Hyperuricemia increases the risk of acute kidney injury: a systematic review and meta-analysis

Risk factors and renal outcomes of AKI in children with secondary steroid-resistant nephrotic syndrome

BACKGROUND

Acute kidney injury (AKI) is increasingly prevalent in children with nephrotic syndrome (NS). It is associated with adverse outcomes in NS, especially steroid-resistant nephrotic syndrome (SRNS). The incidence, risk factors and outcomes of AKI in secondary SRNS remain undefined. The main objectives of this study were to determine the risk factors and prognosis of AKI in hospitalized children with secondary SRNS.

MATERIAL AND METHODS

This retrospective study was conducted from January 2014 to December 2019, involving 172 hospitalizations with secondary SRNS admitted to the First Affiliated Hospital of Sun Yat-sen University. AKI was defined and classified in accordance with the 2012 Kidney Disease Improving Global Outcomes (KDIGO) guidelines.

RESULTS

AKI was found in 67 (39.0%) of 172 hospitalizations with secondary SRNS. Average age of onset in our group is 4.4 (3.1, 6.7) years with AKI and 3.7 (1.8, 5.6) years without AKI. Urea nitrogen level is 5.9 (4.1, 10.0) mmol/L with AKI and 5.1 (3.7, 7.0) mmol/L. Uric acid level is 446.0 (340.0, 567.0) umol/L with AKI and 401.0 (303.0, 496.0) umol/L. 24-h urinary protein level is 4.14 (2.9, 6.5) g with AKI and 2.5 (1.3, 5.3) without AKI. Multivariate logistic regression revealed that infection (OR = 5.287; 95% confidence interval, 2.349 to 11.899; p < 0.001), age at onset (OR = 1.180; 95% confidence interval, 1.032 to 1.349; p = 0.015) and uric acid level (OR = 1.003; 95% confidence interval, 1.000 to 1.006; p = 0.031) were significantly associated with the development of AKI in children with secondary SRNS. Among 72 children with secondary SRNS, six went to end-stage kidney disease (ESKD). Children in the AKI group were more likely to progress to ESKD compared with children in the non-AKI group (p = 0.017) with a median follow-up of 48.5months.

CONCLUSION

AKI occurred in 39.0% of total hospitalizations associated with secondary SRNS. Risk factors including infection, age of onset, and uric acid level are associated with AKI in children with secondary SRNS. Furthermore, AKI was identified as a risk factor for the progression of secondary SRNS to ESKD.

Uric acid and acute kidney injury in high-risk patients for developing acute kidney injury undergoing cardiac surgery: A prospective multicenter study

PURPOSE

It is unclear whether preoperative serum uric acid (SUA) elevation may play a role in the development of acute kidney injury (AKI) associated with cardiac surgery (CSA-AKI). We conducted a cohort study to evaluate the influence of preoperative hyperuricemia on AKI in patients at high risk for developing SC-AKI.

DESIGN

Multicenter prospective international cohort study.

SETTING

Fourteen university hospitals in Spain and the United Kingdom.

PARTICIPANTS

We studied 261 consecutive patients at high risk of developing CSA-AKI, according to a Cleveland score ≥ 4 points, from July to December 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

AKIN criteria were used for the definition of AKI. Multivariable logistic regression models and propensity score-matched pairwise analysis were used to determine the adjusted association between preoperative hyperuricemia (≥7 mg/dL) and AKI. Elevated preoperative AUS (≥7 mg/dL) was present in 190 patients (72.8%), whereas CSA-AKI occurred in 145 patients (55.5%). In multivariable logistic regression models, hyperuricemia was not associated with a significantly increased risk of AKI (adjusted Odds Ratio [OR]: 1.58; 95% confidence interval [CI]: 0.81-3; P = .17). In propensity score-matched analysis of 140 patients, the hyperuricemia group experienced similar adjusted odds of AKI (OR 1.05, 95%CI 0.93-1.19, P = .37).

CONCLUSIONS

Hyperuricemia was not associated with an increased risk of AKI in this cohort of patients undergoing cardiac surgery at high risk of developing CSA-AKI.

Uric acid in predicting the traumatic rhabdomyolysis induced acute kidney injury; a systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis was to assess the value of uric acid in predicting acute kidney injury caused by traumatic rhabdomyolysis.

METHODS

The search was conducted in MEDLINE, Scopus, Embase and Web of Science until November 1, 2023. Based on the inclusion and exclusion criteria, the articles were included by two independent researchers. Data regarding study design, patient characteristics, number of patients with and without AKI, mean and SD of uric acid and prognostic characteristics of uric acid were extracted from relevant studies. STATA version 17.0 was used to compute pooled measures of standardized mean differences, odds ratios, and diagnostic accuracy. I2 and chi-square tests were used to assess heterogeneity between studies.

RESULTS

We found 689 non-redundant studies, 44 of them were potentially relevant. Six articles met the inclusion criteria and were included in the review. The results of the meta-analysis confirmed that there was a significant correlation between serum uric acid levels and the occurrence of AKI (SMD = 1.61, 95% CI = 0.69 to 2.54, I2 = 96.94%; p value = 0.001). There were no significant publication biases.

CONCLUSION

According to this meta-analysis, uric acid levels could be considered as a predictor of acute kidney injury following traumatic rhabdomyolysis.

Design, Synthesis, Evaluation, and Molecular Docking Study of Ascorbic Acid Dual-Coated Omeprazole Pellets and the Antioxidative Effect of Ascorbic Acid on Omeprazole-Induced Renal Injury in an Animal Model

The present study was carried out to investigate the antioxidant effect of ascorbic acid on omeprazole (O.P.)-induced acute kidney infection (AKI). Design of experiment (DoE) was employed to fabricate formulations (P1-P8) by the extrusion spheronization technique, and they were evaluated using various analytical techniques. P1-P8 formulations have % drug loading ranging from 56.34 ± 1.10 to 98.67 ± 1.05%, encapsulation efficiency from 70.98 ± 0.96 to 98.67 ± 1.05%, percentage drug release varying from 36.56 ± 1.34 to 93.45 ± 1.45%, Hausner's ratio ranging from 1.026 ± 0.05 to 1.065 ± 0.02%, and Carr's index varying from 2.3 ± 0.07 to 6.1 ± 0.06 g/mL. The optimized formulation (P6) was dual-coated with Eudragit L-100 (5% w/v) and ascorbic acid (2% w/v). A smooth uniform morphology was found after coating, and particle size nonsignificantly changed from 85.31 ± 77.43 to 101.99 ± 65.56 μm. IR spectra showed omeprazole characteristic peaks confirming drug loading, and peaks at 1747.40 and 1611.51 cm-1 confirmed ascorbic acid and Eudragit L-100 coating. X-ray diffraction (XRD) analysis confirmed the crystalline nature, and thermal degradation studies until 500 °C demonstrated increased stability after coating. Cytotoxicity analysis with 97% cell viability revealed the nontoxic behavior of pellets. In vitro dissolution studies of coated pellets showed <20% drug release at pH 1.2 and 99.54% at pH 6.8. Animal studies showed that pure omeprazole showed a nonsignificant decrease in weight, urine output, and fecal output compared to rodents on ascorbic acid pellets. Increased uric acid and creatinine levels in the group on pure omeprazole indicated AKI. Histopathological studies of renal cells also supported these results. The integration of experimental pellet formulation with molecular docking simulations has unveiled the potential of ascorbic acid and omeprazole as highly promising therapeutic agents for addressing oxidative stress and inflammation.

