intolerance, insulin resistance, abdominal adiposity, elevated blood pressure, and low HDL cholesterol is referred to as metabolic syndrome. Individuals with this syndrome have an increased risk of developing cardiovascular disease (CVD). The World Health Organisation and the National Cholesterol Education Programme’s Adult Treatment Panel III (NCEP-ATP III) have outlined specific diagnostic criteria for the diagnosis of the metabolic syndrome to help in the Identification of this syndrome in clinical practice. While the WHO criteria were specifically developed for use in research, the NCEP criteria are useful in clinical diagnosis of the metabolic syndrome. The metabolic syndrome is amenable to lifestyle modifications such as increased physical activity, weight loss, and possibly intake of low-glycemic foods. Drug therapy may be used to treat individual components of the syndrome such as elevated blood pressure and dyslipidemia. To control elevated glucose levels (when there is failure of lifestyle modification), medications such as metformin, thiazolidinedione derivatives and alpha glucosidase inhibitors may be used.

The Cardiometabolic Syndrome as a Cardiovascular Risk Factor

The cardiometabolic syndrome (CMS) is associated with cardiovascular disease (CVD) and includes a constellation of risk factors such as central obesity, hypertension, insulin resistance, dyslipidemia, microalbuminuria, and hypercoagulability. Collectively, these risk factors increase CVD endpoints such as stroke, congestive heart failure, chronic kidney disease (CKD), and overall mortality. The CMS is associated with endothelial dysfunction, inflammation, abnormal thrombolysis, and increased oxidative stress that accentuate progression of CVD. We will review how the varying components of the CMS relate to an increased CVD and renal disease risk.

The metabolic syndrome defined by factor analysis and incident type 2 diabetes in a chinese population with high postprandial glucose

OBJECTIVE

The aim of this study was to examine how the major components of the metabolic syndrome relate to each other and to the development of diabetes using factor analysis.

RESEARCH DESIGN AND METHODS

The screening survey for type 2 diabetes was conducted in 1994, and a follow-up study of nondiabetic individuals at baseline was carried out in 1999 in the Beijing area. Among 934 nondiabetic and 305 diabetic subjects at baseline, factor analysis was performed using the principle components analysis with varimax orthogonal rotation of continuously distributed variables considered to represent the components of the metabolic syndrome. Fasting insulin was used as a marker for insulin resistance. Of the 559 subjects without diabetes at baseline, 129 developed diabetes during the 5-year follow-up. Factors identified at baseline were used as independent variables in univariate and multivariate logistic regression models to determine risk factor clusters predicting the development of diabetes.

RESULTS

Four factors were identified in nondiabetic and diabetic subjects. Fasting insulin levels, BMI, and waist-to-hip ratio were associated with one factor. Systolic and diastolic blood pressures were associated with the second factor. Two-hour postload plasma glucose (2-h PG) and serum insulin and fasting plasma glucose were associated with the third factor. Serum total cholesterol and triglycerides were associated with the fourth factor. The first and the third factors predicted the development of diabetes. In diabetic patients at baseline, the combination of systolic and diastolic blood pressure was the most important factor, and urinary albumin excretion rate clustered with fasting and 2-h PG levels.

CONCLUSIONS

Insulin resistance alone does not underlie all features of the metabolic syndrome. Different physiological processes associated with various components of the metabolic syndrome contain unique information about diabetes risk. Microalbunuria is more likely to be a complication of type 2 diabetes or hypertension than a marker for the metabolic syndrome.

Albuminuria predicts cardiovascular events independently of left ventricular mass in hypertension: a LIFE substudy

We wanted to investigate whether urine albumin/creatinine ratio (UACR) and left ventricular (LV) mass, both being associated with diabetes and increased blood pressure, predicted cardiovascular events in patients with hypertension independently. After 2 weeks of placebo treatment, clinical, laboratory and echocardiographic variables were assessed in 960 hypertensive patients from the LIFE Echo substudy with electrocardiographic LV hypertrophy. Morning urine albumin and creatinine were measured to calculate UACR. The patients were followed for 60+/-4 months and the composite end point (CEP) of cardiovascular (CV) death, nonfatal stroke or nonfatal myocardial infarction was recorded. The incidence of CEP increased with increasing LV mass (below the lower quartile of 194 g to above the upper quartile of 263 g) in patients with UACR below (6.7, 5.0, 9.1%) and above the median value of 1.406 mg/mmol (9.7, 17.0, 19.0%(***)). Also the incidence of CV death increased with LV mass in patients with UACR below (0, 1.4, 1.3%) and above 1.406 mg/mmol (2.2, 6.4, 8.0%(**)). The incidence of CEP was predicted by logUACR (hazard ratio (HR)=1.44(**) for every 10-fold increase in UACR) after adjustment for Framingham risk score (HR=1.05(***)), history of peripheral vascular disease (HR=2.3(*)) and cerebrovascular disease (HR=2.1(*)). LV mass did not enter the model. LogUACR predicted CV death (HR=2.4(**)) independently of LV mass (HR=1.01(*) per gram) after adjustment for Framingham risk score (HR=1.05(*)), history of diabetes mellitus (HR=2.4(*)) and cerebrovascular disease (HR=3.2(*)). (*)P<0.05, (**)P<0.01, (***)P<0.001. In conclusion, UACR predicted CEP and CV death independently of LV mass. CV death was predicted by UACR and LV mass in an additive manner after adjustment for Framingham risk score and history of CV disease.

