Urinary and Serum Biomarkers after Cardiac Catheterization in Diabetic Patients with Stable Angina and without Severe Chronic Kidney Disease

THE RISK OF ACUTE KIDNEY INJURY AFTER ELECTIVE VERSUS EMERGENCY CORONARY INTERVENTION

OBJECTIVE

The aim: A serious and common complication after percutaneous coronary intervention is acute kidney injury, which is associated with an increased risk of renal, cardiovascular and even mortality; therefore, early prognosis and identification of patients at higher risk are essential for early initiation of preventive measures. The aim of this study is to predict and compare the risk for the development of CI-AKI in patient with ACS who undergo emergency PCI or elective (i.e. after medical stabilization) PCI by utilizing the sensitivity of serum NGAL as an early and reliable predictor for CI-AK.

PATIENTS AND METHODS

Materials and methods: The study include 37 patients with acute coronary syndrome, baseline serum creatinine, complete blood count and pre and two hours post operative serum neutrophil gelatinase-associated lipocalin were measured and all patients underwent percutaneous coronary intervention according to the standard protocol used in Al Najaf Cardiac Center.

RESULTS

Results: This is a Two-Arm study that included a total of 37 patients with acute coronary syndrome aged 38-83 years. Eighteen of them had emergency percutaneous coronary intervention while the remaining 19 had elective percutaneous coronary intervention (after medical stabilization). Elevation of serum neutrophil gelatinase-associated lipocalin level two hours after percutaneous coronary intervention was found to be significantly higher among emergency percutaneous coronary intervention group compared to elective group.

CONCLUSION

Conclusions: Acute coronary syndrome patients are undergoing emergency percutaneous coronary intervention are at an increasing risk for the development of contrast induced acute kidney injury than those undergoing elective percutaneous coronary intervention.

Value of point-of-care neutrophil gelatinase associated lipocalin in early diagnosis of acute kidney injury in patients with left ventricular systolic dysfunction after coronary angiography

BACKGROUND

Increased neutrophil gelatinase-associated lipocalin (NGAL) levels are associated with toxic or ischemic renal injury.

OBJECTIVE

This study aimed to assess the usefulness of serial NGAL measurements with a point-of-care assay in patients with left ventricular systolic dysfunction (LVSD) for earlier detection of contrast-induced nephropathy (CIN).

MATERIALS AND METHODS

A total of 84 patients with LVSD patients referred for coronary angiography were consecutively enrolled in the study. The study population was divided into two groups as the CIN and the non-CIN groups according to the CIN's determination. The serum creatinine levels were calculated 24 h before the procedure and at the 48th and 72nd h after the cardiac catheterization. The plasma NGAL concentration was measured before and at 4 and 24 h after the cardiac catheterization.

RESULTS

Baseline and serial NGAL levels were significantly higher in patients with CIN compared to the patients without CIN. NGAL 24th h levels after the index procedure were found to be an independent and significant predictor of CIN in multivariate analysis.

CONCLUSIONS

Serial point-of-care NGAL measurements might help earlier detection of CIN in patients with heart failure after coronary angiography.

Kinetic GFR Outperforms CKD-EPI for Slow Graft Function Prediction in the Immediate Postoperative Period Following Kidney Transplantation

Background: Rapid identification of patients at high risk for slow graft function (SGF) is of major importance in the immediate period following renal graft transplantation, both for early therapeutic decisions and long-term prognosis. Due to the high variability of serum creatinine levels after surgery, glomerular filtration rate (GFR) estimation is challenging. In this situation, kinetic estimated GFR (KeGFR) equations are interesting tools but have never been assessed for the identification of SGF patients. Methods: We conducted a single-center retrospective cohort study, including all consecutive kidney allograft recipients in the University Hospitals of Geneva from 2008 to 2016. GFR was estimated using both CKD-EPI and KeGFR formulae. Their accuracies for SGF prediction were compared. Patients were followed up for one year after transplantation. Results: A total of 326 kidney recipients were analyzed. SGF occurred in 76 (23%) patients. KeGFR estimation stabilized from the day following kidney transplantation, more rapidly than CKD-EPI. Discrimination ability for SGF prediction was better for KeGFR than CKD-EPI (AUC 0.82 and 0.66, p < 0.001, respectively). Conclusion: KeGFR computed from the first day after renal transplantation was able to predict SGF with good discrimination, outperforming CKD-EPI estimation. SGF patients had lower renal graft function overall at the one-year follow up.

