Use of allopurinol in slowing the progression of renal disease through its ability to lower serum uric acid level

Elevated uric acid level and metabolic syndrome in Non-Hispanic Black American adults

Objectives

To ascertain the direct and indirect link between elevated uric acid (eUA) and metabolic syndrome (MetSyn) in Non-Hispanic Black (NHB) American adults.

Design

Structural equation modeling (SEM) was used to disentangle the U.S. National Health and Nutritional Examination Survey (2015-2018 NHANES) dataset and investigate the connection between eUA and components of MetSyn as per the criteria from the National Cholesterol Education Program (NCEP) Adult Treatment Panel III. The association between eUA and MetSyn was determined using odds ratios from sex-specific multivariable logistic regression analysis. The analysis was adjusted for age, physical activity, alcohol use, and smoking. SEM coefficients were used to measure the strength of the link between eUA and MetSyn components.

Results

NHB American men with eUA had 1.41-fold greater odds of MetSyn, and NHB American women with eUA had 2.70-fold greater odds of MetSyn after adjusting for confounding factors. Elevated uric acid was more strongly and directly linked to abdominal obesity (β = 0.320, p < 0.01) in NHB American men, and with abdominal obesity (β = 0.423, p < 0.01), dyslipidemia (β = 0.151, p < 0.01) and hypertension (β = 0.121, p < 0.01) in NHB American women than between eUA and other components of MetSyn.

Conclusions

This study's finding linking eUA to MetSyn components in NHB American adults needs reaffirmation through a robust prospective study design. If validated, eUA could help predict and prevent MetSyn in NHB American adults.

Molecular mechanisms of Lycii Fructus (Goji berries) against xanthine dehydrogenase in hyperuricemia management: Integrating computational, metabolomic, and experimental approaches

Lycii Fructus (LF), commonly known as Goji berries, has shown potential for managing hyperuricemia, though its underlying mechanisms remain poorly understood. This study employs a combination of network-based systems pharmacology, computer-aided drug discovery, untargeted metabolomics and experiments to explore the urate-lowering effects of LF. Molecular docking simulations of 3,760 LF compound-target interactions identified xanthine dehydrogenase (XDH) as a key target. Among the compounds, glycitein exhibited the highest binding affinity in molecular dynamics simulations. Metabolomics confirmed the presence of glycitein in LF particles, and it significantly reduced urate levels in hyperuricemia zebrafish models. Further in vitro assays and Cellular Thermal Shift Assays corroborated its inhibitory effect on xanthine oxidase. These findings suggest that glycitein may serve as a novel inhibitor of xanthine oxidase, with potential applications in nutraceuticals, functional foods, and drug development for hyperuricemia.

Assessment of Vertebral Bone Marrow Perfusion, Fat/Water Content, and Trabecular Bone Changes Using Multimodal MRI and Micro-CT in a Rat Model of Chronic Kidney Disease

Background

Disturbances in calcium and phosphorus homeostasis resulting from chronic kidney disease (CKD) may lead to atherosclerotic changes in blood vessels, potentially altering bone marrow perfusion. Our study aimed to investigate vertebral bone marrow perfusion using dynamic contrast-enhanced (DCE) MRI with a pharmacokinetic model. We also measured possible changes in water and fat content and bony trabeculae using T2* quantification, MR spectroscopy (MRS), and microcomputed tomography (μCT).

Methods

Twelve rats were randomly separated into a normal control group and a CKD (5/6 nephrectomy) group. Their lumbar spines were imaged, with monitoring of the L5 vertebral body conducted at 0, 8, 16, 30, and 43 weeks. After Week 43, all rats were sacrificed, and histologic changes were correlated with MRI and μCT results.

Results

The CKD group demonstrated significantly lower A and k el values (p < 0.05), significantly increased T2* values (p < 0.05), significantly decreased fat content and trabeculation (p < 0.05), sinusoidal dilatation, and decreased adipocytes in the vertebral bone marrow.

Conclusion

Using quantitative MRI and μCT to assess CKD-related arthropathy of the vertebral body is feasible. Lumbar spine bone marrow perfusion deficiency in experimental CKD may be associated with decreased fat content, increased water content, and sparse trabeculation.

Associations of Serum Urate and Cardiovascular Events in a Clinical Trial of Interleukin-1β Blockade

BACKGROUND

Serum urate (SU) associates with cardiovascular (CV) events, mortality, and gout.

OBJECTIVES

The purpose of this study was to assess whether SU predicts CV risk in a trial of interleukin (IL)-1β inhibition with canakinumab, and whether IL-1β blockade, kidney function, or gout alter these associations.

METHODS

This study is a subanalysis of the Canakinumab Antiinflammatory Thrombosis Outcome Study (CANTOS), which randomized 10,061 patients with prior myocardial infarction and elevated high-sensitivity C-reactive protein to 3 doses of canakinumab or placebo. SU was measured at baseline. Cox proportional hazards models compared major adverse cardiovascular events (MACE), CV death, and all-cause mortality among those with SU ≤6.8 mg/dL (normal), 6.8 to 9.0 mg/dL (elevated), and ≥9.0 mg/dL (markedly elevated). Cox regressions were repeated within subgroups, including canakinumab vs placebo, estimated glomerular filtration rate ≥60 vs <60 mL/min, and gout vs no gout.

RESULTS

Markedly elevated SU associated with MACE (HR: 1.66 [95% CI: 1.38-1.99]; P < 0.0001), CV death (HR: 2.52 [95% CI: 1.98-3.21]; P < 0.0001), and all-cause mortality (HR: 2.43 [95% CI: 2.01-2.94]; P < 0.0001) compared to normal SU. After multivariable adjustment for a minimal set of potential confounders, SU independently predicted all 3 endpoints. Associations were unchanged after IL-1β blockade with canakinumab. For normal estimated glomerular filtration rate, SU associated with CV and all-cause mortality, but not MACE. Participants with gout had higher event rates independent of SU.

CONCLUSIONS

In over 10,000 patients with coronary artery disease, individuals with markedly elevated SU have elevated CV risk despite aggressive treatment. IL-1β blockade did not modify these associations. Baseline kidney function and monosodium urate deposition may function as effect modifiers.

Association between mixed venous oxygen saturation and serum uric acid levels in patients with heart failure

Hypoxia leads to increased purine metabolism in tissues, resulting in increased serum uric acid levels, and may also cause impaired uric acid excretion in the kidneys and intestinal tract. However, the relationship between hypoxia and serum uric acid levels in patients with heart failure remains largely unexplored. Because mixed venous oxygen saturation is an acute indicator of systemic oxygenation, in this study, we investigated the relationship between mixed venous oxygen saturation and serum uric acid levels. This retrospective analysis included 386 patients with heart failure who underwent cardiac catheterization at our institution. The relationship between mixed venous oxygen saturation and serum uric acid levels was examined by single regression analysis. Stratified regression analysis, structural equation modeling, and partial correlation analysis were used to examine the effects of eight factors known to influence mixed venous oxygen saturation and serum uric acid levels. The single regression analysis showed a significant negative correlation between mixed venous oxygen saturation and serum uric acid levels (P<0.001). Significant negative correlations were also observed in many subgroups in the stratified analysis, in the path diagram based on structural equation modeling, and in the partial correlation analysis. These results suggest that there may be a direct relationship between mixed venous oxygen saturation and serum uric acid levels that is not mediated by any known factor.

Target Serum Urate Achievement and Chronic Kidney Disease Progression in Patients With Gout and Kidney Disease

Importance

Clinicians often approach urate-lowering therapy (ULT) cautiously in patients with gout and impaired kidney function because they are concerned about the risk of progression to severe or end-stage kidney disease. However, evidence from randomized clinical trials of this association remains inconclusive.

Objective

To evaluate the association between achieving target serum urate level with ULT and progression of chronic kidney disease (CKD) to severe or end-stage in patients with gout and impaired kidney function.

Design, Setting, and Participants

This was a cohort study using the target trial emulation approach using data from a general practice database (IQVIA Medical Research Database) for 2000 to 2023. Eligible patients were 40 to 89 years old and had gout and CKD stage 3. Data analyses were performed from November 2023 to September 2024.

Exposures

Lowering serum urate level to target level (<6 mg/dL) using ULT.

Main Outcomes and Measures

Severe or end-stage kidney disease, determined by an estimated glomerular filtration rate of less than 30 mL/min/1.73 m2 on at least 2 occasions more than 90 days apart within 1 year, or at least 1 Read code (per the Refined Etiology, Anatomical Site, and Diagnosis classification) for CKD stages 4 or 5, hemodialysis, peritoneal dialysis, or kidney transplant. The prespecified noninferiority margin of the hazard ratio (HR) was set at 1.2, comparing those who achieved the target serum urate level with those who did not.

Results

Among the 14 792 participants (mean [SD] age, 73.1 [9.5] years; 9215 men [62.3%] and 5577 women [37.7%]) with gout and with CKD stage 3, the 5-year risk of severe or end-stage kidney disease was 10.32% for those who achieved the target serum urate level and 12.73% for those who did not. Compared with those not achieving the target level, the adjusted 5-year risk difference and HR of severe or end-stage kidney disease for patients achieving the target serum urate level was -2.41% (95% CI, -4.61% to -0.21%) and 0.89 (95% CI, 0.80 to 0.98), respectively.

Conclusions and Relevance

The findings of this cohort study indicate that in patients with gout and CKD stage 3, lowering serum urate level to less than 6 mg/dL vs 6 mg/dL or greater using ULT was not associated with an increased risk of severe or end-stage kidney disease. These findings support optimizing ULT to achieve target serum urate levels when treating patients with gout and impaired kidney function.