Update on the cardiometabolic syndrome

An array of metabolic, hemodynamic, and renal abnormalities constitutes the cardiometabolic syndrome. A hallmark of this syndrome is visceral obesity and associated insulin resistance/hyperinsulinemia. The syndrome is also associated with essential hypertension, abnormalities in the circadian rhythm of blood pressure and heart rate, the diabetic dyslipidemic syndrome, hypercoagulability, hyperuricemia, increased cardiovascular inflammation, and microalbuminuria, all of which contribute to an increased risk of cardiovascular disease morbidity and mortality. This article reviews current knowledge about the interrelationship of the various factors that make up the cardiometabolic syndrome and its implications for individuals with and without diabetes mellitus.

Microalbuminuria, cardiovascular disease and risk factors in a nondiabetic/nonhypertensive population. The Nord-Trøndelag Health Study (HUNT, 1995-97), Norway

OBJECTIVE

Microalbuminuria (MA) as an independent marker of cardiovascular morbidity and mortality in nondiabetic/nonhypertensive individuals is under international debate. The aim of this study was to investigate the associations between MA and known cardiovascular risk factors/markers and disease in a randomly selected nondiabetic/nonhypertensive sample.

DESIGN

Cross-sectional study.

SETTING

Participants in the population-based Nord-Trøndelag Health Study (HUNT), Norway (n = 65 258).

SUBJECTS

A total of 2113 individuals (> or =20 years), randomly selected without diabetes and treated hypertension, delivered three morning urine samples for MA analysis.

MAIN OUTCOME MEASURES

MA expressed as albumin-to-creatinine ratio (ACR), cardiovascular risk factors and disease.

RESULTS

Increasing age, pulse pressure, systolic (SBP) and diastolic blood pressure (DBP) and coronary heart disease (CHD) significantly predicted MA in men and increasing pulse pressure, SBP and DBP were associated with MA in women, adjusted for other cardiovascular risk factors/markers. After excluding individuals with known CHD and untreated hypertension (SBP > or = 140 mmHg, DBP > or = 90 mmHg) and hence a high total risk of cardiovascular disease (CVD), only increasing age was associated with ACR in men and increasing SBP and pulse pressure in women. Smoking, elevated lipid and glucose levels were strongly associated with MA in individuals with a high total risk of CVD than in individuals with a low total risk.

CONCLUSION

MA was associated with increasing blood pressure in both genders, age and CHD in men. Other cardiovascular risk factors/markers might be more influential in predicting ACR variation in nondiabetic/nonhypertensive individuals with a high total risk of CVD than in individuals with a low total risk.

Microalbuminuria in diabetes: focus on cardiovascular and renal risk reduction

Albuminuria has long been recognized as a harbinger for the progression of diabetic nephropathy. Recently, it has become increasingly recognized that albuminuria is a powerful risk factor for cardiovascular disease and stroke. In this article we explore evidence for albuminuria being an integral component of the cardiometabolic syndrome and a risk factor for cardiovascular disease and stroke.

Use of the albumin/creatinine ratio to detect microalbuminuria: implications of sex and race

The recommended albumin (microg)/creatinine (mg) ratio (ACR) (30 microg/mg) to detect microalbuminuria does not account for sex or racial differences in creatinine excretion. In a nationally representative sample of subjects, the distribution of urine albumin and creatinine concentrations was examined by using one ACR value (> or =30 microg/mg) and sex-specific cutpoints (> or =17 microg/mg in men and > or =25 microg/mg in women) measured in spot urine specimens. Mean urine albumin concentrations were not significantly different between men and women, but urine creatinine concentrations were significantly higher (P < 0.0001). Compared with non-Hispanic whites, urine creatinine concentrations were significantly higher in non-Hispanic blacks (NHB) and Mexican Americans, whereas urine albumin concentrations were significantly higher in NHB (P < 0.0001) but not Mexican Americans. When a single ACR is used, the prevalence of microalbuminuria was significantly lower among the men compared with women (6.0 versus 9.2%; P < 0.0001) and among non-Hispanic whites compared with NHB (7.2 versus 10.2%; P < 0.0001). No significant difference in the prevalence of microalbuminuria between men and women was noted when sex-specific ACR cutpoints were used. In the multivariate adjusted model, female sex (odds ratio, 1.62; 95% confidence interval, 1.29 to 2.05) and NHB race/ethnicity (odds ratio, 1.34; 95% confidence interval, 1.12 to 1.61) were independently associated with microalbuminuria when a single ACR threshold was used. When a sex-specific ACR was used, NHB race/ethnicity remained significantly associated with microalbuminuria but sex did not. The use of one ACR value to define microalbuminuria may underestimate microalbuminuria in subjects with higher muscle mass (men) and possibly members of certain racial/ethnic groups.

