Serum uric acid is associated with microalbuminuria in prehypertension

Ethnic disparities in bidirectional causal effects between serum uric acid concentrations and kidney function: Trans-ethnic Mendelian randomization study

Introduction

Researchers have investigated the causal effect between serum uric acid (SUA) concentrations and kidney function for decades, but studies produced inconsistent results. This study aimed to clarify the bidirectional causal effects between SUA concentrations and kidney function and to explore the potential ethnic disparities by conducting a trans-ethnic Mendelian randomization study in European, African, and Asian ancestries.

Materials and methods

The summary-level data for this study were obtained from the Global Urate Genetics Consortium, CKDGen Consortium, UK Biobank, and Japan Biobank for different outcomes and exposures, respectively. The traits of kidney function were estimated glomerular filtration rate from serum creatinine (eGFRcr), estimated glomerular filtration rate from cystatin C (eGFRcys), and blood urea nitrogen (BUN). Using the multiplicative random-effects inverse variance weighting mode, our primary analysis produced robust results despite heterogeneity. Additionally, we performed the Mendelian randomization pleiotropy residual sum and outlier test to eliminate the horizontal pleiotropy and obtain accurate results.

Results

Our findings revealed that elevated SUA concentrations had causal effects on declined eGFRcys, BUN, and a diagnosis of chronic kidney disease in European ancestries and eGFRcr in Asian ancestries. Additionally, the causal effects of declined eGFRcr and elevated BUN concentrations on elevated SUA concentrations were observed in both European and Asian ancestries. However, no bidirectional causal effect was found between SUA concentrations and eGFRcr among African ancestries.

Conclusions

This trans-ethnic Mendelian randomization study confirmed the bidirectional causal effects between SUA concentrations and kidney function and highlighted the importance of considering ethnic disparities in clinical treatments.

The association among uric acid, microalbumin and estimated glomerular filtration rate in hypertensive patients: a case control study

OBJECTIVE

To estimate the relationship among uric acid (UA), 24-h microalbumin (24 h-MAU) and estimated glomerular filtration rate (eGFR) in hypertensive patients.

METHOD

The study enrolled adult patients hospitalized in TEDA International Cardiovascular Hospital. The study was used to explore the correlation among UA, 24 h-MAU and eGFR. Univariate analysis was used to compare continuous or categorical data groups according to data type. Multivariate analysis was used to explore the correlation among UA, Log 24 h-MAU and eGFR by linear regression, and the relationship among UA, 24 h-MAU ≥ 30 mg/24 h (increased 24 h-MAU) and eGFR < 90 ml·min^-1·1.73 m^-2 (mildly decreased eGFR) by logistic regression. Mediation effect analysis was used to explore the mediating effect of increased 24 h-MAU between UA and mildly decreased eGFR. Subgroup analysis was used to investigate the correlation among UA, 24 h-MAU and eGFR in different gender.

RESULT

Seven hundred and thirty-three inpatients were enrolled in the study, including 257 patients with hyperuricemia. The level of UA was 377.8 ± 99.9 μmol/L in all patients enrolled, and it was about 50.1% higher in hyperuricemia group (482.3 ± 58.8 μmol/L vs. 321.4 ± 63.5 μmol/L, P < 0.001). The prevalence of hyperuricemia was 35.1% (95%CI 31.6-38.5%). The univariate regression analysis showed that UA was significant related to Log 24 h-MAU, increased 24 h-MAU, eGFR and mildly decreased eGFR. After adjusted confounding factors, UA was significant related to Log 24 h-MAU (β = 0.163, P < 0.001), eGFR (β = - 0.196, P < 0.001), increased 24 h-MAU (quantitative analysis: OR = 1.045, 95%CI 1.020-1.071, P < 0.001; qualitative analysis: OR = 2.245, 95%CI 1.410-3.572, P = 0.001), but had no significant relationship with mildly decreased eGFR. Mediating effect analysis showed that increased 24 h-MAU partially mediated the relationship between UA and mildly decreased eGFR (relative indirect effect: 25.0% and 20.3% in quantitative analysis and qualitative analysis respectively). In the subgroup analysis, the results were stable and similar to the analysis for entry patients.

CONCLUSION

The prevalence of hyperuricemia was higher in hypertensive inpatients. UA was strongly associated with Log 24 h-MAU, eGFR and increased 24 h-MAU, while the correlation with mildly decreased eGFR was affected by multiple factors. And increased 24 h-MAU might be the intermediate factor between UA and mildly decreased eGFR.

Novel sedentary cage induced sedentariness in rats: evidence from relevant biomarkers

BACKGROUND

Sedentary behavior or physical inactivity is considered a foremost contributor to the rise in obesity and overweight and a risk factor for several non-communicable diseases. However, its effect on the etiopathogenesis of some diseases is underestimated in both developed and developing countries worldwide. The present study designed a novel sedentary cage with a view to achieving sedentariness in rats, and also investigated the effectiveness of the cage in achieving sedentariness by assessing some markers of cardiometabolic risks in Wistar rats.

METHODS

Adult male Wistar rats were divided into 3 groups of six rats. Rats in Group 1 were the control. The sedentary groups were 4-hr. sedentary and 8-hr. sedentary. The sedentary rats were subjected to restrained movements for 4 and 8 hours daily in the sedentary cage for 3 months. Anthropometric indices, food consumption and blood pressure parameters of the rats were measured. Microalbuminuria and serum glucose, uric acid, albumin, nitric oxide, endothelin-1, insulin, inflammatory markers were also Measured.

RESULTS

Results indicated significant increases in body weight, BMI, Lee index, food consumption, systolic and diastolic pressure and decrease in serum nitric oxide bioavailability in the 8-hr sedentary rats. There were also significant increases in serum glucose, uric acid, endothelin-1, insulin, CRP and microalbuminuria in the 8-hr. sedentary rats in comparison with the control. The interleukin-6 and TNF-α also revealed a significant increase in the 8-hr. sedentary rats compared with the control. However, there was no significant difference in cortisol level across all the groups.

CONCLUSIONS

We concluded that the novel sedentary cage successfully caused sedentariness in the rats as evident by the alteration in the cardiometabolic health in the rats, especially the group that were made sedentary for 8 h.

Uric Acid Is Not Associated With Blood Pressure Phenotypes and Target Organ Damage According to Blood Pressure Phenotypes

BACKGROUND

Hypertensive patients with increased serum uric acid (SUA) are at increased cardiovascular (CV) risks. Both the European and American hypertension guidelines endorse the utilization of 24 h-ambulatory blood pressure monitoring (24 h-ABPM) for hypertensive patients with increased CV risk. While there is difference in identifying uric acid as a CV risk factor between the European and American guidelines. Therefore, it is unknown whether 24 h-ABPM should be used routinely in hypertensive patients with increased SUA.

METHODS

To address this knowledge gap, we investigated (i) the correlation between SUA and 24 h-ABP; (ii) the association between SUA and blood pressure (BP) phenotypes (controlled hypertension [CH], white-coat uncontrolled hypertension [WCUH], masked uncontrolled hypertension [MUCH], and sustained uncontrolled hypertension [SUCH]); (iii) the association between SUA and target organ damage (TOD: microalbuminuria, left ventricular hypertrophy [LVH], and arterial stiffness) according to BP phenotypes.

RESULTS

In 1,336 treated hypertensive patients (mean age 61.2 and female 55.4%), we found (i) there was no correlation between SUA and 24 h, daytime, and nighttime systolic blood pressure/diastolic blood pressure, respectively; (ii) in reference to CH, SUA increase was not associated WCUH (odds ratio [OR] 0.968, P = 0.609), MUCH (OR 1.026, P = 0.545), and SUCH (OR 1.003, P = 0.943); (iii) the overall prevalence of microalbuminuria, LVH, and arterial stiffness was 2.3%, 16.7%, and 23.2%, respectively. After adjustment for covariates, including age, sex, smoking, body mass index, diabetes mellitus, and estimated glomerular filtration rate, there was no association between SUA and TOD in all BP phenotypes.

