Hyperuricemia as a risk factor for contrast-induced nephropathy in patients with chronic kidney disease

Differential Incidence of Contrast-Associated Acute Kidney Injury: Comparing Intravenous and Intraarterial Contrast Administration

PURPOSE OF THE REVIEW

Contrast-associated acute kidney injury (CA-AKI) remains a significant concern in diagnostic and invasive procedures, particularly in the context of iodinated contrast material administration. The traditional definition of CA-AKI, based on serum creatinine elevation following contrast exposure, may not accurately capture its multifactorial nature.

RECENT FINDINGS

Studies have provided new insights into the differential incidence of CA-AKI between intravenous and intraarterial contrast administration, emphasizing the importance of tailored preventative strategies for high-risk procedures. This higher risk may arise from two proposed mechanisms: one implicating free radical formation leading to cytotoxicity and apoptosis in renal cells and another suggesting that contrast media alter renal hemodynamics, particularly in the outer medulla, by constricting the vasa recta and reducing medullary flow. Advances in technology and patient care, including contemporary use of low-osmolar contrast agents and hydration protocols, mitigate CA-AKI risk. Diagnostic and invasive procedures should not be avoided solely due to concerns about renal dysfunction if the patient is likely to benefit clinically.

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.

Neutrophil gelatinase-associated lipocalin monitoring reveals persistent subclinical kidney injury following intraarterial administration of iodinated contrast agents

Clinically overt contrast-induced nephropathy (CIN) is one of the most feared complications in patients exposed to iodinated contrast media and has been extensively studied over the years. Meanwhile, the incidence and evolution of subclinical contrast-induced kidney injury remain elusive. With the continuous increase in the number of patients that are repeatedly exposed to contrast media, elucidating these issues is of critical importance. Accordingly, we aimed to evaluate the incidence and the evolution of clinical and subclinical kidney injury in patients exposed to contrast media. A total of 178 patients who underwent elective percutaneous angioplasty procedures were evaluated prospectively. Serum creatinine and neutrophil gelatinase-associated lipocalin (NGAL) levels were evaluated pre-procedurally, 48 h and 1 month after administration of contrast media. The evolution of creatinine and NGAL levels was analyzed at the three time points, and the potential predictors of contrast-induced clinical and subclinical renal injury were evaluated. Clinically overt CIN occurred in 10 (5.6%) patients. Baseline serum creatinine and the volume of contrast media were the only independent predictors of CIN and in all 10 patients creatinine levels returned to baseline by 1 month (p = 0.32). Subclinical contrast-induced kidney injury was much more common, affecting 32 (17.9%) patients, was only predicted by the baseline serum creatinine, and persisted in 53.1% of patients after 1 month. This study showed that whereas clinically overt CIN is rather rare and regressive, subclinical contrast-induced kidney injury is considerably more frequent, affecting almost 18% of patients that receive intraarterial contrast media. More importantly, subclinical kidney injury persisted after 1 month in more than 50% of the initially affected patients, who may thus be at increased risk for further renal impairment, particularly if exposed to nephrotoxic agents or repeated administration of contrast media.

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.

NLRP3 Inflammasome in Metabolic-Associated Kidney Diseases: An Update

Metabolic syndrome (MS) is a group of complex metabolic disorders syndrome, which refers to the pathological state of metabolism disorder of protein, fat, carbohydrate and other substances in human body. The kidney is an important organ of metabolism, and various metabolic disorders can lead to the abnormalities in the structure and function of the kidney. The recognition of pathogenesis and treatment measures of renal damage in MS is a very important part for the renal function preserve. Inflammatory response caused by various metabolic factors is a protective mechanism of the body, but persistent inflammation will become a harmful factor and aggravate kidney damage. Inflammasomes are sensors of the innate immune system that play crucial roles in initiating inflammation in response to acute infections and chronic diseases. They are multiprotein complex composed of cytoplasmic sensors (mainly NLR family members), apoptosis-associated speck-like protein (ASC or PYCARD) and pro-caspase-1. After receiving exogenous and endogenous stimuli, the sensors begin to assemble inflammasome and then promote the release of inflammatory cytokines IL-1β and IL-18, resulting in a special way of cell death named pyroptosis. In the kidney, NLRP3 inflammasome can be activated by a variety of pathways, which eventually leads to inflammatory infiltration, renal intrinsic cell damage and renal function decline. This paper reviews the function and specific regulatory mechanism of inflammasome in kidney damage caused by various metabolic disorders, which will provide a new therapeutic perspective and targets for kidney diseases.

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.

Predictive Value of Hypoalbuminemia for Contrast-Associated Acute Kidney Injury: A Systematic Review and Meta-Analysis

Contrast-associated acute kidney injury (CA-AKI) is a major adverse complication of intravascular administration of contrast medium. Current studies have shown that hypoalbuminemia might be a novel risk factor of CA-AKI. This systematic review and meta-analysis was performed to evaluate the predictive value of hypoalbuminemia for CA-AKI. Relevant studies were identified in Ovid-Medline, PubMed, Embase, and Cochrane Library up to December 31, 2019. Two authors independently screened studies, consulting with a third author when necessary to resolve discrepancies. The pooled odds ratio (OR) was calculated to assess the association between hypoalbuminemia and CA-AKI using a random-effects model or fixed-effects model. Eight relevant studies involving a total of 18 687 patients met our inclusion criteria. The presence of hypoalbuminemia was associated with an increased risk of CA-AKI development (pooled OR: 2.59, 95% CI: 1.80-3.73). Hypoalbuminemia is independently associated with the occurrence of CA-AKI and may be a potentially modifiable factor for clinical intervention. This systematic review and meta-analysis was registered in PROSPERO (CRD42020168104).