Uric Acid and Atherosclerosis in Patients with Chronic Kidney Disease: Recent Progress, Mechanisms, and Prospect

Background

Chronic kidney disease (CKD) is a prevalent global health concern, significantly linked to increased cardiovascular morbidity and mortality. Among various risk factors, uric acid (UA) has emerged as a potentially modifiable contributor to cardiovascular complications in CKD patients.

Summary

Elevated serum uric acid levels frequently occur in individuals with CKD and are associated with the development of atherosclerosis (AS). Uric acid has been demonstrated to exacerbate inflammatory processes, promote oxidative stress, and cause endothelial dysfunction, which are critical factors that drive the formation of atherosclerotic plaques. Furthermore, high uric acid levels can worsen renal function, establishing a detrimental cycle that amplifies cardiovascular risk.

Key Messages

This review investigates the complex interconnection between UA and AS in patients with CKD, highlighting the underlying mechanisms and therapeutic considerations. A more profound comprehension of this relationship is essential for enhancing cardiovascular health and outcomes in this vulnerable population.

Multicenter randomized controlled trial of intensive uric acid lowering therapy for CKD patients with hyperuricemia: TARGET-UA

BACKGROUND

We investigate whether Intensive uric acid (UA)-lowering therapy (ULT) provides increased renal protection compared with standard therapy in chronic kidney disease (CKD) patients.

METHODS

This was a multicenter randomized controlled trial. Only CKD patients with hyperuricemia were included in this study. The participants were randomly assigned to either the Intensive therapy group (target serum UA level ≥ 4.0 mg/dL and < 5.0 mg/dL) or the standard therapy group (serum UA level ≥ 6.0 mg/dL and < 7.0 mg/dL). ULT was performed using topiroxostat, a non-purine-type selective xanthine oxidase inhibitor. The primary endpoint was change in the logarithmic value of urine albumin to the creatinine ratio (ACR) between baseline and week 52 of the treatment.

RESULTS

Three hundred fifty-two patients were included in the full analysis set. In the Standard therapy group, mean serum UA was 8.23 mg/dL at baseline and 6.13 mg/dL at 52 weeks. In the Intensive therapy group, mean serum UA was 8.15 mg/dL at baseline and 5.25 mg/dL at 52 weeks. There was no significant difference in changes in log ACR at 52 weeks between the Intensive therapy and the Standard therapy groups.

CONCLUSION

This study did not reveal the benefit of Intensive ULT to improve albuminuria levels. (UMIN000026741 and jRCTs051180146).

Hyperuricemia: An Intriguing Connection to Metabolic Syndrome, Diabetes, Kidney Disease, and Hypertension

PURPOSE OF THE REVIEW

Our review explores the epidemiology, physiology, and clinical data surrounding the connection between hyperuricemia and metabolic syndrome, chronic kidney disease, and hypertension.

RECENT FINDINGS

Compelling physiologic mechanisms have been proposed to explain a causal relationship between hyperuricemia and metabolic syndrome, chronic kidney disease, and hypertension but clinical studies have given mixed results in terms of whether intervening with hyperuricemia using urate-lowering therapy has any beneficial effects for patients with these conditions. Despite the large amount of research already put into this topic, more randomized placebo-controlled trials are needed to more firmly establish whether a cause-effect relationship exists and whether lowering uric acid levels in patients with these conditions is beneficial.

Association of serum uric acid with all-cause and cardiovascular mortality in chronic kidney disease stages 3-5

BACKGROUND AND AIMS

The role of serum uric acid (SUA) in the prognosis of chronic kidney disease (CKD) is inconclusive. To explore the association of SUA level with all-cause and cardiovascular disease (CVD) mortality in patients with CKD.

METHODS AND RESULTS

Leveraging data from the National Health and Nutritional Examination Survey (NHANES) and linked national death records up to December 31 2019, we explored the association of SUA with all-cause and CVD mortality using weighted cox proportional hazards regression models and restricted cubic spline (RCS) models in patients with CKD stages 3-5. The study finally included 2644 patients with CKD stages 3-5, with a median SUA level of 6.5 mg/dL. After a median follow-up of 55 months, a total of 763 deaths were recorded, with 279 of them attributed to CVD. In the fully adjusted model, per 1 mg/dL increment in SUA concentration was found to be associated with increased HRs (95% CIs) of 1.07 (1.00, 1.14) for all-cause mortality and 1.11 (1.00, 1.24) for CVD mortality. Compared to Q2 (reference), those in Q4 had adjusted HRs of 1.72 (1.36, 2.17) for all-cause mortality and 2.17 (1.38, 3.41) for CVD mortality, while those in Q1 had adjusted HRs of 1.49 (1.19, 1.85) for all-cause mortality and 1.93 (1.26, 2.98) for CVD mortality.

CONCLUSIONS

Both higher and lower SUA levels were associated with increased risks of all-cause and CVD mortality in patients with CKD stages 3-5.

Assessment of Bitterness in Non-Charged Pharmaceuticals with a Taste Sensor: A Study on Substances with Xanthine Scaffold and Allopurinol

Taste sensors with an allostery approach have been studied to detect non-charged bitter substances, such as xanthine derivatives, used in foods (e.g., caffeine) or pharmaceuticals (e.g., etofylline). In this study, the authors modified a taste sensor with 3-bromo-2,6-dihydroxybenzoic acid and used it in conjunction with sensory tests to assess the bitterness of non-charged pharmaceuticals with xanthine scaffolds (i.e., acefylline and doxofylline), as well as allopurinol, an analogue of hypoxanthine. The results show that the sensor was able to differentiate between different levels of sample bitterness. For instance, when assessing a 30 mM sample solution, the sensor response to acefylline was 34.24 mV, which corresponded to the highest level of bitterness (τ = 3.50), while the response to allopurinol was lowest at 2.72 mV, corresponding to relatively weaker bitterness (τ = 0.50). Additionally, this study extended the application of the sensor to detect pentoxifylline, an active pharmaceutical ingredient in pediatric medicines. These results underscore the taste sensor's value as an additional tool for early-stage assessment and prediction of bitterness in non-charged pharmaceuticals.

Uric acid in health and disease: From physiological functions to pathogenic mechanisms

Owing to renal reabsorption and the loss of uricase activity, uric acid (UA) is strictly maintained at a higher physiological level in humans than in other mammals, which provides a survival advantage during evolution but increases susceptibility to certain diseases such as gout. Although monosodium urate (MSU) crystal precipitation has been detected in different tissues of patients as a trigger for disease, the pathological role of soluble UA remains controversial due to the lack of causality in the clinical setting. Abnormal elevation or reduction of UA levels has been linked to some of pathological status, also known as U-shaped association, implying that the physiological levels of UA regulated by multiple enzymes and transporters are crucial for the maintenance of health. In addition, the protective potential of UA has also been proposed in aging and some diseases. Therefore, the role of UA as a double-edged sword in humans is determined by its physiological or non-physiological levels. In this review, we summarize biosynthesis, membrane transport, and physiological functions of UA. Then, we discuss the pathological involvement of hyperuricemia and hypouricemia as well as the underlying mechanisms by which UA at abnormal levels regulates the onset and progression of diseases. Finally, pharmacological strategies for urate-lowering therapy (ULT) are introduced, and current challenges in UA study and future perspectives are also described.

Effect of uric acid reduction on chronic kidney disease. Systematic review and meta-analysis

Accumulating evidence suggests that hyperuricemia is a pathological factor in the development and progression of chronic kidney disease. However, the potential benefit afforded by the control of uric acid (UA) is controversial. Individual studies show discrepant results, and most existing meta-analysis, especially those including the larger number of studies, lack a placebo or control group as they aim to compare efficacy between drugs. On these grounds, we performed a me-ta-analysis restricted to studies including the action of any anti-gout therapies referenced to a control or placebo arm. This approach allows for a clearer association between UA reduction and renal effect. Of the twenty-nine papers included, most used allopurinol and febuxostat and, therefore, solid conclusions could only be obtained for these drugs. Both were very effective in reducing UA, but only allopurinol was able to significantly improve glomerular filtration rate (GFR), although not in a dose-dependent manner. These results raised doubts as to whether it is the hypouricemic effect of anti-gout drugs, or a pleiotropic effect, what provides protection of kidney function. Accordingly, in a correlation study that we next performed between UA reduction and GFR improvement, no association was found, which suggests that additional mechanisms may be involved. Of note, most trials show large inter-individual response variability, probably because they included patients with heterogeneous phenotypes and pathological characteristics, including different stages of CKD and comorbidities. This highlights the need to sub classify the effect of UA-lowering therapies according to the pathological scenario, in order to identify those CKD patients that may benefit most from them. Systematic Review Registration: CRD42022306646 https://www.crd.york.ac.uk/prospero/.

