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

The Cellular Genesis of Metabolic Syndrome and the Role of Anti-urate Drugs in Hyperuricemia Patients: A Systematic Review

Hyperuricemia results due to the underexcretion of uric acid through kidneys or overproduction due to either intake of purine-rich foods, a high caloric diet, or a decreased activity of purine recycler hypoxanthine-guanine phosphoribosyl transferase (HGPRT). Increased xanthine oxidoreductase (XOR) enzyme activity may contribute to hyperuricemia. Literature provides growing evidence that an independent component that contributes to the development of metabolic syndrome (MetS) and associated comorbidities is hyperuricemia. Thus, precise cellular mechanisms involved during MetS and related comorbidities in hyperuricemia, and the role of anti-urate medicines in these mechanisms require further investigations. We searched online libraries PubMed and Google Scholar for data collection. We used Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines for literature identification, selection, screening, and determining eligibility to produce unbiased meaningful outcomes. We applied quality assessment tools for the quality appraisal of the studies. And, outcomes were extracted from the selected studies, which revealed the relationship between hyperuricemia and MetS components by causing inflammation, endothelial dysfunction, oxidative stress, and endoplasmic reticulum stress. The selected studies reflected the role of xanthine oxide (XO) inhibitors beyond inhibition. This systematic review concluded that hyperuricemia independently causes inflammation, oxidative stress, endothelial damage, and endoplasmic reticulum stress in patients with hyperuricemia. These mechanisms provide a cellular basis for metabolic syndrome and related comorbidities. In this context, XO inhibitors and their beneficial effects go beyond XOR inhibition to ameliorate these pathological mechanisms.

Asymptomatic hyperuricemia associated with increased risk of nephrolithiasis: a cross-sectional study

BACKGROUND

Existing evidence shows that there is an independent correlation between nephrolithiasis and gout, and hyperuricemia is the most important risk factor for gout. However, hyperuricemia was often used as an accompanying symptom of gout to explore its association with nephrolithiasis, there were few studies to explore whether hyperuricemia itself or serum uric acid (SUA) is related to the risk of nephrolithiasis. Evidence on the relationship between hyperuricemia and nephrolithiasis is still insufficient.

METHODS

A total of 22,303 participants aged 30 to 79 years who participated in the China Multi-Ethnic Cohort (CMEC) study in Yunnan Province from May 2018 to September 2019 were included in the study. All participants received standardized face-to-face interviews, medical examinations, and biochemical examinations. Logistic regression was used to estimate the association between hyperuricemia and nephrolithiasis, and a restricted cubic spline (RCS) model was used to explore the dose-response relationship between SUA and the risk of nephrolithiasis.

RESULTS

14.5% of all participants were diagnosed with hyperuricemia, and 12.1% were diagnosed with nephrolithiasis. After adjusting for all potential confounders, the OR (95%CI) for nephrolithiasis in participants with hyperuricemia compared with participants without hyperuricemia was 1.464 (1.312,1.633), p < 0.001. Restricted cubic spline regression analysis showed that the risk of nephrolithiasis increased with the increase of SUA, and when the level of SUA is higher than 356 μmol/L in males and higher than 265 μmol/L in females, there is a dose-response relationship between the increase of SUA and the risk of nephrolithiasis in both males and females (p for nonlinearity = 0.1668, p for nonlinearity = 0.0667).

CONCLUSION

Asymptomatic hyperuricemia is associated with an increased risk of developing nephrolithiasis. Before reaching the diagnostic criteria for hyperuricemia, the risk of nephrolithiasis rises with the increase in SUA. This suggests that controlling SUA levels may be significant for the prevention of nephrolithiasis.

Association of blood pressure and hyperuricemia with proteinuria and reduced renal function in the general population

