Relation of albumin/creatinine ratio to C-reactive protein and to the metabolic syndrome

Metabolic syndrome and its components are related to a higher risk for albuminuria and proteinuria: Evidence from a meta-analysis on 10,603,067 subjects from 57 studies

BACKGROUND & AIM

Previous studies have explored the relation of metabolic syndrome (MetS), its components and the risk of albuminuria/proteinuria but their results are inconsistent. Then, we aimed to conduct a meta-analysis in order to resolve these controversies.

METHOD

PubMed and Scopus were systematically searched from their inception to 1 march 2018. Risk estimates and their 95% confidence intervals were extracted and pooled using the random-effects approach.

RESULT

A total of 57 studies, 44 studies on albuminuria and 13 studies on proteinuria, with a total sample size of 10,603,067 participants, were included in this meta-analysis. Overall, MetS was contributed to higher risks of proteinuria (OR = 2.08, 95%CI = 1.85-2.34) and albuminuria (OR = 1.92, 95%CI = 1.71-2.15), independent of diabetes status; although, this relationship was more noticeable in studies that used the WHO definition of MetS and in non-East Asian populations. Also, the relationship between MetS and proteinuria was sex independent, while, for albuminuria was significant only in men. MetS components such as obesity, impaired fasting glucose, elevated blood pressure and hypertriglyceridemia were associated with significant increases in proteinuria and albuminuria risk, while lower HDL-Cholesterol was only linked to greater risk of proteinuria. Moreover, the total impact of MetS on proteinuria was more remarkable than each component of the syndrome and an escalating dose-response association was found between the number of MetS components and albuminuria risk.

CONCLUSION

MetS and its components are potential risk factors for albuminuria and proteinuria.

Suppressive effects of valsartan on microalbuminuria and CRP in patients with metabolic syndrome (Val-Mets)

The presence of metabolic syndrome (Mets) increases the risk for cardiovascular disease. There is a significant correlation between the levels of urinary albumin to creatinine ratio (UACR) and high-sensitive C-reactive peptide (hs-CRP), and accumulation of each Mets component. Increasing evidence has shown the importance of blockade of renin-angiotensin-systems (RAS) for reducing urinary albumin excretion and hs-CRP levels in Mets patients. However, the impact of RAS blockade on these effects in hypertensive (HT) Mets patients without diabetes mellitus (DM) has not been evaluated. We prospectively measured the levels of UACR and hs-CRP in 153 HT patients with and without Mets. Body weight; waist circumference; presence of dyslipidemia and DM, and levels of HOMA-R, UACR, and hs-CRP were significantly higher in HT patients with Mets than in those without Mets. After we treated these Mets patients with valsartan for 6 months, blood pressure (BP), UACR, and hs-CRP were decreased, whereas body weight, HOMR-R, and the lipid profile were not changed. In HT Mets patients without DM, 6 months after valsartan administration, levels of UACR and hs-CRP were also significantly decreased by 37.8% (-9.0-56.5%, p < 0.05) and 23.6% (-28.7-73.4%, p < 0.05), respectively. However, the percentage change of UACR and hs-CRP was not correlated with the reduction in BP. Valsartan administration lowered increased levels of chronic inflammation in both HT Mets patients with DM and in those without DM. These results indicate that the anti-inflammatory properties of valsartan might also have beneficial effects in Mets patients without DM.

Metabolic syndrome is strongly associated with chronic subclinical inflammation in patients achieving optimal low-density lipoprotein-cholesterol levels in secondary prevention of cardiovascular disease

BACKGROUND

The dual goals of low-density lipoprotein-cholesterol (LDL-C) and C-reactive protein (CRP) reduction are important for secondary prevention of cardiovascular disease. However, the relevant factors of subclinical inflammation in patients with optimal LDL-C were not clearly demonstrated. This study sought to test the hypothesis that the metabolic syndrome (MetS) is associated with subclinical inflammation in patients achieving optimal LDL-C.

METHODS AND RESULTS

A total of 227 Japanese subjects with a prior history of ischemic heart disease and optimal LDL-C (LDL-C <100 mg/dl) were enrolled. When compared with patients with low CRP (<0.1 mg/dl), those with a high CRP (> or =0.1 mg/dl) had a significantly higher prevalence of visceral obesity, elevated triglyceride, lower high-density lipoprotein-cholesterol (HDL-C), hypertension, impaired fasting glucose, and a higher prevalence of MetS. A linear relationship between an increase in number of MetS components and CRP was observed (trend, p<0.001). In multivariate logistic analysis, visceral obesity (odds ratio 6.54; 95% confidence interval 2.99-14.3), low HDL-C (2.78; 1.09-7.12) and impaired fasting glucose (6.72; 3.30-13.7), and MetS (10.4; 5.18-20.7) were associated with higher CRP.