A Possible Therapeutic Application of the Selective Inhibitor of Urate Transporter 1, Dotinurad, for Metabolic Syndrome, Chronic Kidney Disease, and Cardiovascular Disease

The reabsorption of uric acid (UA) is mainly mediated by urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidneys. Dotinurad inhibits URAT1 but does not inhibit other UA transporters, such as GLUT9, ATP-binding cassette transporter G2 (ABCG2), and organic anion transporter 1/3 (OAT1/3). We found that dotinurad ameliorated the metabolic parameters and renal function in hyperuricemic patients. We consider the significance of the highly selective inhibition of URAT1 by dotinurad for metabolic syndrome, chronic kidney disease (CKD), and cardiovascular disease (CVD). The selective inhibition of URAT1 by dotinurad increases urinary UA in the proximal tubules, and this un-reabsorbed UA may compete with urinary glucose for GLUT9, reducing glucose reabsorption. The inhibition by dotinurad of UA entry via URAT1 into the liver and adipose tissues increased energy expenditure and decreased lipid synthesis and inflammation in rats. Such effects may improve metabolic parameters. CKD patients accumulate uremic toxins, including indoxyl sulfate (IS), in the body. ABCG2 regulates the renal and intestinal excretion of IS, which strongly affects CKD. OAT1/3 inhibitors suppress IS uptake into the kidneys, thereby increasing plasma IS, which produces oxidative stress and induces vascular endothelial dysfunction in CKD patients. The highly selective inhibition of URAT1 by dotinurad may be beneficial for metabolic syndrome, CKD, and CVD.

Plasma Metabolomics of Dietary Intake of Protein-Rich Foods and Kidney Disease Progression in Children

OBJECTIVE

Evidence regarding the efficacy of a low-protein diet for patients with CKD is inconsistent and recommending a low-protein diet for pediatric patients is controversial. There is also a lack of objective biomarkers of dietary intake. The purpose of this study was to identify plasma metabolites associated with dietary intake of protein and to assess whether protein-related metabolites are associated with CKD progression.

METHODS

Nontargeted metabolomics was conducted in plasma samples from 484 Chronic Kidney Disease in Children (CKiD) participants. Multivariable linear regression estimated the cross-sectional association between 949 known, nondrug metabolites and dietary intake of total protein, animal protein, plant protein, chicken, dairy, nuts and beans, red and processed meat, fish, and eggs, adjusting for demographic, clinical, and dietary covariates. Cox proportional hazards models assessed the prospective association between protein-related metabolites and CKD progression defined as the initiation of kidney replacement therapy or 50% eGFR reduction, adjusting for demographic and clinical covariates.

RESULTS

One hundred and twenty-seven (26%) children experienced CKD progression during 5 years of follow-up. Sixty metabolites were significantly associated with dietary protein intake. Among the 60 metabolites, 10 metabolites were significantly associated with CKD progression (animal protein: n = 1, dairy: n = 7, red and processed meat: n = 2, nuts and beans: n = 1), including one amino acid, one cofactor and vitamin, 4 lipids, 2 nucleotides, one peptide, and one xenobiotic. 1-(1-enyl-palmitoyl)-2-oleoyl-glycerophosphoethanolamine (GPE, P-16:0/18:1) was positively associated with dietary intake of red and processed meat, and a doubling of its abundance was associated with 88% higher risk of CKD progression. 3-ureidopropionate was inversely associated with dietary intake of red and processed meat, and a doubling of its abundance was associated with 48% lower risk of CKD progression.

CONCLUSIONS

Untargeted plasma metabolomic profiling revealed metabolites associated with dietary intake of protein and CKD progression in a pediatric population.

Febuxostat dose requirement according to renal function in patients who achieve target serum urate levels: A retrospective cohort study

OBJECTIVES

To determine the febuxostat dose requirement according to renal function in patients who achieve target serum urate (SU) levels.

METHODS

Of 3153 gout patients who underwent febuxostat treatment, 873 patients with an initial SU level>6mg/dL were included and categorized by the estimated glomerular filtration rate: normal, chronic kidney disease (CKD) stage 3, and stages 4-5. Ninety-five patients with insufficient follow-up were further excluded. The dose of febuxostat in patients who achieved the SU target (< 6mg/dL) was defined as the average daily dosage at the time of SU target achievement.

RESULTS

The cohort of 778 gout patients had a median age of 52.0 years (IQR, 41.0-63.0) and comprised 711 (91.4%) men. The mean SU at febuxostat initiation was higher in the CKD 4-5 (9.6 [± 3.1] mg/dL) than in the other groups (CKD 3, 8.7 [± 1.7]; normal, 8.4 [± 1.7]; P<0.001). Patients achieved target SU at a median of 4.0 (1.9-9.6) months and in those who achieved target SU, the dose of febuxostat at the time of SU target achievement was significantly lower in the CKD 4-5 group (50.0 [± 16.5] mg) than in the other groups (vs. CKD stage 3, 60.0 [± 19.5] mg; P<0.01, vs. normal, 60.0 [± 19.8] mg; P<0.01). Furthermore, CKD stage 4-5 had a negative correlation with the febuxostat dose requirement (Beta: -2.334, P<0.05).

CONCLUSION

Among patients who achieved SU target, those with severely decreased renal function (CKD 4-5) required a lower febuxostat dose to achieve the target SU level compared to patients with normal or mild renal impairment.

Effects of uric acid-lowering therapy (ULT) on renal outcomes in CKD patients with asymptomatic hyperuricemia: a systematic review and meta-analysis

BACKGROUND

It is well known that asymptomatic hyperuricemia and gout play an important role in patients with chronic kidney disease (CKD). However, the effect of uric acid-lowering therapy (ULT) on the prognosis of CKD patients with asymptomatic hyperuricemia remains controversial. Therefore, we aim to investigate the influence of ULT on renal outcomes in these patients.

METHODS

Comprehensive searches were conducted in PubMed, EMBASE, China National Knowledge Internet (CNKI), and the Cochrane Library, up until January 2024. We included randomized controlled trials (RCTs) that evaluated the effects of ULT on renal outcomes in CKD patients with asymptomatic hyperuricemia.

RESULTS

A total of 17 studies were included in the meta-analysis. Compared with placebo or no treatment, ULT preserved the loss of estimated glomerular filtrating rate (eGFR) (Weighted mean difference [WMD] and its 95% confidence intercal(CI): 2.07 [0.15,3.98] mL/min/1.73m2) at long-term subgroup. At the same time, short-term subgroup also proved the preserved loss of eGFR (WMD 5.74[2.09, 9.39] mL/min/1.73m2). Compared with placebo or no treatment, ULT also reduced the increase in serum creatinine (Scr) at short-term (WMD -44.48[-84.03,-4.92]μmol/L) subgroup and long-term (WMD -46.13[-65.64,-26.62]μmol/L) subgroup. ULT was associated with lower incidence of the events of doubling of Scr without dialysis (relative risk (RR) 0.32 [0.21, 0.49], p < 0.001). However, no difference was found for lower incidence of acute kidney injury (AKI) (p = 0.943).

CONCLUSIONS

According to our study, ULT is beneficial for slowing CKD progression both in short to long-term follow-ups. Additionally, in patients younger than 60 years old, the protective effect of ULT on renal outcome is more pronounced. However, it showed no significant difference in the incidence of AKI. These findings underscore the importance of considering ULT in clinical strategies for CKD patients with asymptomatic hyperuricemia.

Identification of inhibitors from a functional food-based plant Perillae Folium against hyperuricemia via metabolomics profiling, network pharmacology and all-atom molecular dynamics simulations

Introduction

Hyperuricemia (HUA) is a metabolic disorder caused by purine metabolism dysfunction in which the increasing purine levels can be partially attributed to seafood consumption. Perillae Folium (PF), a widely used plant in functional food, has been historically used to mitigate seafood-induced diseases. However, its efficacy against HUA and the underlying mechanism remain unclear.

Methods

A network pharmacology analysis was performed to identify candidate targets and potential mechanisms involved in PF treating HUA. The candidate targets were determined based on TCMSP, SwissTargetPrediction, Open Targets Platform, GeneCards, Comparative Toxicogenomics Database, and DrugBank. The potential mechanisms were predicted via Gene Ontology (GO) and Kyoto Gene and Genome Encyclopedia (KEGG) analyses. Molecular docking in AutoDock Vina and PyRx were performed to predict the binding affinity and pose between herbal compounds and HUA-related targets. A chemical structure analysis of PF compounds was performed using OSIRIS DataWarrior and ClassyFire. We then conducted virtual pharmacokinetic and toxicity screening to filter potential inhibitors. We further performed verifications of these inhibitors' roles in HUA through molecular dynamics (MD) simulations, text-mining, and untargeted metabolomics analysis.

Results

We obtained 8200 predicted binding results between 328 herbal compounds and 25 potential targets, and xanthine dehydrogenase (XDH) exhibited the highest average binding affinity. We screened out five promising ligands (scutellarein, benzyl alpha-D-mannopyranoside, elemol, diisobutyl phthalate, and (3R)-hydroxy-beta-ionone) and performed MD simulations up to 50 ns for XDH complexed to them. The scutellarein-XDH complex exhibited the most satisfactory stability. Furthermore, the text-mining study provided laboratory evidence of scutellarein's function. The metabolomics approach identified 543 compounds and confirmed the presence of scutellarein. Extending MD simulations to 200 ns further indicated the sustained impact of scutellarein on XDH structure.

Conclusion

Our study provides a computational and biomedical basis for PF treating HUA and fully elucidates scutellarein's great potential as an XDH inhibitor at the molecular level, holding promise for future drug design and development.

Age- and Sex-Specific Reference Values for Renal Volume and Association with Risk Factors for Chronic Kidney Disease in a General Population-An MRI-Based Study

BACKGROUND

Renal volume (RV) is associated with renal function and with a variety of cardiovascular risk factors (CVRFs). We analysed RV using magnetic resonance imaging (MRI) in a large population-based study (Study of Health in Pomerania; SHIP-TREND) to find sex- and age-specific reference values for RV and to test the influence of several markers on RV. The main objective is to describe reference values for RV in people from the general population without kidney disease.