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.

A retrospective cross-sectional study of the associated factors of hyperuricemia in patients with chronic kidney disease

Objective

To investigate the prevalence of hyperuricemia in patients at different stages of chronic kidney disease (CKD) and the association of serum uric acid (SUA) with several clinical factors in a retrospective cross-sectional study of non-dialysis CKD patients at two hospitals in Shanghai, China.

Methods

The prevalence of hyperuricemia in CKD patients and the association of SUA with other clinical factors were examined using analysis of variance, chi-squared test, multivariate analysis, and other statistical methods.

Results

A total of 663 CKD patients were enrolled, of which approximately 52% had hyperuricemia. CKD patients with hyperuricemia had lower hemoglobin and estimated glomerular filtration rate (eGFR) levels but higher blood urea nitrogen, serum creatinine, and serum phosphate levels than those without hyperuricemia. Serum uric acid level was positively associated with age, blood urea nitrogen , serum creatinine, cystatin C, and serum phosphate and negatively associated with hemoglobin and eGFR. In addition, CKD patients with anemia and hyperphosphatemia had a higher prevalence of hyperuricemia than those without anemia or hyperphosphatemia.

Conclusions

The prevalence of hyperuricemia increased with CKD progression supporting the use of urate-lowering treatment for patients with CKD stage 1 to 4.

Risk factors analysis for hyperuricemic nephropathy among CKD stages 3-4 patients: an epidemiological study of hyperuricemia in CKD stages 3-4 patients in Ningbo, China

Objective: Uric acid (UA) is a risk marker of CKD and SUA level in CKD 3–4 patients closely correlates with hyperuricemic nephropathy (HN) morbidity. This study was designed to evaluate the risk factors for HN in CKD 3–4 patients.

Methods: The 461 CKD 3–4 patients were recruited and all patients were divided into three groups (24 h UUA normal, underexeret, and overproduct type groups) according to the 24 h UUA level after receiving low purine food for five days. Clinical and biochemical characteristics of CKD patients were collected for the logistic regression analysis. Correlation analysis of the mRNA relative expression level of hUAT and hURAT1 with serum UA (SUA) level also was evaluated.

Results: There were significant increases in characteristics including average age, waist-to-height ratio (WHR), SUA levels, HN ratio, TG/HDL ratio, body mass index (BMI), blood pressure (BP), uNgal/Cr. ratio, and uKim-1/Cr. ratio in overproduct type group in comparison with the other two groups. Logistic regression analysis showed SUA, CHO, uKim-1/Cr. ratio and uNgal/Cr. ratio were independent and multiple risk factors for HN. Moreover, hUAT and hURAT1 mRNA relative expression levels were significantly correlated with SUA level in the underexeret type CKD 3–4 patients.

Conclusions: These results showed SUA and other characteristics contributed to HN morbidity in CKD 3–4 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.

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

Background

Mounting evidence indicated that the elevated serum uric acid level was associated with an increased risk of acute kidney injury (AKI). Our goal was to systematically evaluate the correlation of serum uric acid (SUA) level and incidence of AKI by longitudinal cohort studies.

Methods

We searched electronic databases and the reference lists of relevant articles. 18 cohort studies with 75,200 patients were analyzed in this random-effect meta-analysis. Hyperuricemia was defined as SUA levels greater than 360-420 μmol/L (6–7 mg/dl), which was various according to different studies. Data including serum uric acid, serum creatinine, and incidence of AKI and hospital mortality were summarized using random-effects meta-analysis.

Results

The hyperuricemia group significantly exerted a higher risk of AKI compared to the controls (odds ratio OR 2.24, 95% CI 1.76-2.86, p < 0.01). Furthermore, there is less difference of the pooled rate of AKI after cardiac surgery between hyperuricemia and control group (34.3% vs 29.7%, OR 1.24, 95% CI 0.96-1.60, p = 0.10), while the rates after PCI were much higher in hyperuricemia group than that in control group (16.0% vs 5.3%, OR 3.24, 95% CI 1.93-5.45, p < 0.01). In addition, there were significant differences in baseline renal function at admission between hyperuricemia and control groups in most of the included studies. The relationship between hyperuricemia and hospital mortality was not significant. The pooled pre-operative SUA levels were higher in AKI group than that in the non-AKI group.

Conclusions

Elevated SUA level showed an increased risk for AKI in patients and measurements of SUA may help identify risks for AKI in these patients.

