Effect of uric acid lowering therapy on the prevention of acute kidney injury in cardiovascular surgery

A wide scope, pan-comparative, systematic meta-analysis of the efficacy of prophylactic strategies for cardiac surgery-associated acute kidney injury

Acute kidney injury (AKI) is the most common complication of cardiac surgery. Cardiac surgery-associated AKI (CSA-AKI) is caused by systemic and renal hemodynamic impairment and parenchymal injury. Prophylaxis of CSA-AKI remains an unmet priority, for which preventive strategies based on drug therapies, hydration procedures, and remote ischemic preconditioning (RIPC) have been tested in pre-clinical and clinical studies, with variable success. Contradicting reports and scarce or insufficiently pondered information have blurred conclusions. Therefore, with an aim to contribute to consolidating the available information, we carried out a wide scope, pan-comparative meta-analysis including the accessible information about the most relevant nephroprotective approaches assayed. After a thorough examination of 1892 documents retrieved from PubMed and Web of Science, 150 studies were used for the meta-analysis. Individual odds ratios of efficacy at reducing AKI incidence, need for dialysis, and plasma creatinine elevation were obtained for each alleged protectant. Also, the combined class effect of drug families and protective strategies was also meta-analyzed. Our results show that no drug family or procedure affords substantial protection against CSA-AKI. Only, a mild but significant reduction in the incidence of CSA-AKI by preemptive treatment with dopaminergic and adrenergic drugs, vasodilators, and the RIPC technique. The integrated analysis suggests that single-drug approaches are unlikely to cope with the variety of individual pathophysiological scenarios potentially underlying CSA-AKI. Accordingly, a theragnostic approach involving the etiopathological diagnosis of kidney frailty is necessary to guide research towards the development of pharmacological combinations concomitantly and effectively addressing the key mechanisms of CSA-AKI.

A single-center clinical study of acute kidney injury associated with acute myocardial infarction

OBJECTIVE

To investigate the risk factors of acute kidney injury (AKI) patients with acute myocardial infarction (AMI) and establish potential microRNA (miRNA) biomarkers in the peripheral blood of AMI-AKI patients.

METHODS

Patients hospitalized from 2016 to 2020 and diagnosed with AMI (with AKI or without AKI groups) were recruited. The data of the two groups were compared and the risk factors of AMI-AKI were analyzed by logistic regression. The receiver operator characteristics (ROC) curve was drawn and the predictive value of risk factors in AMI-AKI was evaluated. Six AMI-AKI patients were selected and six healthy subjects were enrolled as the control. The peripheral blood samples of the two groups were collected for miRNA high-throughput sequencing.

RESULTS

A total of 300 AMI patients were collected, including 190 patients with AKI and 110 patients without AKI. Multivariate logistic regression analysis indicated that diastolic pressure (68-80 mmHg), urea nitrogen, creatinine, serum uric acid (SUA), aspartate aminotransferase (AST), and left ventricular ejection fraction were the dependent risk factors of AMI-AKI patients (P < 0.05). ROC curve showed that the incidence of AMI-AKI patients was most correlated with urea nitrogen, creatinine, and SUA. In addition, 60 differentially expressed miRNAs were identified between AMI-AKI and controls. Then, hsa-miR-2278, hsa-miR-1827, and hsa-miR-149-5p were more corrected with predictors. Twelve of them targeted 71 genes involved in phagosome, oxytocin signaling pathway, and microRNAs in cancer pathways.

CONCLUSION

Urea nitrogen, creatinine, and SUA were the dependent risk factors and important predictors for AMI-AKI patients. Three miRNAs may be considered as biomarkers for AMI-AKI.

Machine learning in the prediction of cardiac surgery associated acute kidney injury with early postoperative biomarkers

Purpose

To establish novel prediction models for predicting acute kidney injury (AKI) after cardiac surgery based on early postoperative biomarkers.

Patients and methods

This study enrolled patients who underwent cardiac surgery in a Chinese tertiary cardiac center and consisted of a discovery cohort (n = 452, from November 2018 to June 2019) and a validation cohort (n = 326, from December 2019 to May 2020). 43 biomarkers were screened using the least absolute shrinkage and selection operator and logistic regression to construct a nomogram model. Three tree-based machine learning models were also established: eXtreme Gradient Boosting (XGBoost), random forest (RF) and deep forest (DF). Model performance was accessed using area under the receiver operating characteristic curve (AUC). AKI was defined according to the Kidney Disease Improving Global Outcomes criteria.

Results

Five biomarkers were identified as independent predictors of AKI and were included in the nomogram: soluble ST2 (sST2), N terminal pro-brain natriuretic peptide (NT-proBNP), heart-type fatty acid binding protein (H-FABP), lactic dehydrogenase (LDH), and uric acid (UA). In the validation cohort, the nomogram achieved good discrimination, with AUC of 0.834. The machine learning models also exhibited adequate discrimination, with AUC of 0.856, 0.850, and 0.836 for DF, RF, and XGBoost, respectively. Both nomogram and machine learning models had well calibrated. The AUC of sST2, NT-proBNP, H-FABP, LDH, and UA to discriminate AKI were 0.670, 0.713, 0.725, 0.704, and 0.749, respectively. In addition, all of these biomarkers were significantly correlated with AKI after adjusting clinical confounders (odds ratio and 95% confidence interval of the third vs. the first tertile: sST2, 3.55 [2.34-5.49], NT-proBNP, 5.50 [3.54-8.71], H-FABP, 6.64 [4.11-11.06], LDH, 7.47 [4.54-12.64], and UA, 8.93 [5.46-15.06]).

Conclusion

Our study provides a series of novel predictive models and five biomarkers for enhancing the risk stratification of AKI after cardiac surgery.