METHODS

1815 participants without kidney disease (930 women) aged 21-81 years were included in our study. Right and left RV with and without body surface area (BSA) indexation were compared among three age groups (22-39 years, 40-59 years, 60-81 years) by median and interquartile range and tested separately in women and men.

RESULTS

The estimated glomerular filtration rate (eGFR), serum uric acid, and right and left RV were higher in men compared to women (all p < 0.001). Left kidneys were larger than right kidneys (both sexes). With age, RV showed a continuously decreasing trend in women and an upside-down U-shaped relation in men. In multivariable linear regression models, current smoking (β = 14.96, 95% CI 12.12; 17.79), BSA (β = 97.66, 95% CI 90.4; 104.93), diastolic blood pressure (β = 0.17, 95% CI 0.01; 0.32), and eGFR (β = 0.57, 95% CI 0.50; 0.65) were positively associated with both left and right RV, whereas uric acid (β = -0.03, 95% CI -0.05; -0.01) showed an inverse association with RV. Interestingly, the same eGFR correlated with higher RV in men compared to women.

CONCLUSION

Reference values for RV are different for age groups and sex. For any given age, female kidneys are smaller than male kidneys. RV associates positively with eGFR, but for any chosen eGFR, renal volume in females is lower compared to males. RV decreases with age, but in men showed a U-shaped correlation. This may reflect hyperfiltration and glomerular hypertrophy associated with the presence of CVRF in middle-aged males.

Nonlinearity association between hyperuricemia and all-cause mortality in patients with chronic kidney disease

Controversy surrounds the role of serum uric acid and whether treatment intervention is favorable in retarding the progression of chronic kidney disease (CKD). The association of serum uric acid levels and CKD patient mortality risk needs to be further determined by large sample cohort studies. The National Health and Nutrition Examination Survey participants with CKD from 1998 to 2017 were enrolled in the study. Multivariable Cox regression models were used to reveal the association of serum uric acid concentrations and CKD mortality risks. A total of 9891 CKD patients were enrolled in the study, and 3698 individuals died during the follow-up. Increasing serum uric acid levels are independently relevant to higher mortality risks of CKD patients (HR per SD increase). A restricted cubic spline curve showed a nonlinear association between serum uric acid and CKD mortality risks (p for nonlinearity = 0.046). CKD patients with higher levels of serum uric acid (≥ 5.900 mg/dL) show a significant increase in mortality risks (HR = 1.102, 95% CI 1.043-1.165). Sensitivity analysis demonstrated that the results were stable and robust. High serum uric acid levels (≥ 5.900 mg/dL) may be associated with increased mortality risks in CKD patients.

Use of rasburicase to improve kidney function in children with hyperuricemia and acute kidney injury

BACKGROUND

Hyperuricemia contributes to decrease in kidney function and induces additional renal damage in children with acute kidney injury (AKI). Rasburicase oxidizes uric acid (UA), decreasing its serum quantities in less than 24 h.

METHODS

This is a retrospective study involving hospitalized patients under 18 years of age with underlying pathology diagnosed with AKI and severe hyperuricemia treated with rasburicase over a 4-year period.

RESULTS

We describe 15 patients from 4 days of life to 18 years (median: 4.4 years). Seventy-three percent had known underlying pathologies. All presented worsening of basal renal function or AKI data. All received the usual medical treatment for AKI without response. Twenty percent received an extrarenal depuration technique. All had hyperuricemia with a mean (± SD) of 13.1 (± 2.19) mg/dl. After rasburicase administration UA levels fell to a mean (± SD) of 0.76 (± 0.62) mg/dl (p < 0.001) in less than 24 h. In parallel, a decrease in the mean plasma creatinine was observed (2.92 mg/dl to 1.93 mg/dl (p = 0.057)) together with a significant improvement of the mean glomerular filtration rate (16.3 ml/min/1.73 m2 to 78.6 ml/min/1.73 m2) (p = 0.001)). No side effects were recorded. Kidney function normalized in all cases or returned to baseline levels.

CONCLUSIONS

Although the use of rasburicase is not routinely approved in pediatric patients with severe hyperuricemia and AKI, it has been used successfully without complications, and helped prevent progressive kidney damage. This study could serve as a basis for suggesting the off-label use of rasburicase for the management of complex pediatric patients in whom UA plays an important role in the development of AKI.

Management of Patients with Gout and Kidney Disease: A Review of Available Therapies and Common Missteps

Gout, a common form of inflammatory arthritis, is characterized by deposition of monosodium urate crystals in articular and periarticular tissues. Repeated flares of gout cause joint damage as well as significant health care utilization and decreased quality of life. Patients with CKD have a higher prevalence of gout. Treating Patients with CKD and gout is challenging because of the lack of quality data to guide management in this specific population. This often leads to suboptimal treatment of patients with gout and impaired renal function because concerns regarding the efficacy and safety of available gout therapies in this population often result in significant interphysician variability in treatment regimens and dosages. Acute gout flares are treated with various agents, including nonsteroidal anti-inflammatory drugs, colchicine, glucocorticoids, and-more recently-IL-1 inhibitors. These medications can also be used as prophylaxis if urate-lowering therapy (ULT) is initiated. While these drugs can be used in patients with gout and CKD, there are often factors that complicate treatment, such as the numerous medication interactions involving colchicine and the effect of glucocorticoids on common comorbidities, such as diabetes and hypertension. ULT is recommended to treat recurrent flares, tophaceous deposits, and patients with moderate-to-severe CKD with a serum urate goal of <6 mg/dl recommended to prevent flares. While many misconceptions exist around the risks of using urate-lowering agents in patients with CKD, there is some evidence that these medications can be used safely in Patients with renal impairment. Additional questions exist as to whether gout treatment is indicated for Patients on RRT. Furthermore, there are conflicting data on whether ULT can affect renal function and cardiovascular disease in patients. All of these factors contribute to the unique challenges physicians face when treating patients with gout and CKD.

Uric acid and neurological disease: a narrative review

Hyperuricemia often accompanies hypertension, diabetes, dyslipidemia, metabolic syndrome, and chronic renal disease; it is also closely related to cardiovascular disease. Moreover, several epidemiological studies have linked hyperuricemia and ischemic stroke. However, uric acid may also have neuroprotective effects because of its antioxidant properties. An association between low uric acid levels and neurodegenerative diseases has been suggested, which may be attributed to diminished neuroprotective effects as a result of reduced uric acid. This review will focus on the relationship between uric acid and various neurological diseases including stroke, neuroimmune diseases, and neurodegenerative diseases. When considering both the risk and pathogenesis of neurological diseases, it is important to consider the conflicting dual nature of uric acid as both a vascular risk factor and a neuroprotective factor. This dual nature of uric acid is important because it may help to elucidate the biological role of uric acid in various neurological diseases and provide new insights into the etiology and treatment of these diseases.

Asymptomatic hyperuricaemia in chronic kidney disease: mechanisms and clinical implications

Asymptomatic hyperuricaemia (HU) is considered a pathogenic factor in multiple disease contexts, but a causative role is only proven for the crystalline form of uric acid in gouty arthritis and urate nephropathy. Epidemiological studies document a robust association of HU with hypertension, cardiovascular disease (CVD) and CKD progression, but CKD-related impaired uric acid (UA) clearance and the use of diuretics that further impair UA clearance likely accounts for these associations. Interpreting the available trial evidence is further complicated by referring to xanthine oxidase inhibitors as urate-lowering treatment, although these drugs inhibit other substrates, so attributing their effects only to HU is problematic. In this review we provide new mechanistic insights into the biological effects of soluble and crystalline UA and discuss clinical evidence on the role of asymptomatic HU in CKD, CVD and sterile inflammation. We identify research areas with gaps in experimental and clinical evidence, specifically on infectious complications that represent the second common cause of death in CKD patients, referred to as secondary immunodeficiency related to kidney disease. In addition, we address potential therapeutic approaches on how and when to treat asymptomatic HU in patients with kidney disease and where further interventional studies are required.

Impact of Hyper- and Hypo-Uricemia on Kidney Function

Uric acid (UA) forms monosodium urate (MSU) crystals to exert proinflammatory actions, thus causing gout arthritis, urolithiasis, kidney disease, and cardiovascular disease. UA is also one of the most potent antioxidants that suppresses oxidative stress. Hyper andhypouricemia are caused by genetic mutations or polymorphism. Hyperuricemia increases urinary UA concentration and is frequently associated with urolithiasis, which is augmented by low urinary pH. Renal hypouricemia (RHU) is associated with renal stones by increased level of urinary UA, which correlates with the impaired tubular reabsorption of UA. Hyperuricemia causes gout nephropathy, characterized by renal interstitium and tubular damage because MSU precipitates in the tubules. RHU is also frequently associated with tubular damage with elevated urinary beta2-microglobulin due to increased urinary UA concentration, which is related to impaired tubular UA reabsorption through URAT1. Hyperuricemia could induce renal arteriopathy and reduce renal blood flow, while increasing urinary albumin excretion, which is correlated with plasma xanthine oxidoreductase (XOR) activity. RHU is associated with exercise-induced kidney injury, since low levels of SUA could induce the vasoconstriction of the kidney and the enhanced urinary UA excretion could form intratubular precipitation. A U-shaped association of SUA with organ damage is observed in patients with kidney diseases related to impaired endothelial function. Under hyperuricemia, intracellular UA, MSU crystals, and XOR could reduce NO and activate several proinflammatory signals, impairing endothelial functions. Under hypouricemia, the genetic and pharmacological depletion of UA could impair the NO-dependent and independent endothelial functions, suggesting that RHU and secondary hypouricemia might be a risk factor for the loss of kidney functions. In order to protect kidney functions in hyperuricemic patients, the use of urate lowering agents could be recommended to target SUA below 6 mg/dL. In order to protect the kidney functions in RHU patients, hydration and urinary alkalization may be recommended, and in some cases an XOR inhibitor might be recommended in order to reduce oxidative stress.