CONCLUSIONS

These preliminary findings did not support routine use of 24 h-ABPM in treated hypertensive patients with increased SUA.

Sensing soluble uric acid by Naip1-Nlrp3 platform

Uric acid (UA), a product of purine nucleotide degradation able to initiate an immune response, represents a breakpoint in the evolutionary history of humans, when uricase, the enzyme required for UA cleavage, was lost. Despite being inert in human cells, UA in its soluble form (sUA) can increase the level of interleukin-1β (IL-1β) in murine macrophages. We, therefore, hypothesized that the recognition of sUA is achieved by the Naip1-Nlrp3 inflammasome platform. Through structural modelling predictions and transcriptome and functional analyses, we found that murine Naip1 expression in human macrophages induces IL-1β expression, fatty acid production and an inflammation-related response upon sUA stimulation, a process reversed by the pharmacological and genetic inhibition of Nlrp3. Moreover, molecular interaction experiments showed that Naip1 directly recognizes sUA. Accordingly, Naip may be the sUA receptor lost through the human evolutionary process, and a better understanding of its recognition may lead to novel anti-hyperuricaemia therapies.

The role of uric acid in inflammasome-mediated kidney injury

PURPOSE OF REVIEW

Uric acid is produced after purine nucleotide degradation, upon xanthine oxidase catalytic action. In the evolutionary process, humans lost uricase, an enzyme that converts uric acid into allantoin, resulting in increased serum uric acid levels that may vary according to dietary ingestion, pathological conditions, and other factors. Despite the controversy over the inflammatory role of uric acid in its soluble form, crystals of uric acid are able to activate the NLRP3 inflammasome in different tissues. Uric acid, therefore, triggers hyperuricemic-related disease such as gout, metabolic syndrome, and kidney injuries. The present review provides an overview on the role of uric acid in the inflammasome-mediated kidney damage.

RECENT FINDINGS

Hyperuricemia is present in 20-35% of patients with chronic kidney disease. However, whether this increased circulating uric acid is a risk factor or just a biomarker of renal and cardiovascular injuries has become a topic of intense discussion. Despite these conflicting views, several studies support the idea that hyperuricemia is indeed a cause of progression of kidney disease, with a putative role for soluble uric acid in activating renal NLRP3 inflammasome, in reprograming renal and immune cell metabolism and, therefore, in promoting kidney inflammation/injury.

SUMMARY

Therapies aiming to decrease uric acid levels prevent renal NLRP3 inflammasome activation and exert renoprotective effects in experimental kidney diseases. However, further clinical studies are needed to investigate whether reduced circulating uric acid can also inhibit the inflammasome and be beneficial in human conditions.

Nutritional risk markers among stroke out-patients at the neurology clinic of a teaching hospital in Ghana

Introduction

stroke survivors are at risk of malnutrition due to inadequate dietary intake, as a result of neurological disorders causing dysphagia, depression and impaired ability to self-feed. There is paucity of information on nutritional status of stroke survivors after discharge from hospital care, hence, this study sought to determine the nutritional risk markers among stroke out-patients at the Neurology Clinic of Komfo Anokye Teaching Hospital, Kumasi, Ghana.

Methods

a cross-sectional study was conducted among 106 stroke survivors at Komfo Anokye Teaching Hospital, Kumasi, Ghana. Nutritional status of stroke survivors was assessed, using body mass index (BMI) and mid upper arm circumference (MUAC). Biochemical and haematological nutrition indicators including total serum protein, serum albumin, total lymphocyte count, uric acid and haemoglobin were also determined. Independent t-test and ANOVA were used to test differences between mean values.

Results

the mean age of study participants was 58.47±14.2 years, with 56% being females. Overall, 96 (88.7%) of the participants had malnutrition, of whom 66 (68.8%) were undernourished, while 30 (31.2%) had overnutrition. It was also found that 38.7% of the participants were anaemic, based on haemoglobin levels. Using mean BMI, stroke survivors who had been discharged over five years were significantly overweight (p = 0.010).

Conclusion

there was high level of malnutrition among stroke out-patients in this study. The most common nutrition-related problem in the stroke survivors studied was anaemia. Findings from this study suggest the need for nutrition intervention strategies to address the high burden of malnutrition among the stroke survivors.

Study on the Risk Factors for Hyperuricaemia and Related Vascular Complications in Patients with Type 2 Diabetes Mellitus

Purpose

The study aimed to identify diseases that exhibit significant differences between hyperuricaemia (HUA) and non-hyperuricaemia (NHUA) groups and analyse the risk factors for HUA based on the related diseases in type 2 diabetes mellitus (T2DM).

Methods

A total of 3264 T2DM patients were investigated from 2013 to 2017 in the Jinyang and Sanlin communities by obtaining basic data from the electronic medical record system (EMRS). From September 2018 to July 2019, 3000 patients (264 patients were missing during follow-up) were investigated with questionnaires, physical examinations and biochemical index tests. After removing missing values, 2899 patients were divided into HUA and NHUA groups. The chi-square test was used to identify diseases with differences. Using Lasso analysis and logistic regression analysis, risk factors for HUA based on the related diseases were obtained. The C-index, receiver operating characteristic (ROC) curve and calibration plot were used to validate the discrimination and accuracy of the factors.

Results

The chi-square test showed that there were significant differences in coronary heart disease (CHD) and diabetic nephropathy (DN) between the HUA group and the NHUA group. Through Lasso regression, glycosylated haemoglobin A1c (HbA1c), triglyceride (TG), blood urea nitrogen (BUN) and serum creatinine (SCR) were screened in the CHD group. Body mass index (BMI), HbA1c, total cholesterol (TC), TG, BUN, SCR and urine microalbumin (UMA) were screened in the DN group. The P-value of all the variables was less than 0.05. Through the C-index, calibration, and ROC curve analyses, these risk factors had medium accuracy.

Conclusion

HUA was significantly related to CHD and DN. The level of UA was correlated with HbA1c, TG, BUN, and SCR based on CHD. The level of UA was associated with BMI, HbA1c, TC, TG, BUN, SCR, and UMA based on DN.

U-shaped relationship between serum uric acid level and decline in renal function during a 10-year period in female subjects: BOREAS-CKD2

While hyperuricemia is recognized as a risk factor for chronic kidney disease (CKD), the risk of CKD in subjects with a low level of serum uric acid (UA) remains controversial. Here, we examined whether the association of CKD risk with serum UA level differs depending on the sex and age of subjects in a general population. Of subjects who received annual health checkups, we enrolled 6,779 subjects (male/female: 4,454/2,325; age: 45 ± 9 years) with data from a 10-year follow-up after excluding subjects taking anti-hyperuricemic drugs and those with CKD at baseline. During the follow-up period, 11.4% of the males and 11.7% of the females developed CKD. A significant interaction of sex, but not age, with the effect of baseline UA level on CKD risk was found. A restricted cubic spline analysis showed a U-shaped association of the baseline UA level with the risk of CKD in females. Multivariable Cox proportional hazard analyses for females showed that baseline UA levels in the 5th quintile (Q5, ≥5 mg/dL; HR: 1.68) and the 1st quintile (Q1, ≤3.5 mg/dL; HR: 1.73) were independent risk factors for CKD when compared with UA levels in the 4th quintile (Q4, 4.5-4.9 mg/dL). In males, restricted cubic spline analysis indicated increased CKD risk in subjects with a higher baseline UA level but not in those with a low UA level. In conclusion, a low UA level is a significant risk factor for CKD in females, while an elevated UA level increases the risk of CKD in both sexes.