Development and internal validation of a prediction model for acute kidney injury following cardiac valve replacement surgery

BACKGROUND

Acute kidney injury (AKI) is a common complication after cardiac surgery. This study aims to develop and validate a risk model for predicting AKI after cardiac valve replacement surgery.

METHODS

Data from patients undergoing surgical valve replacement between January 2015 and December 2018 in our hospital were retrospectively analyzed. The subjects were randomly divided into a derivation cohort and a validation cohort at a ratio of 7:3. The primary outcome was defined as AKI within 7 days after surgery. Logistic regression analysis was conducted to select risk predictors for developing the prediction model. Receiver operator characteristic curve (ROC), calibration plot and clinical decision curve analysis (DCA) will be used to evaluate the discrimination, precision and clinical benefit of the prediction model.

RESULTS

A total of 1159 patients were involved in this study. The prevalence of AKI following surgery was 37.0% (429/1159). Logistic regression analysis showed that age, hemoglobin, fibrinogen, serum uric acid, cystatin C, bicarbonate, and cardiopulmonary bypass time were independent risk factors associated with AKI after surgical valve replacement (all P < 0.05). The areas under the ROC curves (AUCs) in the derivation cohort and the validation cohort were 0.777 (95% CI 0.744-0.810) and 0.760 (95% CI 0.706-0.813), respectively. The calibration plots indicated excellent consistency between the prediction probability and actual probability. DCA demonstrated great clinical benefit of the prediction model.

CONCLUSIONS

We developed a prediction model for predicting AKI after cardiac valve replacement surgery that was internally validated to have good discrimination, calibration, and clinical practicability.

Strategies for post-cardiac surgery acute kidney injury prevention: A network meta-analysis of randomized controlled trials

Objects

Cardiac surgery is associated with acute kidney injury (AKI). However, the effects of various pharmacological and non-pharmacological strategies for AKI prevention have not been thoroughly investigated, and their effectiveness in preventing AKI-related adverse outcomes has not been systematically evaluated.

Methods

Studies from PubMed, Embase, and Medline and registered trials from published through December 2021 that evaluated strategies for preventing post-cardiac surgery AKI were identified. The effectiveness of these strategies was assessed through a network meta-analysis (NMA). The secondary outcomes were prevention of dialysis-requiring AKI, mortality, intensive care unit (ICU) length of stay (LOS), and hospital LOS. The interventions were ranked using the P-score method. Confidence in the results of the NMA was assessed using the Confidence in NMA (CINeMA) framework.

Results

A total of 161 trials (involving 46,619 participants) and 53 strategies were identified. Eight pharmacological strategies {natriuretic peptides [odds ratio (OR): 0.30, 95% confidence interval (CI): 0.19-0.47], nitroprusside [OR: 0.29, 95% CI: 0.12-0.68], fenoldopam [OR: 0.36, 95% CI: 0.17-0.76], tolvaptan [OR: 0.35, 95% CI: 0.14-0.90], N-acetyl cysteine with carvedilol [OR: 0.37, 95% CI: 0.16-0.85], dexmedetomidine [OR: 0.49, 95% CI: 0.32-0.76;], levosimendan [OR: 0.56, 95% CI: 0.37-0.84], and erythropoietin [OR: 0.62, 95% CI: 0.41-0.94]} and one non-pharmacological intervention (remote ischemic preconditioning, OR: 0.76, 95% CI: 0.63-0.92) were associated with a lower incidence of post-cardiac surgery AKI with moderate to low confidence. Among these nine strategies, five (fenoldopam, erythropoietin, natriuretic peptides, levosimendan, and remote ischemic preconditioning) were associated with a shorter ICU LOS, and two (natriuretic peptides [OR: 0.30, 95% CI: 0.15-0.60] and levosimendan [OR: 0.68, 95% CI: 0.49-0.95]) were associated with a lower incidence of dialysis-requiring AKI. Natriuretic peptides were also associated with a lower risk of mortality (OR: 0.50, 95% CI: 0.29-0.86). The results of a sensitivity analysis support the robustness and effectiveness of natriuretic peptides and dexmedetomidine.

Conclusion

Nine potentially effective strategies were identified. Natriuretic peptide therapy was the most effective pharmacological strategy, and remote ischemic preconditioning was the only effective non-pharmacological strategy. Preventive strategies might also help prevent AKI-related adverse outcomes. Additional studies are required to explore the optimal dosages and protocols for potentially effective AKI prevention strategies.

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.

New conductive filament ready-to-use for 3D-printing electrochemical (bio)sensors: Towards the detection of SARS-CoV-2

The 3D printing technology has gained ground due to its wide range of applicability. The development of new conductive filaments contributes significantly to the production of improved electrochemical devices. In this context, we report a simple method to producing an efficient conductive filament, containing graphite within the polymer matrix of PLA, and applied in conjunction with 3D printing technology to generate (bio)sensors without the need for surface activation. The proposed method for producing the conductive filament consists of four steps: (i) mixing graphite and PLA in a heated reflux system; (ii) recrystallization of the composite; (iii) drying and; (iv) extrusion. The produced filament was used for the manufacture of electrochemical 3D printed sensors. The filament and sensor were characterized by physicochemical techniques, such as SEM, TGA, Raman, FTIR as well as electrochemical techniques (EIS and CV). Finally, as a proof-of-concept, the fabricated 3D-printed sensor was applied for the determination of uric acid and dopamine in synthetic urine and used as a platform for the development of a biosensor for the detection of SARS-CoV-2. The developed sensors, without pre-treatment, provided linear ranges of 0.5-150.0 and 5.0-50.0 μmol L^-1, with low LOD values (0.07 and 0.11 μmol L^-1), for uric acid and dopamine, respectively. The developed biosensor successfully detected SARS-CoV-2 S protein, with a linear range from 5.0 to 75.0 nmol L^-1 (0.38 μg mL^-1 to 5.74 μg mL^-1) and LOD of 1.36 nmol L^-1 (0.10 μg mL^-1) and sensitivity of 0.17 μA nmol^-1 L (0.01 μA μg^-1 mL). Therefore, the lab-made produced and the ready-to-use conductive filament is promising and can become an alternative route for the production of different 3D electrochemical (bio)sensors and other types of conductive devices by 3D printing.