Chinese Sumac (Rhus chinensis Mill.) Fruits Prevent Hyperuricemia and Uric Acid Nephropathy in Mice Fed a High-Purine Yeast Diet

Hyperuricemia (HUA) is a prevalent chronic disease, characterized by excessive blood uric acid levels, that poses a significant health risk. In this study, the preventive effects and potential mechanisms of ethanol extracts from Chinese sumac (Rhus chinensis Mill.) fruits on HUA and uric acid nephropathy were comprehensively investigated. The results demonstrated a significant reduction in uric acid levels in hyperuricemia mice after treatment with Chinese sumac fruit extract, especially in the high-dose group, where the blood uric acid level decreased by 39.56%. Visual diagrams of the kidneys and hematoxylin and eosin (H&E)-stained sections showed the extract's effectiveness in protecting against kidney damage caused by excessive uric acid. Further investigation into its mechanism revealed that the extract prevents and treats hyperuricemia by decreasing uric acid production, enhancing uric acid excretion, and mitigating the oxidative stress and inflammatory reactions induced by excessive uric acid in the kidneys. Specifically, the extract markedly decreased xanthine oxidase (XOD) levels and expression in the liver, elevated the expression of uric acid transporters ABCG2, and lowered the expression of uric acid reabsorption proteins URAT1 and SLC2A9. Simultaneously, it significantly elevated the levels of endogenous antioxidant enzymes (SOD and GSH) while reducing the level of malondialdehyde (MDA). Furthermore, the expression of uric-acid-related proteins NLRP3, ACS, and Caspase-3 and the levels of IL-1β and IL-6 were significantly reduced. The experimental results confirm that Chinese sumac fruit extract can improve HUA and uric acid nephropathy in mice fed a high-purine yeast diet. This finding establishes a theoretical foundation for developing Chinese sumac fruit as a functional food or medicine for preventing and treating HUA.

Uric acid promotes interleukin-17 expression to cause kidney injury

Uric acid, an oxidation end-product of purine metabolism, is reportedly to be a risk factor for kidney injury. However, its underlying mechanism is still a mystery. This study aimed to reveal the detailed roles of uric acid in inducing kidney injury and the possible mechanisms. Injection of rats with uric acid significantly increased tubular injury score, and levels of blood urea nitrogen, serum creatinine, and urine kidney injury molecule-1. Uric acid increased the expression of collagen I, alpha-smooth muscle actin, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6. Kyoto Encyclopedia of Genes and Genomes analysis result showed the IL-17 signaling pathway as the most significantly enriched pathway involved in hyperuricemia-related kidney injury. Long-term injection of uric acid induced significant production of IL-17 and recruitment of Th17 cells. Treating rats with the anti-IL-17 mAb attenuated uric acid-induced kidney injury, accompanied by the inactivation of nuclear factor-κB (NF-κB). In conclusion, uric acid was confirmed to be a risk factor for kidney injury via inducing IL-17 expression. Neutralization of IL-17 using the specific mAb relieved uric acid-induced kidney injury via inhibition of NF-κB signaling.

Polyphenol Composition, Antioxidant Capacity and Xanthine Oxidase Inhibition Mechanism of Furong Plum Fruits at Different Maturity Stages

An experiment was conducted on the polyphenol content, flavonoid content, anthocyanin content, and antioxidant capacity of Furong plum (Prunus salicina Lindl. cv. "furong") at different maturity stages to determine the most suitable maturity stage. The inhibition of plum polyphenols on xanthine oxidase (XOD) was measured, and its kinetics were studied to reveal the inhibitory mechanism. The experimental results showed that the polyphenol, flavonoid and anthocyanin contents of plums at the ripe stage were the highest, reaching 320.46 mg GAE/100 g FW, 204.21 mg/100 g FW, and 66.24 mg/100 g FW, respectively, in comparison those of the plums at the immature and mid-ripe stages. The antioxidant capacity of the ripe plums was stronger than it was during the other stages of the plums growth. Among them, the total polyphenols of the ripe plums exhibited the strongest antioxidant capacity (IC50 values against DPPH and hydroxyl radicals were 28.19 ± 0.67 μg/mL and 198.16 ± 7.55 μg/mL, respectively), which was between the antioxidant capacity of the free polyphenols and bound polyphenols. The major phenolic monomer compounds of plum polyphenols were flavan-3-ols (epicatechin, catechin, proanthocyanidin, and procyanidin B2), flavonols (myricetin), and phenolic acids (chlorogenic acid, ferulic acid, and protocatechuic acid). Additionally, plum polyphenols exhibited a strong inhibitory effect on XOD, with an IC50 value of 77.64 μg/mL. The inhibition kinetics showed that plum polyphenols are mixed-type inhibitors that inhibit XOD activity and that the inhibition process is reversible. The calculated values of Ki and α were 16.53 mmol/L and 0.26, respectively.

Effect of Intestinal Flora on Hyperuricemia-Induced Chronic Kidney Injury in Type 2 Diabetic Patients and the Therapeutic Mechanism of New Anti-Diabetic Prescription Medications

This article examined the current research on hyperuricemia (HUA) exacerbating diabetic kidney damage and novel anti-diabetic medications for treating these people. Hyperuricemia and type 2 diabetes (T2D), both of which are frequent metabolic disorders, are closely connected. Recent studies have shown that hyperuricemia can increase kidney injury in T2D patients by aggravating insulin resistance, by activating the renin-angiotensin-aldosterone system (RAAS), and by stimulating inflammatory factors, and the diversity, distribution, and metabolites of intestinal flora. Considering this, there are just a few of the research examining the effect of hyperuricemia on diabetic kidney injury via intestinal flora. Through the gut-kidney axis, intestinal flora primarily influences renal function. The primary mechanism is that variations in diversity, distribution, and metabolites of intestinal flora led to alterations in metabolites (such as short-chain fatty acids, Indoxyl sulfate and p-cresol sulfate, Trimethylamine N-oxide TMAO). This article reviewed the research and investigates the association between hyperuricemia and T2D, as well as the influence of hyperuricemia on diabetic kidney injury via intestinal flora. In addition, the current novel antidiabetic drugs are discussed, and their characteristics and mechanisms of action are reviewed. These novel antidiabetic drugs include SGLT2 inhibitors, GLP-1 receptor agonists, DDP-4 inhibitors, glucokinase (GK) enzyme activators (GK agonists), and mineralocorticoid receptor antagonists (MRA). Recent studies suggest that these new anti-diabetic medications may have a therapeutic effect on hyperuricemia-induced kidney impairment in diabetes patients via various mechanisms. Some of these medications may reduce blood uric acid levels, while others may improve kidney function by attenuating the overstimulation of RAAS or by decreasing insulin resistance and inflammation in the kidneys. These novel antidiabetic medicines may have a multifaceted approach to treating hyperuricemia-induced kidney impairment in diabetic patients; nevertheless, additional study is required to establish their efficacy and comprehend their specific mechanisms.

Association of hyperhomocysteinemia and chronic kidney disease in the general population: a systematic review and meta-analysis

BACKGROUND

Increasing evidence shows that an elevated homocysteine(Hcy) level is associated with an increased risk of chronic kidney disease (CKD). This study systematically evaluated the correlation between homocysteine level and the incidence of CKD reported in cohort and cross-sectional studies.

METHODS

We searched electronic databases and reference lists for relevant articles. 4 cohort studies and 7 cross-sectional studies including 79,416 patients were analyzed in a meta-analysis. Hyperhomocysteinemia was defined as a Hcy level > 15 µmol/L, which was the criterium used in previous studies. Meta-analyses were conducted of literature searches from online databases such as PubMed, Embase, Cochrane and Scopus. Computed pooled adjusted odds ratios with corresponding 95% confidence intervals (95% CI) were used to estimate the risk of new-onset CKD according to Hcy levels in the general population.

RESULTS

People with high Hcy levels were more likely to suffer from CKD than people with normal Hcy levels (pooled OR, 2.09; 95% CI, 1.72-2.55). This positive relationship persisted across different study types such as cohort studies (summary OR, 2.2; 95% CI, 1.55-3.13) and cross-sectional studies (summary OR, 2.07; 95% CI, 1.63-2.63).

CONCLUSIONS

People with hyperhomocysteinemia have a higher incidence of CKD, Hyperhomocysteinemia may also be an independent risk factor for CKD in the general population.

