Uric Acid is a Useful Tool to Predict Contrast-Induced Nephropathy

Prospective Randomized Trial of Na/K Citrate for the Prevention of Contrast-Induced Nephropathy in High-risk Patients

Background

Contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury (CI-AKI) refers to an acute kidney injury (AKI) occurring after exposure to contrast media, commonly used in diagnostic procedures or therapeutic angiographic interventions. Recently, Na/K citrate, used for urine alkalinization, has been assessed for preventing CIN. This experiment evaluated Na/K citrate's efficacy in preventing CIN in high-risk patients undergoing cardiac catheterization.

Methods

A prospective randomized clinical trial involved 400 patients with moderate- to high-risk factors for CIN undergoing elective percutaneous coronary intervention (PCI). They were randomly assigned to either the control or Na/K citrate groups. The Na/K citrate group (n = 200) received a 5 g Na/K citrate solution diluted in 200 mL water 2 hours before and 4 hours after the first administration, along with intravenous hydration for 2 hours before and 6 hours after the procedure. In contrast, the control group (n = 200) received only intravenous hydration. Serum creatinine (SCr) levels were measured before contrast exposure and 48 hours afterward. CIN was defined as a 25% increase in serum creatinine (SCr) or > 0.5 mg/dL 48 hours after contrast administration. The significance level was set at P ˂ 0.05.

Results

CIN was observed in 33 patients (16.5%) in the control group and 6 patients (3%) in the Na/K citrate group. The incidence of CIN was found to have a significant difference between the 2 groups 48 hours after receiving the radiocontrast agent (P < 0.001).

Conclusion

Our results show that Na/K citrate is helpful and substantially reduces the incidence of CIN.

C-Reactive Protein to Albumin Ratio as a Predictor of Contrast-Induced Nephropathy After Carotid Angiography

This study evaluated the role of the C-reactive protein (CRP)/albumin ratio (CAR) in estimating the probability of occurring contrast-induced nephropathy (CIN) after carotid artery angiography (CAAG). Patients (n = 410) who had CAAG for carotid artery stenosis (CAS) were included in this study. A spike in serum creatinine was used to define CIN within 72 h of the procedure (>.5 mg/dL or >25% above baseline). CAR was calculated by dividing the CRP by the albumin level. Patients with CIN had higher numbers of white blood cells (P = .002), numbers of neutrophils (P = .007), neutrophil-lymphocyte ratios (P = .026), high-sensitivity CRP levels (P < .001), and CAR levels (P < .001) than those without CIN. They were also older (P < .001) and more likely to have diabetes mellitus (P = .006) and hypertension (P = .016). According to receiver operator characteristic curve (ROC) analysis, the CAR value has a 75% sensitivity and a 68% specificity for identifying CIN at a cutoff of 1.8. Also, NLR and CRP predicted CIN with 71% sensitivity and 67% specificity, 71% sensitivity and 66% specificity at the best cutoff values of 1.96 and 7.91, respectively. According the present study, in patients with CAS, the development of CIN after CAAG is independently correlated with CAR at admission.

Age-Related Effect of Uric Acid on Contrast-Induced Acute Kidney Injury of Patients Undergoing Coronary Angiography

Background

The association between uric acid (UA) and contrast-induced acute kidney injury (CI-AKI) following coronary angiography (CAG) has been established. However, whether the association would vary with age remained undetermined.

Methods

We performed the retrospective analysis based on the Cardio-renal Improvement II study, (ClinicalTrials.gov NCT05050877), which enrolled consecutive patients undergoing coronary angiography in 5 teaching hospitals in China from 2007 to 2020. The primary outcome was CI-AKI defined as the rise of serum creatinine (SCr) ≥ 0.5 mg/dL or 25% compared with the baseline value within 48 hours following CAG. The effect of age on the association between uric acid and CI-AKI was assessed by the logistic regression model.