Serum NGAL, KIM-1, IL-18, L-FABP: new biomarkers in the diagnostics of acute kidney injury (AKI) following invasive cardiology procedures

PURPOSE

The aim of this study was to assess the levels of selected markers in patients who underwent planned or emergency coronary angiography and to examine if they correlated with the occurrence of AKI.

METHODS

The study included 52 patients who underwent planned or emergency coronary angiography and received contrast agent. Serum levels of markers (NGAL, L-FABP, KIM-1, IL-18) were analyzed in all patients using ELISA tests, at baseline, after 24 and 72 h from angiography.

RESULTS

9.62% of patients developed CI-AKI. No significant differences were observed between markers levels in patients who developed CI-AKI and those who did not. After 24 h, serum levels of IL-18 were higher in patients with CI-AKI, however, this difference was on the verge of significance. Increase in serum NGAL, KIM-1 and IL-18 was observed after 24 h. Serum levels of biomarkers were insignificantly higher in group with CI-AKI. Significant changes in levels in time (baseline vs. 24 h vs. 72 h) were observed only for NGAL [157.9 (92.4-221.0) vs. 201.8 (156.5-299.9) vs. 118.5 (73.4-198.7); p < 0.0001]. No significant correlations were observed between the decrease in eGFR or the increase in creatinine and biomarkers level.

CONCLUSION

Obtained results do not allow for the indication of efficient AKI biomarkers. Their further validation in large studies of CI-AKI patients is required.

Predictive value of cystatin C and neutrophil gelatinase-associated lipocalin in contrast-induced nephropathy: A meta-analysis

Background

There are still limited studies comprehensively examining the diagnostic performance of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C in contrast-induced nephropathy (CIN). The study aimed to investigate and compare the predictive value of NGAL and cystatin C in the early diagnosis of CIN.

Methods and materials

We searched the PubMed, EMBASE and Cochrane Library databases until November 10, 2019. The methodological quality of the included studies was assessed by the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Bivariate modeling and hierarchical summary receiver operating characteristic (HSROC) modeling were performed to summarize and compare the diagnostic performance of blood/urine NGAL and serum cystatin C in CIN. Subgroup and meta-regression analyses were performed according to the study and patient characteristics.

Results

Thirty-seven studies from thirty-one original studies were included (blood NGAL, 1840 patients in 9 studies; urine NGAL, 1701 patients in 10 studies; serum cystatin C, 5509 patients in 18 studies). Overall, serum cystatin C performed better than serum/urine NGAL (pooled DOR: 43 (95%CI: 12–152); AUROC: 0.93; λ: 3.79); serum and urine NGAL had a similar diagnostic performance (pooled DOR: 25 (95%CI: 6–108)/22(95%CI: 8–64); AUROC: 0.90/0.89; λ: 3.20/3.08). Meta-regression analysis indicated that the sources of heterogeneity might be CIN definition, assays, and nationalities.

Conclusion

Both NGAL and cystatin C can serve as early diagnostic indicators of CIN, while cystatin C may perform better than NGAL.

Kidney Biomarkers of Injury and Repair as Predictors of Contrast-Associated AKI: A Substudy of the PRESERVE Trial

RATIONALE & OBJECTIVE

The PRESERVE trial used a 2 × 2 factorial design to compare intravenous saline solution with intravenous sodium bicarbonate solution and oral N-acetylcysteine with placebo for the prevention of 90-day major adverse kidney events and death (MAKE-D) and contrast-associated acute kidney injury (CA-AKI) among patients with chronic kidney disease undergoing angiography. In this ancillary study, we evaluated the predictive capacities of preangiography injury and repair proteins in urine and plasma for MAKE-D, CA-AKI, and their impact on trial design.

STUDY DESIGN

Longitudinal analysis.

SETTING & PARTICIPANTS

A subset of participants from the PRESERVE trial.

EXPOSURES

Injury (KIM-1, NGAL, and IL-18) and repair (MCP-1, UMOD, and YKL-40) proteins in urine and plasma 1 to 2 hours preangiography.

OUTCOMES

MAKE-D and CA-AKI.

ANALYTICAL APPROACH

We analyzed the associations of preangiography biomarkers with MAKE-D and with CA-AKI. We evaluated whether the biomarker levels could enrich the MAKE-D event rate and improve future clinical trial efficiency through an online biomarker prognostic enrichment tool available at prognosticenrichment.com.