Ameliorative effect of cheqianzi decoction on hyperuricemia and kidney injury and underlying mechanism in rats

Cheqianzi Decoction (CQD) is a Traditional Chinese Medicine (TCM) formula comprising four herbs and is recorded in the Ancient Materia Medica "Shengji Zonglu". Individually, these four herbs have been shown to reduce uric acid (UA) levels, to treat hyperuricemia (HUA), and alleviate kidney damage. However, the therapeutic efficacy of the CQD and related mechanism are not yet clear. In this study, high performance liquid chromatography (HPLC) analysis confirmed that the contents of the chemical components of the four herbal medicines were in accordance with the provisions of the Chinese Pharmacopoeia. A total of 99 potential targets were identified in the network pharmacology analysis of CQD, indicating its involvement in the regulation of inflammatory and apoptotic signaling pathways, and potential value for treating HUA and alleviating kidney injury. In vivo pharmacodynamic studies showed that compared with the Model group, significantly decreased levels of serum uric acid (SUA), serum creatinine (SCr), blood urea nitrogen (BUN) (all P < 0.05), and inflammatory factors (P < 0.01) were detected in the CQD group. Quantitative real-time PCR and Western blot analyses showed that compared with the Model group, adenosine triphosphate (ATP)-binding cassette efflux transporter G2 (ABCG2) expression in the CQD group was significantly upregulated (P < 0.01) at both the mRNA and protein levels, while mRNA expression of Caspase3 and NOD-like receptor family member 3 (NLRP3) (P < 0.05) and protein expression of NLRP3 (P < 0.01) were significantly downregulated. In conclusion, CQD promotes UA excretion by activating ABCG2, and induces inflammasome NLRP3-mediated reduction in inflammatory and apoptotic factors to achieve renal protection. Thus, our findings indicate the therapeutic potential of CQD in HUA with kidney injury.

Lipidomics analysis facilitate insight into the molecular mechanisms of urate nephropathy in a gout model induced by combination of MSU crystals injection and high-fat diet feeding

Renal injury is one of the most common clinical manifestations of patients with hyperuricaemia/gout. The precise pathophysiological mechanism(s) for the renal injury is still unknown. Furthermore, it is also unclear whether the clinical therapies (e.g., colchicine and febuxostat) could prevent its progression or not. Lipids are involved in almost all of important biological processes and play critical roles in maintaining the renal functions. Herein, shotgun lipidomics was performed for class-targeted lipid analysis of cellular lipidomes in renal tissue of a gouty model induced by combination of monosodium urate crystals injection and high-fat diet feeding with/without treatment with either colchicine or febuxostat. Serum uric acid (UA), proinflammatory cytokines (i.e., TNF-α and IL-6), xanthine oxidase activity, footpad swelling, and pain threshold were determined to evaluate the gouty severity. Renal histopathological changes, blood urea nitrogen, creatinine, and kidney index were used to reflect renal injury. Lipidomics analysis revealed that altered triacylglycerol (TAG) profile, impaired mitochondrial function resulted by decreased tetra 18:2 cardiolipin, reduced 4-hydroxyalkenal (HNE) species, and elevated lysophospholipids were already present in the kidneys at early stage of renal injury, probably contributing to its occurrence and development. In addition to significantly reduce the UA level and relief the gouty severity, treatment with either colchicine or febuxostat could restore HNE bioavailability, thereby delaying the progression of renal injury. However, both of them could not recover the altered TAG profile and the impaired mitochondrial function, indicating that treatment with either of them could not completely prevent the development of renal injury in the gouty model.

Interaction of Uric Acid and Neutrophil-to-Lymphocyte Ratio for Cardiometabolic Risk Stratification and Prognosis in Coronary Artery Disease Patients

Oxidative stress and inflammation are key factors in cardiometabolic diseases. We set out to evaluate the relationship between serum uric acid (UA) and the neutrophil-to-lymphocyte ratio (NLR) with cardiometabolic risk factors in coronary artery disease (CAD) patients, and their additive and multiplicative interactive effects on outcomes (cardiac death/CD and hard events (HE)-death plus reinfarction). A total of 2712 patients (67 ± 11 years, 1960 males) who underwent coronary angiography was retrospectively analyzed and categorized into no-CAD patients (n =806), stable-CAD patients (n =1545), and patients with acute myocardial infarction (AMI) (n =361). UA and NLR were reciprocally correlated and associated with cardiometabolic risk factors. During a mean follow-up period of 27 ± 20 months, 99-3.6% deaths, and 213-7.8% HE were registered. The Kaplan-Meier survival estimates showed significantly worse outcomes in patients with elevated UA or NLR levels. Multivariate Cox regression analysis demonstrated that NLR independently predicted CD and HE. There was no multiplicative interaction between UA and NLR; however, the use of measures of additive interaction evidenced a positive additive interaction between UA and NLR for CD and HE. Although it is clear that correlation does not imply causation, the coexistence of NRL and UA appears to have a synergistic effect, providing further information for the risk stratification of CAD patients.

Hypouricemic effect of gallic acid, a bioactive compound from Sonneratia apetala leaves and branches, on hyperuricemic mice

As a tropical medicinal plant, Sonneratia apetala is mainly distributed in the southeast coastal areas of China. Recently, the hypouricemic effect of Sonneratia apetala leaves and branches (SAL) has been reported, but the active compound and its mechanism are unclear. Thus, this study aims to explore the effective fraction of SAL and the mechanism of its active compound on uric acid formation and excretion. SAL was extracted with ethyl acetate and concentrated to obtain solvent-free extracts (SAL-EA). The remains fraction (SAL-E) and the supernatant fraction (SAL-S) of SAL resulting from water extraction and alcohol precipitation were collected and dried. The effects of different fractions were explored on hyperuricemic mice. SAL-S showed excellent activities in decreasing the levels of uric acid (UA), blood urea nitrogen (BUN), and creatinine (CRE) in serum and in attenuating kidney damage. Then, the active compound gallic acid (GA) identified by HPLC was assayed for its mechanism of regulating uric acid metabolism in hyperuricemic mice. The hypouricemic effect of GA was probably associated with the downregulation of URAT1 and GLUT9, upregulation of ABCG2 and decreased activities of adenosine deaminase (ADA) and xanthine oxidase (XOD). Moreover, GA suppressed the level of MDA, IL-6, IL-1β, TNF-α, TGF-β1, COX-2 and cystatin-C (Cys-C), and enhanced the activities of SOD, GSH-Px, CAT, and Na⁺-K⁺-ATPase (NKA) in the kidneys. These results indicated that GA protects against hyperuricemia-induced kidney injury via suppressing oxidative stress and inflammation as well as decreasing the serum levels of UA by regulating urate transporters.

Chronic kidney disease: Which role for xanthine oxidoreductase activity and products?

The present review explores the role of xanthine oxidoreductase (XOR) in the development and progression of chronic kidney disease (CKD). Human XOR is a multi-level regulated enzyme, which has many physiological functions, but that is also implicated in several pathological processes. The main XOR activities are the purine catabolism, which generates uric acid, and the regulation of cell redox state and cell signaling, through the production of reactive oxygen species. XOR dysregulation may lead to hyperuricemia and oxidative stress, which could have a pathogenic role in the initial phases of CKD, by promoting cell injury, hypertension, chronic inflammation and metabolic derangements. Hypertension is common in CKD patients and many mechanisms inducing it (upregulation of renin-angiotensin-aldosterone system, endothelial dysfunction and atherosclerosis) may be influenced by XOR products. High XOR activity and hyperuricemia are also risk factors for obesity, insulin resistance, type 2 diabetes and metabolic syndrome that are frequent CKD causes. Moreover, CKD is common in patients with gout, which is characterized by hyperuricemia, and in patients with cardiovascular diseases, which are associated with hypertension, endothelial dysfunction and atherosclerosis. Although hyperuricemia is undoubtedly related to CKD, controversial findings have been hitherto reported in patients treated with urate-lowering therapies.

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 Between Clinical Competencies and Mental Health Symptoms Among Frontline Medical Staff During the COVID-19 Outbreak: A Cross-Sectional Study

Background

In China, mental health of frontline medical staff might be influenced by clinicians' ability to handle the outbreak of coronavirus disease 2019 (COVID-19). Few studies to-date have addressed the association between clinicians' competencies and mental health in this context. This cross-sectional study was to examine the prevalence of mental health symptoms among frontline medical staff that fought against the COVID-19 outbreak, and explore the associations between their competencies, and separate and concurrent depressive and anxiety symptoms.

Methods

A total of 623 frontline medical staff was included in this study. Competencies, depressive symptoms, and anxiety symptoms were assessed using a self-reported short form of the Chinese clinical physicians' competency model, Patient Health Questionnaire-9, and Generalized Anxiety Disorder-7 questionnaire, respectively. Logistic regression models were used to evaluate the associations between one SD increase in competency scores and the prevalence of mental health problems.