Results

A total of 36,550 patients (mean age 63.08±5.6-year-old, 41.7% men) were included in the study. After adjusting for the confounders, the risk of CI-AKI between each quartile of uric acid was insignificant in the young group. In patients of the middle group, lower UA was associated with a lower risk of CI-AKI while higher UA was associated with a higher risk (Q1 OR: 0.853, 95% CI: 0.734-0.993; Q4 OR: 1.797, 95% CI: 1.547-2.09). In patients of the elder group, lower and higher UA were both associated with a higher risk of CI-AKI (Q1 OR: 1.247, 95% CI: 1.003-1.553; Q4 OR: 1.688, 95% CI: 1.344-2.124). The restricted cubic spline indicated a non-linear association between UA and CI-AKI in middle and elder age groups but a linear association in the young age group.

Conclusion

The association between uric acid and CI-AKI vary in patients of different age. Patients with elder age should maintain a middle level of uric acid while patients with middle age should consider a lower level of uric acid to reduce the risk of CI-AKI. The level of UA was an insignificant risk factor for CI-AKI in young patients.

Serum Uric Acid to Albumin Ratio Can Predict Contrast-Induced Nephropathy in ST-Elevation Myocardial Infarction Patients Undergoing Primary Percutaneous Coronary Intervention

Contrast-induced nephropathy (CIN) is one of the common complication of ST-elevation myocardial infarction (STEMI) following primary percutaneous coronary intervention (pPCI). Serum uric acid to albumin ratio (UAR) is a novel marker, which is associated with acute kidney injury in intensive care unit patients. We investigated the predictive value of UAR for the development of CIN in STEMI patients (n = 1379) after pPCI. The diagnosis of CIN was made based on an increase of basal creatinine levels >.5 mg/dL or 25% within 72 h after pPCI; 128 patients were in the CIN (+) group and 1251 patients were in the CIN (-) group. CIN (+) patients had higher serum uric acid (SUA), UAR, and lower albumin levels than CIN (-) patients. Age, diabetes, hypertension, hemoglobin, glucose at admission, basal creatinine, peak troponin I, total bilirubin, contrast volume/glomerular filtration rate, and UAR were independent predictors of CIN. A cutoff value of 1.62 for UAR detected CIN development with a sensitivity of 54% and specificity of 87.4%, and the discrimination ability of UAR was better than that of SUA or albumin. In conclusion, UAR was an independent predictor of the development of CIN.

Prospective randomized comparison of effect on coronary endothelial and renal function between febuxostat and benzbromarone in hyperuricemic patients with coronary artery disease: EFEF study

Background and Aims

Methods

Results

Conclusion

A Novel Predictor of Contrast-Induced Nephropathy in Patients With Carotid Artery Disease; the Systemic Immune Inflammation Index

Contrast-induced nephropathy (CIN) is associated with increased mortality and morbidity. The present study investigated the role of systemic immune inflammation index (SII) in predicting the risk of developing CIN after carotid artery angiography (CAAG). This study included 262 patients who underwent CAAG for symptomatic carotid artery stenosis (CAS). Simultaneous carotid stenting was applied to 232 of these patients. CIN was defined as an increase in serum creatinine level ≥.5 mg/dL or ≥25% above baseline within 72 hours after the procedure. The SII score was calculated as platelet × neutrophil/lymphocyte counts. Patients who developed CIN, had higher glucose (P = .009), total cholesterol (P < .001), low density lipoprotein cholesterol (<.001), and high sensitivity C-reactive protein (P = .001) levels, as well as greater neutrophil counts (P < .001), platelet counts (P < .001), neutrophil-lymphocyte ratio (P < .001), and SII score (P < .001) than those who did not develop CIN. The Receiver Operating Characteristic analysis showed that at a cutoff of 519.9, the SII exhibited 80% sensitivity and 64% specificity for detecting CIN. SII levels on admission were independently associated with CIN development after CAAG in patients with CAS.

Kidney Injury Molecule-1 Is Associated with Contrast-Induced Nephropathy in Elderly Patients with Non-STEMI

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with an increased risk of major adverse cardiovascular events (MACE), and the association between CIN and oxidative mechanisms is well documented.

OBJECTIVE

This study aimed to evaluate the relationship between serum levels of kidney injury molecule-1 (KIM-1) and CIN in elderly patients with non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

This study included a total of 758 patients with NSTEMI, who underwent percutaneous coronary intervention (PCI); 15 developed CIN after PCI, and another 104 were the control group, matched for age > 65 years. Baseline to 48-to-72-hour laboratory values and clinical outcomes were recorded. Patients were followed during one year. P values of < 0.05 were considered significant.