Mechanisms in the development of type 2 diabetes mellitus

The leading cause of death among patients with type 2 diabetes mellitus (DM) is cardiovascular disease, with 75% of these deaths attributed to coronary heart disease. Over the previous two decades the pathophysiological basis of type 2 DM has been extensively investigated. Although many of the underlying molecular mechanisms involved in the development of this disorder remain to be explained, it is clear that type 2 DM is a complex medical disorder characterized by insulin resistance and defects in insulin secretion. The process through which the metabolic derangements of type 2 DM accelerate the development of cardiovascular disease in type 2 DM has yet to be determined and remains an area of intense investigation, focusing on hyperglycemia and insulin resistance as major underlying contributors. This article explores current information related to the pathophysiology of type 2 DM alone and its relationship to the development to cardiovascular disease.

Proteinuria after renal transplantation affects not only graft survival but also patient survival

BACKGROUND

Proteinuria is associated with an increased risk of renal failure. Moreover, proteinuria is associated with an increased death risk in patients with diabetes mellitus or hypertension and even in the general population.

METHODS

One year after renal transplantation, we studied the influence of the presence of proteinuria on the risk of either graft failure or death in all 722 recipients of a kidney graft in our center who survived at least 1 year with a functioning graft. Proteinuria was analyzed both as a categorical variable (presence versus absence) and as a continuous variable (quantification of 24 hr urine). Other variables included in this analysis were: donor/recipient age and gender, original disease, race, number of HLA-A and HLA-B mismatches, previous transplants, postmortal or living related transplantation, and transplantation year. At 1 year after transplantation, we included: proteinuria, serum cholesterol, serum creatinine, blood pressure, and the use of antihypertensive medication.

RESULTS

In the Cox proportional hazards analysis, proteinuria at 1 year after transplantation (both as a categorical and continuous variable) was an important and independent variable influencing all endpoints. The influence of proteinuria as a categorical variable on graft failure censored for death showed no interaction with any of the other variables. There was an adverse effect of the presence of proteinuria on the graft failure rate (RR=2.03). The influence of proteinuria as a continuous variable showed interaction with original disease. The presence of glomerulonephritis, hypertension, and systemic diseases as the original disease significantly increased the risk of graft failure with an increasing amount of proteinuria at 1 year. The influence of proteinuria as a categorical variable on the rate ratio for patient failure was significant, and there was no interaction with any of the other significant variables (RR=1.98). The death risk was almost twice as high for patients with proteinuria at 1 year compared with patients without proteinuria. The influence of proteinuria as a continuous variable was also significant and also without interaction with other variables. The death risk increased with increasing amounts of proteinuria at 1 year. Both the risks for cardiovascular and for noncardiovascular death were increased.

CONCLUSION

Proteinuria after renal transplantation increases both the risk for graft failure and the risk for death.

Urinary albumin excretion in lean, overweight and obese glucose tolerant individuals: its relationship with dyslipidaemia, hyperinsulinaemia and blood pressure

The presence of microalbuminuria has become an important tool for therapeutic intervention. In this study we investigated whether the dysmetabolic syndrome of obesity was associated with or could occur in the absence of microalbuminuria. The study was conducted in 71 clinically healthy, glucose tolerant Hispanics (age: 43 +/- 1.4 years, body mass index (BMI): 28.7 +/- 0.6 kg/m(2), systolic blood pressure (SBP): 117 +/- 2 mm Hg, diastolic blood pressure (DBP): 77 +/- 1.3 mm Hg, urinary albumin excretion: 10.2 +/- 0.6 mg/24 h). Subjects were classified as lean (BMI <25), overweight (BMI >25 <30) and obese (BMI >30 kg/m(2)). Greater BMI was associated with higher body weight, waist-to-hip ratio (WHR), BP, fasting insulin, triglyceride, post glucose load insulin and glucose, and lower high-density lipoprotein (HDL) cholesterol levels. However, no significant differences in the urinary albumin excretion (mg/24 h) were found between lean (9.0 +/- 0.9; median: 9.1), overweight (11.3 +/- 1.2; median: 10.5) and obese (11.1 +/- 1.2; median: 9.7) subjects. In addition, microalbuminuria (urinary albumin excretion >30 mg/24 h) was not found in any of the study subjects. For all subjects combined, as well as for each of the groups separately, the urinary albumin excretion was unrelated to the BMI, WHR, body weight, triglyceride, cholesterol (total, LDL or HDL), fasting or post-load glucose and insulin plasma concentrations. Neither in females nor in males, abdominal fat accumulation was associated with an increase in the urinary albumin excretion. However, in the obese groups, urinary albumin excretion was strongly related to the level of SBP (r(2): 0.67; P < 0.0001) and DBP (r(2): 0.55; P < 0.0001). In summary, obesity, hyperinsulinaemia and dyslipidaemia per se are not determinants of increased albumin excretion. However, in the obese subjects, the BP, particularly the SBP, was a strong determinant of the level of albumin in the urine. Microalbuminuria may occur later in the course of the dysmetabolic syndrome, due to worsening of hypertension and development of hyperglycaemia.