This study aimed to investigate the effect of hyperuricemia (HU) on the association of systolic blood pressure (SBP) with the prevalence of proteinuria and low estimated glomerular filtration rate (eGFR) in the general population. This cross-sectional study enrolled 24,728 Japanese individuals (11,137 men and 13,591 women) who underwent health checkups in 2010. The prevalence of proteinuria and low eGFR (< 60 mL/min/1.73 m2) among participants classified according to serum uric acid levels and SBP was compared. HU was defined as serum uric acid levels higher than the 75th percentile in male and female participants (> 7.2 and > 5.4 mg/dL, respectively). The odds ratio (OR) for proteinuria increased with elevated SBP. This trend was significantly evident in participants with HU. Moreover, there was an interactive effect of SBP and HU on the prevalence of proteinuria in the male (Pfor interaction = 0.04) and female (Pfor interaction = 0.04) participants. Next, we evaluated the OR for low eGFR (< 60 mL/min/1.73 m2) with and without proteinuria based on the presence of HU. The multivariate analysis revealed that the OR for low eGFR with proteinuria increased with elevated SBP, but that for low eGFR without proteinuria decreased. These trends of OR tended to be prevalent among those with HU. The association between SBP and the prevalence of proteinuria was more pronounced in participants with HU. However, the association between SBP and decreased renal function with and without proteinuria might be different regardless of HU.

Prevalence of Hyperuricemia and Its Association with Cardiovascular Risk Factors and Subclinical Target Organ Damage

The role of uric acid levels in the cardiovascular continuum is not clear. Our objective is to analyze the prevalence of hyperuricemia (HU) and its association with cardiovascular risk factors (CVRF), subclinical target organ damage (sTOD), and cardiovascular diseases (CVD). We evaluated the prevalence of HU in 6.927 patients included in the baseline visit of the IBERICAN study. HU was defined as uric acid levels above 6 mg/dL in women, and 7 mg/dL in men. Using adjusted logistic regression models, the odds ratios were estimated according to CVRF, sTOD, and CVD. The prevalence of HU was 16.3%. The risk of HU was higher in patients with pathological glomerular filtration rate (aOR: 2.92), heart failure (HF) (aOR: 1.91), abdominal obesity (aOR: 1.80), hypertension (HTN) (aOR: 1.65), use of thiazides (aOR: 1.54), left ventricular hypertrophy (LVH) (aOR: 1.36), atrial fibrillation (AFIB) (aOR: 1.29), and albuminuria (aOR: 1.27). On the other hand, being female (aOR: 0.82) showed a reduced risk. The prevalence of HU was higher in men, in patients presenting CVRF such as HTN and abdominal obesity, and with co-existence of LVH, atrial fibrillation (AFIB), HF, and any form of kidney injury. These associations raise the possibility that HU forms part of the early stages of the cardiovascular continuum. This may influence its management in Primary Healthcare because the presence of HU could mean an increased CV risk in the patients.

Association between uric acid level and incidence of albuminuria in patients with type 2 diabetes mellitus: A 4.5-year cohort study

Using animal models and molecular biology researches, hyperuricemia has been shown to instruct renal arteriolopathy, arterial hypertension, and microvascular injury involving the renin-angiotensin system and resulting in renal function impairment. Nevertheless, the association between uric acid levels and the development of albuminuria has been under-investigated in patients with type 2 diabetes mellitus. Patients with type 2 diabetes and regular outpatient visits were recruited from the Puli Branch of the Taichung Veterans General Hospital in Taiwan since January 2014. Demographics, lifestyle features, and medical history were gathered by well-trained interviewers. All participants underwent comprehensive physical examinations, including a biochemical assay of venous blood specimens and urine samples after an 8-hour overnight fast. Participants were followed until June 2018. The primary outcome was the albuminuria incidence. Univariable and multivariable Cox regression analysis were employed to explore the relation between uric acid and incident albuminuria. Uric acid cutoffs for incident albuminuria were determined with the receiver operator characteristic curve. We included 247 qualified subjects (mean age: 64.78 years old [standard deviation = 11.29 years]; 138 [55.87%] men). During a 4.5-year follow-up duration, 20 subjects with incident albuminuria were recognized. Serum uric acid was significantly associated with an increased risk of incident albuminuria (adjusted hazard ratio = 2.39; 95% confidence interval: 1.53-3.75; P < .001) with potential confounders adjustment. The uric acid cutoff point was 6.9 mg/dL (area under the curve 0.708, sensitivity 60.0%, specificity 84.58%) for incident albuminuria. Serum uric acid was associated with incident albuminuria among patients with type 2 diabetes.

Short sleep duration increases the risk of hyperuricemia among Chinese adults: findings from the China Health and Nutrition Survey

STUDY OBJECTIVES

Hyperuricemia is a growing public health problem with its increasing prevalence. Few studies have investigated the association between sleep duration and hyperuricemia. The objective of this study is to explore whether short sleep duration is an independent risk factor of hyperuricemia in Chinese adults.