The Hong Kong Society of Rheumatology consensus recommendations for the management of gout

Gout is one of the most common noncommunicable diseases in Hong Kong. Although effective treatment options are readily available, the management of gout in Hong Kong remains suboptimal. Like other countries, the treatment goal in Hong Kong usually focuses on relieving symptoms of gout but not treating the serum urate level to target. As a result, patients with gout continue to suffer from the debilitating arthritis, as well as the renal, metabolic, and cardiovascular complications associated with gout. The Hong Kong Society of Rheumatology spearheaded the development of these consensus recommendations through a Delphi exercise that involved rheumatologists, primary care physicians, and other specialists in Hong Kong. Recommendations on acute gout management, gout prophylaxis, treatment of hyperuricemia and its precautions, co-administration of non-gout medications with urate-lowering therapy, and lifestyle advice have been included. This paper serves as a reference guide to all healthcare providers who see patients who are at risk and are known to have this chronic but treatable condition.

The effect of dapagliflozin on uric acid excretion and serum uric acid level in advanced CKD

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) exhibit renoprotective effect in patients with chronic kidney disease (CKD) and reduce serum uric acid (UA) in patients with diabetes mellitus. However, it is not clarified whether SGLT2i reduce serum UA levels in patients with advanced CKD. This study aimed to investigate the impact of SGLT2i on change in serum UA levels in patients with advanced CKD. Data of 121 Japanese patients with CKD who were newly administered 10 mg dapagliflozin in our department between August 2021 and August 2022 were analyzed. Changes in UA and fractional excretion of UA (FEUA) were analyzed using multiple regression analysis. Of 75 patients, 21 (28.0%) patients, 24 (32.0%) patients, 29 (38.7%) patients, and 1 (1.3%) patient were categorized as having CKD stage 3a, 3b, 4, and 5, respectively. The median age was 67 years, and 72.0% were male. 23 (30.7%) of patients had diabetes mellitus. The median estimated glomerular filtration rate, serum UA, and FEUA were 35.7 mL/min/1.73 m², 6.4 mg/dL, and 6.76%, respectively, at the time of dapagliflozin administration. After administration, serum UA decreased to 5.6 mg/dL and FEUA increased to 9.22%. Dapagliflozin increases FEUA and reduces serum UA levels in patients with advanced CKD.

Therapeutics in rheumatology and the kidney

The field of rheumatology has advanced significantly in recent years to provide rheumatologists with an extensive array of medications to combat rheumatic joint conditions. In contrast to an older era, when NSAIDs and other nephrotoxic agents were the mainstay of treatment, modern DMARDs vary considerably in their nephrotoxic potential and their use is not always precluded in populations with pre-existing chronic kidney disease (CKD). This review will explore in detail the safety and efficacy profiles of medications used to treat rheumatologic disease, specifically in the setting of CKD. Specifically, we discuss both traditional agents used, i.e. NSAIDs, CSs and conventional synthetic DMARDs, as well as novel biologic DMARDs and targeted synthetic DMARDs. Anti-gout prescribing in CKD is also reviewed. We aim to provide practical guidance to rheumatologists, nephrologists and general physicians when prescribing these medications in the setting of CKD.

Association of hyperuricemia with cardiovascular diseases: current evidence

The aim of the present study is to present a historical and unified perspective on the association of serum uric acid (SUA) in the cause of cardiovascular diseases (CVDs). The association of hyperuricemia (HUC) with CVD begun to be appreciated in the middle 1950s and early 1990s when clinical evidence was shown on the association of HUC with CVD. However, this association was disputed by several investigators including the Framingham group and by professional societies, like the American Heart Association and the American Society of Hypertension. This dispute was weakened or reversed by later studies, which showed a positive association of HUC with CVD, CHD, HF, CKD, and stroke, mediated by several risk factors, both molecular such as, oxidative stress, inflammatory stress, insulin resistance, and endothelial dysfunction, as well as clinical factors such as, atherosclerosis, hypertension, metabolic syndrome, and type 2 diabetes mellitus. The great majority of recent studies show a positive association of HUC with CVDs, and CKD. However, the cutoff of the damaging levels of SUA have not been established as yet. The European Society of Hypertension (ESH) Treatment Guidelines have proposed a cutoff level of SUA for CVD > 7 mg/dl for men and > 6 mg/dl for women. In contrast, the URRAH study has shown a SUA level of 4.7 mg/dl for all-cause mortality and 5.6 mg/dl for CV mortality. These levels are lower than the SUA levels proposed by the ESH, which are consistent with HUC. For a better understanding of this association, a Medline search of the English literature was conducted between 2015 and 2022 and 44 pertinent papers were selected. These papers together with collateral literature will be discussed in this review.

Urate Transporter ABCG2 Function and Asymptomatic Hyperuricemia: A Retrospective Cohort Study of CKD Progression

RATIONALE & OBJECTIVE

Treatment of asymptomatic hyperuricemia is not commonly implemented. However, it is unclear whether urate deposition that begins during asymptomatic hyperuricemia can induce nephropathy. Dysfunction of ATP-binding cassette subfamily G member 2 (ABCG2), a urate efflux transporter, leads to elevated serum uric acid concentration (SUA). We investigated the association between asymptomatic hyperuricemia and decreased estimated glomerular filtration rate (eGFR), and the impact of ABCG2 on this relationship.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

1,885 Japanese adults undergoing routine health care follow-up between 2007 and 2017 who had eGFR ≥60 mL/min/1.73 m², of which 311 had asymptomatic hyperuricemia (SUA >7.0 mg/dL). Study participants were classified into 3 categories of estimated ABCG2 function (full, 75%, and ≤50% function).

PREDICTORS

Baseline SUA and estimated ABCG2 function.

OUTCOME

Change in eGFR over time.

ANALYTICAL APPROACH

Linear mixed-effect models were used to analyze the relationship between asymptomatic hyperuricemia, ABCG2 function, and eGFR decline.

RESULTS

Asymptomatic hyperuricemia was negligibly associated with eGFR decline overall. However, among those with eGFR 60-89 mL/min/1.73 m² and ≤50% ABCG2 function, eGFR decline was associated with asymptomatic hyperuricemia (P = 0.03). ABCG2 was not associated with eGFR reductions when the SUA was <6.0 mg/dL. Among participants with SUA ≥6.0 mg/dL and eGFR 60-89 mL/min/1.73 m², ≤50% ABCG2 function was associated with approximately 1.2-fold faster eGFR decline compared with fully functional ABCG2 (P = 0.02). Among the participants with SUA ≥6.0 mg/dL and eGFR 60-89 mL/min/1.73 m², the adjusted eGFR slopes (given as mean ± standard error of the mean, in mL/min/1.73 m² per year) were -0.946 ± 0.049, -1.040 ± 0.046, and -1.148 ± 0.069 for full, 75%, and ≤50% ABCG2 function, respectively.

LIMITATIONS

Lack of measurement of urinary urate and uremic toxins that are known to be transported by ABCG2, and no independent validation cohort.

CONCLUSIONS

Asymptomatic hyperuricemia was not associated with eGFR decline, except when in the presence of ≤50% ABCG2 function.

PLAIN-LANGUAGE SUMMARY

The urate transporter ABCG2 is a protein that regulates serum urate concentrations; when dysfunctional, it can lead to elevated serum concentrations of this compound (ie, hyperuricemia). Although persistent hyperuricemia induces gout and kidney injury, the effects on organs during the asymptomatic phase have yet to be established. Therefore, to clarify the relationship between ABCG2, asymptomatic hyperuricemia, and kidney function, we conducted a retrospective cohort study of 1,885 healthy participants, including 311 participants with asymptomatic hyperuricemia. We found that the coexistence of asymptomatic hyperuricemia and severe ABCG2 dysfunction was associated with the age-dependent decline in kidney function. We concluded that asymptomatic hyperuricemia represents a risk factor for chronic kidney disease, at least in individuals with highly dysfunctional ABCG2. This new finding highlights the potential importance of ABCG2 in the pathogenesis of hyperuricemia-induced kidney injury.

Association between serum uric acid level and systemic lupus erythematosus kidney outcome: An observational study in Southern Chinese population and a meta-analysis

OBJECTIVE

The study aimed to explore the effect of serum uric acid (SUA) level on the progression of kidney function in systemic lupus erythematosus (SLE) patients.

METHODS

A total of 123 biopsy-proven lupus nephritis (LN) patients were included in this retrospective observational study. Cox proportional hazard regression analyses as well as restricted cubic spline analyses were performed to identify predictors of renal outcome in LN patients. We also performed a systematic review and meta-analysis for SUA and overall kidney outcomes in SLE patients.