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.

Large animal models for translational research in acute kidney injury

While extensive research using animal models has improved the understanding of acute kidney injury (AKI), this knowledge has not been translated into effective treatments. Many promising interventions for AKI identified in mice and rats have not been validated in subsequent clinical trials. As a result, the mortality rate of AKI patients remains high. Inflammation plays a fundamental role in the pathogenesis of AKI, and one reason for the failure to translate promising therapeutics may lie in the profound difference between the immune systems of rodents and humans. The immune systems of large animals such as swine, nonhuman primates, sheep, dogs and cats, more closely resemble the human immune system. Therefore, in the absence of a basic understanding of the pathophysiology of human AKI, large animals are attractive models to test novel interventions. However, there is a lack of reviews on large animal models for AKI in the literature. In this review, we will first highlight differences in innate and adaptive immunities among rodents, large animals, and humans in relation to AKI. After illustrating the potential merits of large animals in testing therapies for AKI, we will summarize the current state of the evidence in terms of what therapeutics have been tested in large animal models. The aim of this review is not to suggest that murine models are not valid to study AKI. Instead, our objective is to demonstrate that large animal models can serve as valuable and complementary tools in translating potential therapeutics into clinical practice.

Hyperuricemia in Kidney Disease: A Major Risk Factor for Cardiovascular Events, Vascular Calcification, and Renal Damage

Kidney disease, especially when it is associated with a reduction in estimated glomerular filtration rate, can be associated with an increase in serum urate (uric acid), suggesting that hyperuricemia in subjects with kidney disease may be a strictly secondary phenomenon. Mendelian randomization studies that evaluate genetic scores regulating serum urate also generally have not found evidence that serum urate is a causal risk factor in chronic kidney disease. Nevertheless, this is countered by a large number of epidemiologic, experimental, and clinical studies that have suggested a potentially important role for uric acid in kidney disease and cardiovascular disease. Here, we review the topic in detail. Overall, the studies strongly suggest that hyperuricemia does have an important pathogenic role that likely is driven by intracellular urate levels. An exception may be the role of extracellular uric acid in atherosclerosis and vascular calcification. One of the more striking findings on reviewing the literature is that the primary benefit of lowering serum urate in subjects with CKD is not by slowing the progression of renal disease, but rather by reducing the incidence of cardiovascular events and mortality. We recommend large-scale clinical trials to determine if there is a benefit in lowering serum urate in hyperuricemic subjects in acute and chronic kidney disease and in the reduction of cardiovascular morbidity and mortality in subjects with end-stage chronic kidney disease.

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.

The Predictive Value of Hyperuricemia on Renal Outcome after Contrast-Enhanced Computerized Tomography

The aim of this study was to determine whether elevated serum level of uric acid (sUA) could predict renal outcome after contrast-enhanced computerized tomography (CCT). We used a historical cohort of 58,106 non-dialysis adult patients who received non-ionic iso-osmolar CCT from 1 June 2008 to 31 March 2015 to evaluate the association of sUA and renal outcome. The exclusion criteria were patients with pre-existing acute kidney injury (AKI), multiple exposure, non-standard volume of contrast, and missing data for analysis. A total of 1440 patients were enrolled. Post-contrast-AKI (PC-AKI), defined by the increase in serum creatinine ≥ 0.3 mg/dL within 48 h or ≥50% within seven days after CCT, occurred in 180 (12.5%) patients and the need of hemodialysis within 30 days developed in 90 (6.3%) patients, both incidences were increased in patients with higher sUA. sUA ≥ 8.0 mg/dL was associated with an increased risk of PC-AKI (odds ratio (OR) of 2.62; 95% confidence interval (CI), 1.27~5.38, p = 0.009) and the need of hemodialysis (OR, 5.40; 95% CI, 1.39~21.04, p = 0.015). Comparing with sUA < 8.0 mg/dL, patients with sUA ≥ 8.0 mg/dL had higher incidence of PC-AKI (16.7% vs. 11.1%, p = 0.012) and higher incidence of hemodialysis (12.1% vs. 4.3%, p < 0.001). We concluded that sUA ≥ 8.0 mg/dL is associated with worse renal outcome after CCT. We suggest that hyperuricemia may have potential as an independent risk factor for PC-AKI in patients receiving contrast-enhanced image study.

Hyperuricemia complicated with acute kidney injury is associated with adverse outcomes in patients with severely decompensated acute heart failure

Background

The relationship between the serum level of uric acid (UA) and the acute kidney injury on admission in patients with acute heart failure (AHF) remain unclear.