N-acetyl cysteine versus allopurinol in the prevention of contrast nephropathy in patients with chronic kidney disease: A randomized controlled trial

Contrast media administration can lead to acute deterioration in renal function particularly in patients with pre-existing chronic kidney disease. This prospective, randomized controlled open-label parallel group study was undertaken at Nizam's Institute of Medical Sciences, Hyderabad, from June to December 2015. A total of 95 patients were included, of which 35 received n-acetylcysteine (NAC) + normal saline (NS), 30 patients received allopurinol (ALL) + NS, and 30 patients received placebo. In our study, the overall incidence of CIN was 24%. Incidence of CIN in NAC + NS, ALL + NS, and placebo group were 20%, 16%, and 36%, respectively. The major finding of this study was there was no significant difference between NAC and allopurinol in the prevention of contrast nephropathy. However, only allopurinol was superior to placebo. In our study, hyperuricemia and baseline serum creatinine were the only risk factors associated with CIN.

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.

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.

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

Developing contrast-induced nephropathy (CIN) after primary percutaneous coronary intervention (pPCI) has a negative impact on survival and morbidity. We assessed the predictive value of serum uric acid (SUA) for the development of CIN in patients with ST-segment elevation myocardial infarction (STEMI) who underwent pPCI. Contrast-induced nephropathy was defined an increase of ≥25% or ≥0.5 mg/dL in creatinine concentrations within 72 hours after pPCI. Patients were divided into 2 groups according to admission median SUA level. Serum uric acid level was <5.4 mg/dL (group 1; n = 222) and ≥5.4 mg/dL (group 2; n = 228). Compared to group 1, development of CIN (12% vs 20%, P < .001) was significantly greater in group 2. Using a cut point of >5.45 mg/dL, the SUA level predicted development of CIN with a sensitivity of 70% and specificity of 67%. In multiple logistic regression analysis, SUA level, diabetes mellitus, left ventricular ejection fraction <50%, contrast volume, estimated glomerular filtration rate, and C-reactive protein level emerged as independent predictors of CIN. In conclusion, elevated SUA is an independent risk factor for the development of CIN after pPCI in patients with STEMI.

Heat Stress Nephropathy From Exercise-Induced Uric Acid Crystalluria: A Perspective on Mesoamerican Nephropathy

Mesoamerican nephropathy (MeN), an epidemic in Central America, is a chronic kidney disease of unknown cause. In this article, we argue that MeN may be a uric acid disorder. Individuals at risk for developing the disease are primarily male workers exposed to heat stress and physical exertion that predisposes to recurrent water and volume depletion, often accompanied by urinary concentration and acidification. Uric acid is generated during heat stress, in part consequent to nucleotide release from muscles. We hypothesize that working in the sugarcane fields may result in cyclic uricosuria in which uric acid concentrations exceed solubility, leading to the formation of dihydrate urate crystals and local injury. Consistent with this hypothesis, we present pilot data documenting the common presence of urate crystals in the urine of sugarcane workers from El Salvador. High end-of-workday urinary uric acid concentrations were common in a pilot study, particularly if urine pH was corrected to 7. Hyperuricemia may induce glomerular hypertension, whereas the increased urinary uric acid may directly injure renal tubules. Thus, MeN may result from exercise and heat stress associated with dehydration-induced hyperuricemia and uricosuria. Increased hydration with water and salt, urinary alkalinization, reduction in sugary beverage intake, and inhibitors of uric acid synthesis should be tested for disease prevention.

Relationship between Hyperuricemia and Haar-Like Features on Tongue Images

Objective. To investigate differences in tongue images of subjects with and without hyperuricemia. Materials and Methods. This population-based case-control study was performed in 2012-2013. We collected data from 46 case subjects with hyperuricemia and 46 control subjects, including results of biochemical examinations and tongue images. Symmetrical Haar-like features based on integral images were extracted from tongue images. T-tests were performed to determine the ability of extracted features to distinguish between the case and control groups. We first selected features using the common criterion P < 0.05, then conducted further examination of feature characteristics and feature selection using means and standard deviations of distributions in the case and control groups. Results. A total of 115,683 features were selected using the criterion P < 0.05. The maximum area under the receiver operating characteristic curve (AUC) of these features was 0.877. The sensitivity of the feature with the maximum AUC value was 0.800 and specificity was 0.826 when the Youden index was maximized. Features that performed well were concentrated in the tongue root region. Conclusions. Symmetrical Haar-like features enabled discrimination of subjects with and without hyperuricemia in our sample. The locations of these discriminative features were in agreement with the interpretation of tongue appearance in traditional Chinese and Western medicine.

Uric acid levels and the risk of Contrast Induced Nephropathy in patients undergoing coronary angiography or PCI

BACKGROUND AND AIM

Contrast Induced Nephropathy (CIN) is a common complication of procedures that require the use of contrast media, and seems to be mediated by oxidative stress and reactive oxygen species generation. Hyperuricemia is characterized by inhibited nitric oxide system and enhanced synthesis of reactive oxygen species. However, few studies have so far investigated the association between hyperuricemia and CIN that is therefore the aim of the current study among patients undergoing coronary angiography or percutaneous intervention.