STRUCTURAL AND FUNCTIONAL VASCULAR CHANGES IN HIGH NORMAL ARTERIAL PRESSURE

The PURPUSE of the present study is changes in function and structure of large arteries in individuals with High Normal Arterial Pressure (HNAP) to be established. MATERIAL and METHODS: Structural and functional changes in the large arteries were investigated in 80 individuals with HNAP and in 45 with optimal arterial pressure (OAP). In terms of arterial stiffness, pulse wave velocity (PWV), augmentation index (AI), central aortic pressure (CAP), pulse pressure (PP) were followed up in HNAP group. Intima media thickness (IMT), flow-induced vasodilatation (FMD), ankle-brachial index (ABI) were also studied. RESULTS: Significantly increased values of pulse wave velocity, augmentation index, central aortic pressure, pulse pressure are reported in the HNAP group. In terms of IMT and ABI, being in the reference interval, there is no significant difference between HNAP and OAP groups. The calculated cardiovascular risk (CVR) in both groups is low. CONCLUSION: Significantly higher values of pulse wave velocity, augmentation index, central aortic pressure and pulse pressure in the HNAP group are reported.

Treatment of asymptomatic hyperuricemia complicated by renal damage: a controversial issue

The prevalence of asymptomatic HUA is increasing year after year. HUA is a risk factor for the occurrence and development of renal diseases. However, the role of urate-lowering therapy in asymptomatic HUA complicated by renal damage is still controversial. In some experiments, the treatment of asymptomatic HUA complicated by renal damage may delay the progression of kidney damage. In addition, there is increasing evidence, suggesting that elevated serum uric acid is an independent risk factor for kidney disease. However, in other studies, uric acid-lowering therapy did not improve renal function, and uric acid levels could not be used as an independent predictor for CKD development. Further experimental studies are needed to determine the starting threshold and target value of asymptomatic HUA complicated by renal damage. At the same time, confirmation of the benefits of urate-lowering therapy for kidneys requires studies with larger samples and high-quality RCTs.

Impact of Serum Uric Acid Levels on Outcomes following Renal Artery Revascularization in Patients with Renovascular Disease

BACKGROUND

Percutaneous transluminal renal angioplasty (PTRA) improves blood pressure (BP) and renal function only in selected patients with atherosclerotic renovascular disease (ARVD). Hyperuricemia is associated with elevated risk for hypertension and chronic renal disease, but its role in renovascular hypertension is unclear. We hypothesized that hyperuricemia negatively impacts renal and BP outcomes among patients with ARVD undergoing PTRA.

METHODS

This retrospective, observational cohort study included 94 patients with ARVD and preserved systolic cardiac function, who underwent PTRA at Mayo Clinic, Rochester, Minnesota. Renal, BP, and mortality outcomes were compared among patients according to their serum uric acid (SUA) levels. Multivariate analysis was used to determine significant predictors of renal, BP, and mortality outcomes after PTRA.

RESULTS

Compared to patients with normal basal SUA levels (≤5.7 mg/dl), patients with very high SUA (≥8.7 mg/dl) had lower baseline estimated glomerular filtration rate (eGFR), more extensive use of antihypertensive and diuretic drugs, increased baseline systolic blood pressure (SBP), and elevated left ventricular mass index. After PTRA, multiple logistic regression analysis showed that, compared to normal SUA, very high SUA was associated with decreased odds ratio (OR) of change in eGFR (adjusted OR=0.90; 95% confidence interval [CI], 0.86-0.95), but not of change in SBP. In multivariate linear analysis SUA independently predicted delta urine protein/creatinine ratio (β: 26.0; 95% confidence interval, 13.9 to 38.1).

CONCLUSION

Severe hyperuricemia in patients with AVRD may have a negative impact on outcomes of renal revascularization.

Relationship Between Uric Acid, Proteinuria, and Atherogenic Index of Plasma in Renal Transplant Patients

This study aimed to determine the association of atherogenic index of plasma (AIP) with both hyperuricemia and proteinuria in renal transplant recipients.

MATERIAL AND METHODS

Between the years 2015 and 2017, 61 renal transplant recipients with at least 1 year of follow-up were included in this retrospective cohort study. Uric acid levels of ≥7 mg/dL in men and ≥6 mg/dL in women were accepted as hyperuricemia. The patients were separated into groups according to their serum uric acid and AIP levels.

RESULTS

The prevalence of patients with hyperuricemia was 37.7% (n = 23). The triglycerides (P = .009), AIP (P = .005), proteinuria (P = .04), and C-reactive protein (P = .049) were significantly higher in the hyperuricemic group compared with the nonhyperuricemic group. The levels of uric acid (P = .008) and proteinuria (P = .005) increased significantly with an elevation in AIP levels. Additionally, in multivariate linear regression analysis, uric acid (β = 0.325; P = .008) and estimated glomerular filtration rate (β = -0.291; P = .02) were found to be independently associated factors for proteinuria in renal transplant patients (R² = 0.242; P < .001).

CONCLUSION

We indicated that uric acid, AIP, and proteinuria are closely related. Further prospective studies are needed to evaluate the causal relationship between uric acid, AIP, and proteinuria in this patient group.

Uric acid and cardiovascular disease

Uric acid (UA) is an end product of purine metabolism in humans and great apes. UA acts as an antioxidant and it accounts for 50% of the total antioxidant capacity of biological fluids in humans. When present in cytoplasm of the cells or in acidic/hydrophobic milieu in atherosclerotic plaques, UA converts into a pro-oxidant agent and promotes oxidative stress and through this mechanism participates in the pathophysiology of human disease including cardiovascular disease (CVD). Most epidemiological studies but not all of them suggested the existence of an association between elevated serum UA level and CVD, including coronary heart disease (CHD), stroke, congestive heart failure, arterial hypertension and atrial fibrillation as well as an increased risk for mortality due to CVD in general population and subjects with confirmed CHD. Evidence available also suggests an association between elevated UA and traditional cardiovascular risk factors, metabolic syndrome, insulin resistance, obesity, non-alcoholic fatty liver disease and chronic kidney disease. Experimental and clinical studies have evidenced several mechanisms through which elevated UA level exerts deleterious effects on cardiovascular health including increased oxidative stress, reduced availability of nitric oxide and endothelial dysfunction, promotion of local and systemic inflammation, vasoconstriction and proliferation of vascular smooth muscle cells, insulin resistance and metabolic dysregulation. Although the causality in the relationship between UA and CVD remains unproven, UA may be pathogenic and participate in the pathophysiology of CVD by serving as a bridging mechanism mediating (enabling) or potentiating the deleterious effects of cardiovascular risk factors on vascular tissue and myocardium.

Urinary excretion of uric acid is negatively associated with albuminuria in patients with chronic kidney disease: a cross-sectional study

Background

Increasing evidence has shown that albuminuria is related to serum uric acid. Little is known about whether this association may be interrelated via renal handling of uric acid. Therefore, we aim to study urinary uric acid excretion and its association with albuminuria in patients with chronic kidney disease (CKD).

Methods

A cross-sectional study of 200 Chinese CKD patients recruited from department of nephrology of Huadong hospital was conducted. Levels of 24 h urinary excretion of uric acid (24-h Uur), fractional excretion of uric acid (FEur) and uric acid clearance rate (Cur) according to gender, CKD stages, hypertension and albuminuria status were compared by a multivariate analysis. Pearson and Spearman correlation and multiple regression analyses were used to study the correlation of 24-h Uur, FEur and Cur with urinary albumin to creatinine ratio (UACR).