RESULTS

We measured plasma biomarkers in 916 participants and urine biomarkers in 797 participants. After adjusting for urinary albumin-creatinine ratio and baseline estimated glomerular filtration rate, preangiography levels of 4 plasma (KIM-1, NGAL, UMOD, and YKL-40) and 3 urine (NGAL, IL-18, and YKL-40) biomarkers were associated with MAKE-D. Only plasma KIM-1 level was significantly associated with CA-AKI after adjustment. Biomarker levels provided modest discriminatory capacity for MAKE-D. Screening patients using the 50th percentile of preangiography plasma KIM-1 or YKL-40 levels would have reduced the required sample size by 30% (∼2,000 participants).

LIMITATIONS

Evaluation of prognostic enrichment does not account for changing trial costs, time needed to screen patients, or loss to follow-up. Most participants were male, limiting the generalizability of our findings.

CONCLUSIONS

Preangiography levels of injury and repair biomarkers modestly predict the development of MAKE-D and can be used to improve the efficiency of future CA-AKI trials.

The role of the tubular biomarkers NAG, kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin in patients with chest pain before contrast media exposition

Aim: We evaluated the role of the tubular biomarkers N-acetyl-ß-D-glucosaminidase (NAG), kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) in patients with chest pain. Methods: Serum and urine samples were collected of 223 patients and 47 healthy controls. None of them was exposed to contrast media. Results: NAG showed among others significant correlation with N-terminal pro brain natriuretic peptide (NTproBNP), troponin I and creatinine. KIM-1 and NGAL showed weaker correlations. NAG was significantly elevated in all subgroups of acute coronary syndrome (ACS) compared with chest wall syndrome and controls. NAG was an independent predictor for the diagnosis of myocardial infarction. Conclusion: NAG may demonstrate the presence of acute tubular injury due to cardiac impairment already in the emergency department. NAG should be evaluated as marker of acute cardiorenal syndrome in patients with chest pain.

Relationship between Renalase Expression and Kidney Disease: an Observational Study in 72 Patients Undergoing Renal Biopsy

The relationship between the levels of renalase and changes in proteinuria, hypertension, renal function, renal tubular epithelial cell apoptosis and B-cell lymphoma-2 (Bcl-2) expression was investigated in patients (chronic nephritis, primary nephrotic syndrome or other kidney disease) that underwent renal biopsy. The study group comprised 72 patients undergoing renal biopsy. Patient profiles and renal function were collected. Concentrations of renalase and Bcl-2 were measured by immunohistochemistry. Tubular injury was detected by periodic acid Schiff staining (PAS) and renal tubular epithelial cell apoptosis was assessed by TUNEL assay. The expression of renalase was significantly lower in renal biopsy specimens than in normal kidney tissues. There was a positive linear relationship between renalase and some serum and cardiac indices; a negative correlation was found between age, eGFR, Ccr and 24-h urinary protein. Renal tubule injury index and tubular epithelial cell apoptosis index showed a negative linear correlation with renalase. The results showed that renalase probably increased the expression of Bcl-2. By two independent samples t-test, renalase levels were significantly increased in the non-hypertension group than in the hypertension group. One-way ANOVA showed that renalase expression was higher in samples with Lee's grade III than in those with Lee's grade V. The expression of renalase was significantly decreased in patients who underwent renal biopsy, and was also associated with blood and renal function. The research proved that renalase may reduce renal tubular injury and apoptosis of renal tubular epithelial cells through the mitochondrial apoptosis pathway, finally achieving the purpose of delaying the progress of renal failure.

Urinary cGMP predicts major adverse renal events in patients with mild renal impairment and/or diabetes mellitus before exposure to contrast medium

BACKGROUND

The use of iodine-based contrast agents entails the risk of contrast induced nephropathy (CIN). Radiocontrast agents elicit the third most common cause of nephropathy among hospitalized patients, accounting for 11-12% of cases. CIN is connected with clinically significant consequences, including increased morbidity, prolonged hospitalization, increased risk of complications, potential need for dialysis, and increased mortality rate. The number of in-hospital examinations using iodine-based contrast media has been significantly increasing over the last decade. In order to protect patients from possible complications of such examinations, new biomarkers are needed that are able to predict a risk of contrast-induced nephropathy. Urinary and plasma cyclic guanosine monophosphate (cGMP) concentrations are influenced by renal function. Urinary cGMP is primarily of renal cellular origin. Therefore, we assessed if urinary cGMP concentration may predict major adverse renal events (MARE) after contrast media exposure during coronary angiography.