METHODS AND RESULTS

We analyzed a total of 1950 patients with Creatinine clearance <90 ml/min) undergoing elective or urgent coronary angiography and/or angioplasty. Patients were divided according to tertiles of baseline uric acid (Group 1, ≤ 5.5 mg/dL n = 653; Group 2, 5.6-7.0 mg/dL, n = 654; Group 3, ≥ 7.0 mg/dL, n = 643). CIN was defined as an absolute ≥ 0.5 mg/dl or a relative ≥ 25% increase in the serum creatinine level at 24 or 48 h after the procedure. Patients with higher uric acid levels were older, previous smokers, with higher prevalence of hypertension and diabetes, but with lower family history of CAD. They had more often history of a previous CABG and baseline renal dysfunction. Patients of the third Tertile had also higher levels of white blood cells, higher triglycerides and lower HDL-cholesterol and higher percentage of dilated cardiomyopathy/valvular disease as indication for angiography and consequently a lower prevalence of PCI. Patients with higher SUA were more often on therapy with ACE inhibitors and diuretics, but less often with statins, nitrate, ASA and Clopidogrel at admission. The occurrence of CIN was observed in 251 patients (12.9%), and was significantly associated with uric acid levels (12.3% in Group 1, 10.4% in Group 2 and 16.0% in Group 3; p = 0.04). Similar results were observed when the analysis was performed according to each tertiles values in both male and female gender. The association between elevated uric acid (≥ 7 mg/dl) and CIN was confirmed by multivariate analysis after correction for baseline confounding (Adjusted OR [95%CI] = 1.42 [1.04-1.93], p = 0.026). Similar results were observed across major subgroups of high-risk patients, such as patients with diabetes, female gender, renal failure, hypertension, and elderly.

CONCLUSIONS

This is the first large study showing that among patients undergoing coronary angiography or percutaneous interventions elevated uric acid level is independently associated with an increased risk of CIN.

Hyperuricemia Is an Independent Predictor of Contrast-Induced Acute Kidney Injury and Mortality in Patients Undergoing Percutaneous Coronary Intervention

We investigated whether hyperuricemia is an independent predictor of contrast-induced acute kidney injury (CI-AKI) and mortality in patients undergoing percutaneous coronary intervention (PCI). In a single-center study of 1772 patients undergoing PCI, the development of CI-AKI and mortality during a 2.8-year median follow-up period was assessed. The incidence of CI-AKI was significantly higher in the hyperuricemic group than in the normouricemic group (5.78% vs 1.76%, P < .001). According to multivariate analysis (after adjusting for potential confounding factors), hyperuricemia predicted CI-AKI (odds ratio: 1.962; 95% confidence interval [CI]: 1.014-3.798; P = .045). The other risk factors for CI-AKI were >75 years, emergent PCI, chronic kidney disease (CKD), and anemia. Hyperuricemia with a tendency toward significantly independently predicted long-term mortality, after adjusting for CI-AKI, CKD, and emergent PCI (hazard ratio: 1.571; 95% CI: 1.006-2.452; P = .047). In patients undergoing PCI, hyperuricemia is associated with a risk of CI-AKI. Furthermore, after adjusting for other variables, including CI-AKI and CKD, long-term mortality after PCI was higher in those with hyperuricemia than with normouricemia.

Efficacy of oral hydration in the prevention of contrast-induced acute kidney injury in patients undergoing coronary angiography or intervention

BACKGROUND

Efficacy of intravenous (IV) volume expansion in preventing contrast-induced acute kidney injury (CI-AKI) is well known. However, the role of oral hydration has not been well established. The aim of this work was to evaluate the efficacy of oral hydration in preventing CI-AKI.

METHODS

We prospectively randomized 225 patients undergoing coronary angiography and/or percutaneous coronary intervention in either oral hydration or IV hydration groups. Patients who have at least one of the high-risk factors for developing CI-AKI (advanced age, type 2 diabetes mellitus, anemia, hyperuricemia, a history of cardiac failure or systolic dysfunction) were included in the study. All patients had normal renal function or stage 1-2 chronic kidney disease. Patients in the oral hydration group were encouraged to drink unrestricted amounts of fluids freely whereas isotonic saline infusion was performed by the standard protocol in the IV hydration group.

RESULTS

CI-AKI occurred in 8/116 patients (6.9%) in the oral hydration group and 8/109 patients (7.3%) in the IV hydration group (p = 0.89). There was also no statistically significant difference between the two groups when different CI-AKI definitions were taken into account.

CONCLUSION

Oral hydration is as effective as IV hydration in preventing CI-AKI in patients with normal kidney function or stage 1-2 chronic kidney disease, and who also have at least one of the other high-risk factors for developing CI-AKI.

Atorvastatin combining with probucol: a new way to reduce serum uric acid level during perioperative period of interventional procedure

Uric acid has ever been considered as one of contrast induced acute kidney injury's risk factors. Atorvastatin and probucol can both improve contrast induced acute kidney injury separately. This prospective study is to assess their effect on reducing serum uric acid level and contrast induced acute kidney injury during perioperative period of interventional procedure. On the basis of different doses of atorvastatin and probucol, 208 cases admitted for coronary angiography or percutaneous coronary intervention were randomly classified into standard combined group (S-C group), intensive combined group (I-C group), and intensive atorvastatin group (I-A group). Patients' blood urea nitrogen, serum creatinine, and serum uric acid were measured and estimated glomerular filtration rate was evaluated 24 hours before and after the procedure. After procedure, blood urea nitrogen in all the three groups decreased; Scr of S-C group and I-A group increased significantly, while estimated glomerular filtration decreased in the S-C group (P < 0.05); serum uric acid in S-C group and I-C group decreased significantly (P < 0.05). Combination treatment of atorvastatin and probucol before intervention could reduce perioperative serum uric acid level; meanwhile, the intensive combined treatment can improve the contrast induced acute kidney injury. The result was the same for hypertensive patients.