Results

The multivariate analysis showed that 24-h Uur and Cur were lower and FEur was higher in the hypertension group, stage 3–5 CKD and macro-albuminuria group (UACR> 30 mg/mmol) than those in the normotensive group, stage 1 CKD group and the normo-albuminuria group (UACR< 3 mg/mmol) (all P < 0.05). Moreover, males had higher 24-h Uur and lower FEur than females (both P < 0.05). Multiple linear regression analysis showed that UACR was negatively associated with 24-h Uur and Cur (P = 0.021, P = 0.007, respectively), but not with FEur (P = 0.759), after adjusting for multiple confounding factors.

Conclusions

Our findings suggested that urinary excretion of uric acid is negatively associated with albuminuria in patients with CKD. This phenomenon may help to explain the association between albuminuria and serum uric acid.

Serum uric acid, protein intake and mortality in hemodialysis patients

Background

The association between serum uric acid (SUA) and mortality has been conflicting among studies using hemodialysis (HD) patients. Given the close link between purine and protein in foods, we hypothesized that normalized protein catabolic rate (nPCR), a dietary protein intake surrogate, modifies the SUA-mortality association in the HD population.

Methods

We identified 4298 patients who initiated HD and had one or more SUA measurement in a contemporary cohort of HD patients over 5 years (1 January 2007-31 December 2011), and examined survival probability according to the first uric acid measurement, adjusting for dialysis vintage, case-mix and malnutrition-inflammation complex-related variables.

Results

Mean SUA concentration was 6.6 ± 1.8 mg/dL. There was a consistent association of higher SUA with better nutritional status and lower all-cause mortality irrespective of adjusted models (Ptrend < 0.001). In the case-mix adjusted model, the highest SUA category (≥8.0 mg/dL) compared with the reference group (>6.0-7.0 mg/dL) showed no significant mortality risk [hazard ratio (HR) 0.90, 95% confidence interval (CI) 0.72-1.13], while the lowest category (<5.0 mg/dL) was associated with higher mortality (HR 1.42, 95% CI 1.16-1.72). The hypouricemia-mortality association was significantly modified by nPCR (Pinteraction = 0.001). Mortality risk of low SUA (<5.0 mg/dL) persisted among patients with low nPCR (<0.9 g/kg/day; HR 1.73, 95% CI 1.42-2.10) but not with high nPCR (≥0.9 g/kg/day; HR 0.99, 95% CI 0.74-1.33).

Conclusions

SUA may be a nutritional marker in HD patients. Contrary to the general population, low but not high SUA is associated with higher all-cause mortality in HD patients, especially in those with low protein intake. Nutritional features of SUA warrant additional studies.

Asymptomatic hyperuricemia is independently associated with coronary artery calcification in the absence of overt coronary artery disease: A single-center cross-sectional study

Recently, the pathogenic role of uric acid (UA) in both systemic metabolic and atherosclerotic diseases has been investigated. We sought to determine the independent correlation between serum UA levels and coronary artery calcification, as a marker of subclinical atherosclerosis. A total of 4188 individuals without prior coronary artery disease or urate-deposition disease were included. All of the participants underwent multidetector computed tomography (MDCT) for the evaluation of coronary artery calcification (CAC) during their health check-ups. The subjects were divided into thre groups according to CAC scores (group 1: 0; group 2: 1-299; group 3: ≥300). After controlling for other confounders, serum UA levels were found to be positively associated with increasing CAC scores (P = 0.001). Adjusted mean serum UA levels in each CAC group were estimated to be 5.2 ± 0.1 mg/dL, 5.3 ± 0.1 mg/dL, and 5.6 ± 0.2 mg/dL from groups 1, 2, and 3, respectively. Subsequent subgroup analyses revealed that this positive association was only significant in participants who were male, relatively older, less overweight, and did not have diabetes mellitus (DM), hypertension, smoking history, or renal dysfunction. In conclusion, serum uric acid levels were independently associated with CAC score severity and this finding is particularly relevant to the subjects who were male, relatively older, less overweight (body mass index < 25 kg/m), and without a history of DM, hypertension, smoking, or renal dysfunction.

The Impact of Blood Pressure and Visceral Adiposity on the Association of Serum Uric Acid With Albuminuria in Adults Without Full Metabolic Syndrome

BACKGROUND

The impact of metabolic phenotypes on the association of uricemia with urinary albumin/creatinine ratio (uACR) remains unresolved. We evaluated the association between serum uric acid and uACR in persons with 0, and 1-2 metabolic syndrome (MetS) components and determined the modification effects of visceral adiposity index (VAI), mean arterial pressure (MAP), and fasting glucose on this association.

METHODS

Using data from a cross-sectional survey of a representative Czech population aged 25-64 years (n = 3612), we analyzed 1,832 persons without decreased glomerular filtration rate <60ml/min/1.73 m2, diabetes, and MetS. MetS components were defined using the joint statement of the leading societies.

RESULTS

Of the 1,832 selected participants, 64.1% (n = 1174) presented with 1-2 MetS components (age 46.3±11.2; men 51.7%), whereas 35.9% (n = 658) were free of any component (age 39.4±10.0; men 34.2 %). In fully adjusted multiple linear regression models for uricemia, uACR was an independent factor for increase in uric acid levels only in persons with 1-2 MetS components (standardized beta (Sβ) 0.048; P = 0.024); however, not in those without any component (Sβ 0.030; P = 0.264). Uric acid levels increased by the interaction of uACR with VAI (Sβ 0.06; P = 0.012), and of uACR with MAP (Sβ 0.05; P = 0.009). Finally, the association of uACR with uricemia was confined to persons whose VAI together with MAP were ≥the median of 1.35 and 98mm Hg, respectively (Sβ 0.190; P < 0.001).

CONCLUSIONS

We demonstrated a strong modification effect of VAI and MAP on the association between uACR and uricemia, which suggests obesity-related hypertension as the underlying mechanism.

Low-grade albuminuria and incidence of cardiovascular disease and all-cause mortality in nondiabetic and normotensive individuals

BACKGROUND

Recent studies indicate that, in people with diabetes or hypertension and in the general population, low-grade albuminuria (LGA) below the microalbuminuria threshold is a predictor for incidence of cardiovascular disease (CVD) and mortality. However, it remains unclear whether LGA predicts the risk of CVD incidence and death in nondiabetic and normotensive individuals.

METHODS

A total of 3599 individuals aged not less than 40 years from the general population who are free of CVD in nondiabetic and normotensive individuals with preserved glomerular filtration rate were followed for CVD incidence and all-cause death. LGA was defined as urinary albumin to creatinine ratio (UACR) less than 30  mg/g. It was examined whether there is an association between LGA and CVD incidence or all-cause death.

RESULTS

During the average 5.9 years of follow-up, 61 individuals had first CVD events, and 85 individuals died. The hazard ratios (HRs) for CVD incidence and all-cause death after full adjustment by potential confounders increased significantly in the top tertile of LGA (UACR ≥ 9.6  mg/g for men, ≥ 12.0  mg/g for women) compared with the first tertile [HR = 2.79, 95% confidence interval (CI), 1.41-5.52, HR = 1.69, 95% CI, 1.00-2.84, respectively]. Population-attributable fractions of the top tertile of LGA for CVD incidence and all-cause death were 37.9 and 20.1%, respectively.

CONCLUSION

In apparently healthy individuals with optimal blood pressure and no diabetes, LGA independently predicts CVD incidence and all-cause death, particularly with the large contribution to the excessive incidence of CVD.