METHODS

The data we analyzed was extracted from the 2009 wave of the China Health and Nutrition Survey. The population we analyzed included 8289 participants aged 18 years or older with sleep of 5-10 h per 24 h. We categorized the population into three groups by sleep duration: 5-6 h (short sleeper),7-8 h (regular sleeper), and 9-10 h (long sleeper). Hyperuricemia was defined as serum uric acid ≥7 mg/dL in men and ≥6 mg/dL in women.

RESULTS

Among the three groups, 9.8% were short sleepers, 68.4% were regular sleepers and 21.8% were long sleepers. The prevalences of hyperuricemia were 19.5%,15.2% and 15.5% respectively. The risks of hyperuricemia in regular and long sleep groups were lower than short sleep group, and the association remained after adjusting for indexes including age, gender, chronic kidney disease, hypertension, diabetes mellitus, high low-density lipoprotein cholesterol (LDL-c), and obesity. In subgroup analysis, we found the association was still observed in participants without hypertension, diabetes mellitus or obesity.

CONCLUSIONS

Our findings suggest that short sleep duration is associated with higher risk of hyperuricemia independently of cardiometabolic risk factors, especially in individuals without traditional hyperuricemia risk factors.

Alcohol consumption and serum uric acid are synergistically associated with renal dysfunction among community-dwelling persons

Background

Serum uric acid (SUA) is a key risk factor contributing to renal failure, a serious public health problem. However, few studies have examined whether the interactive relationship between alcohol consumption and SUA is independently associated with the estimated glomerular filtration rate (eGFR).

Methods

Our sample comprised 742 men aged 69 ± 11 years (mean ± standard deviation) and 977 women aged 69 ± 10 years from a rural area. We cross‐sectionally examined the relationships between the confounding factors of alcohol consumption and SUA with renal function denoted by eGFR estimated using CKD‐EPI (Chronic Kidney Disease Epidemiology Collaboration) equations modified by a Japanese coefficient.

Results

In both genders, eGFR increased with a rise in alcohol consumption. This tendency was more pronounced in participants with hyperuricemia, where SUA was greater than 7.0 mg/dL in men and greater than 6.0 mg/dl in women (men: F = 41.98, p < 0.001; women: F = 41.98, p < 0.001). A multiple linear regression analysis showed that alcohol consumption (men: β = 0.112, p < 0.001; women: β = 0.060, p = 0.011) and SUA (men: β = −0.282, p < 0.001; women: β = 0.317, p < 0.001) were significantly and independently related to eGFR. Further, the interactive relationship between alcohol consumption and SUA (men: F = 6.388, p < 0.001; women: F = 5.368, p < 0.001) was a significant and independent indicator of eGFR.

Conclusions

These results suggested that alcohol consumption and SUA were synergistically associated with renal dysfunction among community‐dwelling persons.

Effect of Intensive Urate Lowering With Combined Verinurad and Febuxostat on Albuminuria in Patients With Type 2 Diabetes: A Randomized Trial

RATIONALE & OBJECTIVE

Hyperuricemia has been implicated in the development and progression of chronic kidney disease. Verinurad is a novel, potent, specific urate reabsorption inhibitor. We evaluated the effects on albuminuria of intensive urate-lowering therapy with verinurad combined with the xanthine oxidase inhibitor febuxostat in patients with hyperuricemia and type 2 diabetes mellitus (T2DM).

STUDY DESIGN

Phase 2, multicenter, prospective, randomized, double-blind, parallel-group, placebo-controlled trial.

SETTING & PARTICIPANTS

Patients 18 years or older with hyperuricemia, albuminuria, and T2DM.

INTERVENTION

Patients randomly assigned 1:1 to verinurad (9mg) plus febuxostat (80mg) or matched placebo once daily for 24 weeks.

OUTCOMES

The primary end point was change in urinary albumin-creatinine ratio (UACR) from baseline after 12 weeks' treatment. Secondary end points included safety and tolerability and effect on glomerular filtration.

RESULTS

60 patients were enrolled (n=32, verinurad and febuxostat; n=28, placebo). UACRs after treatment with verinurad plus febuxostat were lower than after placebo at 1, 12, and 24 weeks: -38.6% (90% CI, -60.9% to-3.6%), -39.4% (90% CI, -61.8% to-3.8%), and-49.3% (90% CI, -68.2% to-19.0%), respectively. Serum urate levels after treatment with verinurad plus febuxostat were 59.6% and 63.7% lower than after placebo at 12 and 24 weeks, respectively. No clinically meaningful changes were observed in estimated glomerular filtration rate or serum creatinine or serum cystatin C concentrations. Verinurad plus febuxostat was well tolerated.