CONCLUSIONS

MetS is well associated with higher CRP concentrations in patients who achieved optimal LDL-C levels.

Aggravation of albuminuria by metabolic syndrome in type 2 diabetic Asian subjects

AIMS

We investigated the relationship of urinary albumin excretion (UAE) to metabolic syndrome and type 2 diabetes in Asian.

METHODS

A total of 446 subjects (187 without diabetes and 259 with type 2 diabetes) were enrolled in this study. The components of metabolic syndrome, high sensitivity C-reactive protein (hs-CRP) and UAE were assessed. Based on metabolic syndrome and diabetes status, participants were categorized into one of the following groups: neither metabolic syndrome nor diabetes (MS-DM-), metabolic syndrome without diabetes (MS+DM-), diabetes without metabolic syndrome (MS-DM+) and both metabolic syndrome and diabetes (MS+DM+).

RESULTS

The UAE in the MS+DM- group was higher than that in the MS-DM- group (P<0.001) and lower than that in the MS+DM+ group (P<0.001), but not significantly different from that in the MS-DM+ group (P=0.349). The trend of increasing UAE in these four groups was independent of hs-CRP.

CONCLUSION

UAE was lowest in subjects with neither metabolic syndrome nor diabetes and highest in subjects with both metabolic syndrome and type 2 diabetes; however, there was no significant difference between the metabolic syndrome alone group and the type 2 diabetes alone group.

Relation of left ventricular hypertrophy with systemic inflammation and endothelial damage in resistant hypertension

The relation between left ventricular hypertrophy (LVH) and unfavorable cardiovascular prognosis may involve systemic inflammation and endothelial dysfunction/damage. The aim of this study was to investigate in a cross-sectional design the relationships of LVH with C-reactive protein (CRP) levels (a marker of systemic low-grade inflammation) and with microalbuminuria (a marker of glomerular endothelial damage) in 705 patients with resistant hypertension. At baseline, all were submitted to a laboratory evaluation including 24-hour urinary albumin excretion, 2D echocardiogram, and 24-hour ambulatory blood pressure monitoring. A total of 463 patients also had high-sensitivity CRP levels determined. LVH was defined as an indexed left ventricular mass >110 g/m(2) in women and >125 g/m(2) in men. Microalbuminuria was evaluated in 3 categories: low normal (<15 mg/24 hours), high normal (between 15 and 29 mg/24 hours), and abnormal (between 30 and 299 mg/24 hours). CRP was dichotomized at the median value (3.7 mg/L). Associations with LVH were examined after adjustment for all of the potential confounders by multivariate logistic regression. A total of 534 patients (75.7%) had LVH. After full adjustment, both abnormal microalbuminuria (odds ratio: 1.97; 95% CI: 1.04 to 3.73) and high CRP (OR: 1.76; 95% CI: 1.06 to 2.93) were independently associated with LVH occurrence. The high-normal albuminuria was associated with a borderline significant 46% increased chance of having LVH. Furthermore, the association between high CRP and LVH was observed exclusively in the subgroup with normal albuminuria. In conclusion, both systemic inflammation and endothelial damage were associated with LVH occurrence. These relationships offer insight into the pathophysiological mechanisms linking LVH to atherosclerosis and to increased cardiovascular morbidity and mortality.

The Prevalence of Metabolic Syndrome in Various Populations

The insulin resistance/metabolic syndrome is characterized by the variable co-existence of hyperinsulinemia, obesity, dyslipidemia (small dense low-density lipoprotein, hypertriglyceridemia, and decreased high-density lipoprotein cholesterol), and hypertension. The pathogenesis of the syndrome has multiple origins. However, obesity and sedentary lifestyle coupled with diet and still largely unknown genetic factors clearly interact to produce the syndrome. This multifactorial and complex trait of metabolic syndrome leads to increased risk of cardiovascular disease. The scope of this review is to examine the differences in prevalence of the metabolic syndrome in various groups (eg, according to age, sex, ethnicity, social status, or presence of obesity) that could help with the better understanding of the pathogenesis of this syndrome. This review also considers the impact of metabolic syndrome on cardiovascular disease.