Methods and results

A total of 1326 AHF patients were screened, and data for 1047 patients who were admitted to the intensive-care unit were analyzed. The patients were assigned to a low-UA group (UA ≤ 7.0 mg/dl, n = 569) or a high-UA group (UA > 7.0 mg/dl, n = 478) according to their UA level at admission. Acute kidney injury (AKI) at admission was defined based on the ratio of the serum creatinine value recorded on admission to the baseline creatinine value: no-AKI (n = 736) or AKI (n = 311). The patients were therefore assigned to four groups: low-UA/no-AKI (n = 428), high-UA/no-AKI (n = 308), low-UA/AKI (n = 141) and high-UA/AKI (n = 170). The high-UA patients were significantly more frequent in the AKI group than in the non-AKI group among all patients and the non-chronic kidney injury (CKD) cohort. A Kaplan-Meier curve showed a significantly lower 365-day survival rate in the high-UA/AKI group than in the other groups. The multivariate Cox regression model identified only high-UA/AKI as an independent predictor of 365-day mortality (hazard ratio [HR]: 2.511, 95% confidence interval [CI] 1.671–3.772 in all AHF patients, HR: 1.884, 95% CI 1.022–3.473 in non-CKD patients and HR: 3.546, 95% CI 2.136–5.884 in CKD patients).

Conclusion

An elevated serum UA level complicated with AKI was an independent predictor of mortality in patients with severely decompensated AHF.

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.

Probiotic supplements prevented oxonic acid-induced hyperuricemia and renal damage

Hyperuricemia is highly prevalent and especially common in subjects with metabolic, cardiovascular and renal diseases. In chronic kidney disease, hyperuricemia is extremely common, and uric acid (UA) excretion relies on gut uricolysis by gut microbiota. Current therapy for lowering serum UA includes drugs that may produce undesired secondary effects. Therefore, this pilot study was designed to evaluate the potential of two probiotic supplements to reduce systemic uric acid concentrations. Secondary objectives were to assess whether the hypouricemic effect related to a therapeutic benefit on the hyperuricemia-induced renal damage and hypertension. Analysis of fecal microbiota was also performed. Groups of 6 rats each were followed for 5 weeks and allocated in the following treatment groups: C = Control; HU-ND = Oxonic acid-induced hyperuricemia (HU) +regular diet; HU-P = HU+placebo; HU-F1 = HU+ probiotics formula 1 and HU-F2 = HU+ probiotics formula 2. We confirmed that oxonic acid-induced hyperuricemia produced hypertension and renal functional and structural changes, along with modest changes in the overall composition of fecal microbiota. Both probiotic-containing diets prevented HU, elevated UA urinary excretion and intrarenal UA accumulation induced by oxonic acid. The hypouricemic effect conferred by probiotic supplementation also prevented the renal changes and hypertension caused by hyperuricemia. However, probiotic treatment did not restore the fecal microbiota. In conclusion, we demonstrated for the first time the ability of probiotics containing uricolytic bacteria to lower serum uric acid in hyperuricemic animals with beneficial consequences on blood pressure and renal disease. As probiotics supplements are innocuous for human health, we recommend clinical studies to test if probiotic supplements could benefit hyperuricemic individuals.

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

Association and prognostic value of serum Cystatin C, IL-18 and Uric acid in urological patients with acute kidney injury

PURPOSE

To assess the role of serum Cystatin C, IL-18 and Uric acid in acute kidney injury (AKI) in urological patients, along with their prognostic significance.

MATERIALS AND METHODS

Prospective observational study included 61 cases, admitted in urology ward with baseline serum creatinine ≤1.5 mg/dL. All patients had at least one or more predisposing factors for AKI. Daily urine output and creatinine level were checked. Serum levels of biomarkers were measured at baseline and postoperatively after 24 h. Development of AKI and its outcome were analysed.

RESULTS

Thirty nine patients (63.9%) developed AKI in the study. Patients with AKI were found to have a greater percentage rise of Cystatin C (118.7% v/s 81.8%, p = 0.005), IL-18 (59.0% v/s 25.5%, p = 0.004) and Uric acid (34.3% v/s 19.2%, p = 0.008) after 24 h. Absolute Uric acid level at day 1 was also significantly associated with AKI (5.18 ± 0.91 v/s 4.45 ± 0.86, p = 0.003). Risk stratification of AKI was poor for all biomarkers. Area under curve for Cystatin C, IL-18 and Uric acid was 0.715, 0.696 and 0.734 respectively. Renal function after 3 months, had a positive correlation with baseline creatinine and baseline Cystatin C levels (r = 0.56 & 0.39).

CONCLUSIONS

Postoperative serum Cystatin C, IL-18 and Uric acid after 24 h were significantly associated with AKI. Baseline Cystatin C had moderate capability to predict short term renal function.

Hyperuricemia, Acute and Chronic Kidney Disease, Hypertension, and Cardiovascular Disease: Report of a Scientific Workshop Organized by the National Kidney Foundation

Urate is a cause of gout, kidney stones, and acute kidney injury from tumor lysis syndrome, but its relationship to kidney disease, cardiovascular disease, and diabetes remains controversial. A scientific workshop organized by the National Kidney Foundation was held in September 2016 to review current evidence. Cell culture studies and animal models suggest that elevated serum urate concentrations can contribute to kidney disease, hypertension, and metabolic syndrome. Epidemiologic evidence also supports elevated serum urate concentrations as a risk factor for the development of kidney disease, hypertension, and diabetes, but differences in methodologies and inpacts on serum urate concentrations by even subtle changes in kidney function render conclusions uncertain. Mendelian randomization studies generally do not support a causal role of serum urate in kidney disease, hypertension, or diabetes, although interpretation is complicated by nonhomogeneous populations, a failure to consider environmental interactions, and a lack of understanding of how the genetic polymorphisms affect biological mechanisms related to urate. Although several small clinical trials suggest benefits of urate-lowering therapies on kidney function, blood pressure, and insulin resistance, others have been negative, with many trials having design limitations and insufficient power. Thus, whether uric acid has a causal role in kidney and cardiovascular diseases requires further study.

Are There Modifiable Risk Factors to Improve AKI?