LIMITATIONS

Sample size and study duration were insufficient to evaluate definitive effects of verinurad plus febuxostat on UACR and glomerular filtration. Generalizability was limited by exclusion of patients with stages 4 and 5 chronic kidney disease.

CONCLUSIONS

Verinurad plus febuxostat reduced albuminuria and lowered serum urate concentrations in patients with T2DM, albuminuria, and hyperuricemia. Definitive assessment of their combined impact on preservation of kidney function awaits larger clinical studies.

FUNDING

This study was supported by AstraZeneca.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT03118739.

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.

Changes in Urinary Microalbumin Levels after Correction of Hyperuricemia in Patients with Gout: An Observational Cohort Study

Background

Gout is commonly associated with metabolic syndrome. Strong association between the serum uric acid level and microalbuminuria has also been observed in various studies.

Aim

To observe the change in urinary microalbumin after urate-lowering treatment in patients with gout and microalbuminuria. Methodology. A prospective, observational study was conducted at a tertiary-level rheumatic center (NCRD) in Kathmandu, Nepal. Adults diagnosed with gout using the 2015 ACR/EULAR criteria and microalbuminuria were enrolled in the study after obtaining informed consent. Sociodemographic profile and clinical history were recorded at baseline. Serum uric acid levels, spot urinary microalbumin (MAU) excretion, blood sugar, lipid profile, and blood pressure were measured at baseline, 3-month follow-up, and 6-month follow-up. A paired t-test was used to compare the change in mean MAU after treatment.

Results

A total of 778 patients diagnosed with gout were screened for microalbuminuria. Among them, 114 (14.6%) had urinary microalbumin levels of >30.0 mg/L during presentation. Mean MAU level among those with microalbuminuria was 132.4 ± 124.6 mg/L. Thirty-five patients had concomitant HTN and were put on ARBs (20 mg of telmisartan). All received 40 mg of febuxostat. In patients with ARBs, MAU reduced significantly after 3 months of treatment with ARBs. Reduction in MAU in those without ARBs was seen after the 6-month follow-up, and the change was statistically significant.

Conclusions

There is significant reduction in MAU after the use of urate-lowering drugs in patients with gout.

Microalbuminuria mediates the association between serum uric acid and elevation of blood pressure: a longitudinal analysis in the Gusu cohort

OBJECTIVES

Although hyperuricemia, microalbuminuria, and hypertension are highly correlated, their temporal relationship is largely unknown. We aimed to examine whether microalbuminuria mediated the association between hyperuricemia and hypertension.

METHODS

Leveraging a longitudinal cohort including 1981 Chinese adults who had blood pressures, urinary albumin to creatinine ratio (UACR), and uric acid measured twice 4 years apart, we examined the temporal relationships among hyperuricemia, microalbuminuria, and hypertension by cross-lagged panel analysis followed by a causal mediation analysis to confirm the temporal consequence. Age, sex, education level, cigarette smoking, alcohol consumption, obesity, blood glucose, and lipids were adjusted.

RESULTS

The cross-lagged panel analysis demonstrated that the relationship from baseline UACR to follow-up uric acid was significantly smaller than that from baseline uric acid to follow-up UACR (β: 0.010 vs. 0.054, P < 0.001). The relationships from baseline blood pressures to follow-up UACR were also significantly smaller than that from baseline UACR to follow-up blood pressures (β: 0.031 vs. 0.092, P < 0.001 for systolic and β: 0.015 vs. 0.096, P < 0.001 for diastolic). The causal mediation analysis found that UACR partially mediated the association of baseline uric acid with follow-up SBP (mediate proportion: 9.14%, 95% CI: 1.58-23.00%) and DBP (mediate proportion: 7.38%, 95% CI: 1.05-19.00%).

CONCLUSION

Microalbuminuria may follow elevated uric acid and partially mediate its effect on future risk of hypertension in Chinese adults.

Gender-specific association between uric acid level and chronic kidney disease in the elderly health checkup population in China

Objective: To evaluate the association between serum uric acid (SUA) levels with CKD in elderly health checkup population and explore the gender difference.