RESULTS

Based on the laboratory tests at renal biopsy, 72 (58.5%) of the 123 patients had hyperuricemia. The median (IQR) follow-up duration was 3.67 years (1.79-6.63 years), and a total of 110 (89.4%) patients experienced progression of LN. Increased serum uric acid level, whether analyzed as continuous or categorical variable, was associated with higher risk of LN progression in Cox proportional hazard regression model (hazard ratio [HR]: 1.003, 95% confidence interval [CI]: 1.001-1.005; HR: 1.780, 95% CI: 1.201-2.639, respectively). This relationship maintained in women (HR: 1.947, 95% CI: 1.234-3.074) but not men (HR: 2.189, 95% CI: 0.802-5.977). The meta-analysis showed a similar result that both continuous and categorical SUA were positively associated with the risk of kidney function progression in LN (weighted mean difference [WMD]: 1.73, 95% CI: 0.97-2.49; odds ratio [OR]: 1.55, 95% CI: 1.20-2.01, respectively).

CONCLUSIONS

Our study found overall and especially in women that higher SUA in LN patients were associated with increased risk of renal progression. Meta-analysis yielded consistent results. Future studies are required to establish if uric acid can be used as a biomarker for risk assessment and/or as a novel therapeutic target in SLE.

Renal Papillary Necrosis (RPN) in an African Population: Disease Patterns, Relevant Pathways, and Management

Renal papillary necrosis (RPN) is characterized by coagulative necrosis of the renal medullary pyramids and papillae. Multiple conditions and toxins are associated with RPN. Several RPN risk factors, or POSTCARDS, have been identified, with most patients presenting with RPN having at least two contributing risk factors. Currently, there is no specific test to diagnose and confirm RPN; however, several imaging tools can be used to diagnose the condition. RPN is currently underdiagnosed in African populations, often with fatal outcomes. In African clinical settings, there is a lack of consensus on how to define and describe RPN in terms of kidney anatomy, pathology, endourology, epidemiology, the identification of African-specific risk factors, the contribution of oxidative stress, and lastly an algorithm for managing the condition. Several risk factors are unique to African populations including population-specific genetic factors, iatrogenic factors, viral infections, antimicrobial therapy, schistosomiasis, substance abuse, and hypertension (GIVASSH). Oxidative stress is central to both GIVASSH and POSTCARDS-associated risk factors. In this review, we present information specific to African populations that can be used to establish an updated consensual definition and practical grading system for radiologists, urologists, nephrologists, nuclear physicians, and pathologists in African clinical settings.

Medium- and Long-Term Effects of Dapagliflozin on Serum Uric Acid Level in Patients with Type 2 Diabetes: A Real-World Study

We aimed to explore the medium- and long-term (≥12 weeks) effects of dapagliflozin on serum uric acid (SUA) level in patients with type 2 diabetes mellitus (T2DM) in the real world study and to explore the influencing factors of dapagliflozin on reducing SUA level. This observational, prospective cohort study was based on the real world. There were 77 patients included in this study. They were divided into two groups. Patients in treatment group (n = 38) were treated as dapagliflozin 10 mg/d combined with therapy of routine glucose-lowering drugs (GLDs), and patients in the control group (n = 39) were treated with their routine GLDs. All measurements of physical examinations, blood, and urine samples, including age, sex, weight, height, systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), and SUA, were collected at baseline for all patients in these two groups and repeated after 12, 24, and 48 weeks of therapy. We compared the changes of metabolic indicators including SUA in these two groups to evaluate the effects of dapagliflozin and analyzed its influencing factors. In the dapagliflozin group, mean SUA levels significantly decreased from 334.2 ± 99.1 μmol/L at baseline to 301.9 ± 73.2 μmol/L after 12 weeks therapy (t = 2.378, p = 0.023). There was no significant statistical difference of SUA levels after 24 weeks treatment of dapagliflozin compared with 12-week and 48-week treatment with dapagliflozin (p > 0.05). We found that baseline SUA had a significant impact on the effect of dapagliflozin on reducing SUA (OR 1.014, 95%CI 1.003−1.025, p = 0.014) by logistic regression analysis. Receiver operating characteristic (ROC) curve showed that T2DM patients with SUA level ≥ 314.5 μmol/L had relative accuracy in recognizing the good effects of dapagliflozin on reducing SUA (sensitivity 76.9%, specificity 76.2%). Combination therapy of dapagliflozin with routine blood-glucose-lowering drugs in T2DM patients showed the significant and sustained stable effect of lowering SUA level in this real-world study.

Does uric acid-lowering treatment slow the progression of chronic kidney disease? A meta-analysis of randomized controlled trials

INTRODUCTION

Hyperuricemia has been proposed as an independent factor in the development and progression of chronic kidney disease (CKD). However, the effect of uric acid-lowering therapies on delaying CKD progression is still uncertain. Therefore, this systemic review aims to assess the effect of uric acid-lowering therapies on renal outcomes in pre-dialysis CKD patients.

METHODS

PubMed, Cochrane Library, and Lilacs databases were searched until April 24, 2021, for randomized clinical trials of CKD patients on uric acid-lowering treatment with xanthine-oxidase (XO) inhibitors. The weighted mean difference (WMD) or standard mean difference (SMD) with confidence interval (CI) were pooled using a random-effects model.

RESULTS

Among 567 studies found, eighteen met the inclusion criteria (n=2463 participants). Compared to the patient's control group, the WMD for the glomerular filtration ratio (GFR) and serum creatinine changes of the treated group was 2.02ml/min/1.73m² (95%CI 0.41 to 3.63, P=0.014) and -0.19mg/dl (95%CI -0.34 to -0.04, I²=86.2%, P=0.011), respectively. Subgroup analyses showed that the difference in follow-up time and CKD population type in the studies may explain the controversy about the role of uric acid-lowering therapies in CKD progression. The GFR and creatinine outcomes analysis by types of XO inhibitors showed no difference between the control and treated groups. Uric acid-lowering therapies were strongly associated with decreased serum uric acid and urinary protein-creatinine ratio and urinary albumin-creatinine ratio.

CONCLUSIONS

These findings suggest that uric acid-lowering treatment may slow CKD progress and reduce protein and albumin excretion. However, larger and properly powered randomized clinical trials with specific CKD populations are needed to confirm these findings.

Caring for Australians and New Zealanders With Kidney Impairment Guidelines: Rapid Development of Urate Lowering Therapy Guidelines for People With CKD

Introduction

The slow transformation of new research findings into clinical guidelines is a barrier to providing evidence-based care. The Caring for Australians and New Zealanders with Kidney Impairment (CARI) guidelines are developing models to improve guideline production, one methodology involves more functional concordance between trial groups, such as the Australian Kidney Trials Network (AKTN) and CARI. The objective of this project was to rapidly produce an evidence-based guideline on urate-lowering therapy in patients with chronic kidney disease (CKD), in response to new clinical trial publications on the topic by the AKTN.

Methods

To produce a guideline as rapidly as possible, an existing systematic review was utilized as the evidence base, and then updated with the inclusion of clinical trials that had been published subsequently. A Work Group was convened to review the evidence and compose an appropriate guideline using CARI/GRADE methodology. The group met 3 times over 45 days to formulate the guideline.

Results

The result was a strong recommendation against the use urate-lowering therapies in individuals with CKD (not receiving dialysis) and asymptomatic hyperuricemia. The process of identifying an appropriate existing systematic review, updating the literature search, and synthesizing the evidence, was done by 2 individuals over 15 days. The Work Group was formulated and composed the guideline over 45 days. In all, a new guideline incorporating the most up-to-date evidence was formulated in 60 days.

Conclusion

This method of guideline development represents a potentially new way of releasing guidelines that encapsulates all available evidence in a time-efficient manner.

High Uric Acid Levels in Acute Myocardial Infarction Provide Better Long-Term Prognosis Predictive Power When Combined with Traditional Risk Factors

The current study aimed to investigate the association between serum UA levels and the mortality rate of AMI patients. We analyzed 5888 patients with successfully revascularized AMI (mean age: 64.0 ± 12.7 years). The subjects were divided into the high UA group (uric acid >6.5 mg/dL for males, >5.8 mg/dL for females) or the normal UA group based on initial serum UA level measured at admission. The primary outcome was all-cause mortality. A total of 4141 (70.3%) and 1747 (29.7%) patients were classified into the normal UA group and high UA groups, respectively. Over a median follow-up of 5.02 (3.07, 7.55) years, 929 (21.5%) and 532 (34.1%) patients died in each group. Cox regression analysis identified high UA levels as an independent predictor of all-cause mortality (unadjusted hazard ratio (HR) 1.69 [95% CI 1.52−1.88]; p < 0.001, adjusted HR 1.18 [95% CI: 1.05−1.32]; p = 0.005). The results were consistent after propensity-score matching and inverse probability weighting to adjust for baseline differences. The predictive accuracies of conventional clinical factor discrimination and reclassification were significantly improved upon the addition of hyperuricemia (C-index 0.788 [95% CI 0.775−0.801]; p = 0.005, IDI 0.004 [95% CI 0.002−0.006]; p < 0.001, NRI 0.263 [95% CI 0.208−0.318]; p < 0.001).

Diabetic Kidney Disease: From Pathogenesis to Novel Treatment Possibilities

One of the microvascular complications of diabetes is diabetic kidney disease (DKD), often leading to end stage renal disease (ESRD) in which patients require costly dialysis or transplantation. The silent onset and irreversible progression of DKD are characterized by a steady decline of the estimated glomerular filtration rate, with or without concomitant albuminuria. The diabetic milieu allows the complex pathophysiology of DKD to enter a vicious cycle by inducing the synthesis of excessive amounts of reactive oxygen species (ROS) causing oxidative stress, inflammation, and fibrosis. As no cure is available, intensive research is required to develop novel treatments possibilities. This chapter provides an overview of the important pathomechanisms identified in diabetic kidney disease, the currently established therapies, as well as recently developed novel therapeutic strategies in DKD.