Microalbuminuria is associated with the insulin resistance syndrome independent of hypertension and type 2 diabetes in the Korean population

To investigate whether microalbuminuria is associated with the insulin resistance syndrome independent of hypertension and type 2 diabetes, we studied the association between microalbuminuria and features of insulin resistance syndrome in Korean general population. We selected 1006 subjects by a random cluster sampling among residents aged >40 years living in the Chung-Up district, a rural area of South Korea. Subjects were stratified by oral glucose tolerance status [normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetes mellitus], and by the presence or absence of hypertension. Urinary albumin excretion rate (UAER) was determined using timed overnight urine collection. Various cardiovascular risk factors including anthropometric indices, serum lipid, true insulin and proinsulin concentrations were also measured. The prevalence of microalbuminuria (UAER between 20 and 200 microg/min) increased as the glucose tolerance worsened (6.0% in NGT, 11.8% in IGT, and 21.8% in diabetes; chi(2) trend=25.9, P<0.001). Subjects with microalbuminuria had a higher body mass index (BMI), waist-to-hip circumference ratio (WHR), systolic and diastolic blood pressure (BP), fasting and 2 h plasma glucose, fasting plasma insulin and proinsulin levels, and lower HDL-cholesterol level than subjects without microalbuminuria. In multiple regression analysis, BMI, diastolic BP, 2 h plasma glucose, and fasting plasma insulin levels were found to be independent factors associated with UAER. Multiple logistic regression analysis showed that not only diabetes mellitus and hypertension, but also fasting hyperinsulinemia and waist-to-hip ratio were independent factors associated with the presence of microalbuminuria. When the normotensive, non-diabetic subjects were analyzed separately, fasting hyperinsulinemia and impaired glucose tolerance remained independent variables associated with the presence of microalbuminuria. These results show that microalbuminuria in the Korean general population is associated with hyperinsulinemia and central obesity, and suggest that microalbuminuria is a feature of the insulin resistance syndrome independent of hypertension or type 2 diabetes.

Elevated urinary albumin excretion is associated with impaired arterial dilatory capacity in clinically healthy subjects

BACKGROUND

Elevated urinary albumin excretion (UAE) predicts atherosclerotic cardiovascular disease. It is hypothesized that elevated UAE is associated with a generalized vascular dysfunction. This study tested this hypothesis for conduit arteries.

METHODS AND RESULTS

Clinically healthy subjects were selected: 19 with UAE >90th percentile in the background population (6.6 microgram/min<UAE<150 microgram/min) and 41 with normoalbuminuria (UAE <6.6 microgram/min). External ultrasound was used to measure the dilatory response of the brachial artery to postischemic increased blood flow (endothelium-dependent, flow-associated dilation) and to nitroglycerin (endothelium-independent, nitroglycerin-induced dilation). Plasma concentrations of the endothelial markers nitrate/nitrite, thrombomodulin, and von Willebrand factor antigen were also measured. Both flow-associated and nitroglycerin-induced dilations were significantly impaired in subjects with elevated UAE as compared with normoalbuminuric control subjects: 102.0+/-1.0% (mean+/-SEM) versus 104.3+/-0.6% (P<0.05) and 120.1+/-1.5% versus 123.8+/-1.0% (P<0.05). No differences in the plasma concentrations of endothelial markers were found. Conclusions-Slightly elevated UAE is associated with impaired conduit arterial dilatory capacity in clinically healthy subjects, and this impairment may be explained by a reduced dilatory response to nitric oxide of both endogenous and exogenous origin. Impaired arterial dilatory capacity may contribute to the increased cardiovascular risk in subjects with elevated UAE.