Methods: A total of 4242 subjects were included in the cross-sectional study. All of the subjects participated in the annual checkup between June 2016 and June 2017. Chronic kidney disease (CKD) was defined by estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m². We examined the association between SUA levels and CKD. Multivariate binary logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) by comparing association between the SUA level and CKD. The models were adjusted for age, gender, body mass index (BMI), hypertension, diabetes, triglyceride and high-density lipoprotein cholesterol (HDL-C).

Result: The prevalence of hyperuricemia was 22.2%, and it was significantly higher in male than in female (25.2% vs. 17%, p < .001). The prevalence of hyperuricemia increased with age, especially in the female. The prevalence of CKD was 27.8% in male and 20.2% in female (p < .001). Compared with the SUA first quartile, the multivariate-adjusted odds for CKD of fourth quartiles were 6.05 (95%CI: 4.32–8.49) in male and 8.21(95%CI: 5.37–12.54) in female.

Conclusion: Our finding showed gender-specific differences in the association between high SUA and an increased risk of CKD in the elderly population. The association of SUA and CKD was independent of other potential confounding factors including age, glucose, hypertension, HDL, TG and BMI.

High Serum Uric Acid Is Associated with Tubular Damage and Kidney Inflammation in Patients with Type 2 Diabetes

Background

Uric acid presents different roles in an organism. High serum uric acid concentrations may induce inflammatory pathways and promote kidney damage through different mechanisms. Therefore, this study investigated the association among high serum uric acid concentrations, renal tubular damage, and renal inflammation assessed via estimation of urinary kidney injury molecule-1 (KIM-1) and inflammatory cytokines in patients with type 2 diabetes (T2D).

Methods

Urinary concentrations of KIM-1, IL-1, IL-6, IL-10, and TNF-alpha, as well as other biochemical parameters, were assessed in 125 patients with T2D who were grouped into two groups based on the serum uric acid levels (<6.0 mg/dL and ≥6.0 mg/dL). Patients were also stratified according to the tertiles of serum uric acid concentrations.

Results

Urinary KIM-1, IL-1, IL-6, and TNF-alpha were higher in patients with serum uric acid concentrations ≥ 6.0 mg/dL. However, the differences between the groups were not statistically significant when the urinary values of KIM-1 and cytokines were normalized by the urinary creatinine concentration. Serum uric acid concentrations were significantly associated with urinary KIM-1 (values normalized by urinary creatinine concentration) and urinary TNF-alpha (absolute values and values normalized by urinary creatinine concentration), independent of the body mass index (BMI) and estimated glomerular filtration rate (eGFR).

Conclusions

High serum uric acid concentrations were associated with high urinary KIM-1 levels accompanied by the increase of urinary proinflammatory cytokines in patients with T2D. However, normalization of urinary markers by urine creatinine concentration seems to influence the profile of the results.

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 incident chronic kidney disease in dyslipidemic individuals

BACKGROUND

Elevated uric acid (UA) is a recognized risk factor for chronic kidney disease (CKD). This study aimed to investigate whether this association exists in dyslipidemic patients receiving multifactorial treatment.

METHODS

An observational study conducted in Greece including 1,269 dyslipidemic individuals followed-up in a lipid clinic for ≥3 years. Estimated glomerular filtration rate (eGFR) was calculated by CKD-EPI equation and CKD was defined as ≤60 mL/min/1.73 m². The correlation was assessed between UA levels and the CKD risk after adjusting for potential confounding factors, after defining the following UA quartiles: Q1: < 4, Q2: 4-5, Q3: 5-6, and Q4: > 6 mg/dL.