Relation of uric acid and contrast-induced nephropathy in patients undergoing primary percutaneous coronary intervention in the ED

OBJECTIVES

To investigate the predictive role of serum uric acid (SUA) levels measured in the emergency department (ED) to monitor contrast-induced nephropathy (CIN) and correlation with severity of nephropathy in patients undergoing primary percutaneous coronary intervention (PCI).

METHOD

The patients who were admitted to our ED and underwent primary PCI were enrolled retrospectively. Their baseline characteristics including SUA and creatinine levels in the ED and their creatinine levels 48 hours after PCI were noted. Nephropathy was graded as follows: grade 0, ΔCr ≤25% and ≤0.5 mg/dL; grade 1, ΔCr >25% but ≤0.5 mg/dL; and grade 2, ΔCr >0.5 mg/dL. A multiple logistic regression analysis was used to define the independent predictors of CIN.

RESULTS

Of a total of 744 patients, CIN was observed in 12.5% (n = 93). Serum uric acid levels were significantly higher in the CIN (+) group compared with the CIN (-) group (6.09 ± 2.01 mg/dL vs 4.89 ± 1.32 mg/dL, respectively; P < .001). Patients with grade 0 CIN had significantly lower SUA levels than did those with grades 1 and 2 (4.89 ± 1.32 mg/dL vs 5.88 ± 1.99 and 6.41 ± 2.02 mg/dL, respectively; P < .001), but there was no significant difference between grade 1 and grade 2 CIN cases in terms of SUA levels (5.88 ± 1.99 mg/dL vs 6.41 ± 2.02 mg/dL, P = .10). The cutoff value for SUA was 5.05 mg/dL for the prediction of CIN (area under the curve, 0.685; P < .001; sensitivity, 66%; specificity, 60%) in the population.

CONCLUSIONS

The SUA level is a simple independent early predictor of CIN in patients who underwent primary PCI, and early detection may help prevent the progression of CIN.

Hyperuricemia is an independent risk factor for mortality only if chronic kidney disease is present

BACKGROUND/AIMS

Hyperuricemia has been considered a risk factor for renal disease and cardiovascular disease. However, the potential contribution of hyperuricemia to mortality remains uncertain, and the results in the available literature vary according to kidney function. The aim of this study was to determine the association between hyperuricemia and mortality in patients undergoing percutaneous coronary intervention (PCI) across the interaction of kidney function.

METHOD

We retrospectively reviewed patients who underwent PCI from 2003 to 2009. Propensity scores for hyperuricemia (>7 mg/dl for males and >6 mg/dl for females) were used to assemble a matched cohort of 693 pairs of patients with and without hyperuricemia for analysis from the 3,201 patients who fulfilled the inclusion criteria among the 4,842 patients who underwent PCI.

RESULTS

Of the 3,201 patients who underwent PCI and for whom data were available regarding their baseline serum uric acid level, 763 (23.8%) had hyperuricemia. The hyperuricemia-associated hazard ratios (HRs) [95% confidence intervals (CIs)] for all-cause mortality were 1.780 (1.270-2.495) in the unmatched cohort and 1.655 (1.109-2.468) in the matched cohort. The HRs (95% CI) for all-cause mortality among those with and without chronic kidney disease (CKD) were 2.080 (1.318-3.283) and 1.592 (0.778-3.256), respectively (p for interaction, 0.001).

CONCLUSIONS

Hyperuricemia is an independent risk factor for all-cause mortality in those patients with CKD but not in those without CKD.

The relationship between hyperuricemia and the risk of contrast-induced acute kidney injury after percutaneous coronary intervention in patients with relatively normal serum creatinine

OBJECTIVES

Hyperuricemia is a risk factor for contrast-induced acute kidney injury in patients with chronic kidney disease. This study evaluated the value of hyperuricemia for predicting the risk of contrast-induced acute kidney injury in patients with relatively normal serum creatinine who were undergoing percutaneous coronary interventions.

METHODS AND RESULTS

A total of 788 patients with relatively normal baseline serum creatinine (<1.5 mg/dL) undergoing percutaneous coronary intervention were prospectively enrolled and divided into a hyperuricemic group (n = 211) and a normouricemic group (n = 577). Hyperuricemia is defined as a serum uric acid level>7 mg/ dL in males and >6 mg/dL in females. The incidence of contrast-induced acute kidney injury was significantly higher in the hyperuricemic group than in the normouricemic group (8.1% vs. 1.4%, p<0.001). In-hospital mortality and the need for renal replacement therapy were significantly higher in the hyperuricemic group. According to a multivariate analysis (adjusting for potential confounding factors) the odds ratio for contrast-induced acute kidney injury in the hyperuricemic group was 5.38 (95% confidence interval, 1.99-14.58; p = 0.001) compared with the normouricemic group. The other risk factors for contrast-induced acute kidney injury included age >75 years, emergent percutaneous coronary intervention, diuretic usage and the need for an intra-aortic balloon pump.

CONCLUSION

Hyperuricemia was significantly associated with the risk of contrast-induced acute kidney injury in patients with relatively normal serum creatinine after percutaneous coronary interventions. This observation will help to generate hypotheses for further prospective trials examining the effect of uric acid-lowering therapies for preventing contrast-induced acute kidney injury.