Results

The prevalence of depressive, anxiety, and comorbid depressive and anxiety symptoms was 40.93, 31.78, and 26.00%, respectively. Among the medical staff with higher total competency scores, the prevalence of depressive [odds ratios (ORs) = 0.67, 95% confidence intervals (CIs): 0.55-0.81], anxiety (OR = 0.68, 95% CI: 0.56-0.83), and comorbid anxiety and depressive symptoms (OR = 0.69, 95% CI: 0.55-0.83) was lower than among their lower-scoring counterparts. Subgroup analyses stratified by core competency scores revealed similar associations as the main analyses.

Conclusion

The present findings highlight the association between high core competency scores and lower prevalence of depressive, anxiety, and comorbid anxiety and depressive symptoms.

Acute kidney injury in patients with primary nephrotic syndrome: influencing factors and coping strategies

Background

Acute kidney injury (AKI) is a frequent and serious complication in patients with primary nephrotic syndrome (PNS). We aimed to evaluate the influencing factors of AKI in patients with PNS, to provide implications for the clinical management and nursing care of patients with PNS.

Methods

PNS patients who were treated in the Department of Nephrology in our hospital from January 1, 2020 to July 31, 2021 were included. The clinical characteristics and pathological type of PNS patients were evaluated. Pearson correlation and Logistic regression analysis were performed to analyze the related risk factors of AKI in patients with PNS.

Results

A total of 328 patients with PNS were included, the incidence of AKI in PNS patients was 28.05%. Pearson correlation analysis showed that diabetes(r = 0.688), pulmonary infection (r = 0.614), albumin (r = 0.779), serum creatinine (r = 0.617), uric acid (r = 0.522), blood urea nitrogen (r = 0.616), renal tubular casts (r = 0.707) were correlated with AKI in PNS patients (all P < 0.05). Logistic regression analysis indicated that diabetes (OR2.908, 95%CI1.844 ~ 4.231), pulmonary infection(OR3.755, 95%CI2.831 ~ 4.987), albumin ≤ 24 g/L (OR1.923, 95%CI1.214 ~ 2.355), serum creatinine ≥ 90 μmol/L (OR2.517, 95%CI2.074 ~ 3.182), blood urea nitrogen ≥ 6.5 mmol/L (OR1.686, 95%CI1.208 ~ 2.123), uric acid ≥ 390 μmol/L (OR2.755, 95%CI2.131 ~ 3.371), renal tubular casts(OR1.796, 95%CI1.216 ~ 2.208) were the independently influencing factors of AKI in PNS patients (all P < 0.05).

Conclusions

AKI is common in PNS patients. Actively controlling diabetes and pulmonary infection, strengthening nutrition support and renal function monitoring are essential to reduce the occurrence of AKI in PNS patients.

Prognostic value of hyperuricemia for patients with sepsis in the intensive care unit

This study evaluated the relationship between hyperuricemia at admission and the clinical prognosis of patients with sepsis. The data were obtained from the Intensive Care Medical Information Database III. The patients were divided into a normal serum uric acid group and a hyperuricemia group. The main outcome was 90-day mortality, and the secondary outcomes were hospital mortality, 30-day mortality, and acute kidney injury. Propensity score matching was used to balance the baseline characteristics of the groups. Our study retrospectively included 954 patients. Before and after propensity score matching, the incidence of AKI, the 30-day and 90-day mortality rates were significantly higher in the hyperuricemia group. Cox regression analysis showed that hyperuricemia was significantly associated with 90-day mortality (HR 1.648, 95% CI 1.215–2.234, p = 0.006), and hyperuricemia was significantly associated with the incidence of AKI (HR 1.773, 95% CI 1.107–2.841, p = 0.017). The Kaplan–Meier survival curve showed that the 90-day survival rate was significantly lower in the hyperuricemia group. In patients with sepsis in the intensive care unit, hyperuricemia was significantly associated with increased risk 90-day all-cause mortality and the incidence of AKI.

Effects of hyperuricaemia, with the superposition of being overweight and hyperlipidaemia, on the incidence of acute kidney injury following cardiac surgery: a retrospective cohort study

OBJECTIVES

Acute kidney injury (AKI) is a common complication of cardiac surgery. This study aimed to explore the effects of hyperuricaemia, being overweight and hyperlipidaemia as risk factors for AKI in patients following cardiac surgery (cardiac surgery-associated acute kidney injury (CSA-AKI)).

DESIGN

Retrospective observational study.

SETTING

University teaching, grade-A tertiary hospital in Shanghai, China.

PARTICIPANTS

Patients who underwent cardiac surgery from July 2015 to December 2015 in Zhongshan Hospital, Fudan University.

MAIN OUTCOME MEASURES

We investigated the effect of hyperuricaemia, in combination with being overweight and hyperlipidaemia, on the risk of CSA-AKI.

RESULTS

A total of 1420 patients were enrolled. The AKI incidence in the highest uric acid group was 44.4%, while that in the lowest uric acid group was 28.5% (p<0.001). Patients in the higher uric acid quartiles were more likely to be overweight and hyperlipidaemic at the same time (p<0.001). Multivariate logistic regression analysis showed that hyperuricaemia was an independent risk factor for AKI (OR=1.237, 95% CI 1.095 to 1.885; p=0.009); being overweight or hyperlipidaemia alone was not an independent risk factor, but the combination of being overweight and hyperlipidaemia was (OR=1.544, 95% CI 1.059 to 2.252; p=0.024). In the final model, the OR value increased to 3.126 when hyperuricaemia was combined with being overweight and hyperlipidaemia, and the Hosmer-Lemeshow test showed that all three models fit well (p=0.433, 0.638 and 0.597, respectively).

CONCLUSIONS

The combination of being overweight and having hyperlipidaemia was an independent risk factor, but being overweight or having hyperlipidaemia alone was not. The combination of hyperuricaemia, being overweight and hyperlipidaemia further increased the risk of CSA-AKI.

Prevalence and Outcomes Associated with Hyperuricemia in Hospitalized Patients with COVID-19

INTRODUCTION

Coronavirus 2019 (COVID-19) can increase catabolism and result in hyperuricemia. Uric acid (UA) potentially causes kidney damage by alteration of renal autoregulation, inhibition of endothelial cell proliferation, cell apoptosis, activation of the pro-inflammatory cascade, and crystal deposition. Hyperuricemia in patients with COVID-19 may contribute to acute kidney injury (AKI) and poor outcomes.

METHODS

We included 834 patients with COVID-19 who were >18 years old and hospitalized for >24 h in the Mount Sinai Health System and had at least 1 measurement of serum UA. We examined the association between the first serum UA level and development of acute kidney injury (AKI, defined by KDIGO criteria), major adverse kidney events (MAKE, defined by a composite of all-cause in-hospital mortality or dialysis or 100% increase in serum creatinine from baseline), as well as markers of inflammation and cardiac injury.

RESULTS

Among the 834 patients, the median age was 66 years, 42% were women, and the median first serum UA was 5.9 mg/dL (interquartile range 4.5-8.8). Overall, 60% experienced AKI, 52% experienced MAKE, and 32% died during hospitalization. After adjusting for demographics, comorbidities, and laboratory values, a doubling in serum UA was associated with increased AKI (odds ratio [OR] 2.8, 95% confidence interval [CI] 1.9-4.1), MAKE (OR 2.5, 95% CI 1.7-3.5), and in-hospital mortality (OR 1.7, 95% CI 1.3-2.3). Higher serum UA levels were independently associated with a higher level of procalcitonin (β, 0.6; SE 0.2) and troponin I (β, 1.2; SE 0.2) but were not associated with serum ferritin, C-reactive protein, and interleukin-6.

CONCLUSION

In patients admitted to the hospital for COVID-19, higher serum UA levels were independently associated with AKI, MAKE, and in-hospital mortality in a dose-dependent manner. In addition, hyperuricemia was associated with higher procalcitonin and troponin I levels.