Acute kidney injury (AKI) is a common critical syndrome, with high morbidity and mortality. Patients with AKI typically have an adverse prognosis, from incident chronic kidney disease (CKD), progression to end-stage renal disease (ESRD), subsequent cardiovascular disease, and ultimately death. However, there is currently no effective therapy for AKI. Early detection of risk factors for AKI may offer a good approach to prevention or early intervention. Traditional risk factors include extreme age, many common comorbid diseases, such as preexisting CKD, some specific exposures, such as sepsis, and exposure to some nephrotoxic agents. Recently, several novel risk factors for AKI, such as hyperuricemia, hypoalbuminemia, obesity, anemia, and hyperglycemia, have been identified. The underlying mechanisms between these nontraditional risk factors and AKI and whether their correction can reduce AKI occurrence remain to be clarified. This review describes the current epidemiology of AKI, summarizes its outcome, outlines the traditional risk profile, and finally highlights some recently identified novel risk factors.

Serum uric acid and acute kidney injury: A mini review

Acute kidney injury causes great morbidity and mortality in both the community and hospital settings. Understanding the etiological factors and the pathophysiological principles resulting in acute kidney injury is essential in prompting appropriate therapies. Recently hyperuricemia has been recognized as a potentially modifiable risk factor for acute kidney injury, including that associated with cardiovascular surgery, radiocontrast administration, rhabdomyolysis, and associated with heat stress. This review discussed the evidence that repeated episodes of acute kidney injury from heat stress and dehydration may also underlie the pathogenesis of the chronic kidney disease epidemic that is occurring in Central America (Mesoamerican nephropathy). Potential mechanisms for how uric acid might contribute to acute kidney injury are also discussed, including systemic effects on renal microvasculature and hemodynamics, and local crystalline and noncrystalline effects on the renal tubules. Pilot clinical trials also show potential benefits of lowering uric acid on acute kidney injury associated with a variety of insults. In summary, there is mounting evidence that hyperuricemia may have a significant role in the development of acute kidney injury. Prospective, placebo controlled, randomized trials are needed to determine the potential benefit of uric acid lowering therapy on kidney and cardio-metabolic diseases.

Serum Uric Acid Exhibits Inverse Relationship with Estimated Glomerular Filtration Rate

BACKGROUND

In this study, we investigated the relationship between serum uric acid (SUA) and renal function in a unique patient cohort wherein SUA levels fluctuate during the course of standard care.

METHODS

Correlation coefficients between SUA and serum creatinine (SCr) and kinetic estimated GFR (KeGFR) were retrospectively investigated in acute myeloid leukemia (AML) patients, and statistically significant and clinically relevant determinants were studied in multiple regression models.

RESULTS

One hundred and twenty-six patients were included in the analysis. Baseline SUA was associated with an increased risk for acute kidney injury (AKI; OR 1.27, 95% CI 1.1-1.5, p = 0.003) and laboratory tumor lysis syndrome (OR 1.26, 95% CI 1.1-1.5, p = 0.005). Prophylactic uric acid-lowering therapy and hydration resulted in lower SUA values from baseline in 88.1% of the patients, the lowest values were observed on post-induction day 1 (20.4% reduction). Significant linear correlations were observed between SUA and SCr (r = 0.35, p < 0.001) values with a significant inverse correlation between SUA and KeGFR on day 1 (r = -0.33, p < 0.001) that persisted through day 4. By subgroup analysis, patients with primary AML (r = -0.49, p < 0.001), baseline SUA >5.5 mg/dl (r = -0.41, p = 0.002) and baseline eGFR >60 ml/min/1.73 m2 (r = -0.51, p < 0.001) demonstrated robust relationships between SUA and KeGFR. The relationship was more robust when the groups were combined (primary AML plus baseline SUA >5.5 mg/dl plus baseline eGFR >60 ml/min/1.73 m2, r = -0.52, p < 0.001).

CONCLUSION

The demonstration of linear relationship between SUA and SCr and inverse relationship between SUA and KeGFR reinforces the emerging translational physiological evidence regarding the role of uric acid in AKI.

Serum Uric Acid and Risk for Acute Kidney Injury Following Contrast

Contrast-induced acute kidney injury (CI-AKI) is a common cause of hospital-acquired acute kidney injury (AKI). We evaluated the evidence that uric acid (UA) plays a pathogenic role in CI-AKI. Ten studies were eligible for inclusion for meta-analysis. Hyperuricemia predicted risk for cases with AKI in prospective cohort studies. Higher levels of serum UA (SUA), as defined by the authors, were associated with a 2-fold increased risk to develop AKI (pooled odds ratio 2.03; 95% confidence interval [CI] 1.48-2.78). Significant heterogeneity was found in cohort studies ( P = .001, I² = 85.7%). In 2 clinical trials, lowering of SUA with saline hydration was significantly associated with reduced risk for AKI compared with saline hydration alone or saline hydration with N-acetyl cysteine. An analysis of 2 randomized controlled trials found that allopurinol with saline hydration had a significant protective effect on renal function (assessed by serum creatinine values) compared with hydration alone (mean difference: -0.52 mg/dL; 95% CI: -0.81 to -0.22). Hyperuricemia independently predicts CI-AKI. Two clinical trials suggest lowering SUA may prevent CI-AKI. The mechanism by which UA induces CI-AKI is likely related to acute uricosuria.

Prediction and Prevention of Acute Kidney Injury after Cardiac Surgery

The incidence of acute kidney injury after cardiac surgery (CS-AKI) ranges from 33% to 94% and is associated with a high incidence of morbidity and mortality. The etiology is suggested to be multifactorial and related to almost all aspects of perioperative management. Numerous studies have reported the risk factors and risk scores and novel biomarkers of AKI have been investigated to facilitate the subclinical diagnosis of AKI. Based on the known independent risk factors, many preventive interventions to reduce the risk of CS-AKI have been tested. However, any single preventive intervention did not show a definite and persistent benefit to reduce the incidence of CS-AKI. Goal-directed therapy has been considered to be a preventive strategy with a substantial level of efficacy. Many pharmacologic agents were tested for any benefit to treat or prevent CS-AKI but the results were conflicting and evidences are still lacking. The present review will summarize the current updated evidences about the risk factors and preventive strategies for CS-AKI.