Timing and route of exposure affects crystal formation in melamine and cyanuric exposed male and female rats: gavage vs. feeding

Effects of the dosing matrix and timing on the onset of renal crystal formation were evaluated in male and non-pregnant female rats (Fisher 344) exposed to both melamine (MEL) and cyanuric acid (CYA) for 28 days. Rats were fed ground feed containing 60 ppm MEL and 60 ppm CYA, (5 mg/kg bw/day equivalent), or exposed via oral gavage to carboxymethylcellulose containing 5 mg/kg bw MEL followed by 5 mg/kg bw CYA either consecutively (<1 min apart) or delayed 45 min after MEL. Staggered gavage exposure to MEL/CYA caused extensive renal crystal formation as compared to when the two compounds were administered consecutively or in feed. Treatment related effects included reduced weight gain, feed consumption, and testicular weight and increased kidney weight, water consumption and urine output. Animals from the staggered MEL/CYA gavage exposure group became ill and were removed after 9 days of exposure. Approximately 1 week after the initiation of exposure microscopic urinalysis revealed MEL/CYA crystals in both groups of gavaged animals but not in the MEL/CYA feed treatment groups. Urinary crystals were smaller (10 μm) in animals consecutively gavaged. In contrast the urinary crystals were larger (20-40 μm) and frequently clumped in the animals in the staggered gavage group.

Contrast-induced nephropathy in patients with ST elevation myocardial infarction treated with primary percutaneous coronary intervention

We assessed the relationship between contrast-induced nephropathy (CIN) and SYNTAX score (SS) and serum uric acid (SUA) levels in patients with ST elevation myocardial infarction (STEMI). A total of 835 STEMI patients in whom primary percutaneous coronary intervention was performed in our cardiology clinic were included in this study (615 male, 220 female; mean age 58.1 ± 12.2 years). The patients were divided into 2 groups (CIN and non-CIN). Contrast-induced nephropathy was observed in 9.6% (80) of patients; SS (13.9 ± 6.2/22.1 ± 5.8) and SUA (5.1 ± 0.9/6.2 ± 0.9) values in the CIN group were higher compared with the non-CIN group (P < .001, for all). All SS (95% confidence interval [CI] = 1.136-1.250, P = .001), SUA (95% CI = 1.877-3.236, P = .002), and diabetes (95% CI = 0.998-1.039, P = .026) were independent predictors of CIN in logistic regression analysis. Procedures that can prevent CIN may be beneficial in patients at high risk as identified by the SS and SUA levels.

Efficacy of allopurinol pretreatment for prevention of contrast-induced nephropathy: a randomized controlled trial

BACKGROUND

Contrast-induced nephropathy (CIN) remains a common complication of radiographic procedures. Radiocontrast agents can cause a reduction in renal function that may be due to reactive oxygen species. Conflicting evidence suggests that administration of antioxidants prevents CIN.

METHODS

We assessed the efficacy of allopurinol in preventing CIN. We prospectively randomized 159 patients with a serum creatinine concentration >1.1mg/dL undergoing cardiac catheterization/interventions to receive allopurinol (300 mg, p.o.) 24h before administration of radiocontrast agent and hydration (1mg/kg/hN/saline for 12h pre- and post-contrast, n=79), or hydration alone (1mg/kg/hN/saline for 12h pre- and post-contrast, n=80).

RESULTS

CIN occurred in 6 of 80 patients (7.5%) in the control group and no subjects in the allopurinol group (p=0.013). In the allopurinol group, median serum creatinine concentration decreased significantly from 1.43 mg/dL [1.1-4.15 mg/dL] to 1.35 mg/dL [0.7-4.15 mg/dl] at 48 h and to 1.27 mg/dL [0.66-4.37 mg/dL] at 4 days after radiocontrast administration (p<0.0001 and p<0.0001 compared with baseline, respectively). In the control group, median serum creatinine concentration decreased non-significantly from 1.48 mg/dL [1.1-2.96 mg/dL] to 1.43 mg/dL [0.73-3.02 mg/dL] and to 1.45 mg/dL [0.86-3.71 mg/dL] (p=0.045 and p=0.57, respectively) 48 h and 4 days after radiocontrast administration.

CONCLUSIONS

Prophylactic oral administration of allopurinol, along with hydration, may protect against CIN in high-risk patients undergoing coronary procedures.

Comparison of risk factors for contrast-induced acute kidney injury between patients with and without diabetes