A simple prediction model of hyperuricemia for use in a rural setting

Currently, the most widely used screening methods for hyperuricemia (HUA) involves invasive laboratory tests, which are lacking in many rural hospitals in China. This study explored the use of non-invasive physical examinations to construct a simple prediction model for HUA, in order to reduce the economic burden and invasive operations such as blood sampling, and provide some help for the health management of people in poor areas with backward medical resources. Data of 9252 adults from April to June 2017 in the Affiliated Hospital of Guilin Medical College were collected and divided randomly into a training set (n = 6364) and a validation set (n = 2888) at a ratio of 7:3. In the training set, non-invasive physical examination indicators of age, gender, body mass index (BMI) and prevalence of hypertension were included for logistic regression analysis, and a nomogram model was established. The classification and regression tree (CART) algorithm of the decision tree model was used to build a classification tree model. Receiver operating characteristic (ROC) curve, calibration curve and decision curve analyses (DCA) were used to test the distinction, accuracy and clinical applicability of the two models. The results showed age, gender, BMI and prevalence of hypertension were all related to the occurrence of HUA. The area under the ROC curve (AUC) of the nomogram model was 0.806 and 0.791 in training set and validation set, respectively. The AUC of the classification tree model was 0.802 and 0.794 in the two sets, respectively, but were not statistically different. The calibration curves and DCAs of the two models performed well on accuracy and clinical practicality, which suggested these models may be suitable to predict HUA for rural setting.

Hypouricaemic and nephroprotective effects of Poria cocos in hyperuricemic mice by up-regulating ATP-binding cassette super-family G member 2

CONTEXT

Poria coco F.A.Wolf (Polyporaceae) dispels dampness and promotes diuresis implying hypouricaemic action.

OBJECTIVE

To examine hypouricaemic action of Poria coco.

MATERIALS AND METHODS

Ethanol extract (PCE) was prepared by extracting the sclerotium of P. cocos with ethanol, and the water extract (PCW) was produced by bathing the remains with water. PCE and PCW (50, 100 and 200 mg/kg, respectively) were orally administered to hyperuricemic Kunming mice (n = 8) to examine its hypouricaemic effect. Also, molecular docking was performed.

RESULTS

P. cocos showed excellent hypouricaemic action, decreasing the serum uric acid of hyperuricaemia (HUA) control (526 ± 112 μmol/L) to 178 ± 53, 153 ± 57 and 151 ± 62 μmol/L (p < 0.01) by PCE and 69 ± 23, 63 ± 15 and 62 ± 20 μmol/L (p < 0.01) by PCW, respectively. According to SCrs, BUNs and H&E staining, PCE and PCW partially attenuated renal dysfunction caused by HUA. They presented no negative effects on ALT, AST and ALP activities. They elevated ABCG2 (ATP-binding cassette super-family G member 2) mRNA and protein expression in comparison to HUA control. In molecular docking, compound 267, 277, 13824, 15730 and 5759 were predicted as the top bioactives of P. cocos against HUA, which even presented better scores than the positive compound, oestrone 3-sulfate.

DISCUSSION AND CONCLUSIONS

This paper demonstrated the hypouricaemic and nephroprotective effects of P. cocos in hyperuricemic mice by up-regulating ABCG2. These results may be useful for the development of a hypouricaemic agent.

Serum uric acid level and all-cause and cardiovascular mortality in Chinese elderly: A community-based cohort study in Shanghai

BACKGROUND AND AIMS

The association between serum uric acid (SUA) and the all-cause and cardiovascular diseases (CVD) mortality remains controversial, but few studies based on the community population in Shanghai have been reported. We aimed to evaluate the association of SUA level with all-cause and CVD mortality in Chinese elderly based on a community-based cohort study in Shanghai of China.

METHODS AND RESULTS

A total of 12,071 eligible participants were included, with a cumulative follow-up period of 46,063.65 person-years and a median of 4.67 years. The time-dependent Cox regression model indicated that when SUA level was classified into quartile groups, no significant association was observed between SUA level and all-cause death in both men and women and between SUA level and CVD mortality in men. However, the HR (95%CI) between SUA groups and CVD death in women was 3.75 (1.49-9.43) for quartile 1, 3.66 (1.53-8.76) for quartile 2, and 2.98 (1.33-6.69) for quartile 4, respectively, when compared with the quartile 3 SUA level. A significant non-linear association was observed between SUA level and CVD death in elderly women. An increased risk of CVD death was observed among women with SUA level less than 4.30 mg/dL at the baseline, and a lower risk, among women with SUA level of 4.30-4.72 mg/dL at the baseline.

CONCLUSION

The non-linear association between SUA level and CVD mortality in elderly women suggests a potential benefit of controlling SUA level at4.30-4.72 mg/dL in elderly Chinese women.

High-Throughput Untargeted Serum Metabolomics Analysis of Hyperuricemia Patients by UPLC-Q-TOF/MS

Hyperuricemia (HUA) as a metabolic disease is closely associated with metabolic disorders. The etiology and pathogenesis of HUA are not fully understood, so there is no radical cure so far. Metabolomics, a specialized study of endogenous small molecule substances, has become a powerful tool for metabolic pathway analysis of selected differential metabolites, which is helpful for initially revealing possible development mechanisms of various human diseases. Twenty HUA patients and 20 healthy individuals participated in the experiment, and ultrahigh performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) was employed to investigate serum samples to find differential metabolites. The statistical techniques used were principal component analysis and orthogonal partial least-squares discriminant analysis. The differences in metabolomics results of samples after pretreatment with different solvents were compared, 38, 20, 26, 28, 33, 50, and 40 potential differential metabolites were found, respectively, in HUA patient samples, and each group involved different metabolic pathways. Repetitive metabolites were removed, 138 differential metabolites in HUA serum were integrated for analysis, and the human body was affected by 7 metabolic pathways of glycerophospholipid metabolism, sphingolipid metabolism, arachidonic acid metabolism, linoleic acid metabolism, phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and α-linolenic acid metabolism. In this work, the metabolomics approach based on UPLC-Q-TOF/MS was employed to investigate serum metabolic changes in HUA patients, 138 potential differential metabolites related to HUA were identified, which provided associations of lipids, amino acids, fatty acids, organic acids, and nucleosides profiles of HUA individuals. Metabolic pathways involved in glycerophospholipid metabolism, sphingolipid metabolism, arachidonic acid metabolism, linoleic acid metabolism, phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and a-linolenic acid metabolism shed light on the understanding of the etiology and pathogenesis process of HUA.

Risk Scoring Systems Including Electrolyte Disorders for Predicting the Incidence of Acute Kidney Injury in Hospitalized Patients

Introduction

Electrolyte disorders are common among hospitalized patients with acute kidney injury (AKI) and adversely affect the outcome. This study aimed to explore the potential role of abnormal electrolyte levels on predicting AKI and severe AKI.

Methods

In this retrospective, observational study, we included all hospitalized patients in our hospital in China from October 01, 2014, to September 30, 2015. Since only a few patients had arterial blood gas analysis (ABG), all subjects involved were divided into two groups: patients with ABG and patients without ABG. Severe AKI was defined as AKI stage 2 or 3 according to KDIGO guideline.

Results

A total of 80,091 patients were enrolled retrospectively and distributed randomly into the test cohort and the validation cohort (2:1). Logistic regression was performed in the test cohort to analyze risk factors including electrolyte disorders and elucidate the association. The test data (derivation cohort) led to AUC values of 0.758 (95% CI: 0.743–0.773; AKI with ABG), 0.751 (95% CI: 0.740–0.763; AKI without ABG), 0.733 (95% CI: 0.700–0.767; severe AKI with ABG), 0.853 (95% CI: 0.824–0.882; severe AKI without ABG). Application of the scoring system in the validation cohort led to AUC values of 0.724 (95% CI: 0.703–0.744; AKI with ABG), 0.738 (95% CI: 0.721–0.755; AKI without ABG), 0.774 (95% CI: 0.732–0.815; severe AKI with ABG), 0.794 (95% CI: 0.760–0.827; severe AKI without ABG). Hosmer–Lemeshow tests revealed a good calibration.

Conclusion

The risk scoring systems involving electrolyte disorders were established and validated adequately efficient to predict AKI and severe AKI in hospitalized patients. Electrolyte imbalance needs to be carefully monitored and corrections should be made on time to avoid further adverse outcome.

Is there any association between contrast-induced nephropathy and serum uric acid levels?