Bridging translation for acute kidney injury with better preclinical modeling of human disease

The current lack of effective therapeutics for patients with acute kidney injury (AKI) represents an important and unmet medical need. Given the importance of the clinical problem, it is time for us to take a few steps back and reexamine current practices. The focus of this review is to explore the extent to which failure of therapeutic translation from animal studies to human studies stems from deficiencies in the preclinical models of AKI. We will evaluate whether the preclinical models of AKI that are commonly used recapitulate the known pathophysiologies of AKI that are being modeled in humans, focusing on four common scenarios that are studied in clinical therapeutic intervention trials: cardiac surgery-induced AKI; contrast-induced AKI; cisplatin-induced AKI; and sepsis associated AKI. Based on our observations, we have identified a number of common limitations in current preclinical modeling of AKI that could be addressed. In the long term, we suggest that progress in developing better preclinical models of AKI will depend on developing a better understanding of human AKI. To this this end, we suggest that there is a need to develop greater in-depth molecular analyses of kidney biopsy tissues coupled with improved clinical and molecular classification of patients with AKI.

Serum Uric Acid Levels and Renal Impairment among ST-Segment Elevation Myocardial Infarction Patients Undergoing Primary Percutaneous Intervention

BACKGROUND

Elevated serum uric acid (UA) levels are associated with adverse outcomes in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI). However, the relation between UA and acute kidney injury (AKI) in this population is unclear. We evaluated the effect of elevated UA levels on the risk to develop AKI among consecutive STEMI patients treated with primary PCI.

METHODS

We performed a retrospective analysis of 1,372 consecutive patients admitted with the diagnosis of STEMI between January 2008 and February 2015. Patients were stratified into quartiles according to UA levels as follows: quartile 1, <4.7 mg/dl; quartile 2, 4.8 to <5.6 mg/dl; quartile 3, 5.7 to <6.6 mg/dl, and quartile 4, >6.7 mg/dl.

RESULTS

STEMI patients with elevated UA levels had a higher frequency of AKI (4 vs. 6% vs. 10 vs. 24%; p < 0.001). In a subgroup analysis of patients with reduced baseline estimated glomerular filtration rate (≤60 ml/min/1.73 m(2)), an elevated UA level was associated with a significant risk to develop AKI, with 46% of patients developing AKI in the highest UA quartile. In a multivariate logistic regression model, for every 1-mg/dl increase in the UA concentration, the adjusted risk for AKI increased by 46% (OR = 1.46, 95% CI 1.18-1.66; p < 0.001).

CONCLUSIONS

Among STEMI patients undergoing primary PCI, elevated UA levels are an independent predictor of AKI.

Serum uric acid and AKI: is it time?

Acute kidney injury (AKI) is a well-recognized complication in hospitalized patients, with associated mortality and morbidity. Studies that aim to prevent or reverse AKI using pharmacological and interventional therapies in clinical practice have been disappointing. Work is continuing to identify potentially modifiable risk factors for AKI. Early identification and modification of these risk factors may help prevent or favorably influence the outcome of AKI. The role of uric acid as a potential risk factor is being revisited in chronic kidney disease and AKI. Apart from the established crystal precipitation with profound hyperuricemia, various non-crystal mechanisms have also been proposed in the pathogenesis of AKI. The association of serum uric acid levels with the development of AKI has been reported in various clinical settings. Together, the results of these studies highlight hyperuricemia as a potential risk factor of AKI and the need for further work on this subject.

Relationship between Serum Uric Acid Concentration and Acute Kidney Injury after Coronary Artery Bypass Surgery

An elevated serum concentration of uric acid may be associated with an increased risk of acute kidney injury (AKI). The aim of this study was to investigate the impact of preoperative uric acid concentration on the risk of AKI after coronary artery bypass surgery (CABG). Perioperative data were evaluated from patients who underwent CABG. AKI was defined by the AKI Network criteria based on serum creatinine changes within the first 48 hr after CABG. Multivariate logistic regression was utilized to evaluate the association between preoperative uric acid and postoperative AKI. We evaluated changes in C statistic, the net reclassification improvement, and the integrated discrimination improvement to determine whether the addition of preoperative uric acid improved prediction of AKI. Of the 2,185 patients, 787 (36.0%) developed AKI. Preoperative uric acid was significantly associated with postoperative AKI (odds ratio, 1.18; 95% confidence interval, 1.10-1.26; P<0.001). Adding uric acid levels improved the C statistic and had significant impact on risk reclassification and integrated discrimination for AKI. Preoperative uric acid is related to postoperative AKI and improves the predictive ability of AKI. This finding suggests that preoperative measurement of uric acid may help stratify risks for AKI in in patients undergoing CABG.

Admission hyperuricemia increases the risk of acute kidney injury in hospitalized patients(.)

Background

The association between elevated admission serum uric acid (SUA) and risk of in-hospital acute kidney injury (AKI) is limited. The aim of this study was to assess the risk of developing AKI in all hospitalized patients with various admission SUA levels.

Methods

This is a single-center retrospective study conducted at a tertiary referral hospital. All hospitalized adult patients who had admission SUA available from January 2011 through December 2013 were analyzed in this study. Admission SUA was categorized based on its distribution into six groups (<3.4, 3.4–4.5, 4.5–5.8, 5.8–7.6, 7.6–9.4 and >9.4 mg/dL). The primary outcome was in-hospital AKI occurring after hospital admission. Logistic regression analysis was performed to obtain the odds ratio (OR) of AKI of various admission SUA levels using the most common SUA level range (5.8–7.6 mg/dL) as the reference group.