RESULTS

CIN was observed in 12.60% of the patients. Serum KIM-1 was significantly higher in the CIN group than in the non-CIN group (14.02 [9.53 - 19.90] vs. 5.41 [3.41 - 9.03], p < 0.001). The Mehran score was significantly higher in the CIN group than in the non-CIN group (14 [5 - 22] vs. 5 [2 - 7], p = 0.001). MACE were significantly higher in the CIN group than in the non-CIN group (7 [46.70%] vs. 12 [11.50%], p = 0.001). Multivariate logistic regression analysis showed that baseline KIM-1 level (OR = 1.652, 95% CI: 1.20 - 2.27, p = 0.002) and Mehran score (OR = 1.457, 95% CI: 1.01 - 2.08, p = 0.039) were independent predictors of CIN in elderly patients with NSTEMI.

CONCLUSION

Baseline serum KIM-1 concentration and Mehran score are independent predictors of CIN in elderly patients with NSTEMI. Additionally, all-cause mortality, cardiovascular death, myocardial reinfarction, stroke, and MACE were significantly higher in the CIN group at one-year follow-up. (Arq Bras Cardiol. 2021; [online].ahead print, PP.0-0).

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.

The relationship between hyperuricemia and contrast-induced acute kidney injury undergoing primary percutaneous coronary intervention: secondary analysis protocol for the ATTEMPT RESCIND-1 study

Background

Contrast-induced acute kidney injury (CI-AKI) contributes toward unfavorable clinical outcomes after primary percutaneous coronary intervention (pPCI). We will assess whether hyperuricemia is an independent predictor of CI-AKI and outcomes in patients undergoing pPCI.

Methods/design

Our study is a secondary analysis for the database from ATTEMPT study, enrolling 560 ST-segment elevation myocardial infarction (STEMI) patients undergoing pPCI. Patients will be divided into 2 groups according to the admission serum uric acid (SUA) level. Hyperuricemia will be defined as a SUA level > 7 mg/dL (417 mmol/L) in males and > 6 mg/dL (357 mmol/L) in females. The primary endpoint was CI-AKI, defined as > 25% or 0.5 mg/dL increase in serum creatinine from baseline during the first 48–72 h post-procedurally. Multivariate analyses for CI-AKI and long-term mortality will be performed using the logistic regression and Cox regression analyses, respectively.

Discussion

This study will determine the predictive value of hyperuricemia for the development of CI-AKI and outcomes in patients with STEMI undergoing pPCI. We predict that hyperuricemia will be associated with a risk of CI-AKI in patients with pPCI. Furthermore, after adjusting for other variables, long-term mortality after pPCI may be higher in those with hyperuricemia than in those with normouricemia. Results of this study may provide scientific evidence for the effect of hyperuricemia on CI-AKI and long-term outcomes, thereby offering the potential possibility of lowering SUA on the development of CI-AKI and outcomes.

Trial registration

ClinicalTrials.gov NCT02067195, Registered on 20 February 2014.

Serum osmolarity as a potential predictor for contrast-induced nephropathy following elective coronary angiography

BACKGROUND AND OBJECTIVES

Contrast-induced nephropathy (CIN) is a relatively common complication following primary coronary angiography (CAG) or percutaneous coronary intervention (PCI), especially in at-risk patients. The goal of this study is to evaluate the role of pre-procedural serum osmolarity as a risk factor for CIN in patients undergoing elective CAG for stable coronary artery disease (CAD).

MATERIALS AND METHODS

A total of 356 stable CAD patients scheduled to undergo CAG or PCI were included in this two-center study. Serum osmolarity was calculated on admission. CIN was defined according to the KDIGO criteria.