Efficacy and safety of urate-lowering agents in asymptomatic hyperuricemia: systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

Asymptomatic hyperuricemia was found to be associated with increased cardiovascular disease risk but the potential benefits of urate-lowering therapy (ULT) remain controversial. We conducted a systematic review and network meta-analysis (NMA) with frequentist model to estimate the efficacy and safety of ULT in asymptomatic hyperuricemia.

METHODS

MEDLINE, Embase, and Scopus were searched without language restrictions. Randomized controlled trials (RCT) of adults with asymptomatic hyperuricemia were eligible if they compared any pair of ULTs (i.e., allopurinol, febuxostat, probenecid, benzbromarone, sulfinpyrazone, rasburicase, lesinurad, and topiroxostat) and placebo or no ULT, and had outcomes of interest, including composite renal events, major adverse cardiovascular events, serum urate levels, estimated glomerular filtration rate (eGFR), systolic blood pressure, and adverse events.

RESULTS

NMA with frequentist approach was applied to estimate relative treatment effects, i.e., risk ratio (RR) and mean difference (MD). A total of 23 RCTs were eligible. NMA identified beneficial effects of ULT on composite renal events and eGFR but not for other outcomes. Allopurinol and febuxostat had significantly lower composite renal events than placebo (RR 0.39, 95% confidence interval [CI] 0.23 to 0.66, and RR 0.68, 95% CI 0.46 to 0.99, respectively). Both treatments also resulted in significantly higher eGFR than placebo (MD 3.69 ml/min/1.73 m², 95% CI 1.31 to 6.08, and MD 2.89 ml/min/1.73 m², 95% CI 0.69 to 5.09, respectively). No evidence of inconsistency was identified.

CONCLUSIONS

Evidence suggests that allopurinol and febuxostat are the ULTs of choice in reducing composite renal events and improving renal function.

TRIAL REGISTRATION

This study was registered with PROSPERO: CRD42019145908. The date of the first registration was 12^th November 2019.

Association of Uric Acid-Lowering Therapy With Incident Chronic Kidney Disease

IMPORTANCE

Uric acid is a waste metabolite produced from the breakdown of purines, and elevated serum uric acid levels are associated with higher risk of hypertension, cardiovascular disease, and mortality and progression of chronic kidney disease (CKD). Treatment of hyperuricemia in patients with preexisting CKD has not been shown to improve kidney outcomes, but the associations of uric acid-lowering therapies with the development of new-onset kidney disease in patients with estimated glomerular filtration rate (eGFR) within reference range and no albuminuria is unclear.

OBJECTIVE

To examine the association of initiating uric acid-lowering therapy with the incidence of CKD.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included patients with eGFR of 60 mL/min/1.73 m2 or greater and no albuminuria treated at US Department of Veterans Affairs health care facilities from 2004 to 2019. Clinical trial emulation methods, including propensity score weighting, were used to minimize confounding. Data were analyzed from 2020 to 2022.

EXPOSURE

Newly started uric acid-lowering therapy.

MAIN OUTCOMES AND MEASURES

The main outcomes were incidences of eGFR less than 60 mL/min/1.73 m2, new-onset albuminuria, and end-stage kidney disease.

RESULTS

A total of 269 651 patients were assessed (mean [SD] age, 57.4 [12.5] years; 252 171 [94%] men). Among these, 29 501 patients (10.9%) started uric acid-lowering therapy, and 240 150 patients (89.1%) did not. Baseline characteristics, including serum uric acid level, were similar among treated and untreated patients after propensity score weighting. In the overall cohort, uric acid-lowering therapy was associated with higher risk of both incident eGFR less than 60 mL/min/1.73 m2 (weighted subhazard ratio [SHR], 1.15 [95% CI, 1.10-1.20; P < .001) and incident albuminuria (SHR, 1.05 [95% CI, 1.01-1.09; P < .001) but was not associated with the risk of end-stage kidney disease (SHR, 0.96 [95% CI, 0.62-1.50]; P = .87). In subgroup analyses, the association of uric acid-lowering therapy with worse kidney outcomes was limited to patients with baseline serum uric acid levels of 8 mg/dL or less.

CONCLUSIONS AND RELEVANCE

These findings suggest that in patients with kidney function within reference range, uric acid-lowering therapy was not associated with beneficial kidney outcomes and may be associated with potential harm in patients with less severely elevated serum uric acid levels.

Serum Uric Acid and Coronary Arterial Disease in Predialysis Chronic Kidney Disease Patients

Background–Aim:

Uric acid is considered a marker of high cardiovascular risk. We investigated the association between serum uric acid and coronary arterial disease (CAD) in pre-dialysis chronic kidney disease (CKD) patients.

Methods:

We enrolled 110 subjects on mean age 69.02 ± 14.3 years old. The participants were categorized for both estimated glomerular filtration rate (eGFR) and albuminuria according to criteria 2012 of the Kidney Disease Improving Global Outcomes. Estimated pulse wave velocity (ePWV) was calculated using an equation including the age and mean blood pressure. The CAD prevalence rate was recorded.

Results:

The patients were divided in two groups according to uric acid cutoff point value related to high ePWV. The patients with higher uric acid were older and they had significantly higher systolic blood pressure, pulse pressure, and parathyroid hormone, but significantly lower eGFR and 1,25(OH)2 Vit D3 levels. The association between high uric acid and both high ePWV and CAD occurrence was found to be significant ( x2 = 6.7, P = .008 and x2 = 4.1, P = .03, respectively), although the relationship with albuminuria was found to be nonsignificant. In a built multifactorial model, the low serum uric acid rather than the high was found to be an independent predictor for CAD demonstration entering traditional and specific confounders.

Conclusion:

The low serum uric acid levels were proved to be a significant predictor for CAD accounting potential covariates, even though the high uric acid per se was found to be connected with cardiovascular disease characteristics including arterial stiffness in predialysis CKD patients.

Serum Cystatin C Trajectory Is a Marker Associated With Diabetic Kidney Disease

Objective

To explore the association of the trajectory of serum Cystatin C (Cysc) with diabetic kidney disease (DKD), a retrospective cohort study of Chinese subjects was carried out.

Method

A review of 2,928 diabetes mellitus (DM) patients admitted to the clinic and ward of the Endocrinology Department, Shengjing Hospital of China Medical University from January 1, 2014 to December 31, 2014 was performed. Subsequent visits to the hospital were followed until December 31, 2020. The primary endpoint was the incidence of DKD as diagnosed by urinary albumin/creatinine ratio ≥30 mg/g and/or estimated glomerular filtration rate <60 ml/min per 1.73 m2. Healthy control subjects were identified from a health checkup database in Shengjing Hospital from 2016 to 2019. The latent class growth mixed modeling (LCGMM) method was used to analyze latent classes of serum Cysc in healthy and DM subjects. Finally, the hazard ratios (HRs) of latent classes of Cysc in DM subjects were analyzed by Cox regression analysis.

Results

A total of 805 type 2 diabetes mellitus (T2DM) and 349 healthy subjects were included in the trial. The HRs of quartiles of baseline Cysc in T2DM subjects were 7.15 [95% confidence interval (CI), 2.79 to 25.57], 2.30 (95% CI, 1.25 to 4.24), and 2.05 (95% CI, 1.14 to 3.70), respectively, for quartile 4 (Q4), Q3, and Q2 when compared with Q1. Through LCGMM, a 1-class linear model was selected for the Cysc latent class in healthy subjects. In contrast, a 3-class linear model was selected for that in DM subjects. The slopes of the three latent classes in T2DM subjects were larger than the slope in healthy subjects. The HRs of incident DKD were 3.43 (95% CI, 1.93 to 6.11) for the high-increasing class and 1.80 (95% CI, 1.17 to 2.77) for the middle-increasing class after adjusting for confounding variables.

Conclusions

Patients with T2DM had a higher velocity of increase in Cysc than healthy subjects. Patients with high baseline Cysc values and high latent increasing velocity of Cysc had a higher risk of developing DKD in later life. More attention should be paid to patients with these high-risk factors.

U-shaped association of uric acid to overall-cause mortality and its impact on clinical management of hyperuricemia

Serum uric acid (SUA) is significantly elevated in obesity, gout, type 2 diabetes mellitus, and the metabolic syndrome and appears to contribute to the renal, cardiovascular and pulmonary comorbidities that are associated with these disorders. Most previous studies have focused on the pathophysiologic effects of high levels of uric acid (hyperuricemia). More recently, research has also shifted to the impact of hypouricemia, with multiple studies showing the potentially damaging effects that can be caused by abnormally low levels of SUA. Along with these observations, recent inconclusive data from human studies evaluating the treatment of hyperuricemia with xanthine oxidoreductase (XOR) inhibitors have added to the debate about the causal role of UA in human disease processes. SUA, which is largely derived from hepatic degradation of purines, appears to exert both systemic pro-inflammatory effects that contribute to disease and protective antioxidant properties. XOR, which catalyzes the terminal two steps of purine degradation, is the major source of both reactive oxygen species (O2.-, H2O2) and UA. This review will summarize the evidence that both elevated and low SUA may be risk factors for renal, cardiovascular and pulmonary comorbidities. It will also discuss the mechanisms through which modulation of either XOR activity or SUA may contribute to vascular redox hemostasis. We will address future research studies to better account for the differential effects of high versus low SUA in the hope that this will identify new evidence-based approaches for the management of hyperuricemia.