Elevated urinary albumin excretion is not linked to the angiotensin I-converting enzyme gene polymorphism in clinically healthy subjects

An elevated urinary albumin excretion (UAE) in non-diabetic subjects without renal or cardiovascular disease has been shown to be predictive of ischaemic heart disease. An insertion (I)/deletion (D) polymorphism in the angiotensin I-converting enzyme (ACE) gene has been identified and the D allele may be associated with cardiovascular disease. The aim of this study was to find a potential linkage between this polymorphism and elevated UAE. For studies of UAE and cardiovascular pathophysiology, a highly selected population sample has been identified comprising all clinically healthy subjects aged 40-65 years with elevated UAE in a dipstick negative urinary sample (n = 27) from The Copenhagen City Heart Study. Neither the ACE genotype distribution (p = 0.12) nor the D and I allele frequencies (p = 0.69) differed significantly between subjects with elevated UAE and a matched normoalbuminuric control group (n = 46). Elevated UAE in clinically healthy subjects is not linked to the ACE gene polymorphism.

Microalbuminuria and markers of the atherosclerotic process: the D.E. S.I.R. study

The relationship between microalbuminuria and tissue-type plasminogen activator antigen (tPA-ag) and fibrinogen was evaluated in non-diabetic subjects. Subjects were participants of the D.E.S.I. R. (Data from an Epidemiological Study on the Insulin Resistance syndrome) Study. Analyses were carried out on 2248 women and 2402 men for fibrinogen and on 272 women and 284 men for tPA-ag. Microalbuminuria was defined as urinary albumin concentration greater than 20 mg/l. Men with microalbuminuria had a 6% higher fibrinogen concentration than those without (3.07 g/l (95% confidence interval: 2.99,3.15) vs. 2.89 g/l (2.87,2.91), adjusted for age and smoking). This relationship existed in hypertensive as well as non-hypertensive subjects. The association between microalbuminuria and tPA-ag existed only in hypertensive men, those with microalbuminuria having a 21% higher tPA-ag than those without (4.39 ng/ml (3.70,5.08) vs. 3.63 ng/ml (3.32,3.94), adjusted for age and smoking). Adjustment for other risk markers for cardiovascular disease did not change the results. There was no relationship between microalbuminuria and these haemostatic factors in women. The results of this study suggest that in non-diabetic men, microalbuminuria is associated with fibrinogen, but with tPA-ag only when concomitant with hypertension.

Plasma concentrations of endothelial vasoactive substances in clinically healthy subjects. associations with urinary albumin excretion and ambulatory blood pressure

Elevated urinary albumin excretion (UAE) is a predictor of cardiovascular disease, and one possible explanation is that elevated UAE reflects a generalized vascular dysfunction. The present study tests whether the plasma concentrations of the two main endothelial vasoactive substances (nitric oxide and endothelin-1 [ET-1]) are changed in clinically healthy subjects with elevated UAE (>6.6 microg/ min-the 90th percentile in the background population) and to test associations between these concentrations and systemic blood pressure. Twenty-seven subjects with elevated UAE were compared with 46 matched controls with normoalbuminuria. Plasma concentration of ET-1 was measured using an ELISA method and plasma concentration of nitrate/nitrite using a photometric method. Twenty-four-hour blood pressure was measured using a portable recorder (TM-2421). No significant differences in the concentrations of nitrate/nitrite and ET-1 were found between the groups, e.g. 21 (10-105) vs. 18 (11 -152) (p=0.33) and 0.98 (0.58 1.95) vs. 1.10 (0.54 -1.50) (p = 0.27), respectively. However, plasma nitrate/nitrite was significantly positively correlated to systolic and diastolic blood pressure in subjects with normoalbuminuria but not in subjects with elevated UAE. In contrast, plasma ET-1 concentration was significantly positively correlated to systolic blood pressure only in subjects with elevated UAE. In conclusion, elevated UAE is not associated with changed plasma concentrations of endothelial vasoactive substances in clinically healthy subjects. However, nitrate/nitrite is positively correlated to BP only in subjects with normoalbuminuria, and ET-1 is positively correlated to BP only in subjects with elevated UAE.

Arterial hypertension, microalbuminuria, and risk of ischemic heart disease

Albumin excretion in urine is positively correlated with the presence of ischemic heart disease and atherosclerotic risk factors. We studied prospectively whether a slight increase of urinary albumin excretion, ie, microalbuminuria, adds to the increased risk of ischemic heart disease among hypertensive subjects. In 1983 and 1984, blood pressure, urinary albumin/creatinine concentration ratio, plasma total and HDL cholesterol levels, body mass index, and smoking status were obtained in a population-based sample of 2085 subjects, aged 30 to 60 years, who were free from ischemic heart disease, diabetes mellitus, and renal or urinary tract disease. Untreated arterial hypertension or borderline hypertension was present in 204 subjects, who were followed until 1993 by the National Hospital and Death Certificate Registers with respect to development of ischemic heart disease. During 1978 person-years, 18 (9%) of the hypertensive subjects developed ischemic heart disease. Microalbuminuria, defined as a urinary albumin/creatinine ratio above the upper decile (1.07 mg/mmol), was the strongest predictor of ischemic heart disease, with an unadjusted relative risk of 4.2 (95% CI 1.5 to 11.9, P=0.006) and a relative risk of 3.5 (95% CI 1.0 to 12.1, P=0.05) when adjusted for all other atherosclerotic risk factors, including age and gender. In conclusion, microalbuminuria confers a 4-fold increased risk of ischemic heart disease among hypertensive or borderline hypertensive subjects. Urinary albumin excretion should be measured regularly in a hypertension clinic, and a rigorous control of blood pressure and of other atherosclerotic risk factors is recommended in hypertensive patients with microalbuminuria.