Although it is well known that diabetics are at a higher risk of contrast-induced acute kidney injury (CI-AKI) than nondiabetic patients, the reason for this discrepancy is not well known. Thus, in this study, we compared the predisposing factors for CI-AKI between patients with and without diabetes. We prospectively studied 290 consecutive in-hospital patients including 88 diabetics undergoing coronary angiography or a percutaneous coronary intervention in Kowsar hospital, and we compared risk factors for CI-AKI between diabetic and nondiabetic patients. CI-AKI was defined as RIFLE criteria within 48 hours after contrast exposure. The incidence of CR-AKI was significantly higher in diabetic patients compared with nondiabetics (P<0.05). The incidence of CI-AKI was significantly higher in patients with diabetes and left-ventricular ejection fraction ≤40%, hypercholesterolemia, serum creatinine ≥1.1 mg/dL, estimated glomerular filtration rate (eGFR) <90 mL/min, Contrast volume ≥80 (mL), maximum safe contrast volume factor of 1.5, and dehydration, while in nondiabetics, a significantly higher incidence of CR-AKI was observed in those with serum creatinine ≥1.1 mg/dL (P=0.02) and/or eGFR<60 mL/min (P=0.01). Multiple logistic regression analysis showed hyperchlosteremia to be the strongest predictor of AKI (P=0.01, B:14.5) in diabetics, followed by eGFR<90 (P=0.05, B:12.4) but, in nondiabetics, only eGFR<60 predicted the occurrence of CI-AKI (P=0.04, B:2.3). It seems that the predisposing factors to CI-AKI differ in diabetics and nondiabetics. In patients with diabetes, hypercholesterolemia is the strongest predictor of CI-AKI, followed by eGFR and diabetics are at risk for CI-AKI in the early stage of chronic kidney disease (stage 2), accounting for the higher incidence of CI-AKI in them.

Risk for contrast nephropathy in patients undergoing coronarography

Among the causes of in-hospital acute renal failure, contrast-induced nephropathy ranks third in prevalence. Although it represents a condition of renal impairment with spontaneous recovery, contrast nephropathy should always be considered, because it prolongs hospitalization and it may become a severe complication requiring dialysis. The purposes of this study are: (i) to determine if the application of the most effective contrast-induced nephropathy prevention strategies in the Cardiology Intensive Care Unit can prove to be successful in reducing nephropathy risk; and (ii) to identify which of the involved risk factors persist after the preventive treatment. We examined the patients who had a coronarography at the Bentivoglio hospital from April 2007 to April 2008 who required at least 3 days of permanence in hospital due to the presence of potential risk factors; 136 out of 784 patients were included. Among the selected patients, 21 (15.44%) developed a renal impairment compatible with contrast-induced nephropathy. The risk factors that seemed to display the best correlation with risk of contrast nephropathy were advanced age and an ventricular failure (ejection fraction <40%); however, the critical condition did not appear to be due to a single risk factor, but it resulted from the association of more contextual risk factors. Particularly, the concomitant presence of ventricular failure, anemia, diabetes, previous myocardial infarction and advanced age (>70 years) determined a threefold increased risk of contrast nephropathy. Our data suggest that the development of contrast nephropathy following coronarography is associated with worse renal function during hospitalization and at discharge.

Letter to the Editor: “What Is the Best Definition of Contrast-Induced Nephropathy?”

Radiological procedures require the intravascular administration of iodinated contrast media, which are becoming a great source of an iatrogenic disease known as contrast-induced nephropathy. The development of contrast-induced nephropathy is associated with prolonged hospitalization, the potential need for renal replacement therapy, and increased mortality. Despite numerous clinical and experimental studies, several important issues regarding contrast-induced nephropathy remain controversial. One of the controversial points is its very definition: a universally accepted definition of contrast-induced nephropathy does not exist. This can be a major problem. Differing definitions of contrast-induced nephropathy and the clinical importance of these definitions were discussed in this letter.

Nefropatia induzida por contraste: avaliação da proteção pela n-acetilcisteína e alopurinol em ratos uninefrectomizados

OBJETIVO: A nefropatia por contraste é a terceira causa de insuficiência renal aguda em pacientes hospitalizados. O objetivo deste estudo foi avaliar a ação da n-acetilcisteína e do alopurinol na proteção renal em ratos de ambos os sexos que receberam diatrizoato. MATERIAIS E MÉTODOS: Ratos Wistar adultos jovens, uninefrectomizados e submetidos a restrição hídrica, receberam solução salina (grupo 1: machos; grupo 2: fêmeas), diatrizoato (grupo 3: machos; grupo 4: fêmeas), diatrizoato e n-acetilcisteína (grupo 5: machos), diatrizoato e alopurinol (grupo 6: machos) e diatrizoato e n-acetilcisteína + alopurinol (grupo 7: machos). A filtração glomerular foi avaliada pela creatinina. O teste t de Student e o teste do sinal foram utilizados para análises estatísticas. RESULTADOS: Ratos que receberam diatrizoato apresentaram elevação estatisticamente significante da creatinina sérica, quando comparados aos controles, porém não houve diferença entre os sexos. Os animais que receberam alopurinol não mostraram aumento significante da creatinina, enquanto a administração de n-acetilcisteína não impediu a elevação da creatinina. CONCLUSÃO: O alopurinol mostrou-se mais efetivo que a n-acetilcisteína na proteção funcional renal ao dano induzido pelo diatrizoato de sódio. Não houve diferença entre os sexos na intensidade do dano renal pelo diatrizoato de sódio.