Results

Of 1435 patients enrolled, AKI occurred in 263 patients (18%). The incidence of AKI and need for dialysis was increased in patients with higher admission SUA levels. After adjusting for potential confounders, SUA >9.4 mg/dL was associated with an increased risk of developing AKI, with ORs of 1.79 [95% confidence interval (CI) 1.13–2.82]. Conversely, admission SUA <3.4 and 3.4–4.5 mg/dL were associated with a decreased risk of developing AKI, with ORs of 0.38 (95% CI 0.17–0.75) and 0.50 (95% CI 0.28–0.87), respectively.

Conclusions

Elevated admission SUA was associated with an increased risk for in-hospital AKI.

False-Positive Rate of AKI Using Consensus Creatinine-Based Criteria

BACKGROUND AND OBJECTIVES

Use of small changes in serum creatinine to diagnose AKI allows for earlier detection but may increase diagnostic false-positive rates because of inherent laboratory and biologic variabilities of creatinine.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined serum creatinine measurement characteristics in a prospective observational clinical reference cohort of 2267 adult patients with AKI by Kidney Disease Improving Global Outcomes creatinine criteria and used these data to create a simulation cohort to model AKI false-positive rates. We simulated up to seven successive blood draws on an equal population of hypothetical patients with unchanging true serum creatinine values. Error terms generated from laboratory and biologic variabilities were added to each simulated patient's true serum creatinine value to obtain the simulated measured serum creatinine for each blood draw. We determined the proportion of patients who would be erroneously diagnosed with AKI by Kidney Disease Improving Global Outcomes creatinine criteria.

RESULTS

Within the clinical cohort, 75.0% of patients received four serum creatinine draws within at least one 48-hour period during hospitalization. After four simulated creatinine measurements that accounted for laboratory variability calculated from assay characteristics and 4.4% of biologic variability determined from the clinical cohort and publicly available data, the overall false-positive rate for AKI diagnosis was 8.0% (interquartile range =7.9%-8.1%), whereas patients with true serum creatinine ≥1.5 mg/dl (representing 21% of the clinical cohort) had a false-positive AKI diagnosis rate of 30.5% (interquartile range =30.1%-30.9%) versus 2.0% (interquartile range =1.9%-2.1%) in patients with true serum creatinine values <1.5 mg/dl (P<0.001).

CONCLUSIONS

Use of small serum creatinine changes to diagnose AKI is limited by high false-positive rates caused by inherent variability of serum creatinine at higher baseline values, potentially misclassifying patients with CKD in AKI studies.

Uric Acid as a Marker of Kidney Disease: Review of the Current Literature

Uric acid has been implicated in the pathophysiology of renal disease; however renal clearance makes a causal relationship difficult to prove. We examine the current literature to support a potential role of uric acid in the development of kidney disease and to determine the potential to use uric acid as a marker for future renal decline. After review, we conclude that uric acid is definitively linked to the development of chronic kidney disease and can be a poor prognostic factor for the development of acute renal failure, as well. However, further human research is needed before predictive models utilizing uric acid can be developed and used in the clinical setting.

Serum uric acid may predict development of progressive acute kidney injury after open heart surgery

OBJECTIVES

Acute kidney injury (AKI) is a common complication of cardiac surgery developing in 25-35% cases. Recently, neutrophil gelatinase-associated lipocalin (NGAL) was shown to predict AKI development earlier than serum creatinine. Some studies demonstrated the predictive role of post-operative serum uric acid (SUA) as an early marker of AKI. We aimed to study the role of serum and urine NGAL as well as SUA to predict progression of AKI.

DESIGN AND METHODS

This is a prospective observational study of patients undergoing cardiac surgery. Blood and urine samples for measurement of uric acid, serum and urine NGAL levels were collected prior to cardiac surgery (0 h), and in the time course at 2nd and 24th hours after surgery. Patients who developed AKI were divided into two subgroups as progressing and non-progressing AKI.

RESULTS

Sixty patients (42 males, 18 females) were included. After cardiac surgery, 40 patients developed AKI, 20 of whom non-progressing AKI, and 20 progressing AKI. All of the markers significantly increased in AKI patients. A receiver operator characteristics (ROC) curve analysis showed higher predictive ability of SUA for progressing AKI compared with serum and urine NGAL. When compared markers obtained at the second hour after surgery, UA had significantly large AUC than NGAL to predict AKI developed at 24 and 48 h, particularly in patients, who require renal replacement therapy (RRT).

CONCLUSION

Uric acid seems to predict the progression of AKI and RRT requirement in patients underwent cardiac surgery better than NGAL.

Association of preoperative uric acid and acute kidney injury following cardiovascular surgery

OBJECTIVE

Recent studies suggested that elevated serum uric acid levels may be associated with the risk of acute kidney injury (AKI) in several settings. However, the effect of uric acid on the risk of AKI after cardiovascular surgery remains uncertain.

DESIGN

A retrospective analysis.

SETTING

A tertiary care university hospital.

PARTICIPANTS

All consecutive adult patients (n = 1,019) who underwent cardiovascular surgery between January 2011 and May 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Preoperative and perioperative data were assessed in the study population. AKI was defined and staged as serum creatinine concentration-based Acute Kidney Injury Network criteria. Univariate and multivariate logistic regression analyses were conducted to evaluate the association between preoperative uric acid and postoperative AKI. Preoperative elevated uric acid (≥ 6.5 mg/dL) was associated independently with AKI after cardiovascular surgery (odds ratio 1.46; 95% confidence interval 1.04-2.06, p = 0.030). Results were the same in subgroup analyses. Preoperative elevated uric acid (≥ 6.5 mg/dL) also was associated with a higher incidence of prolonged ICU and hospital stay.