Microalbuminuria in essential hypertension: significance, pathophysiology, and therapeutic implications

Some patients with essential hypertension manifest greater than normal urinary albumin excretion (UAE). The significance of this association, which is the object of this review, is not well established. Hypertensive patients with microalbuminuria manifest greater levels of blood pressure, particularly at night, and higher serum levels of cholesterol, triglycerides, and uric acid than patients with normal UAE. Levels of high-density lipoprotein cholesterol, on the other hand, were lower in patients with microalbuminuria than in those with normal UAE. Patients with microalbuminuria manifested greater incidence of insulin resistance and thicker carotid arteries than patients with normal UAE. After a follow-up of 7 years, we observed that 12 cardiovascular events occurred among 54 (21.3%) patients with microalbuminuria and only two such events among 87 patients with normal UAE (P < 0.0002). Stepwise logistic regression analysis showed that UAE, cholesterol level, and diastolic blood pressure were independent predictors of the cardiovascular outcome. Rate of creatinine clearance from patients with microalbuminuria decreased more than that from those with normal UAE. In conclusion, these studies suggest that hypertensive individuals with microalbuminuria manifest a variety of biochemical and hormonal derangements with pathogenic potential, which results in hypertensive patients having a greater incidence of cardiovascular events and a greater decline in renal function than patients with normal UAE.

Urinary albumin excretion. An independent predictor of ischemic heart disease

Cross-sectional studies suggest that an increased urinary albumin excretion rate is associated with cardiovascular disease, dyslipidemia, and hypertension. The purpose of this study was to analyze prospectively whether the urinary albumin-to -creatinine (A/C) ratio can independently predict ischemic heart disease (IHD) in a population-based cohort. In 1983, urinary albumin and creatinine levels were measured, along with the conventional atherosclerotic risk factors, in 2085 consecutive participants without IHD, renal disease, urinary tract infection, or diabetes mellitus. The participants were followed up until death, emigration, or December 31, 1993. IHD was defined as a hospital discharge diagnosis or cause of death including the diagnoses ICD-8 and 410 to 414. Seventy-nine individuals developed IHD during the 21 130 person-years of follow-up. They were characterized by a preponderance of males and higher age, body mass index, blood pressure, lipoproteins, and proportion of current smokers. Microalbuminuria was defined as an A/C ratio) >90 percentile (>0.65 mg/mmol). When adjusted for other risk factors, the relative risk of IHD associated with microalbuminuria was 2.3 (95% CI, 1.3 to 3.9, P=0.002), and the 10-year disease-free survival decreased from 97% to 91% (P<0.0001) when microalbuminuria was present. An interaction between microalbuminuria and smoking was observed, and the presence of microalbuminuria more than doubled the predictive effect of the conventional atherosclerotic risk factors for development of IHD. It is concluded that microalbuminuria is not only an independent predictor of IHD but also substantially increases the risk associated with other established risk factors.

Prevalence of positive urinary dipstick analysis (leucocyte esterase, nitrite, haemoglobin, or glucose) in a population of 3645 adult subjects--consequence for measurement of urinary albumin excretion rate

OBJECTIVES

To assess prevalence of positive urinary dipstick analysis for leucocyte esterase, nitrite, haemoglobin, or glucose in the general population and measure the urinary albumin excretion rate (UAER) in subjects with or without a positive dipstick analysis.

DESIGN

A cross-sectional study of 3645 subjects.

SETTING

An unselected urban population study.

MAIN OUTCOME MEASURES

Prevalence data of positive dipstick analyses and UAER values.

RESULTS

Prevalence data of a positive dipstick analysis were 12%, 4%, 3% and 6%, respectively, for leucocyte esterase, nitrite, haemoglobin, and glucose. Subjects with any positive dipstick analysis had significantly higher UAER than subjects with a negative analysis: 4.9 (4.4-5.3) (geometric mean (95% confidence interval)) vs 3.0 (2.9-3.1) mg 24 h(-1) (p < 0.001).

CONCLUSIONS

Prevalence data of positive urinary dipstick analyses in a large population based study are provided. Subjects with any positive finding had higher UAER than controls. Exclusion of subjects with a positive finding is recommended in studies of UAER as a cardiovascular risk factor in non-diabetic subjects.