The metabolic syndrome: evolving evidence that thiazolidinediones provide rational therapy

The metabolic syndrome, also known as the dysmetabolic syndrome, syndrome X or the insulin resistance syndrome, refers to the clustering of cardiovascular disease risk factors that are present in many individuals who are at increased risk for both cardiovascular events and type 2 diabetes. Prediabetic subjects typically exhibit an atherogenic pattern of cardiovascular risks that is associated with hyperinsulinaemia. Thus, identification of components of the metabolic syndrome is important if patients are to be treated early enough to prevent cardiovascular events and other complications related to diabetes. Therapies targeted to specific components of the metabolic syndrome such as improving glycaemic control, managing dyslipidaemia and reducing the prothrombotic state should help to minimize cardiovascular risk, particularly if initiated early. Traditional pharmacologic agents used to manage the individual components of the metabolic syndrome do not typically impact the other components. The thiazolidinediones, a new class of agents that improve insulin resistance, have the ability, in addition to their glucose-lowering effects, to exert several powerful anti-atherogenic properties, including anti-inflammatory effects in the vascular endothelium, redistribution of visceral fat and reduction of insulin resistance, hyperinsulinaemia and hyperproinsulinaemia. This makes the thiazolidinediones ideal candidates for the early treatment of many components associated with the metabolic syndrome.

High-sensitivity C-reactive protein is only weakly related to cardiovascular damage after adjustment for traditional cardiovascular risk factors

BACKGROUND

The independent prognostic value of high-sensitivity C-reactive protein (hsCRP) has been questioned, and consequently we decided to investigate whether hsCRP was associated with subclinical cardiovascular (CV) damage independently of traditional CV risk factors.

METHODS

In a population-based sample of 2028 apparently healthy individuals without prior stroke or myocardial infarction not receiving any CV, anti-diabetic or lipid-lowering treatment, aged 41, 51, 61 or 71 years, we measured in 1993 serum hsCRP, traditional CV risk factors (lifestyle, metabolic and hemodynamic) and assessed subclinical CV damage [atherosclerotic plaques in the carotid arteries, pulse wave velocity (PWV), urine albumin/creatinine ratio (UACR), left ventricular (LV) mass and ejection fraction].

RESULTS

Adjusting for age and gender in multiple regression analyses, higher log(hsCRP) was associated with higher logPWV (beta = 0.15) and log(left ventricular mass index) (LVMI) (beta = 0.09, both P < 0.001), LV relative wall thickness (beta = 0.07, P < 0.01), logUACR (beta = 0.04, P = 0.06) and more atherosclerotic plaques (beta = 0.06, P < 0.05). However, higher log(hsCRP) was only weakly associated with higher logPWV(beta = 0.06, P < 0.05) and more atherosclerotic plaques (beta = 0.04, P = 0.06) when adjusting for other significant CV risk factors, such as daily smoking (beta = 0.18), female gender (beta = -0.17), older age (beta = 0.11), lower log(high density lipoprotein cholesterol) (beta = -0.11, all P < 0.001); wider waist (beta = 0.17), higher body mass index (beta = 0.14), higher heart rate (beta = 0.06, all P < 0.01); and higher log(plasma glucose) (beta = 0.05, P < 0.05) (adj. R2 = 0.19, P < 0.001).

CONCLUSION

After adjustment for traditional CV risk factors hsCRP was only associated with PWV and atherosclerotic plaques, indicating a possible effect of low-grade inflammation on macrovascular damage. The close relationship between traditional CV risk factors and hsCRP suggested that hsCRP was an integrated CV risk marker early in the development of atherosclerosis.

What does minor elevation of C-reactive protein signify?

Reports of the predictive value of minor elevation of serum C-reactive protein (CRP) levels (between 3 and 10 mg/L) for atherosclerotic events have generated considerable interest, as well as a degree of controversy and confusion. CRP concentrations in this range are found in about one third of the American population. To better understand the mechanisms underlying minor elevation of CRP, we have surveyed its reported associations with a variety of states and conditions. It has become clear that even minimal environmental irritants and inflammatory stimuli elicit a minor CRP response. Minor CRP elevation has been found associated with a number of genetic polymorphisms, with membership in different demographic and socioeconomic groups, with a variety of dietary patterns and with many medical conditions that are not apparently inflammatory. Finally, minor CRP elevation bears negative prognostic implications for many conditions, particularly age-related diseases, and predicts mortality in both diseased and apparently healthy individuals. In sum, minor CRP elevation is associated with a great many diverse conditions, some of which are, or may prove to be, causal. Many of these reported associations imply a mild degree of tissue stress or injury, suggesting the hypothesis that the presence of distressed cells, rather than a resulting inflammatory response, is commonly the stimulus for CRP production.

Pathophysiology of dyslipidaemia in the metabolic syndrome

The insulin resistance/metabolic syndrome is characterised by the variable coexistence of hyperinsulinaemia, obesity, dyslipidaemia, and hypertension. The pathogenesis of the syndrome has multiple origins, but obesity and sedentary lifestyle coupled with diet and still largely unknown genetic factors clearly interact to produce the syndrome. Dyslipidaemia, the hallmark of the metabolic syndrome, includes increased flux of free fatty acids, raised triglycerides, apolipoprotein B, and small dense low density lipoprotein, and decreased high density lipoprotein cholesterol. The widely prevalent nature of the metabolic syndrome emphasises the importance of its diagnosis and treatment. This review analyses the clinical and dynamic features of this syndrome in the aspect of dyslipidaemia and its management.