RESULTS

There were 45 (12.6%) patients who developed CIN 48-72 h after CAG or PCI. CIN patients had a higher prevalence of diabetes (51.1% in those with CIN vs 24.4% in those without CIN, p < 0.001), higher serum glucose (129 mg/dL in those with CIN vs 108 mg/dL in those without CIN, p < 0.001), blood urea nitrogen (22.4 mg/dL in those with CIN vs 19.0 mg/dL in those without CIN, p = 0.01) and serum osmolarity (294.2 mOsm in those with CIN vs 290.1 mOsm in those without CIN, p < 0.001) levels, had received a higher dose of contrast (250 mL in those with CIN vs 200 mL in those without CIN, p = 0.03) but had lower hemoglobin (12.9 g/dL in those with CIN vs 13.6 g/dL in those without CIN, p = 0.04) level. In multivariate analysis, serum osmolarity [odds ratio (OR) 1.11; 95% confidence interval (CI) 1.04-1.18 for each mOsm/L increase; p = 0.001], diabetes (OR 2.43, 95% CI 1.26-4.71; p = 0.01), C-reactive protein (OR 1.04, 95% CI 1.01-1.08 for each mg/dL increase; p = 0.02) and contrast volume (OR 34.66, 95% CI 1.25-962.22 for each L increase; p = 0.04) remained as independent predictors of CIN. Serum sodium, glucose and blood urea nitrogen contributed to the excess serum osmolarity of CIN patients.

CONCLUSION

Serum osmolarity is a cheap and widely available marker that can reliably predict CIN after CAG or PCI. Future research should focus on determining a clinically optimal cutoff for serum osmolarity that would warrant preventive interventions. Furthermore, later research may investigate the role of serum osmolarity not only as a risk factor but also as a pathogenetic mechanism underlying CIN.

The Effect of Urine pH and Urinary Uric Acid Levels on the Development of Contrast Nephropathy

BACKGROUND

Hyperuricemia may cause acute kidney injury by activating inflammatory, pro-oxidative and vasoconstrictive pathways. In addition, radiocontrast causes an acute uricosuria, potentially leading to crystal formation. We therefore aimed to investigate the effect of urine acidity and urine uric acid level on the development of contrast-induced nephropathy (CIN) in patients undergoing elective coronary angiography.

METHODS

We enrolled 175 patients who underwent elective coronary angiography. CIN was defined as a >25% increase in the serum creatinine levels relative to basal values 48-72 h after contrast use. Prior to coronary angiography and 48-72 h later, serum uric acid, urea, creatinine, bicarbonate levels, and spot uric acid to creatinine ratio (UACR) were measured.

RESULTS

Of the 175 subjects included, 29 (16.6%) developed CIN. Those who developed CIN had a higher prevalence of diabetes, higher UACR (0.60 vs. 0.44, p = 0.014), higher contrast volume, and lower serum sodium level. With univariate analysis of a logistic regression model, the risk of CIN was found to be associated with diabetes (p = 0.0016, OR = 3.8 [95% CI: 1.7-8.7]), urine UACR (p = 0.0027, OR = 9.6 [95% CI: 2.2-42.2]), serum sodium (p = 0.0079, OR = 0.8 [95% CI: 0.77-0.96]), and contrast volume (p = 0.0385, OR = 1.8 [95% CI: 1.03-3.09]). In a multiple logistic regression model with stepwise method of selection, diabetes (p = 0.0120, OR = 3.2 [95% CI: 1.3-8.1]) and UACR (p = 0.0163, OR = 6.9 [95% CI: 1.4-33.4]) were the 2 risk factors finally identified.

CONCLUSIONS

We have demonstrated that higher urine UACR is associated with the development of CIN in patients undergoing elective coronary angiography.

Elevation in serum uric acid levels predicts favourable response to erlotinib treatment in patients with metastatic non-small-cell lung cancer

WHAT IS KNOWN AND OBJECTIVE

Erlotinib is a small molecule tyrosine kinase inhibitor which blocks the activation of epidermal growth factor receptor (EGFR), a transmembrane receptor that is upregulated in many cancer types. Inhibition of angiogenesis with consequent impairments in intratumoral microcirculation is one of the mechanisms through which EGFR inhibition halts the progression of cancer. A consequence of impaired microcirculation is intratumoral hypoxia, which results in increases in serum uric acid levels. The goal of this study was to investigate the relationship between serum uric acid levels and response to erlotinib in metastatic non-small-cell lung cancer (NSCLC).