METHODS

Urine samples were prospectively collected from non-randomized consecutive patients with either diabetes or preexisting impaired kidney function receiving intra-arterial contrast medium (CM) for emergent or elective coronary angiography at the Charité Campus Mitte, University Hospital Berlin. Urinary cGMP concentration in spot urine was analyzed 24 hours after CM exposure. Patients were followed up over 90 days for occurrence of death, initiation of dialysis, doubling of plasma creatinine concentration or MARE.

RESULTS

In total, 289 consecutive patients were included into the study. Urine cGMP/creatinine ratio 24 hours before CM exposure expressed as mean±SD was predictive for the need of dialysis (no dialysis: 89.77±92.85 μM/mM, n = 277; need for dialysis: 140.3±82.90 μM/mM, n = 12, p = 0.008), death (no death during follow-up: 90.60±92.50 μM/mM, n = 280; death during follow-up: 169.88±81.52 μM/mM, n = 9; p = 0.002), and the composite endpoint MARE (no MARE: 86.02±93.17 μM/mM, n = 271; MARE: 146.64±74.68 μM/mM, n = 18, p<0.001) during the follow-up of 90 days after contrast media application. cGMP/creatinine ratio stayed significantly increased at values exceeding 120 μM/mM in patients who developed MARE, required dialysis or died.

CONCLUSIONS

Urinary cGMP/creatinine ratio ≥ 120 μM/mM before CM exposure is a promising biomarker for the need of dialysis and all-cause mortality 90 days after CM exposure in patients with preexisting renal impairment or diabetes.

Prediction of contrast induced acute kidney injury using novel biomarkers following contrast coronary angiography

BACKGROUND/INTRODUCTION

Chronic kidney disease (CKD) is a risk factor for contrast induced acute kidney injury (CI-AKI). Contrast angiography in CKD patients is a common procedure. Creatinine is a delayed marker of CI-AKI and delays diagnosis which results in significant morbidity and mortality.

AIM

Early diagnosis of CI-AKI requires validated novel biomarkers.

DESIGN

A prospective observation study of 301 consecutive CKD patients undergoing coronary angiography was performed.

METHODS

Samples for plasma neutrophil gelatinase-associated lipocalin (NGAL), serum liver fatty acid-binding protein (L-FABP), serum kidney injury marker 1, serum interleukin 18 and serum creatinine were taken at 0, 1, 2, 4, 6 and 48 h post-contrast. Urinary NGAL and urinary cystatin C were collected at 0, 6 and 48 h. Incidence of major adverse clinical events (MACE) was recorded at 1 year. CI-AKI was defined as an absolute delta rise in creatinine of ≥26.5 µmol/l or a 50% relative rise from baseline at 48 h following contrast.

RESULTS

CI-AKI occurred in 28 (9.3%) patients. Plasma NGAL was most predictive of CI-AKI at 6 h. L-FABP performed best at 4 h. A combination of Mehran score > 10, 4 h L-FABP and 6 h NGAL improved specificity to 96.7%. MACE was statistically higher at 1 year in CI-AKI patients (25.0 vs. 6.2% in non-CI-AKI patients).

DISCUSSION/CONCLUSION

Mehran risk score, 4 h serum L-FAPB and 6 h plasma NGAL performed best at early CI-AKI prediction. CI-AKI patients were four times more likely to develop MACE and had a trebling of mortality risk at 1 year.

Urinary metabolites in patients undergoing coronary catheterization via the radial versus femoral artery approach

The transradial approach (TRA) for coronary angiography and percutaneous coronary intervention is associated with lower rates of vascular complications and acute kidney injury when compared to the transfemoral approach (TFA). Urine metabolites and proteins may be useful in identifying the dynamic changes at the vascular endothelial cell level. We attempted to explore the changes in the measurable signals of endothelial and nephron injury within 60 to 90 minutes after catheterization among those with the TRA and TFA approaches. Consecutive patients of a single interventionist who underwent coronary angiography between June 2015 and May 2016 were included. Of the 60 patients included in the analysis, the baseline characteristics were similar between those with a TRA (n = 30) and TFA (n = 30) approach. The values of the biomarkers were natural log transformed for the analysis. We found that the mean values of heat shock protein 27, taurine, and sulfuric acid did not significantly change after the procedure. However, the median value of thioredoxin decreased (P = 0.002) and that of talose increased (P = 0.01) after the procedure. None of the patients in our cohort experienced vascular complications or acute kidney injury. No differences in the values of urinary metabolites (pre, post, and delta) were found between TRA and TFA except for postprocedural thioredoxin. In conclusion, this exploratory study showed no difference in the patterns of acute vascular/renal injury metabolic markers before and after catheterization irrespective of the arterial access site.