Uric Acid and Neurocognitive Function in Survivors of Childhood Acute Lymphoblastic Leukemia Treated with Chemotherapy Only

BACKGROUND

Hyperuricemia is implicated in cardiovascular and cerebrovascular diseases. This study evaluated associations between uric acid (UA), cardiovascular health, and neurocognitive function in adolescent and adult survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only.

METHODS

126 adolescent [mean (SD) age 14.6 (5.0); 7.8 (1.7) years postdiagnosis] and 226 adult survivors [age 25.4 (4.2) years; 18.1 (4.4) years postdiagnosis] completed comprehensive neurocognitive testing. Concurrent UA measurements were conducted for both groups. For adult survivors, cardiovascular risk factors were assessed, and UA measurements during adolescence [12.3 (4.0) years before neurocognitive testing] were also collected. UA levels were categorized into quartiles for age- and gender-based ranking, and associations with neurocognitive outcomes were examined.

RESULTS

Survivors demonstrated worse attention, processing speed, and executive functions than population norms (P values < 0.05). Adolescent survivors with elevated UA had poorer attention (P = 0.04), visual-processing speed (P = 0.03), and cognitive flexibility (P = 0.02). UA was not associated with neurocognitive outcomes in adult survivors. Adult survivors developed dyslipidemia (46%), hypertension (32%), and abdominal obesity (26%), and high UA during adolescence was associated with these cardiovascular risk factors as adults (all P values < 0.01). Fine-motor processing speed was slower in adult survivors with dyslipidemia (P = 0.04) and abdominal obesity (P = 0.04). Poorer attention was marginally associated with hypertension (P = 0.06).

CONCLUSIONS

Elevated UA is associated with neurocognitive performance in adolescent survivors. In adult survivors, relative elevation of UA during adolescence was predictive of cardiovascular health, which was associated with poorer neurocognitive outcomes.

IMPACT

Future studies should evaluate the mediating role of chronic cardiovascular health conditions between elevated UA and subsequent neurocognitive impairment in survivors. Cancer Epidemiol Biomarkers Prev; 25(8); 1259-67. ©2016 AACR.

Prehypertension in Pregnancy and Risks of Small for Gestational Age Infant and Stillbirth

It is not fully known whether maternal prehypertension is associated with increased risk of adverse fetal outcomes, and it is debated whether increases in blood pressure during pregnancy influence adverse fetal outcomes. We performed a population-based cohort study in nonhypertensive women with term (≥37 weeks) singleton births (n=157 446). Using normotensive (diastolic blood pressure [DBP] <80 mm Hg) women as reference, we calculated adjusted odds ratios with 95% confidence intervals between prehypertension (DBP 80–89 mm Hg) at 36 gestational weeks (late pregnancy) and risks of a small-for-gestational-age (SGA) birth or stillbirth. We further estimated whether an increase in DBP from early to late pregnancy affected these risks. We found that 11% of the study population had prehypertension in late pregnancy. Prehypertension was associated with increased risks of both SGA birth and stillbirth; adjusted odds ratios (95% confidence intervals) were 1.69 (1.51–1.90) and 1.70 (1.16–2.49), respectively. Risks of SGA birth in term pregnancy increased by 2.0% (95% confidence intervals 1.5–2.8) per each mm Hg rise in DBP from early to late pregnancy, whereas risk of stillbirth was not affected by rise in DBP during pregnancy. We conclude that prehypertension in late pregnancy is associated with increased risks of SGA birth and stillbirth. Risk of SGA birth was also affected by rise in DBT during pregnancy. Our findings provide new insight to the relationship between maternal blood pressure and fetal well-being and suggest that impaired maternal perfusion of the placenta contribute to SGA birth and stillbirth.

Pretransplant uric acid levels may be predictive for prognosis of renal transplant donors

BACKGROUND

The living kidney donor counseling prior to the operation may be helpful to learn how to properly care for the remaining single kidney for the rest of their lives. Worsening kidney function is associated with elevated serum uric acid (UA) levels. In this study, we compared the baseline laboratory findings of renal transplant donors with their follow-up laboratory values.

METHODS

The study consisted of 173 adult donors including 91 females and 82 males with a mean age of 46.82 ± 11.31 years. The follow-up clinical and laboratory examinations were performed on the third day at the end of the first and the sixth months of the surgery. According to donor's creatinine levels we constituted two groups: high creatinine and normal creatinine.

RESULTS

Patients within the high creatinine group had significantly higher mean serum UA levels when compared with the normal creatinine group. In multivariate analysis, among the other effective variables, UA level alone was found to be the most effective parameter predicting the post-transplant creatinine levels (p = 0.004, odds ratio: 12.4, 95% CI: 2.3-68.3) at sixth month post-transplantation. In the ROC analysis for the effects of UA, the following cutoff values were found: >6 mg/dL in men (sensitivity 81.3%, specificity 76.9%, positive predictive value 89.7%, negative predictive value 62.5%, accuracy 80%) and ≥5 mg/dL in women (sensitivity 72.2, specificity 74.4%, positive predictive value 89.7%, negative predictive value 62.5%, accuracy: 73.7%).

CONCLUSION

Pretransplant serum UA levels can give important clues regarding the renal functions of the donors during the postoperative period.

A pilot study on the impact of a low fructose diet and allopurinol on clinic blood pressure among overweight and prehypertensive subjects: a randomized placebo controlled trial

Fructose and sodium intake have been associated with hypertension and metabolic syndrome. Although various mechanisms are involved, fructose causes hypertension partly through rising intracellular and serum uric acid. To date, there are no studies in adults that have evaluated the impact of low fructose diets and allopurinol on prehypertensive and overweight subjects. The objective of this study was to compare the effect of low fructose diet and allopurinol or placebo on blood pressure (BP) and metabolic syndrome components The study was a controlled clinical trial and consisted of two phases; in the first phase of intervention (4 weeks), patients were randomized to either low fructose diet (34 patients) or control diet (38 patients). In the second phase of intervention (weeks 4-8), the same groups continued with the same diet prescriptions but were further randomized to receive placebo or allopurinol (300 mg/d). Clinic and 24-hour ambulatory BP, anthropometric measures, and laboratory data were determined at baseline, weeks 4 and 8. Seventy-two patients were included in the trial. At the end of the dietary phase, both diet groups significantly reduced their BP, but there were no between-group differences. Compared to placebo, at the end of follow-up, subjects in the allopurinol group had a lower clinic systolic blood pressure and this was significant within- and between-group comparisons. The percentage of dippers was higher in the allopurinol group, and weight was reduced significantly despite the absence of caloric restriction Allopurinol was associated with a significant reduction in clinic BP, an increase in the percentage of dippers, and significant weight loss. Larger studies with longer follow-up are needed to confirm our findings.

Defining, Treating, and Understanding Chronic Kidney Disease--A Complex Disorder

Chronic kidney disease (CKD) is prevalent in more than 20 million people in the United States. The majority of care provided to patients with this disease comes from primary care physicians, although it is often poorly understood. After an extensive literature review, it is clear that it can be difficult to classify and there are many barriers to care. Risk factors for both incident CKD and disease progression include hypertension, poor glycemic control, sociodemographic factors, acute kidney injury, metabolic acidosis, and possibly hyperuricemia and dietary factors. Treatment of patients with CKD should focus on mitigating risk factors, as well as common comorbidities such as cardiovascular disease, anemia, and bone mineral disease. Novel therapies such as pirfenidone, pentoxifylline, and endothelin-1 antagonists are being investigated with promising results.

The association of albuminuria with tubular reabsorption of uric acid: results from a general population cohort

Background

Elevated albuminuria as well as an increased serum uric acid concentration is associated with poor cardiovascular outcome. We questioned whether these 2 variables (albuminuria and serum uric concentration) may be interrelated via tubular uric acid reabsorption.