METHODS

A total of 56 patients with metastatic non-small-cell lung cancer who received erlotinib for a duration of at least 3 months were included in this retrospective cohort study. Demographic characteristics, progression status, baseline serum uric levels and 3-month serum uric acid levels were recorded and analysed.

RESULTS AND DISCUSSION

Of the study population, 21 (37.5%) were female and 35 (62.5%) were male patients. No significant difference in above demographic characteristics was observed among exitus, survivor with progression and survivor without progression groups. Patients who responded favourably to erlotinib with no progression of their disease had significantly increased uric acid levels at 3-month follow-up (P = .01). Such a correlation was not observed if the patient was exitus (P = .47) or had progressed on erlotinib therapy (P = .19).

WHAT IS NEW AND CONCLUSION

In conclusion, this study is the first to demonstrate significant increases in serum uric acid levels in patients with metastatic NSCLC who responded favourably to erlotinib and had no progression under erlotinib therapy. Further studies are required to confirm and characterize serum uric acid as a novel biomarker in predicting the outcome in those with metastatic NSCLC.

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.

Predictive Value of Hepatorenal Status in Contrast-Induced Nephropathy Among Patients Receiving Coronary Angiography and/or Intervention: A Systematic Review and Meta-Analysis

BACKGROUND

Low serum albumin, high blood urea nitrogen (BUN), and uric acid are regarded closely related to the incidence of contrast-induced nephropathy (CIN), whereas it remains unclear whether they can function as predictors of CIN onset. The objective of this systematic review and meta-analysis was to explore the association between abovementioned indicators and CIN incidence rate in patients receiving coronary angiography (CAG) and/or intervention.

METHODS

Clinical studies were retrieved from the electronic databases of PubMed, EMBASE, Google Scholar, Clinical Trials, and ScienceDirect from their inception to July 13, 2018. Meta-analysis was performed on pooled eligible studies to determine whether these hepatorenal indicators were associated with CIN.

RESULTS

A total of 18 studies involving 16 171 patients were included in the meta-analysis. Pooled analysis results revealed that patients with hypoalbuminemia (odds ratio [OR] = 3.09, 95% confidence interval [CI] = 1.44-6.64, P = .004) and hyperuricemia (OR = 1.32, 95% CI = 1.15-1.50, P < .0001) both exhibited significantly higher CIN rates, regardless of the study design, renal function, and whether urgent clinical situation or not. However, there was no significant association between serum BUN and CIN risk.

CONCLUSION

Hypoalbuminemia and hyperuricemia are independently associated with the occurrence of CIN among the patients undergoing CAG and/or intervention.

The Ratio of Fibrinogen to Albumin as a Predictor of Contrast-Induced Nephropathy After Carotid Angiography

Contrast-induced nephropathy (CIN) is acute kidney failure that occurs after exposure to contrast agent. There is no sensitive biomarker to predict the development of CIN. In a retrospective study, we investigated the predictive value of the fibrinogen to albumin ratio (FAR) to determine the risk of CIN in patients (N = 246) who underwent carotid angiography. Contrast-induced nephropathy was defined as a 0.5 mg/dL or 25% increase in serum creatinine levels 48 to 72 hours following exposure to a radiocontrast agent. Patients were grouped according to whether they developed CIN or not, that is, CIN(-) and CIN(+) groups, respectively. Contrast-induced nephropathy developed in 39 (15.8%) of all the patients. The fibrinogen levels, neutrophil to lymphocyte ratio (NLR), and FAR in the CIN (+) group were higher than in the CIN (-) group ( P < .001). Multivariate analysis showed that age, diabetes, NLR, platelet-lymphocyte ratio, and FAR were independent risk factors for CIN. The area under the curve (AUC) of FAR was 0.800 for the prediction of CIN, and the best cutoff value was 57.4 with sensitivity, specificity, positive predictive value, and negative predictive value of 74.4%, 60.8%, 26.4%, and 92.7%, respectively. The FAR may be useful as a predictor of CIN.