RESULTS

After excluding patients with baseline eGFR <60 mL/min/1.73 m², gout and those taking UA-lowering drugs, 1,095 individuals were eligible; of those, 91% and 69% were treated with statins and anti-hypertensive drugs, respectively. During their follow-up (6 years; IQR = 4-10), 11.9% of the subjects developed CKD, whereas the median annual eGFR decline was 0.69 mL/min/1.73 m² (IQR = 0.45-2.33). Multivariate analysis showed that baseline UA levels (HR = 1.26; 95% CI = 1.09-1.45, p = .001), female gender (HR = 1.74; 95% CI = 1.14-2.65, p = .01), age (HR = 1.10; 95% CI = 1.07-1.12, p < .001), diabetes (HR = 1.67; 95% CI = 1.05-2.65, p = .03), cardiovascular disease (HR = 1.62; 95% CI = 1.02-2.58, p = .04), decreased baseline renal function (eGFR <90 mL/min/1.73 m²) (HR = 2.38; 95% CI = 1.14-4.81, p = .02), and low-density lipoprotein cholesterol reduction (HR = 0.995; 95% CI = 0.991-0.998, p = .01) were associated with incident CKD. Additionally, patients with UA ≥6 mg/dL exhibited a higher risk of incident CKD compared with those in the lowest UA quartile (HR = 2.01; 95% CI = 1.11-3.65, p = .02).

CONCLUSION

Higher UA levels are correlated with a higher risk of incident CKD in dyslipidemic individuals taking multifactorial treatment.

Association of serum uric acid with nephropathy in Iranian type 2 diabetic patients

Background

Diabetic nephropathy (DN) is the major cause of end-stage renal disease. Recent studies suggest that it is probable that uric acid is involved in the pathogenesis of diabetic nephropathy. This study aim was to investigate the association between serum uric acid and kidney function in Iranian patients with type 2 diabetes mellitus.

Methods

In this case-control study, a total of 201 diabetic patients with or without impaired kidney function (glomerular filtration rate/GFR < 60 and GFR ≥ 60) were selected. In both groups, serum fasting glucose (FBS), HbA1c, urea, creatinine, uric acid and lipid profile, urine albumin and GFR were measured and results were compared between the two groups. The results also categorized into three groups based on uric acid tertiles.

Results

Serum levels of uric acid, urea and creatinine as well as urine albumin/creatinine ratio (ACR) were significantly different between the two groups. GFR, creatinine and also urea were significantly different between uric acid tertiles (p < 0.05).

Conclusions

Serum uric acid is associated with decreased GFR as well as albuminuria and can be used as an indicator of DN.

Functional and Structural Characterization of Purine Nucleoside Phosphorylase from Kluyveromyces lactis and Its Potential Applications in Reducing Purine Content in Food

Consumption of foods and beverages with high purine content increases the risk of hyperuricemia, which causes gout and can lead to cardiovascular, renal, and other metabolic disorders. As patients often find dietary restrictions challenging, enzymatically lowering purine content in popular foods and beverages offers a safe and attractive strategy to control hyperuricemia. Here, we report structurally and functionally characterized purine nucleoside phosphorylase (PNP) from Kluyveromyces lactis (KlacPNP), a key enzyme involved in the purine degradation pathway. We report a 1.97 Å resolution crystal structure of homotrimeric KlacPNP with an intrinsically bound hypoxanthine in the active site. KlacPNP belongs to the nucleoside phosphorylase-I (NP-I) family, and it specifically utilizes 6-oxopurine substrates in the following order: inosine > guanosine > xanthosine, but is inactive towards adenosine. To engineer enzymes with broad substrate specificity, we created two point variants, KlacPNP^N256D and KlacPNP^N256E, by replacing the catalytically active Asn256 with Asp and Glu, respectively, based on structural and comparative sequence analysis. KlacPNP^N256D not only displayed broad substrate specificity by utilizing both 6-oxopurines and 6-aminopurines in the order adenosine > inosine > xanthosine > guanosine, but also displayed reversal of substrate specificity. In contrast, KlacPNP^N256E was highly specific to inosine and could not utilize other tested substrates. Beer consumption is associated with increased risk of developing gout, owing to its high purine content. Here, we demonstrate that KlacPNP and KlacPNP^N256D could be used to catalyze a key reaction involved in lowering beer purine content. Biochemical properties of these enzymes such as activity across a wide pH range, optimum activity at about 25°C, and stability for months at about 8°C, make them suitable candidates for food and beverage industries. Since KlacPNP^N256D has broad substrate specificity, a combination of engineered KlacPNP and other enzymes involved in purine degradation could effectively lower the purine content in foods and beverages.

Serum Uric Acid as a Risk Factor for Chronic Kidney Disease in a Japanese Community - The Hisayama Study

BACKGROUND

Growing evidence suggests that high serum uric acid (SUA) levels are causally related to increased risk of chronic kidney disease (CKD). However, few studies have investigated the influence of elevated SUA levels on the incidence of kidney dysfunction and albuminuria separately in community-based populations.