Efficacy of Urate-Lowering Therapy in Patients With Chronic Kidney Disease: A Network Meta-Analysis of Randomized Controlled Trials

PURPOSE

The goal of this study was to systematically review the efficacy and safety of urate-lowering therapy in patients with chronic kidney disease (CKD).

METHODS

PubMed, the Cochrane Central Registration of Controlled Trials, and EMBASE databases and several websites were electronically searched to collect randomized clinical trials on the efficacy of urate-lowering therapy in CKD from inception to December 31, 2020. The key primary end points were uric acid or estimated glomerular filtration rate (eGFR) levels; the safety end points were death, renal event, cardiovascular event, and gastrointestinal event. A Bayesian network meta-analysis was conducted with the use of ADDIS and R software.

FINDINGS

A total of 17 randomized clinical trials involving 2059 patients were included. The results of network meta-analysis showed that urate-lowering therapy could reduce urate levels in patients with CKD. Febuxostat was the most effective treatment in lowering urate levels according to the rank probability. Urate-lowering therapy has the tendency to delay the decline of eGFR, but the difference was not statistically significant. Ranking probability showed that benzbromarone, febuxostat, and allopurinol ranked higher than placebo in reducing the decline of eGFR. There were no statistically significant differences between groups in the incidence of all adverse effects.

IMPLICATIONS

All urate-lowering therapies could reduce the urate level in patients with CKD, but the benefit of such therapy in renal disease is still unclear. PROSPERO identifier: CRD42020222601.

Efficacy of Xanthine Oxidase Inhibitors in Lowering Serum Uric Acid in Chronic Kidney Disease: A Systematic Review and Meta-Analysis

Objective: Current guidelines for gout recommend a treat-to-target approach with serum uric acid (SUA). However, there is little evidence for the dose-dependent effects of urate-lowering therapy (ULT). Herein, we analyzed the reported SUA-lowering effect and SUA target achievement differences for various doses of xanthine oxidase inhibitors. Methods: Approved ULT drugs were selected from the FDA Drug Database. We included prospective randomized controlled trials of ULT drugs from ClinicalTrials.gov, articles published in the journal “Drugs”, and Embase, a literature database. A meta-analysis was performed to determine the ability of different ULT drugs and doses to lower and maintain a target SUA < 6 mg/dL. Results: We identified 35 trials including 8172 patients with a baseline SUA of 8.92 mg/dL. The allopurinol, febuxostat, and topiroxostat showed dose-proportional SUA-lowering responses. Compared with allopurinol 300 mg daily, febuxostat 80 mg daily and 120 mg daily more effectively maintained SUA < 6 mg/dL. Conclusion: Allopurinol, febuxostat, and topiroxostat showed dose-proportional ability to lower and achieve a target SUA < 6 mg/dL. Significance and Innovations. We showed dose-dependent SUA lowering effects of allopurinol, febuxostat, and topiroxostat. Febuxostat is effective at ULT compared to allopurinol and could be potentially offered as an alternative agent when patients (1) have CKD, (2) have the human leukocyte antigen HLA-B*5801 allele, and (3) become refractory to allopurinol. Gradual allopurinol dose increase with a lower starting dose is needed in CKD.

R. S, Toh CC, Sundram M, Md Yusoff NA, Nagappan P, Kamaruzaman S, Yeoh WS, Ong TA, Lim J. Cardiovascular risk factors, ethnicity and infection stone are independent factors associated with reduced renal function in renal stone formers

BACKGROUND

Recent evidence suggested the link between nephrolithiasis and renal function impairment. We aimed to determine the renal function profile and potential factors associated with reduced renal function amongst renal stone formers in multi-ethnic Asians.

METHODS

We conducted a cross-sectional study involving patients undergoing percutaneous nephrolithotomy between May 2015 and December 2019. Reduced renal function was defined as having estimated glomerular filtration rate < 60 ml/min per 1.73 m2. Renal stone samples were collected and quantified using infrared spectroscopy. Potential factors associated with reduced renal function including age, ethnicity, educational level, history of diabetes, hypertension, gout, hydronephrosis, serum uric acid level, and type of renal stone were evaluated using univariable and multivariable analyses.

RESULTS

A total of 1162 patients from a multi-ethnic population (Malays 67%, Chinese 19%, Indians 13% and indigenous people 1%) with median age of 57 years (Interquartile range 48-64) were enrolled in the study. Almost a third of patients were found with reduced renal function. Multivariable analysis showed that the odds of having reduced renal function increased with age, ethnicity, lower educational level, history of diabetes, hypertension, gout, bilateral hydronephrosis, elevated serum uric acid level and infection stone.

CONCLUSIONS

Reduced renal function varies between ethnicities and all age groups of renal stone formers. In addition to age and ethnicity, cardiovascular risk factors including diabetes and hypertension may also need to be taken into account in managing stone patients with reduced renal function.

Effectiveness of Urate-Lowering Therapy for Renal Function in Patients With Chronic Kidney Disease: A Meta-Analysis of Randomized Clinical Trials

Background and Objective: Hyperuricemia is closely related to chronic kidney disease (CKD). The effects of urate-lowering therapy (ULT) on renal outcomes are uncertain, and whether it is warranted in CKD patients is currently unclear. The aim of our meta-analysis of randomized clinical trials (RCTs) was to assess the effectiveness and safety of ULT for improving kidney function in patients with CKD.

Methods: RCTs were retrieved from the PubMed, Embase, MEDLINE and Cochrane Central Register of Controlled Trials databases. The meta-analysis was performed using Review Manager and Stata/SE software. The outcomes were changes in renal function and serum uric acid (SUA), serum creatinine, and adverse events.

Results: Twelve RCTs with 1,469 participants were included in the meta-analysis. ULT was found to effectively lower SUA (standard mean difference (SMD): -2.70; 95% confidence interval (CI): -3.71, -1.69) but the renoprotective effects were not superior to those of control therapy (placebo or usual therapy), which were stable in the subgroup analyses and sensitivity analyses. Regarding adverse events, their risks did not increase in the ULT group compared with the control group and were stable in the sensitivity analyses.

Conclusion: The findings of our meta-analysis suggested that ULT can effectively lower SUA, but there is insufficient evidence to support the renoprotective effects of ULT in CKD patients. In addition, ULT is safe for patients with CKD.

Systematic Review Registration:https://clinicaltrials.gov/, identifier PROSPERO (CRD42020200550).

Allopurinol Initiation and All-Cause Mortality Among Patients With Gout and Concurrent Chronic Kidney Disease : A Population-Based Cohort Study

BACKGROUND

Two recent randomized clinical trials of escalating doses of allopurinol for the progression of chronic kidney disease (CKD) reported no benefits but potentially increased risk for death. Whether the risk could occur in patients with gout and concurrent CKD remains unknown.

OBJECTIVE

To examine the relation of allopurinol initiation, allopurinol dose escalation, and achieving target serum urate (SU) level after allopurinol initiation to all-cause mortality in patients with both gout and CKD.

DESIGN

Cohort study.

SETTING

The Health Improvement Network U.K. primary care database (2000 to 2019).

PARTICIPANTS

Patients aged 40 years or older who had gout and concurrent moderate-to-severe CKD.

MEASUREMENTS

The association between allopurinol initiation and all-cause mortality over 5-year follow-up in propensity score (PS)-matched cohorts was examined. Analysis of hypothetical trials were emulated: achieving target SU level (<0.36 mmol/L) versus not achieving target SU level and dose escalation versus no dose escalation for mortality over 5-year follow-up in allopurinol initiators.

RESULTS

Mortality was 4.9 and 5.8 per 100 person-years in 5277 allopurinol initiators and 5277 PS-matched noninitiators, respectively (hazard ratio [HR], 0.85 [95% CI, 0.77 to 0.93]). In the target trial emulation analysis, the HR of mortality for the achieving target SU level group compared with the not achieving target SU level group was 0.87 (CI, 0.75 to 1.01); the HR of mortality for allopurinol in the dose escalation group versus the no dose escalation group was 0.88 (CI, 0.73 to 1.07).

LIMITATION

Residual confounding cannot be ruled out.

CONCLUSION

In this population-based data, neither allopurinol initiation, nor achieving target SU level with allopurinol, nor allopurinol dose escalation was associated with increased mortality in patients with gout and concurrent CKD.

PRIMARY FUNDING SOURCE

Project Program of National Clinical Research Center for Geriatric Disorders.

Association between serum uric acid and α-klotho protein levels in the middle-aged population

This study investigated the association between hyperuricemia and serum klotho protein levels in a representative sample of adults in the United States. We included 11,734 adults aged 40–80 years with available data of serum klotho, uric acid, covariates related to demographics, health behavior-related variables, and medical histories. Hyperuricemia was defined as a serum uric acid level of ≥7.0 mg/dL in men and ≥6.0 mg/dL in women. The geometric mean of serum klotho was 806.5 pg/mL (95% confidence interval: 801.7–811.4). The log-klotho level was negatively correlated with the uric acid level (r = −0.154; p < 0.0001). After adjustment for potential covariates, each one-unit increase in uric acid was significantly associated with a decrease in the log-klotho level (adjusted beta = −0.028; p < 0.0001). Compared with subjects without hyperuricemia, those with hyperuricemia had significantly lower serum klotho levels (adjusted beta = −0.062; p < 0.0001). We found a significant inverse association between serum uric acid and serum klotho levels in the general population, that is, an increase in serum uric acid levels was associated with a decrease in klotho levels. This finding suggests that loss of klotho may be due to the progression of hyperuricemia or, subsequently, gout.