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

Background

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

Methods

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

Results

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

Conclusions

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

Uric acid in the pathogenesis of metabolic, renal, and cardiovascular diseases: A review

The association between uric acid (UA) on one side and systemic hypertension (Htn), dyslipidemia, glucose intolerance, overweight, fatty liver, renal disease and cardiovascular disease (CVD) on the other side is well recognized. However, the causal relationship between UA and these different clinical problems is still debatable. The recent years have witnessed hundreds of experimental and clinical trials that favored the opinion that UA is a probable player in the pathogenesis of these disease entities. These studies disclosed the strong association between hyperuricemia and metabolic syndrome (MS), obesity, Htn, type 2 diabetes mellitus (DM), non-alcoholic fatty liver disease, hypertriglyceridemia, acute kidney injury, chronic kidney disease (CKD), coronary heart disease (CHD), heart failure and increased mortality among cardiac and CKD patients. The association between UA and nephrolithiasis or preeclampsia is a non-debatable association. Recent experimental trials have disclosed different changes in enzyme activities induced by UA. Nitric oxide (NO) synthase, adenosine monophosphate kinase (AMPK), adenosine monophosphate dehydrogenase (AMPD), and nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase are affected by UA. These changes in enzymatic activities can lead to the observed biochemical and pathological changes associated with UA. The recent experimental, clinical, interventional, and epidemiologic trials favor the concept of a causative role of UA in the pathogenesis of MS, renal, and CVDs.

Bilirubin Levels are Associated With Contrast-Induced Nephropathy in Peripheral Artery Disease

The relationship between contrast-induced nephropathy (CIN) and oxidative mechanisms is well documented. Our aim was to demonstrate the possible relationship between CIN and serum bilirubin as an antioxidant molecule. This retrospective study included 359 patients with peripheral artery disease (PAD) who underwent peripheral diagnostic angiography; 179 developed CIN after the intervention and another 180 were the control group, matched for age, gender, and cardiovascular risk factors. Baseline, 48- to 72-hour, and 30-day laboratory values, major adverse cardiovascular events, and dialysis requirements were recorded. Patients with CIN had significantly higher levels of uric acid, red cell distribution width, and neutrophil-to-lymphocyte ratio (NLR) but lower total bilirubin compared to the control patients ( P < .05). Multivariate logistic regression analysis showed that diabetes mellitus, left ventricular ejection fraction, uric acid, NLR, and total bilirubin levels were independent predictors of CIN development ( P = .01, P = .001, P = .001, P = .01, and P = .001, respectively). This study demonstrated that decreased total bilirubin was associated with CIN development after the administration of radiocontrast agents in patients with PAD.

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.

Hyperuricemia and contrast-induced acute kidney injury: A systematic review and meta-analysis

BACKGROUND

Hyperuricemia may be associated with an increased risk of contrast-induced acute kidney injury (CI-AKI). In recent years, studies about the relationship between them gradually appeared. We performed a systematic review and meta-analysis to investigate whether hyperuricemia is an independent risk factor for CI-AKI.

METHODS

Relevant studies were searched in PubMed, Embase, Cochrane Library, and CBM (Chinese Biomedical Literature database) databases until April 18, 2016, without language restriction. Observational studies evaluating serum uric acid (SUA) levels and CI-AKI risks were included. The pooled odds ratio was calculated to assess the association between hyperuricemia and risk of CI-AKI using a random-effects model.

RESULTS

Eighteen relevant studies involving a total of 13,084 patients met our inclusion criteria. Presence of hyperuricemia was associated with an increased risk of CI-AKI development regardless of whether the effect size was adjusted or not (unadjusted OR: 2.08, 95% CI: 1.63-2.64; adjusted OR: 1.68, 95% CI: 1.38-2.04). In-hospital mortality and cases of renal replacement therapy were significantly different between subjects with hyperuricemia and normouricemia undergoing coronary angiography (CAG) and/or percutaneous coronary intervention (PCI).

CONCLUSION

Hyperuricemia is independently associated with the occurrence of CI-AKI and it significantly increases the in-hospital mortality and the risk of renal replacement therapy among the patients after CAG and/or PCI. Future research is needed to determine whether urate-lowering therapy has beneficial effects for reducing the incidence of CI-AKI and in-hospital adverse events.