Methods and Results

Included were 7688 participants of the PREVEND Study, an observational, general population‐based cohort study. Linear regression analyses were used to test associations of baseline albuminuria with baseline serum uric acid concentration and tubular uric acid reabsorption (calculated as [100−fractional uric acid excretion]%). Cox regression analyses were used to study the association of baseline serum uric acid and albuminuria with incident cardiovascular morbidity and mortality. In cross‐sectional analyses, albuminuria was associated positively with serum uric acid concentration, both crude and after adjustment for potential confounders (both P<0.001). Albuminuria was found to be associated positively with tubular uric acid reabsorption, again both crude and after adjustment for potential confounders (both P<0.001). In longitudinal analyses during a median follow‐up of 10.5 years, 702 cardiovascular events occurred. After adjusting for cardiovascular risk factors, both albuminuria and serum uric acid were associated with incident cardiovascular events (Hazard Ratios 1.09 [1.03 to 1.17], P=0.01 and 1.19 [1.09 to 1.30], P<0.001, respectively). A significant interaction between these variables was present (P<0.001), consistent with high serum uric acid being less predictive for cardiovascular morbidity and mortality in the presence of high albuminuria and vice versa.

Conclusions

Albuminuria is strongly associated with tubular uric acid reabsorption, and consequently with serum uric acid concentration. This phenomenon may explain in part why albuminuria is associated with cardiovascular outcome.

Serum uric acid and the risk of hypertension and chronic kidney disease

PURPOSE OF REVIEW

To discuss the evolving data regarding uric acid as a potential cause of hypertension and progressive renal dysfunction and its clinical and research implications.

RECENT FINDINGS

The potential mechanisms by which uric acid could cause vasoconstriction and a progressive ateriolopathy were established in animal models between 1999 and 2004. Since then, there has been a growing interest in the topic and numerous retrospective and prospective observational studies. The preponderance of data support the hypothesis that serum uric acid is a cause or exacerbating factor of hypertension and progressive kidney disease. Over the last couple of years clinical intervention trials, including randomized controlled trials in the young have supported this mechanistic role.

SUMMARY

Current evidence supports the role of uric acid as marker and mediator of risk for both hypertension and progressive decline in renal function. Data on the impact of xanthine oxidase inhibitors or uricosurics on clinical hypertension and chronic kidney disease are suggestive but inconclusive. Considerably, more data will be required to determine if uric acid lowering therapy will become a mainstay of management in diseases other than gout and tumor lysis syndrome.

Hyperuricemia and chronic kidney disease: an enigma yet to be solved

The role of uric acid (UA) on the pathogenesis and progression of chronic kidney disease (CKD) remains controversial. Experimental and clinical studies indicate that UA is associated with several risk factors of CKD including diabetes, hypertension, oxidative stress, and inflammation and hyperuricemia could be considered as a common dominator linking CKD and cardiovascular disease. Notably, the impact of serum UA levels on the survival of CKD, dialysis patients, and renal transplant recipients is also a matter of debate, as there are conflicting results from clinical studies. At present, there is no definite data whether UA is causal, compensatory, coincidental or it is only an epiphenomenon in these patients. In this article, we attempt to review and elucidate the dark side of this old molecule in CKD and renal transplantation.

The impact of elevation of serum uric acid level on the natural history of glomerular filtration rate (GFR) and its sex difference

BACKGROUND

The impact of elevation of the serum uric acid level (SUA) on the natural history of glomerular filtration rate (GFR) remains controversial.

METHODS

If elevation of SUA is a result, rather than a cause, of a decline in GFR, the relationship between SUA and GFR should be the same in the same population over years except for shifts by age-dependent reduction of GFR. We tested this hypothesis using data from two cohorts and a group of allopurinol-treated patients.

RESULTS

In Cohort 1 consisting of urban residents aged 40.6 ± 9.0 years (n = 3 446), SUA was inversely correlated with estimated GFR (eGFR) in both men and women, and the slope of the SUA-eGFR relationship was steeper in women than in men. The slopes of the regression lines became significantly steeper after a 6-year interval in both sexes, and the change in the slope was larger in women. A similar sex difference in the SUA-eGFR relationship and 6-year change in the slope were observed in Cohort 2 consisting of rural town residents aged 61.7 ± 12.2 years (n = 404). Multiple regression analyses showed that explanatory factors of eGFR after a 6-year interval were age and SUA at baseline in both cohorts, and partial regression coefficients of SUA were more negative in women than in men. The SUA-eGFR relationship in allopurinol-treated patients (n = 346, 63.5 ± 13.3 years old) was similar to that in Cohort 2.

CONCLUSIONS

The results indicate that elevation of SUA accelerates the yearly decline in eGFR and that women are more susceptible to urate-induced decline in eGFR.

Serum uric acid level is associated with the development of microalbuminuria in Korean men

BACKGROUND

Elevated serum uric acid (UA) could be a risk factor for hypertension, type 2 diabetes mellitus and cardiovascular disease. In addition, elevated serum UA may be associated with impaired renal function. However, it is unclear whether elevated serum UA is a cause of microalbuminuria or not. Therefore, we performed a prospective cohort study of the temporal relationship between baseline elevated serum UA and the development of microalbuminuria in Korean men.

DESIGN AND METHODS

A microalbuminuria-free cohort of 1743 healthy Korean men, who had their urine albumin-creatinine ratio (UACR) calculated for a medical check-up programme in 2005, was followed until 2010. Microalbuminuria was defined as a urine albumin-creatinine ratio between 30 and 300 μg/mg. Cox proportional hazards model was performed.

RESULTS

During 5884.6 person-years of follow-up, 96 incident cases of microalbuminuria developed between 2006 and 2010. After adjusting for multiple covariates, the hazard ratios (95% confidence intervals) for incident microalbuminuria when comparing the second tertile to the third tertile of serum UA levels vs. the first tertile were 1.52 (0.86-2.70) and 2.27 (1.30-3.98), respectively (P for trend = 0.005).

CONCLUSION

Elevated serum UA level was independent risk factor for the development of microalbuminuria during a 5-year follow-up in Korean men.

Chronic hyperuricemia, uric acid deposit and cardiovascular risk

Hyperuricemia is commonly associated with traditional risk factors such as dysglicemia, dyslipidemia, central obesity and abnormal blood pressure, i.e. the metabolic syndrome. Concordantly, recent studies have revived the controversy over the role of circulating uric acid, hyperuricemia, and gout as an independent prognostic factor for cardiovascular morbidity and mortality. In this regard, different studies also evaluated the possible role of xanthine inhibitors in inducing blood pressure reduction, increment in flow-mediated dilation, and improved cardiovascular prognosis in various patient settings. The vast majority of these studies have been conducted with either allopurinol or its active metabolite oxypurinol, i.e. two purine-like non-selective inhibitors of xanthine oxidase. More recently, the role of uric acid as a risk factor for cardiovascular disease and the possible protective role exerted by reduction of hyperuricemia to normal level have been evaluated by the use of febuxostat, a selective, non purine-like xanthine oxidase inhibitor. In this review, we will report current evidence on hyperuricemia in cardiovascular disease. The value of uric acid as a biomarker and as a potential therapeutic target for tailored old and novel "cardiometabolic" treatments will be also discussed.