Introduction: During the recent years, several studies have investigated that hyperuricemia is associated with greater incidence of contrast induced nephropathy (CIN). Most of them are in acute conditions like primary percutaneous coronary interventions. This study aimed to assess the relationship between high serum uric acid and incidence of acute kidney injury in patients undergoing elective angiography and angioplasty.

Methods: This prospective study was conducted on 211 patients who were admitted to hospital for elective coronary angiography or angioplasty. The researchers measured serum creatinine and uric acid on admission and repeated creatinine measurement in 48 hours and seven days after the procedure. According to serum uric acid, the patients were divided into two groups; group 1 with normal uric acid and group 2 with hyperuricemia which was defined as uric acid more than 6 mg/dL in women and 7 mg/dL in men. CIN is defined as an increased creatinine level of more than 0.5 mg/dL or 25% from the baseline in 48 hours after the intervention.

Results: In total, 211 patients with mean age of 60.58 years were enrolled in the study. Of these, 87 (41.2%) patients were in the high uric acid group and 124 (58.8%) were in the normal uric acid group. CIN was occurred in 16 patients (7.5%). Seven out of 16 (8.04%) were in the high uric acid and nine (7.2%) were in the normal uric acid group. There were no significant differences between the two groups (P =0.831).

Conclusion: The frequency of CIN development was not different in the patients with hyperuricemia.

New-Onset Gout as an Independent Risk Factor for Returning to Dialysis After Kidney Transplantation

Background.

The causal relationship between gout and renal transplant outcomes is difficult to assess due to multiple interacting covariates. This study sought to estimate the independent effect of new-onset gout on renal transplant outcomes using a methodology that accounted for these interactions.

Methods.

This study analyzed data on patients in the US Renal Data System (USRDS) who received a primary kidney transplant between 2008 and 2015. The exposure was new-onset gout, and the primary endpoint was returning to dialysis >12 months postindex date (transplant date). A marginal structural model (MSM) was fitted to determine the relative risk of new-onset gout on return to dialysis.

Results.

18 525 kidney transplant recipients in the USRDS met study eligibility. One thousand three hundred ninety-nine (7.6%) patients developed new-onset gout, and 1420 (7.7%) returned to dialysis >12 months postindex. Adjusting for baseline and time-varying confounders via the MSM showed new-onset gout was associated with a 51% increased risk of return to (RR, 1.51; 95% CI, 1.03-2.20).

Conclusions.

This finding suggests that new onset gout after kidney transplantation could be a harbinger for poor renal outcomes, and to our knowledge is the first study of kidney transplant outcomes using a technique that accounted for the dynamic relationship between renal dysfunction and gout.

A Lanosteryl Triterpene (RA-3) Exhibits Antihyperuricemic and Nephroprotective Effects in Rats

Considering the global health threat posed by kidney disease burden, a search for new nephroprotective drugs from our local flora could prove a powerful strategy to respond to this health threat. In this study we investigated the antihyperuricemic and nephroprotective potential of RA-3, a plant-derived lanosteryl triterpene. The antihyperuricemic and nephroprotective effect of RA-3 was investigated using the adenine and gentamicin induced hyperuricemic and nephrotoxicity rat model. Following the induction of hyperuricemia and nephrotoxicity, the experimental model rats (Sprague Dawley) were orally administered with RA-3 at 50 and 100 mg/kg body weight, respectively, daily for 14 days. Treatment of the experimental rats with RA-3, especially at 100 mg/kg, effectively lowered the serum renal dysfunction (blood urea nitrogen and creatinine) and hyperuricemic (uric acid and xanthine oxidase) biomarkers. These were accompanied by increased antioxidant status with decrease in malondialdehyde content. A much improved histomorphological structure of the kidney tissues was also observed in the triterpene treated groups when compared to the model control group. It is evident that RA-3 possesses the antihyperuricemic and nephroprotective properties, which could be vital for prevention and amelioration of kidney disease.

Association between Nod-like receptor protein 3 inflammasome and gouty nephropathy

Crystalized deposits of monosodium urate activate the Nod-like receptor protein 3 (NLRP3) inflammasome, resulting in kidney damage. The present study investigated whether the NLRP3 inflammasome is associated with the progression of hyperuricaemia and gouty nephropathy. Adult male patients were recruited at the Affiliated Baoan Hospital of Shenzhen and divided into three groups of 15 patients each: The control group, the hyperuricaemia group and the gouty nephropathy group. General characteristics and organ function indicators were also measured for each patient. NLRP3, apoptosis-associated speck like protein (ASC) and caspase-1 mRNA and protein expressions in peripheral blood mononuclear cells were detected. The expression of certain downstream inflammatory factors, including interleukin (IL)-1β and IL-18 were also assessed in plasma. The results demonstrated that the concentration of uric acid and creatinine were increased in the hyperuricaemia and gouty nephropathy groups compared with the control group. NLRP3, ASC and caspase-1 mRNA and protein expression, and IL-1β and IL-18 expression were increased in the hyperuricaemia and gouty nephropathy groups compared with the control group. In addition, ASC and caspase-1 mRNA and protein expression, and IL-1β expression were higher in the gouty nephropathy group compared with the hyperuricaemia group. In conclusion, the present results supported the hypothesis that the NLRP3 inflammasome signalling pathway is associated with gouty nephropathy leading to initiation of the inflammatory response and causing renal damage.

Research Advances in the Mechanisms of Hyperuricemia-Induced Renal Injury

Uric acid is the end product of purine metabolism in humans, and its excessive accumulation leads to hyperuricemia and urate crystal deposition in tissues including joints and kidneys. Hyperuricemia is considered an independent risk factor for cardiovascular and renal diseases. Although the symptoms of hyperuricemia-induced renal injury have long been known, the pathophysiological molecular mechanisms are not completely understood. In this review, we focus on the research advances in the mechanisms of hyperuricemia-caused renal injury, primarily on oxidative stress, endothelial dysfunction, renal fibrosis, and inflammation. Furthermore, we discuss the progress in hyperuricemia management.

Uric acid and kidney damage in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that affects multiple organs; lupus nephritis (LN) is one of the most severe complications of SLE. In the kidneys, an intense inflammatory reaction affects the glomeruli and tubular interstitium. Uric acid has been considered a key molecule in the pathogenesis of some conditions such as metabolic syndrome, hypertension, and kidney disease as it is produced by injured cells and promotes immune-inflammatory responses. In this regard, high serum uric acid concentrations may be involved in the activation of some inflammatory pathways, associated with kidney damage in SLE. Therefore, the purpose of this article was to review the main physiological mechanisms and clinical data on the association between serum uric acid and kidney damage in SLE. Scientific evidence indicates that hyperuricemia has the potential to be an adjuvant in the development and progression of kidney manifestations in SLE. Uric acid may promote the activation of inflammatory pathways and the formation and deposition of autoantibodies in kidneys, leading to a reduction of glomerular filtration rate. Other potential mechanisms of this association include the presence of polymorphisms in the urate transporters, metabolic syndrome, use of some medications, and other situations associated with a reduced renal excretion of uric acid.

Uric acid and inflammation in kidney disease

Asymptomatic hyperuricemia is frequently observed in patients with kidney disease. Although a substantial number of epidemiologic studies have suggested that an elevated uric acid level plays a causative role in the development and progression of kidney disease, whether hyperuricemia is simply a result of decreased renal excretion of uric acid or is a contributor to kidney disease remains a matter of debate. Over the last two decades, multiple experimental studies have expanded the knowledge of the biological effects of uric acid beyond its role in gout. In particular, uric acid induces immune system activation and alters the characteristics of resident kidney cells, such as tubular epithelial cells, endothelial cells, and vascular smooth muscle cells, toward a proinflammatory and profibrotic state. These findings have led to an increased awareness of uric acid as a potential and modifiable risk factor in kidney disease. Here, we discuss the effects of uric acid on the immune system and subsequently review the effects of uric acid on the kidneys mainly in the context of inflammation.

Triglycerides and Total Cholesterol Concentrations in Association with Hyperuricemia in Chinese Adults in Qingdao, China

Objective

To assess the association between triglycerides (TG), total cholesterol (TC) and hyperuricemia (HUA) in the general Chinese population.