CONCLUSIONS

Preoperative elevated serum uric acid is an independent risk factor for AKI in patients undergoing cardiovascular surgery. This finding suggests that preoperative measurements of serum uric acid concentration may help stratify risks for AKI in these patients.

Association between allopurinol and mortality among Japanese hemodialysis patients: results from the DOPPS

Purpose

Allopurinol, for treating hyperuricemia, is associated with lower mortality among hyperuricemic patients without chronic kidney disease (CKD). Greater allopurinol utilization in hemodialysis (HD) in Japan versus other countries provides an opportunity for understanding allopurinol-related HD outcomes.

Methods

Data from 6,252 Japanese HD patients from phases 1–3 of the Dialysis Outcomes and Practice Patterns Study (1999–2008) at ~60 facilities per phase were analyzed. Mortality was compared for patients prescribed (25 %) versus not-prescribed allopurinol using Cox regression, overall, and in patient subgroups.

Results

Patients prescribed allopurinol were more likely to be younger, male, and non-diabetic, and had higher serum creatinine and lower (treated) serum uric acid levels (mean = 7.0 vs. 8.0 mg/dL, p < 0.001). The inverse association between allopurinol prescription and mortality in unadjusted analyses (HR 0.65, 95 % CI 0.52–0.81) was attenuated by covariate adjustment (HR 0.84, 0.66–1.06). In subgroup analyses, allopurinol was associated with lower mortality among patients with no history of cardiovascular disease (CVD) (HR 0.48, 0.28–0.83), but not among patients with CVD (HR 1.00, 0.76–1.32). A similar pattern was seen outside Japan and for cardiovascular (CV)-related mortality.

Conclusions

Allopurinol prescription was not significantly associated with case-mix-adjusted mortality in Japanese HD patients overall, but was associated with lower all-cause and CV-related mortality in the subgroup of patients with no prior CVD history. These findings in HD patients may be related to findings in non-dialysis CKD patients showing lower CV event rates and mortality, and improved endothelial function with allopurinol prescription. These results are useful for designing future trials of allopurinol use in HD patients.

Comorbidities in patients with crystal diseases and hyperuricemia

Crystal arthropathies are among the most common causes of painful inflammatory arthritis. Gout, the most common example, has been associated with cardiovascular and renal disease. In recent years, evidence for these associations and those involving other comorbidities, such as the metabolic syndrome, have emerged, and the importance of asymptomatic hyperuricemia has been established. In this review, an update on evidence, both experimental and clinical, is presented, and associations between hyperuricemia, gout, and several comorbidities are described. Causality regarding calcium pyrophosphate arthropathy and associated comorbidities is also reviewed.

Rasburicase for acute kidney injury

BACKGROUND

Acute kidney injury (AKI) continues to have significant mortality and morbidity and the search is on for any novel therapeutic intervention.

CASE CHARACTERISTICS

Two cases of AKI with elevated SUA (serum uric acid).

INTERVENTION

Rasburicase.

OUTCOME

In Case 1 (late preterm male with AKI) rasburicase resulted in a significant reduction of SUA along with improvement in renal parameters. In Case 2 (6 yrs old boy with multi organ failure), rasburicase failed to provide any significant benefit despite fall in SUA.

MESSAGE

The effect of rasburicase in AKI needs to be studied.

Serum uric Acid as a marker of coronary calcification in patients with asymptomatic coronary artery disease with preserved left ventricular pump function

Objective. To evaluate the interrelation between serum uric acid and artery calcification in asymptomatic coronary artery disease subjects. Design and Methods. 126 subjects with previously documented asymptomatic coronary artery disease were enrolled in the study. Results. Mean value of serum uric acid level was 23.84 mmol/L (95% confidence interval (CI)  =  15.75-31.25 mmol/L). In multivariate Cox regression analysis, the results showed that serum uric acid levels (odds ratio (OR) = 1.42, 95% CI = 1.20-1.82; P < 0.001), osteopontin (OR = 1.14, 95% CI = 1.12-1.25; P < 0.001), osteoprotegerin (OR = 1.45, 95% CI  =  1.20-1.89; P < 0.001), type 2 diabetes mellitus (OR = 1.41, 95% CI  =  1.20-1.72; P < 0.001), and total cholesterol (OR = 1.13, 95% CI = 1.10-1.22; P < 0.001) were factors that independently associated with coronary artery calcification. The Cox models suggested that high quartile of serum uric acid level is very significant in predicting Agatston score index. In conclusion, we suggested that high quartile of serum uric acid level (cutoff point equaled 35.9 mmol/L) was a very significant predictor of coronary calcification examined by Agatston score index in subjects with asymptomatic coronary artery disease.

Update on clinical trials for the prevention of acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

Effective therapeutic agents for the prevention and treatment of acute kidney injury (AKI) after cardiac surgery remain elusive despite the tremendous advances in surgical techniques, technology, and understanding of disease processes. Recent developments and their effect on the incidence of AKI after cardiac surgery are discussed.

DATA SOURCES

Published clinical trials in PubMed, strength of evidence assessed by the guidelines of the American Family Physicians.

CONCLUSIONS

The definition of AKI has changed, and the focus of interventions has shifted from treatment to prevention to recovery from AKI. Antioxidants and biological agents have been added to classic armaments of hydration and diuretics in addition to tighter metabolic control to prevent AKI. Although the treatment options remain unsatisfactory, a lot of progress nevertheless continues to be made in the prevention and treatment of AKI.