Obesity-related cardiorenal disease: the benefits of bariatric surgery

The inexorable increase in the prevalence of obesity is a global health concern, which will result in a concomitant escalation in health-care costs. Obesity-related metabolic syndrome affects approximately 25% of adults and is associated with cardiovascular and renal disease. The heart and kidneys are physiologically interdependent, and the pathological effects of obesity can lead to cardiorenal syndrome and, ultimately, kidney and heart failure. Weight loss can prevent or ameliorate obesity-related cardiorenal syndrome, but long-term maintenance of a healthy weight has been difficult to achieve through lifestyle changes or pharmacotherapy. Bariatric surgery offers both sustained weight loss and favourable metabolic changes, including dramatic improvements in glycaemic control and symptoms of type 2 diabetes mellitus. Procedures such as Roux-en-Y gastric bypass offer immediate multisystemic benefits, including bile flow alteration, reduced gastric size, anatomical gut rearrangement and altered flow of nutrients, vagal manipulation and enteric hormone modulation. In patients with cardiorenal syndrome, bariatric surgery also offers renoprotection and cardioprotection, and attenuates both kidney and heart failure by improving organ perfusion and reversing metabolic dysfunction. However, further research is required to understand how bariatric surgery acts on the cardiorenal axis, and its pioneering role in novel treatments and interventions for cardiorenal disease.

Hyperuricemia is an independent risk factor for new onset micro-albuminuria in a middle-aged and elderly population: a prospective cohort study in taiwan

Background

Hyperuricemia is now regarded as a risk factor for cardiovascular disease. Micro-albuminuria is associated with increased risk for cardiovascular disease and chronic kidney disease. We hypothesized that elevated serum uric acid (UA) is associated with development of micro-albuminuria in the general population.

Methodology/Principal Findings

We conducted a community-based prospective cohort study. A total of 1862 subjects from southern Taiwan, all older than 40 years, were screened and 993 of these participants without micro-albuminuria were followed for 4 years. Urinary albumin-to-creatinine ratio was measured two times per year. A multiple linear regression model indicated that serum UA was independently associated with ln(ACR) after adjustment for 8 factors (age, sex, and 6 metabolic metrics) (β = 0.194, p<0.01). Logistic regression analysis indicated that each 1 mg/dL increase of UA was associated with a 1.42-fold increased risk of micro-albuminuria after adjustment for the same 8 factors (OR = 1.42, 95% CI: 1.27–1.59, p<0.01). A Cox regression model using subjects with serum UA less than 5 mg/dL as reference group indicated higher hazard ratios (HRs) only found in subjects with serum UA more than 7 mg/dL (HR = 3.54, 95% CI: 2.11–5.93, p<0.01) and not in subjects with serum UA of 5 to 7 mg/dL (HR = 1.30, 95% CI: 0.82–2.07, p = 0.15).

Conclusion

Hyperuricemia is significantly associated with micro-albuminuria in middle-aged and elderly males and females from a general population in Taiwan. Elevated serum UA is an independent predictor for development of micro-albuminuria in this population.

Echocardiographic predictors of progression from prehypertension to hypertension

BACKGROUND

Prehypertension (PHT) was recently introduced by replacing former categories of high-normal and above-optimal blood pressure (BP). The rationale for redefining this new category was to emphasize the excess cardiovascular risk associated with BP in this range and to focus high risk for developing hypertension (HT). However, no clear definite markers to identify prehypertensive patients at high risk of progressing to HT have been established yet. Accordingly, we aimed to establish echocardiographic predictors of progression from PHT to HT.

METHODS AND RESULTS

The study population consisted of 98 eligible prehypertensive patients. All patients underwent echocardiographic examination including coronary flow reserve (CFR) at baseline. Twenty-nine (30%) patients developed HT during the 3-year follow-up period. Creatinine level, left ventricular mass index (LVMI), mitral Em and Em/Am had a trend towards a significant crude odds ratio (OR) for the development of HT; however, only baseline SBP [OR = 1.18, 95% confidence interval (CI) = 1.06-1.31; P = 0.002), having metabolic syndrome (OR = 3.75, 95% CI = 1.43-9.78; P = 0.007), high-density lipoprotein (HDL) cholesterol (OR = 0.92, 95% CI = 0.86-0.98; P = 0.01), presence of microalbuminuria (OR = 3.53, 95% CI = 1.11-11.2; P = 0.03) and CFR (OR = 0.65, 95% CI = 0.53-0.77; P = 0.02) were significant independent predictors of progression of PHT into HT. The best cutoff value of CFR to predict incident HT was 1.98 with 94% sensitivity and 79% specificity.

CONCLUSION

This prospective study suggested that baseline SBP, having metabolic syndrome, HDL cholesterol level, presence of microalbuminuria and CFR reflecting coronary microvascular function, but not left ventricular diastolic function parameters, were significant independent markers to identify participants with PHT at high risk for incident HT.

Obesity-related hypertension: pathogenesis, cardiovascular risk, and treatment--a position paper of the The Obesity Society and The American Society of Hypertension

In light of the worldwide epidemic of obesity, and in recognition of hypertension as a major factor in the cardiovascular morbidity and mortality associated with obesity, The Obesity Society and The American Society of Hypertension agreed to jointly sponsor a position paper on obesity-related hypertension to be published jointly in the journals of each society. The purpose is to inform the members of both societies, as well as practicing clinicians, with a timely review of the association between obesity and high blood pressure, the risk that this association entails, and the options for rational, evidenced-based treatment. The position paper is divided into six sections plus a summary as follows: pathophysiology, epidemiology and cardiovascular risk, the metabolic syndrome, lifestyle management in prevention and treatment, pharmacologic treatment of hypertension in the obese, and the medical and surgical treatment of obesity in obese hypertensive patients.

Obesity-related hypertension: pathogenesis, cardiovascular risk, and treatment: a position paper of The Obesity Society and the American Society of Hypertension

In light of the worldwide epidemic of obesity, and in recognition of hypertension as a major factor in the cardiovascular morbidity and mortality associated with obesity, The Obesity Society and the American Society of Hypertension agreed to jointly sponsor a position paper on obesity-related hypertension to be published jointly in the journals of each society. The purpose is to inform the members of both societies, as well as practicing clinicians, with a timely review of the association between obesity and high blood pressure, the risk that this association entails, and the options for rational, evidenced-based treatment. The position paper is divided into six sections plus a summary as follows: pathophysiology, epidemiology and cardiovascular risk, the metabolic syndrome, lifestyle management in prevention and treatment, pharmacologic treatment of hypertension in the obese, and the medical and surgical treatment of obesity in obese hypertensive patients.

Uric acid concentration as a risk marker for blood pressure progression and incident hypertension: a Chinese cohort study

OBJECTIVE

Little is known about serum uric acid (SUA) role for hypertension in the Asian countries with low cardiovascular events. We aimed to explore the relationship in a comprehensive Chinese cohort.

METHODS

Participants in the Taiwanese Survey on Prevalences of Hypertension, Hyperglycemia, and Hyperlipidemia (TwSHHH) who were free of hypertension at baseline recruitment in 2002 (n=3257) were evaluated for the longitudinal association between baseline SUA and blood pressure progression (BPP) and incident hypertension.

RESULTS

During a mean follow-up of 5.41 years, 1119 persons (34.3%) had experienced progression to a higher blood pressure stage and 496 persons (15.2%) had developed hypertension. In multivariate analyses, the adjusted hazard ratios (HRs) [95% confidence intervals (CIs)] comparing the highest and lowest SUA quartiles were 1.78 (1.11-2.02, P for trend .004) for BPP and 1.68 (1.23-2.04, P for trend .028) for incident hypertension. The positively graded relationships between SUA concentration and blood pressure outcomes were observed in both males and females. More interestingly, a statistically significant trend for increasing risk of BPP and incident hypertension across SUA quartiles was most pronounced in participants with abdominal obesity.

CONCLUSION

We concluded that SUA level was an independent predictor of blood pressure progression and incident hypertension in a Chinese population.