Methods

A population-based cross-sectional survey included 9680 participants aged 35–74 years in 2006 and 2009 in Qingdao, China. TG, TC and uric acid (UA) were measured. The logistic regression model was performed to estimate the association between TG, TC, and HUA with an odds ratio (OR) and 95% confidence intervals (CI). Meanwhile, age stratification analysis (<55 years group and ≥55 years group) was performed to evaluate whether age potentially affects the association between TG, TC and HUA using multivariable logistic regression.

Results

Higher TG and TC showed significantly increased HUA prevalence in both men and women (P_trend all <0.05). Multivariate logistic regression indicated that borderline high TG (OR: 1.68, 95% CI: 1.31, 2.15 and HTG (OR: 2.98, 95% CI: 2.39, 3.72) indicated increased risk for HUA in men, and borderline high TG (OR: 2.09; 95% CI: 1.68,2.62); HTG (OR: 3.62; 95% CI: 2.90,4.51), borderline high TC (OR: 2.09, 95% CI: 1.68, 2.62) and HTC (OR: 3.62, 95% CI: 2.90, 4.51) showed significant association with HUA in women after adjusted age, school years, marital status, geographic division, personal monthly income, BMI and HDL-C. Age stratification analyses demonstrated that the association between TG and HUA was stronger in males aged ≥55 years and female aged <55 years, and the association between TC and HUA was stronger in both gender aged <55 years.

Conclusion

This large cross-sectional study focusing on the association between single indictor of blood lipid as exposure and HUA as outcome on the east coast of China for the first time. From a sample of Chinese adults, this study demonstrated that elevated TG in men and women and TC in women were associated with increased HUA prevalence.

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.

Changeover Trial of Febuxostat and Topiroxostat for Hyperuricemia with Cardiovascular Disease: Sub-Analysis for Chronic Kidney Disease (TROFEO CKD Trial)

Background: The TROFEO trial demonstrated that febuxostat causes greater and more rapid reduction of serum uric acid (s-UA) than topiroxostat. We compared these drugs in patients with chronic kidney disease (CKD) by sub-analysis of the TROFEO trial.

Methods: This sub-analysis targeted patients with an estimated glomerular filtration rate (eGFR) ≤60 mL/min/1.73 m². The primary endpoint was the s-UA level. Secondary endpoints included creatinine, eGFR, urinary albumin, cystatin-C, oxidized low-density lipoprotein (Ox-LDL), eicosapentaenoic acid/arachidonic acid ratio, lipid biomarkers, high-sensitivity C-reactive protein, and B-type natriuretic peptide (BNP).

Results: There was no significant difference of s-UA between the two groups either before or after treatment. However, s-UA did not exceed 6.0 mg/dL in febuxostat group during the study period, but it exceeded this level in seven patients from topiroxostat group, with the number being significantly higher in topiroxostat group. Serum creatinine (s-Cr) and eGFR were significantly better after 6 months of febuxostat treatment compared with topiroxostat Cystatin-C was significantly lower after 6 months of febuxostat treatment compared with topiroxostat. The Ox-LDL was significantly lower after 3 and 6 months of febuxostat treatment compared with topiroxostat.

Conclusion: Febuxostat had stronger renoprotective and antioxidant effects than topiroxostat in patients with hyperuricemia and CKD.

Impact of serum uric acid on renal function after bariatric surgery: a retrospective study

BACKGROUND

Despite a known negative association between serum uric acid level (SUA) and renal function, this correlation in patients after bariatric surgery remains unknown.

OBJECTIVE

To assess correlation between postoperative SUA and estimated glomerular filtration rate (eGFR) at 12 months after bariatric surgery.

SETTING

A single tertiary referral center.

METHODS

A total of 252 patients (age = 40.5 ± 11.2; body mass index = 39.0 ± 5.5 kg/m²) undergoing bariatric surgery divided into 2 groups (i.e., normal renal function [90 ≤ eGFR < 125 mL/min/1.73 m², n = 176] versus renal function impairment [eGFR < 90 mL/min/1.73 m², n = 76]) were assessed for relationships between SUA and eGFR in both groups (primary endpoint) and associations of percentage weight loss with changes in SUA (△SUA) and eGFR (△eGFR) for all patients (secondary endpoint) at 12 months.

RESULTS

Overall, prevalence of hyperuricemia was 40.4% and 22.2% (baseline and postoperative 12 mo, respectively). Reverse relationship was observed between SUA and eGFR (r = -.152, P = .007) for all patients with no association noted between baseline SUA and eGFR in each group as well as between SUA and eGFR at 12 months in the normal group (r = -.076, P = .437). The reverse relationship was found (r = -.417, P = .005) in renal function impairment group for whom SUA was identified as a predictor of eGFR at 12 months. There was no association of percentage weight loss with △SUA (r = .089, P = .601) and △eGFR (r = -.046, P = .785).

CONCLUSION

The results demonstrated a negative relationship between postoperative SUA and renal function in patients with preexisting renal dysfunction undergoing bariatric surgery. Clinical significance of our findings warrants further investigation.

Rasburicase versus intravenous allopurinol for non-malignancy-associated acute hyperuricemia in paediatric cardiology patients

OBJECTIVES

Limited data exist for management of hyperuricemia in non-oncologic patients, particularly in paediatric cardiac patients. Hyperuricemia is a risk factor for acute kidney injury and may prompt treatment in critically ill patients. The primary objective was to determine if rasburicase use was associated with greater probability normalisation of serum uric acid compared to allopurinol. Secondary outcomes included percent reduction in uric acid, changes in serum creatinine, and cost of therapy.

DESIGN

A single-centre retrospective chart review.

SETTING

A 20-bed quaternary cardiovascular ICU in a university-based paediatric hospital in California.

PATIENTS

Patients admitted to cardiovascular ICU who received rasburicase or intravenous allopurinol between 2015 and 2016.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data from a cohort of 14 patients receiving rasburicase were compared to 7 patients receiving IV allopurinol. Patients who were administered rasburicase for hyperuricemia were more likely to have a post-treatment uric acid level less than 8 mg/dl as compared to IV allopurinol (100 versus 43%; p = 0.0058). Patients who received rasburicase had a greater absolute reduction in post-treatment day 1 uric acid (-9 mg/dl versus -1.9 mg/dl; p = 0.002). There were no differences in post-treatment day 3 or day 7 serum creatinine or time to normalisation of serum creatinine. The cost of therapy normalised to a 20 kg patient was greater in the allopurinol group ($18,720 versus $1928; p = 0.001).

CONCLUSION

In a limited paediatric cardiac cohort, the use of rasburicase was associated with a greater reduction in uric acid levels and associated with a lower cost compared to IV allopurinol.

Pegloticase Treatment Significantly Decreases Blood Pressure in Patients With Chronic Gout

Serum urate is correlated with blood pressure (BP), and lowering urate may decrease BP, but a consistent effect has not been observed. Here, we evaluated whether pegloticase, a recombinant uricase conjugated to polyethylene glycol, which can lead to persistently low serum urate levels (<1 mg/dL), can modulate BP in subjects with chronic refractory gout. This post hoc analysis used results from two 6-month randomized clinical trials in which subjects were treated with 8 mg pegloticase every 2 or 4 weeks (q2w or q4w) or placebo. Responders in this study were defined as those individuals in whom a persistently low urate level (<6 mg/dL and usually <1 mg/dL) was maintained. Serial sitting BP was measured in 173 subjects, and estimated glomerular filtration rate was determined at baseline and after 3 and 6 months. Significant reductions in mean arterial pressure (MAP) from baseline to 6 months were noted in q2w responders ( P=0.0028), whereas reductions in MAP in other groups were not significant. Significant decreases in both systolic and diastolic BP paralleled the change in MAP. Of the 62% of q2w responders exhibiting persistent decreases in MAP, there were no significant differences in baseline age, sex, race, weight, body mass index, history of hypertension, hyperlipidemia, history of coronary artery disease, gout duration, MAP, serum urate, estimated glomerular filtration rate or urinary uric acid/creatinine ratio compared with those who did not lower MAP. No significant changes in estimated glomerular filtration rate occurred in any of the groups during the study. Responders to biweekly pegloticase who maintained a persistently lower serum urate level throughout the trial experienced significant reductions in both systolic and diastolic BP that were independent of changes in renal function. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT00325195.