Novel Therapies for Acute Kidney Injury

Acute kidney injury (AKI) is a common disease with a complex pathophysiology. The old paradigm of identifying renal injury based on location-prerenal, intrarenal, and postrenal-is now being supplanted with a new paradigm based on observable kidney injury patterns. The pathophysiology of AKI on a molecular and microanatomical level includes inflammation, immune dysregulation, oxidative injury, and impaired microcirculation. Treatment has traditionally been supportive, including the avoidance of nephrotoxins, judicious volume and blood pressure management, hemodynamic monitoring, and renal replacement therapy. Fluid overload and chloride-rich fluids are now implicated in the development of AKI, and resuscitation with a balanced, buffered solution at a conservative rate will mitigate risk. Novel therapies, which address specific observable kidney injury patterns include direct oxygen-free radical scavengers such as α-lipoic acid, curcumin, sodium-2-mercaptoethane sulphonate, propofol, and selenium. In addition, angiotensin II and adenosine receptor antagonists hope to ameliorate kidney injury via manipulation of renal hemodynamics and tubulo-glomerular feedback. Alkaline phosphatase, sphingosine 1 phosphate analogues, and dipeptidylpeptidase-4 inhibitors counteract kidney injury via manipulation of inflammatory pathways. Finally, genetic modifiers such as 5INP may mitigate AKI via transcriptive processes.

Biomarker response to contrast administration in diabetic and nondiabetic patients following coronary angiography

Neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C represent early renal injury markers for contrast-induced nephropathy (CIN). Baseline parameters such as type and quantity of contrast, patient preparation, renal function status, and diabetes mellitus (DM) are known to affect the response of the kidney to contrast-induced injury. This study was taken up to know the biomarker response to contrast administration in 58 diabetic and 59 nondiabetic male patients with same baseline parameters and baseline serum creatinine <1.2 mg/dl undergoing coronary angiography and their role in predicting the development of CIN. Serum creatinine, serum cystatin C, and urinary-NGAL (u-NGAL) were analyzed at baseline (0 h), 4 h, and 24 h after the administration of contrast medium. CIN was defined as a 25% increase in serum creatinine concentration from the baseline value or an absolute increase of at least 0.5 mg/dl within 48 h after the administration of contrast media. Serum creatinine rose 24 h after contrast administration in the diabetic group compared to 48 h in the nondiabetic group. Serum cystatin C levels rose 24 h after contrast administration in both the groups. The earliest marker to rise in both the groups was u-NGAL at 4 h. Diabetic patients had significantly higher u-NGAL (P = 0.005), and serum creatinine levels (P = 0.008) 4 h, and 24 h after contrast administration, respectively. Serum creatinine and u-NGAL/creatinine at 4 h were found to be the best predictors of CIN in the DM and non-DM patients, respectively. Biomarker response to contrast administration is different in diabetic and nondiabetic patients following contrast administration. Diabetic patients exhibit early and greater degree of renal impairment compared to the nondiabetic patients irrespective of the outcome. We propose the use of serum creatinine in patients with DM and u-NGAL/creatinine in non-DM patients to identify CIN as early as 4 h after contrast administration.

Is Kidney Injury Molecule 1 a Valuable Tool for the Early Diagnosis of Contrast-Induced Nephropathy?

AIM/SCOPE

Contrast-induced nephropathy (CIN) is a common complication of diagnostic/therapeutic procedures. Serum creatinine levels are sensitive but often lead to diagnostic delays in acute kidney injury and potential misclassification of actual injury status. Kidney injury molecule (KIM-1) is a novel early marker of acute kidney injury. The aim of our study was to evaluate the KIM-1 levels in patients with CIN. We performed a single-center, nested case-control study.

MATERIALS AND METHODS

Three thousand two hundred patients who had undergone coronary angiography were included in the study. Thirty-two patients were diagnosed with CIN. Twenty patients who had undergone coronary angiography but did not have CIN were evaluated as a control group (n = 20). The diagnosis of CIN was performed according to the KDIGO 2012 Acute Kidney Injury Guideline criteria. Urinary KIM-1 levels were measured by enzyme-linked immunosorbent assay before as well as on the 6th and 48th hours of contrast exposure. Serum creatinine levels were measured before as well as on the 24th and 48th hours after angiographic procedure.