METHODS AND RESULTS

A total of 2,059 community-dwelling Japanese subjects aged ≥40 years without CKD were followed for 5 years. CKD was defined as kidney dysfunction (estimated glomerular filtration rate <60 ml/min/1.73 m(2)) or albuminuria (urine albumin-creatinine ratio ≥30 mg/g). The odds ratio (OR) for the development of CKD was estimated according to quartiles of SUA (≤4.0, 4.1-4.9, 5.0-5.8, and ≥5.9 mg/dl). During the follow-up, 396 subjects developed CKD, of whom 125 had kidney dysfunction and 312 had albuminuria. The multivariable-adjusted risk of developing CKD increased with higher SUA levels (OR 1.00 [reference] for ≤4.0, 1.21 [95% confidence interval, 0.84-1.74] for 4.1-4.9, 1.47 [1.01-2.17] for 5.0-5.8, and 2.10 [1.37-3.23] for SUA ≥5.9 mg/dl, respectively). Similarly, there were positive associations between SUA level and the adjusted risk of developing kidney dysfunction (OR 1.00 [reference], 2.30 [1.10-4.82], 2.81 [1.34-5.88], and 3.73 [1.65-8.44]) and albuminuria (1.00 [reference], 1.12 [0.76-1.65], 1.35 [0.90-2.03], and 1.81 [1.14-2.87], respectively).

CONCLUSIONS

Higher SUA levels were a significant risk factor for the development of both kidney dysfunction and albuminuria in a general Japanese population. (Circ J 2016; 80: 1857-1862).

The impact of serum uric acid on the natural history of glomerular filtration rate: a retrospective study in the general population

Serum uric acid (SUA) level has been proposed to have important connections with chronic kidney disease (CKD), while the impact of SUA level on the natural history of glomerular filtration rate (GFR) decline remains unknown. The present study aims to study the association of the SUA level with the GFR decline in a general population. Two thousand, seven hundred and eighty-nine subjects who visited the Health Checkup Clinic both at 2008 and 2013 were identified. A significant inverse correlation was observed between change in SUA from 2008–2013 (ΔSUA) and change in eGFR (ΔeGFR) during the same period. Multivariate regression analysis of ΔeGFR indicated that the increase in SUA over time were a negative predictor of the change in eGFR. Our result indicates that the decline of eGFR over years is larger in subjects with an increased SUA level, which helps to underline the importance of SUA level management in the context of kidney function preservation.

Efficacy of Febuxostat for Slowing the GFR Decline in Patients With CKD and Asymptomatic Hyperuricemia: A 6-Month, Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Hyperuricemia is a putative risk factor for the progression of chronic kidney disease (CKD). We hypothesized that control of asymptomatic hyperuricemia may slow disease progression in CKD.

STUDY DESIGN

This was a single-center, double-blind, randomized, parallel-group, placebo-controlled study.

SETTING & PARTICIPANTS

Eligible participants were adults from Eastern India aged 18 to 65 years with CKD stages 3 and 4, with asymptomatic hyperuricemia.

INTERVENTION

The intervention group received febuxostat, 40mg, once daily for 6 months, while the placebo group received placebo; both groups were followed up for 6 months.

OUTCOMES

The primary outcome was the proportion of patients showing a >10% decline in estimated glomerular filtration rate (eGFR) from baseline in the febuxostat and placebo groups. Secondary outcomes included changes in eGFRs in the 2 groups from baseline and at the end of the study period.

RESULTS

45 patients in the febuxostat group and 48 in the placebo group were analyzed. Mean eGFR in the febuxostat group showed a nonsignificant increase from 31.5±13.6 (SD) to 34.7±18.1mL/min/1.73m(2) at 6 months. With placebo, mean eGFR decreased from a baseline of 32.6±11.6 to 28.2±11.5mL/min/1.73m(2) (P=0.003). The difference between groups was 6.5 (95% CI, 0.08-12.81) mL/min/1.73m(2) at 6 months (P=0.05). 17 of 45 (38%) participants in the febuxostat group had a >10% decline in eGFR over baseline compared with 26 of 48 (54%) from the placebo group (P<0.004).

LIMITATIONS

Limitations of this study included small numbers of patients and short follow-up, and ∼10% of the randomly assigned population dropped out prior to completion.

CONCLUSIONS

Febuxostat slowed the decline in eGFR in CKD stages 3 and 4 compared to placebo.