Urinary albumin excretion in hospitalized patients with acute myocardial infarction. Prevalence of microalbuminuria and correlation to left ventricle wall thickness

Microalbuminuria, a subclinical rise in the urinary albumin excretion, is a risk indicator of atherosclerotic cardiovascular disease. The aim of this study was to measure the urinary albumin excretion in patients with acute myocardial infarction, and to correlate this with known atherosclerotic risk factors. One-hundred-and-twenty-six patients and 56 healthy controls matched for age and sex were studied. The albumin/creatinine concentration ratio in morning urine specimens was calculated as an index of the albumin excretion. Microalbuminuria was defined as a urinary albumin/creatinine concentration ratio above 1 mg/mmol. Urinary albumin excretion (0.88 [95% confidence interval 0.69-1.11] versus 0.51 [0.40-0.63] mg/mmol; p = 0.001) and frequency of microalbuminuria (33 [95% confidence interval 25-41] versus 16 [9-23]%; p = 0.03) were higher in patients than controls. This difference was independent of blood pressure, body weight, smoking, diabetes mellitus, renal disease, and thrombolytic treatment. There was a positive correlation between urinary albumin excretion and thickness of the left ventricle wall (R = 0.28; p = 0.001) which was independent of blood pressure. Follow-up examination of the patients will reveal whether microalbuminuria increases the risk for recurrence of acute myocardial infarction.

Ambulatory blood pressure and urinary albumin excretion in clinically healthy subjects

A slightly elevated urinary albumin excretion rate (UAER) is a predictor of atherosclerotic cardiovascular disease. The mechanism is unknown, but moderate office blood pressure elevation has been demonstrated as part of a clustering of known atherosclerotic risk factors in subjects with elevated UAER. Because 24-hour ambulatory blood pressure is a superior predictor of hypertensive target organ involvement, we aimed to investigate blood pressure profile in clinically healthy subjects with elevated UAER. Ambulatory blood pressure monitoring was performed with a portable recorder in 27 subjects with an elevated UAER (>6.6 microg/min, overnight urine collection) and 46 normoalbuminuric control subjects. Mean+/-SD systolic and diastolic ambulatory blood pressures (24-hour) were significantly higher in subjects with elevated UAER than in normoalbuminuric controls (134+/-12 versus 128+/-11 mm Hg and 78+/-7 versus 75+/-6 mm Hg, P<0.05), as were systolic and diastolic blood pressure loads [median (range): 42% (6 to 94%) versus 23% (1 to 89%) and 20% (0 to 68%) versus 6% (0 to 62%), P<0.05]. The circadian variation of blood pressure was normal in subjects with elevated UAER. However, the increased urinary loss of albumin could not be solely related to the higher blood pressure. In conclusion, apparently healthy subjects with elevated UAER had slightly but significantly higher 24-hour systolic and diastolic blood pressure levels in addition to increased blood pressure loads but normal circadian variation. The demonstrated differences in blood pressure may offer a partial explanation for the association between elevated urinary albumin excretion and atherosclerotic cardiovascular risk.

Predictors of renal and cardiovascular mortality in patients with non-insulin-dependent diabetes: a brief overview of microalbuminuria and insulin resistance

Both microalbuminuria and insulin resistance are present at some stage in the natural history of non-insulin-dependent diabetes mellitus (NIDDM). Microalbuminuria predicts both progression to endstage renal disease and an increase in cardiovascular mortality compared to diabetic patients without microalbuminuria. Conversely, microalbuminuria is not a strong predictor of either renal or cardiovascular mortality in hypertensive nondiabetic subjects. This difference in risk may relate to the presence of glycated albumin in patients with diabetes. Glycation of albumin occurs because of persistent hyperglycemia. Glycated albumin is directly toxic to both renal and vascular tissue through stimulation of reactive oxygen species by both renal and immune protective cells. Blunting the rise in microalbuminuria with either aggressive blood glucose control or angiotensin-converting enzyme (ACE) inhibition, early in the course of the disease, markedly reduces renal mortality. In contrast to microalbuminuria, which is a reflection of renal injury, insulin resistance is a genetically determined problem that directly relates to peripheral glucose utilization. In most cases, insulin resistance is phenotypically expressed as diabetes as a result of environmental factors such as obesity. Insulin resistance is associated with an increased risk for development of both hypertension and NIDDM as well as atherosclerosis. Diabetic or hypertensive subjects with insulin resistance have an increased risk of cardiovascular but not renal mortality. Sustained weight loss is the best way to reduce insulin resistance and arterial pressure. Additionally, alpha blockers, more than other antihypertensive agents reduce insulin resistance. This class of drugs, however, has not been shown to reduce either microalbuminuria or overall cardio-renal mortality.