Hyperuricaemia--where nephrology meets rheumatology

Rheumatologists care for patients with gouty arthritis, a condition caused by chronic and uncontrolled hyperuricaemia. Hyperuricaemia, gout and renal dysfunction are often bedfellows, raising the possibility of the former causing the latter. We sought the answer to the question 'Among patients with normal measures of glomerular filtration, does hyperuricaemia predict future renal disease'? We identified prospective cohort studies evaluating the relationship between serum uric acid and chronic kidney function from the past 20 yrs, through MEDLINE, Cochrane Library and EMBASE searches and bibliography cross-referencing. Nine cohort studies that met the selection criteria were found. Because of the extreme heterogeneity, a statistical meta-analysis was not performed. Most (eight out of nine) studies found an independent risk factor for deterioration of kidney function. Nearly all published prospective studies support the role of hyperuricaemia as an independent risk factor for renal dysfunction. In the absence of large randomized controlled trials of uric acid reduction, it remains uncertain if this relation is causal or merely an epiphenomenon. Regardless, our review suggests that hyperuricaemia is a useful, inexpensively measured, widely available and useful early marker for chronic kidney disease.

Conflicting and new risk factors for contrast induced nephropathy

PURPOSE

Iodinated contrast medium is commonly used in diagnostic or interventional procedures in uroradiology. Procedures requiring the intravascular administration of iodinated contrast medium are becoming a great source of an iatrogenic disease known as contrast induced nephropathy. Identifying patients at high risk is the first step to minimize the overall risk of contrast induced nephropathy. This review describes conflicting and new risk factors for contrast induced nephropathy.

MATERIALS AND METHODS

A MEDLINE/PubMed search from 1966 to 2006 was performed. All articles related to the use of contrast medium and the risk factors for contrast induced nephropathy were reviewed.

RESULTS

The classic risk factors for contrast induced nephropathy are preexisting renal failure, diabetes mellitus, advanced age, nephrotoxic agent administration, hypovolemia, use of a large amount of contrast medium or an ionic hyperosmolar contrast medium and congestive heart failure. Metabolic syndrome, prediabetes and hyperuricemia have been identified as new risk factors for contrast induced nephropathy. The use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, renal transplantation, diabetes mellitus with normal renal function, low osmolar contrast medium in patients at high risk for contrast induced nephropathy, multiple myeloma, female gender and cirrhosis have been classified as conflicting risk factors for contrast induced nephropathy.

CONCLUSIONS

Patients at risk for contrast induced nephropathy should be identified before urological procedures requiring contrast administration. In addition to the classic risk factors for contrast induced nephropathy, determining the metabolic syndrome, hyperuricemia and prediabetes as well as the use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers before performing procedures using contrast medium seems to be a useful guide to assess the risk of contrast induced nephropathy.

Contrast medium induced nephropathy in urological practice

PURPOSE

Contrast medium induced nephropathy is the third cause of in-hospital acute renal failure. The first studies in this area were done with reference to urological practice only. Although various guidelines on the management of contrast medium induced nephropathy were provided by the European Society of Urogenital Radiology, more recently many investigators have focused their attention on contrast medium use in interventional vascular radiology and cardiology. We critically reviewed the literature to clarify the impact of contrast medium induced nephropathy in urology and the possible prophylactic measures against it.

MATERIALS AND METHODS

A MEDLINE/PubMed, EMBASE and Cochrane Library search for 1971 to 2006 was performed. All articles related to the use of contrast medium in urological practice and contrast medium induced nephropathy were reviewed.

RESULTS

Many pathological conditions frequently seen by urologists are diagnosed by imaging requiring contrast medium. A basic understanding of the risk factors for contrast medium induced nephropathy and the strategies for its prevention are useful to prepare urological patients for these procedures. Prophylaxis includes the discontinuation of potentially nephrotoxic drugs and the use of protocols for periprocedural hydration.

CONCLUSIONS

The general approach to the recognition and prevention of contrast medium induced nephropathy in patients at risk should be extended to urological clinical practice since no definitive evidence based data are available regarding contrast medium induced nephropathy management in urological patients. Moreover, these patients can frequently present with the most significant risk factor for contrast medium mediated kidney damage, that is preexisting acute or chronic renal failure. Controlled trials are needed to establish the incidence of contrast medium induced nephropathy in diagnostic or interventional procedures in uroradiology.

Contrast Medium Administration in the Elderly Patient: Is Advancing Age an Independent Risk Factor for Contrast Nephropathy after Angiographic Procedures?

Contrast medium-induced nephropathy (CMIN) is the third leading cause of hospital-acquired acute renal dysfunction. Even if the number of patients over 75 years of age undergoing diagnostic and/or interventional procedures and requiring administration of contrast medium (CM) is growing constantly, at present there is no definitive consensus regarding the role of advancing age and related morphologic or functional renal changes as an independent risk factor for CMIN. The authors review the evidence from recent medical literature on the definition, pathophysiology, and clinical presentation of CMIN as well as therapeutic approaches to its prophylaxis. Attention is focused on advancing age as a preexisting physiologic condition that is, per se, able to predispose the patient to CM-induced renal impairment, assuming that every elderly patient is potentially at risk for CMIN.

Risk factors for contrast-induced nephropathy

An increasing number of diagnostic imaging and interventional procedures require the use of radiographic contrast agents which has led to a parallel increase in the incidence of contrast-induced nephropathy (CIN). CIN is a serious clinical problem associated with increased morbidity and mortality, particularly in patients with chronic renal failure (see the Case Report). A key step to minimize CIN is to identify patients at risk of CIN. The aim of the present review was to summarize the knowledge about the risk factors of CIN, including the review of ultimate clinical research and developments.