Is hyperuricemia an independent risk factor for new-onset chronic kidney disease?: A systematic review and meta-analysis based on observational cohort studies

BACKGROUND

Hyperuricemia has been reported to be associated with chronic kidney disease (CKD). However whether an elevated serum uric acid level is an independent risk factor for new-onset CKD remained controversial.

METHODS

A systematic review and meta-analysis using a literature search of online databases including PubMed, Embase, Ovid and ISI Web/Web of Science was conducted. Summary adjusted odds ratios with corresponding 95% confidence intervals (95% CI) were calculated to evaluate the risk estimates of hyperuricemia for new-onset CKD.

RESULTS

Thirteen studies containing 190,718 participants were included. A significant positive association was found between elevated serum uric acid levels and new-onset CKD at follow-up (summary OR, 1.15; 95% CI, 1.05-1.25). Hyperuricemia was found be an independent predictor for the development of newly diagnosed CKD in non-CKD patients (summary OR, 2.35; 95% CI, 1.59-3.46). This association increased with increasing length of follow-up. No significant differences were found for risk estimates of the associations between elevated serum uric acid levels and developing CKD between males and females.

CONCLUSIONS

With long-term follow-up of non-CKD individuals, elevated serum uric acid levels showed an increased risk for the development of chronic renal dysfunction.

Three-year incidence of elevated albuminuria and associated factors in a population-based cohort: The Taichung Community Health Study

BACKGROUND

early-stage elevated albuminuria can be effectively detected by a spot urine albumin-to-creatinine ratio (UACR). Elevated albuminuria is a key predictor of diabetic nephropathy, progression to chronic kidney disease (CKD) or end-stage renal disease (ESRD), plus risk of cardiovascular disease (CVD) and mortality. Understanding these detectors may prevent future renal and cardiovascular disease. This study estimates three-year incidence in a representative sample of Taiwanese metropolitan adults to explore predictors.

METHODS

the Taichung Community Health Study (TCHS) is a representative sample of 2359 Chinese adults aged 40 years and over living in a metropolitan city during 2004-2005. In 2007-2009, a total of 1648 (71.3%) individuals participated in follow-up. This study includes only individuals with normal albumin excretion at baseline examination. Three-year incidence and baseline factors linked with elevated albuminuria were evaluated.

RESULTS

about 87.0% (n = 1434) of subjects exhibited normal albumin excretion at baseline. Three-year age- and gender-weighted incidence was 4.5% (95% CI: 3.4-5.6%). Multivariate logistic regression showed subjects with elevated waist-to-hip ratio (WHR) (OR: 2.2, 95% CI: 1.2-3.9), abnormal creatinine (OR: 3.7, 95% CI: 1.1-12.6), hyperuricaemia (OR: 1.8, 95% CI: 1.0-3.3) and elevated baseline UACR (OR: 4.0, 95% CI: 1.1-14.3 for UACR of 3.20-6.39 mg/g; OR: 16.7, 95% CI: 5.0-55.5 for UACR of 6.40-29.99 mg/g) were more likely to have elevated albuminuria.

CONCLUSIONS

this is the first population-based longitudinal study to rate incidence of elevated albuminuria and identify associated factors in a random sample of a Chinese population. Central obesity, renal function, hyperuricaemia and baseline UACR are independent risk factors.

Serum uric acid concentration and asymptomatic hyperuricemia with subclinical organ damage in general population

We assessed the effect of increased serum uric acid (SUA) concentration and hyperuricemia on subclinical organ damage. A cross-sectional examination of 1243 asymptomatic patients aged 55 to 84 years was conducted from September to October 2012. All participants underwent the measurements of SUA and other established cardiovascular (CV) risk factors. A morning spot urine sample was collected to detect microalbuminuria, and carotid plaque was scanned by B-mode ultrasound; the cardioankle vascular index and ankle-brachial index were obtained to evaluate arterial stiffness and peripheral artery disease (PAD), respectively. After adjustment for established CV risk factors, multiple logistic regression analyses showed that the highest quartile of SUA concentration and hyperuricemia had an independent association with PAD (respective odds ratios: 3.86 [1.26-11.83] and 2.33 [1.14-4.77]); this association maintained significantly in males but disappeared in females. Serum uric acid concentration and hyperuricemia are significantly associated with PAD in males.