Uric Acid and Acute Kidney Injury in the Critically Ill

Rationale & Objective

Uric acid is excreted by the kidney and accumulates in acute kidney injury (AKI). Whether higher plasma uric acid level predisposes to AKI or its complications is not known.

Study Design

Prospective observational cohort study.

Setting & Participants

2 independent cohorts of critically ill patients: (1) 208 patients without AKI admitted to the intensive care unit (ICU) at Brigham & Women's Hospital between October 2008 and December 2016; and (2) 250 participants with AKI requiring renal replacement therapy (RRT) who had not yet initiated RRT enrolled in the Acute Renal Failure Trial Network (ATN) Study.

Exposure

Plasma uric acid level upon ICU admission and before RRT initiation in the ICU and ATN Study cohorts, respectively.

Outcomes

Incident AKI and 60-day mortality in the ICU and ATN Study cohorts, respectively.

Analytical Approach

Logistic regression models were used to test the association of plasma uric acid level with incident AKI and 60-day mortality.

Results

In the ICU cohort, median plasma uric acid level was 4.7 (interquartile range [IQR], 3.6-6.4) mg/dL, and 40 patients (19.2%) developed AKI. Higher plasma uric acid levels associated with incident AKI, but this association was confounded by serum creatinine level and was not significant after multivariable adjustment (adjusted OR per doubling of uric acid, 1.50; 95% CI, 0.80-2.81). In the ATN Study cohort, median plasma uric acid level was 11.1 (IQR, 8.6-14.2) mg/dL, and 125 participants (50.0%) died within 60 days. There was no statistically significant association between plasma uric acid levels and 60-day mortality in either unadjusted models or after multivariable adjustment for demographic, severity-of-illness, and kidney-specific covariates (adjusted OR per doubling of uric acid, 1.15; 95% CI, 0.71-1.86).

Limitations

Heterogeneity of ICU patients.

Conclusions

Plasma uric acid levels upon ICU admission or before RRT initiation are not independently associated with adverse clinical outcomes in critically ill patients.

Acute kidney injury in childhood-onset nephrotic syndrome: Incidence and risk factors in hospitalized patients

Background

Nephrotic syndrome (NS) is the most common glomerulopathy in children. Acute kidney injury (AKI) is a common complication of NS, caused by severe intravascular volume depletion, acute tubular necrosis, interstitial nephritis, or progression of NS. However, the incidence and risk factors of childhood-onset NS in Korea are unclear. Therefore, we studied the incidence, causes, and risk factors of AKI in hospitalized Korean patients with childhood-onset NS.

Methods

We conducted a retrospective review of patients with childhood-onset NS who were admitted to our center from January 2015 to July 2017. Patients with decreased renal function or hereditary/secondary NS, as well as those admitted for management of other conditions unrelated to NS, were excluded.

Results

During the study period, 65 patients with idiopathic, childhood-onset NS were hospitalized 90 times for management of NS or its complications. Of these 90 cases, 29 met the Kidney Disease Improving Global Outcomes criteria for AKI (32.2%). They developed AKI in association with infection (n = 12), NS aggravation (n = 11), dehydration (n = 3), and intravenous methylprednisolone administration (n = 3). Age ≥ 9 years at admission and combined use of cyclosporine and renin-angiotensin system inhibitors were risk factors for AKI.

Conclusion

AKI occurred in one-third of the total hospitalizations related to childhood-onset NS, owing to infection, aggravation of NS, dehydration, and possibly high-dose methylprednisolone treatment. Age at admission and use of nephrotoxic agents were associated with AKI. As the AKI incidence is high, AKI should be considered during management of high-risk patients.

Uric acid and contrast-induced nephropathy: an updated review and meta-regression analysis

Introduction

Previous studies have suggested a relationship between serum uric acid and contrast-induced nephropathy (CIN).

Aim

We performed an updated review and a meta-regression analysis to assess whether serum uric acid is associated with CIN or there exists any relationship between serum uric acid and other risk factors for CIN.

Material and methods

We searched PubMed, Embase and Cochrane databases and reviewed cited references up to July 31, 2018 to identify relevant studies.

Results

A total of 6,705 patients from 10 clinical studies were included. CIN occurred in 774 of the 6,705 (12%) patients. Baseline uric acid levels were significantly higher in those who developed CIN (6.51 vs. 5.67 mg/dl; 95% CI: 0.55–1.22, p = 0.00001). Comparison of clinical features showed that patients with CIN were significantly older (69 vs. 63 years; p < 0.00001) and more often had diabetes (42% vs. 32%; p = 0.002) and hypertension (67% vs. 59%; p = 0.03). Also, patients who developed CIN had lower hemoglobin (12.5 vs. 13.6 mg/dl; p < 0.00001) and higher levels of baseline creatinine (1.27 vs. 1.01 mg/dl; p < 0.0001), but had similar levels of glycemia, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride. Also, they showed a lower ejection fraction (45% vs. 50%; p < 0.00001). Meta-regression analysis revealed that uric acid related only to age (r = 0.13, p = 0.03).

Conclusions

Our investigation indicates that uric acid is significantly associated with CIN. Uric acid correlated significantly with age only, and not with other major predictors of CIN. Further studies are therefore needed to verify the potential of uric acid to improve CIN risk stratification.

Production Inhibition and Excretion Promotion of Urate by Fucoidan from Laminaria japonica in Adenine-Induced Hyperuricemic Mice

This work aims to explore the amelioration of fucoidan on adenine-induced hyperuricemia and hepatorental damage. Adenine-induced hyperuricemic mice were administered with fucoidan, allopurinol and vehicle control respectively to compare the effects of the drugs. Serum uric acid, urea nitrogen, hepatorenal functions, activities of hepatic adenosine deaminase (ADA), xanthine oxidase (XOD), renal urate transporter 1 (URAT1) and NF-κB p65 were assessed. As the serum uric acid, urea nitrogen, creatinine, glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) data demonstrated, the adenine not only mediated hepatorenal function disorders, but also induced hyperuricemia in mice. Meanwhile, activities of hepatic ADA and XOD were markedly augmented by adenine, and the expression of URAT1 was promoted, which was conducive to the reabsorption of urate. However, exposure to fucoidan completely reversed those adenine-induced negative alternations in mice, and the activities of hepatic ADA and XOD were recovered to the normal level. It was obvious that hepatic and renal functions were protected by fucoidan treatment. The expression of URAT1 was returned to normal, resulting in an increase of renal urate excretion and consequent healing of adenine-induced hyperuricemia in mice. Expression and activation of NF-κB p65 was promoted in kidneys of adenine treated mice, but suppressed in kidneys of mice exposed to fucoidan from Laminaria japonica or allopurinol. In conclusion, the fucoidan is a potential therapeutic agent for the treatment of hyperuricemia through dual regulatory roles on inhibition of hepatic metabolism and promotion of renal excretion of urate.

How should we manage asymptomatic hyperuricemia?

The definition of asymptomatic hyperuricemia remains unclear, as no consensus exists about the serum urate cutoff or the relevance of ultrasound findings. Comorbidities associated with hyperuricemia have increased in frequency over the past two decades. Hyperuricemia (and/or gout) may be a cause or a consequence of a comorbidity. Whereas epidemiological studies suggest that hyperuricemia may be linked to cardiovascular, metabolic, and renal comorbidities, Mendelian randomization studies have not provided proof that these links are causal. Discrepancies between findings from observational studies and clinical trials preclude the development of recommendations about the potential benefits of urate-lowering therapy (ULT) in individual patients with asymptomatic hyperuricemia. The risk/benefit ratio of ULT is unclear. The risk of developing gout, estimated at 50%, must be weighed against the risk of cutaneous and cardiovascular side effects of xanthine oxidase inhibitors. The need for optimal comorbidity management, in contrast, is universally accepted. Medications for comorbidities that elevate urate levels should be discontinued and replaced with medications that have the opposite effect. Therapeutic lifestyle changes, weight loss as appropriate, and sufficient physical activity are useful for improving general health. Whether ULT has beneficial effects on comorbidities will be known only when well-powered interventional trials with relevant primary endpoints are available.