Evidence of impaired glomerular charge selectivity in nondiabetic subjects with microalbuminuria: relevance to cardiovascular disease

Microalbuminuria is associated with excess cardiovascular morbidity and mortality in diabetic and nondiabetic subjects. Loss of glomerular charge selectivity may explain the development of microalbuminuria in diabetic subjects. The primary population in this cross-sectional study was 124 subjects aged 40 to 75 years without glucose intolerance and with a previous (3 years before the present study) urinary albumin excretion rate (UAE) in the normal (<20 microgram/min) or microalbuminuric (>20 microgram/min) range. The secondary population consisted of 39 offspring aged 15 to 40 years. The main outcome measures included UAE, urinary IgG/IgG4 selectivity index (SI), and the presence of ischemic heart disease as determined by questionnaire or ECG. Among the primary population, a significant inverse correlation was found between SI and UAE (r=-.40, P<.001). Reduction in SI could be demonstrated in subjects with UAE >10 microgram/min. In multiple regression analysis reduction in SI was found with increasing age, independent of UAE. In 20 subjects with clinical cardiovascular disease a reduction in SI was found (1.9+/-0.6 versus 2.6+/-1.3, P=.001) without concomitant elevation in UAE (P=.99). Offspring from parents with microalbuminuria had an SI comparable to offspring from parents with normal UAE (2.7+/-0.7 versus 3.3+/-1.6, P=.17). In nondiabetic subjects the development of microalbuminuria is associated with reduced SI, suggesting impairment of glomerular charge selectivity. SI may offer a more sensitive monitoring of abnormalities in glomerular permselectivity than does measurements of UAE, but the ability of SI to predict development of cardiovascular disease needs to be evaluated prospectively.

Insulin sensitivity in clinically healthy individuals with microalbuminuria

In epidemiologic studies microalbuminuria is associated with increased atherosclerotic risk profile, morbidity, and mortality. In order to examine whether such association could be explained by impaired insulin sensitivity, 23 clinically healthy subjects with microalbuminuria (urinary albumin excretion rate (UAER) of 6.6 to 150 micrograms/min) and 24 age- and sex-matched controls with normoalbuminuria (UAER < or = 6.6 micrograms/min) underwent a 3 h hyperinsulinaemic euglycaemic clamp investigation using an intravenous insulin infusion rate on 2 mU/(kg body weight x min). Insulin sensitivity (whole body glucose disposal) was similar in the two groups ((mean (95% C.I.)) 351 (321-381) vs. 364 (339-388) mg/(m2 x min); P = 0.51). Among urinary albumin excretion rate, blood pressure, serum lipid concentrations, body mass index waist-hip ratio, fasting concentrations of serum insulin and blood glucose, tobacco and alcohol consumption, physical activity, and age and sex, fasting serum insulin concentration was the only variable independently associated with insulin sensitivity (r = -0.55; P = 0.0001). It is concluded that microalbuminuria is not associated with impaired insulin sensitivity in clinically healthy individuals. The effect of microalbuminuria as predictor of atherosclerotic vascular disease may be mediated through other factors.

Aspects of haemostatic function in healthy subjects with microalbuminuria--a potential atherosclerotic risk factor

Microalbuminuria, i.e., slightly elevated urinary albumin excretion rate (UAER), notifies increased risk for atherosclerotic disease and may reflect an early generalized vascular abnormality in healthy subjects. This study was designed in order to examine whether such abnormality is associated with a shift of the haemostatic balance in prothrombotic direction. The following haemostatic factors were measured in two representative groups of clinically healthy subjects, 28 with microalbuminuria (UAER of 6.6-150 micrograms/min) and 60 age- and sex-matched controls with normoalbuminuria (UAER < 6.6 micrograms/min): Coagulation factors: blood platelet count and mean volume, plasma Factor VII antigen concentration and coagulant activity, and plasma concentrations of prothrombin fragment 1 + 2, thrombin-antithrombin III complexes, fibrinogen, and fibrinopeptide A; fibrinolytic and endothelial factors: plasma concentrations of tissue plasminogen activator antigen and plasminogen activator inhibitor type 1 antigen; and endothelial factor: plasma von Willebrand factor antigen concentration. The fibrinolytic and endothelial factors were measured both before and after 10 minutes of venous occlusion of the arm. None of the haemostatic factors were significantly altered in the microalbuminuric group. Plasma fibrinogen concentration tended to be elevated but not statistically significant ((mean (95% C.I.) 7.8 (7.2-8.3) vs. 7.2 (6.9-7.5) mumol/l; p < 0.1). Neither did any of the haemostatic factors correlate with UAER in regression analyses. It is concluded that the haemostatic balance is unaltered in healthy subjects with microalbuminuria. It is unlikely that a prothrombotic state is present as an intermedial factor early in a causal chain between microalbuminuria and atherosclerotic vascular disease.