Hyperuricemia and hypertension

Over the past century, uric acid has been considered a possible risk factor for hypertension and cardiovascular disease. However, only in the past decade, animal models and clinical trials have supported a more mechanistic link. Results from animal models suggest a 2-phase mechanism for the development of hyperuricemic hypertension in which uric acid induces acute vasoconstriction by activation of renin-angiotensin system, followed by uric acid uptake into vascular smooth muscle cells leading to cellular proliferation and secondary arteriolosclerosis that impairs pressure natriuresis. This acute hypertension remains uric acid dependent and sodium independent, whereas the chronic hypertension becomes uric acid independent and sodium dependent. Small clinical trials, performed in adolescents with newly diagnosed essential hypertension, demonstrate that reduction of serum uric acid can reduce blood pressure. Although more research is clearly necessary, the available data suggest that uric acid is likely causative in some cases of early onset hypertension.

Cardiorenal disturbances in perimenopausal women

Aim. To identify early signs of renal dysfunction; to investigate the associations between renal function and vascular remodelling; to evaluate the role of metabolic and hydrodynamic disturbances in the development of cardiorenal syndrome among perimenopausal women; and to assess the potential of hormone replacement therapy (17β-estradiol 1 mg and drospirenone 2 mg) for the correction of the above-mentioned disturbances. Material and methods. In total, 69 perimenopausal women were divided into two groups. Group I included 69 premenopausal women, while Group II consisted of 43 women in early postmenopause. Mean age in Group I was 49,0 years (95% CI 48,0-51,0 years); in Group II, it was 54,0 (50,0-56,0) years (p<0,01). Age at menopause reached 50,3 (48,0-52,0) years, with median duration of menopause of 3,5 (2,0-5,0) years. All participants underwent biochemical blood tests (creatinine (Cr), uric acid (UA), lipid profile, and glucose tolerance test (GTT)). Large elastic artery remodelling was assessed by intima-media thickness (IMT) of common carotid artery (CCA). Non-invasive assessment of endothelial vasoregulatory function involved the measurement of brachial artery (BA) endothelium-dependent vasodilatation (EDVD) in the reactive hyperemia test (RHT). Renal function was assessed by glomerular filtration rate (GFR) and Cr clearance (CrC). Monoalbuminuria (MAU) was qualitatively assessed with a urine strip test. Postmenopausal women were additionally divided into two groups: 23 patients were administered HRT (17β-estradiol 1 mg and drospirenone 2 mg; Angelique medication), while 20 women not receiving HRT comprised a control group. At the end of the study, after 12 months, the assessment of metabolic status, body mass dynamics, endothelial vasoregulatory function, and CCA IMT was repeated. Results. In most postmenopausal women, lipid and carbohydrate metabolism disturbances were observed, which were typical for metabolic syndrome (MS). Lipid metabolism disturbances were observed as early as in premenopause, but reached their maximum during early postmenopause. Postmenopausal women, compared to their peers in premenopause, had significantly higher fasting and postprandial levels of blood glucose. Structural and functional changes in vascular wall were more severe in postmenopausal vs. premenopausal women (p<0,001). While blood flow velocity in the RHT was comparable in both groups, postmenopausal women did not demonstrate a comparable increase in BA EDVD, in contrast to premenopausal females. This could point to the decrease in BA sensitivity to endothelial shear stress among women in postmenopause. Reduced GFR was observed only in postmenopausal women. MAU was registered in premenopausal women with normal GFR, as well as in postmenopausal females. These data on independent role of MAU and reduced GFR suggest an increase in the proportion of women with subclinical renal injury, as a manifestation of target organ damage. Conclusion. The associations between vascular structure and function, renal function, and main MS components were demonstrated. HRT (17β-estradiol 1 mg and drospirenone 2 mg) had beneficial effects on BP dynamics, visceral obesity, metabolic status, and arterial structure and function.

The role of uric acid in the pathogenesis of hypertension in the young

Uric acid has been suspected to be a risk factor for hypertension since the 1870s. Numerous epidemiological studies demonstrate an association between uric acid and both incident and prevalent hypertension in diverse populations. Studies in elderly patients have had more variable results, raising the possibility that uric acid may be more significant to hypertension in the young. Animal models support a two-phase mechanism for the development of hyperuricemic hypertension. Initially, uric acid induces vasoconstriction by activation of the renin-angiotensin system and reduction of circulating nitric oxide, which can be reversed by lowering uric acid. Over time, uric acid uptake into vascular smooth muscle cells causes cellular proliferation and secondary arteriolosclerosis that impairs pressure natriuresis, causing sodium-sensitive hypertension. Consistent with the animal model data, small clinical trials performed in adolescents with newly diagnosed essential hypertension demonstrate that at least in certain young patients, reduction of serum uric acid can mitigate blood pressure elevation. While more research is clearly necessary, the available data suggest that uric acid is likely causative in some cases of early-onset hypertension.

Validated SNPs for eGFR and their associations with albuminuria

Albuminuria and reduced glomerular filtration rate are manifestations of chronic kidney disease (CKD) that predict end-stage renal disease, acute kidney injury, cardiovascular disease and death. We hypothesized that SNPs identified in association with the estimated glomerular filtration rate (eGFR) would also be associated with albuminuria. Within the CKDGen Consortium cohort (n= 31 580, European ancestry), we tested 16 eGFR-associated SNPs for association with the urinary albumin-to-creatinine ratio (UACR) and albuminuria [UACR >25 mg/g (women); 17 mg/g (men)]. In parallel, within the CARe Renal Consortium (n= 5569, African ancestry), we tested seven eGFR-associated SNPs for association with the UACR. We used a Bonferroni-corrected P-value of 0.003 (0.05/16) in CKDGen and 0.007 (0.05/7) in CARe. We also assessed whether the 16 eGFR SNPs were associated with the UACR in aggregate using a beta-weighted genotype score. In the CKDGen Consortium, the minor A allele of rs17319721 in the SHROOM3 gene, known to be associated with a lower eGFR, was associated with lower ln(UACR) levels (beta = -0.034, P-value = 0.0002). No additional eGFR-associated SNPs met the Bonferroni-corrected P-value threshold of 0.003 for either UACR or albuminuria. In the CARe Renal Consortium, there were no associations between SNPs and UACR with a P< 0.007. Although we found the genotype score to be associated with albuminuria (P= 0.0006), this result was driven almost entirely by the known SHROOM3 variant, rs17319721. Removal of rs17319721 resulted in a P-value 0.03, indicating a weak residual aggregate signal. No alleles, previously demonstrated to be associated with a lower eGFR, were associated with the UACR or albuminuria, suggesting that there may be distinct genetic components for these traits.

Uric acid and chronic kidney disease: new understanding of an old problem

Although an elevation of serum uric acid level is often associated with chronic kidney disease (CKD), it remains controversial whether hyperuricemia per se is a true risk factor for the development or aggravation of CKD. Recent epidemiologic studies in healthy populations or in subjects with established kidney disease have reported the independent role of uric acid in lowering glomerular filtration rate and increasing the risk for new-onset kidney disease. Furthermore, lowering uric acid in patients with established renal disease has been reported to stabilize renal function independent of other confounders, suggesting a causative role of elevated uric acid in progression of CKD, rather than as an incidental finding related to CKD severity. In this manuscript we will discuss the potential role of uric acid in the development and aggravation of CKD based on epidemiologic, clinical and experimental studies. Given the worldwide epidemic of CKD, the importance of identifying modifiable risk factors of CKD, and the clinical implication of hyperuricemia in CKD, we propose large randomized clinical trials to investigate whether uric acid-lowering therapy can slow the progression of CKD.