Cardiovascular protection in patients with type 2 diabetes mellitus: Considerations about the tightness of blood pressure control and the choice of treatment

Diabetes mellitus is rapidly evolving as the epidemic of the 21st century. The presently estimated number of 190 million is predicted to grow to over 300 million by the year 2025. Cardiovascular (CVD) morbidity and mortality is two to five times higher in diabetics, while the microvascular complications considerably compromise the quality of life. The main risk factors for CVD, as well as for microangiopathy, are hypertension, dyslipidemia, insulin resistance, hyperglycemia, endothelial dysfunction, and an inflammatory vascular reaction. This review will focus on hypertension, which develops in most patients within the first 10-15 years of their diabetes. The discussion will encompass the criteria for treatment, the target values of blood pressure, and the choice of antihypertensive drugs as primary agents and in various combinations. The special role of angiotensin-receptor blockers will be highlighted, with an emphasis on cardioprotection, risk reduction of stroke, and attenuation of the course of nephropathy.

Prevention and treatment of the metabolic syndrome

The prevalence of the metabolic syndrome is increasing owing to lifestyle changes leading to obesity. This syndrome is a complex association of several interrelated abnormalities that increase the risk for cardiovascular disease and progression to diabetes mellitus (DM). Insulin resistance is the key factor for the clustering of risk factors characterizing the metabolic syndrome. The National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III defined the criteria for the diagnosis of the metabolic syndrome and established the basic principles for its management. According to these guidelines, treatment involves the improvement of the underlying insulin resistance through lifestyle modification (eg, weight reduction and increased physical activity) and possibly by drugs. The coexistent risk factors (mainly dyslipidemia and hypertension) should also be addressed. Since the main goal of lipid-lowering treatment is to achieve the NCEP low-density lipoprotein cholesterol (LDL-C) target, statins are a good option. However, fibrates (as monotherapy or in combination with statins) are useful for the treatment of the metabolic syndrome that is commonly associated with hypertriglyceridemia and decreased high-density lipoprotein cholesterol (HDL-C) levels. The blood pressure target is < 140/90 mm Hg. The effect on carbohydrate homeostasis should possibly be taken into account in selecting an antihypertensive drug. Patients with the metabolic syndrome commonly have other less well-defined metabolic abnormalities (eg, hyperuricemia and raised C-reactive protein levels) that may also be associated with an increased cardiovascular risk. It seems appropriate to manage these abnormalities. Drugs that beneficially affect carbohydrate metabolism and delay or even prevent the onset of DM (eg, thiazolidinediones or acarbose) could be useful in patients with the metabolic syndrome. Furthermore, among the more speculative benefits of treatment are improved liver function in nonalcoholic fatty liver disease and a reduction in the risk of acute gout.

Low-grade inflammation and microalbuminuria in hypertension

Background- Albuminuria and C-reactive protein (CRP), a marker of systemic low-grade inflammation, are frequently elevated in essential hypertension and predict cardiovascular prognosis independent of conventional risk factors. However, in spite of their potentially important links, the interrelationships between the 2 parameters have not been explored in depth in hypertensive patients.

METHODS AND RESULTS

Albuminuria (the mean of 3 overnight urine collections), high-sensitive CRP (hs-CRP), 24-hour blood pressure (BP), weight, lipids, poststimulative (75 g PO) plasma glucose, insulin, and insulin sensitivity by the homeostasis model assessment model were evaluated in 220 never treated, nondiabetic, uncomplicated essential hypertensive men. Albuminuria > or =15 microg/min was defined as microalbuminuria and hs-CRP values above and below median (2.3 mg/L) as high and low, respectively. Concentric left ventricular hypertrophy was diagnosed by echocardiography, and a full-blown metabolic syndrome was identified in presence of hypertension and at least 3 of following: obesity, subclinical hyperglycemia, low high-density lipoprotein (HDL) and high triglycerides. Microalbuminuria was present in 54 patients, 29 with high hs-CRP characterized by higher 24-hour systolic BP, postload glucose, body mass index, lower HDL cholesterol, more frequent metabolic syndrome, concentric LVH, and active smoking than those with either isolated microalbuminuria (n=27) or normoalbuminuria.

CONCLUSIONS

Microalbuminuria accompanied by evidence of subclinical inflammation is a strong correlate of metabolic abnormalities in essential hypertension and identifies a patient subset at very high cardiovascular risk. In contrast, isolated microalbuminuria may represent a distinct pathophysiological condition characterized by a more benign profile and possibly a better prognosis.