RESULTS

We demonstrated that KIM-1 levels increased in the patients with CIN significantly on the sixth hour when compared with the baseline (P < 0.01; median levels, 0.27 and 0.70 mg/dL) but not in the controls (P = 0.107). The precontrast and 48th-hour KIM-1 levels were median ones and were also significantly different (P = 0.001, the median levels were 0.27 and 0.60 mg/dL, respectively).

CONCLUSIONS

Because creatinine is a sensitive but a late marker of CIN, KIM-1 may be used for early diagnosis and early initiation of treatment and may reduce risk for morbidity.

Prospective Assessment of Hepcidin in Relation to Delayed or Immediate Graft Function in Patients Undergoing Kidney Transplantation

BACKGROUND

Hepcidin is a peptide hormone that regulates iron homeostasis. Hepcidin may represent an early, predictive biomarker of acute kidney injury, another model of ischemia-reperfusion injury. Urinary hepcidin-25 has been shown to be elevated in patients who do not develop acute kidney injury. Creatinine is an unreliable indicator during acute changes in kidney; therefore, the aim of the study was to assess whether hepcidin could predict renal outcome in 31 consecutive patients undergoing kidney allograft transplantation. Serum hepcidin was evaluated before and after 1, 3, 6, and 10 days after kidney transplantation, using commercially available kits. Serum creatinine was assessed at the same time.

METHODS

We found a significant decrease in serum hepcidin, as early as after 1 day after kidney transplantation. Before transplantation, serum hepcidin was related to creatinine. In patients with delayed graft function, there was no decrease in serum hepcidin.

RESULTS

Our findings may have important implications for the clinical treatment of patients undergoing kidney transplantation. The "window of opportunity" is narrow in delayed graft function to distinguish between acute rejection and calcineurin inhibitors nephrotoxicity, and time is limited to introduce proper treatment after initiating insult.

CONCLUSIONS

Hepcidin must be investigated as a potential early marker for delayed graft function, especially in the upcoming setting of early dialysis treatment or anti-rejection therapy and might contribute to early patient risk stratification.

Novel Biomarkers of Acute Kidney Injury After Contrast Coronary Angiography

Acute kidney injury (AKI), defined as a rise in serum creatinine of greater than 25% from baseline measured at 48 hours after renal insult, may follow iodinated contrast coronary angiography. Termed contrast-induced nephropathy, it can result in considerable morbidity and mortality. Measurement of serum creatinine as a functional biomarker of glomerular filtration rate is widely used for detection of AKI, but it lacks sensitivity for the early diagnosis of AKI (typically rising 24 hours after functional loss) and, as a solely functional marker of glomerular filtration rate, is unable to differentiate among the various causes of AKI. These intrinsic limitations to creatinine measurement and the recognition that improved clinical outcomes are linked to a more timely diagnosis of AKI, has led investigators to search for novel biomarkers of "early" kidney injury. Several studies have investigated the utility of renal injury biomarkers in a variety of clinical settings including angiography/percutaneous coronary intervention, coronary artery bypass graft surgery, sepsis in intensive care patients, and pediatric cardiac surgery. In this article, we discuss the use of iodinated contrast for coronary procedures and the risk factors for contrast-induced nephropathy, followed by a review the potential diagnostic utility of several novel biomarkers of early AKI in the clinical settings of coronary angiography/percutaneous coronary intervention. In particular, we discuss neutrophil gelatinase associated lipocalin in depth. If validated, such biomarkers would facilitate earlier AKI diagnosis and improve clinical outcomes.

Risk Stratification for Acute Kidney Injury: Are Biomarkers Enough?

Acute kidney injury (AKI) is a common and serious complication that is associated with several adverse outcomes in hospitalized patients. AKI significantly increases the risk of mortality, need for renal replacement therapy, and intensive care admission, and it also has serious economic ramifications. Effective risk stratification to identify patients at risk for severe AKI is essential for targeting our health care and research resources to tackle this important public health issue. The overwhelming majority of research in earlier diagnosis and risk stratification of AKI over the past 10 years has focused on novel biomarker development. The purpose of this review is to provide an update on other novel risk stratification tools than can be used in the prognostication of AKI. We discuss the utility of the furosemide stress test in predicting the severity of AKI and the renal angina index in predicting the occurrence of AKI. We also discuss NephroCheck, a prognostic test that measures tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 for the early detection of severe AKI.

Analysis of urine biomarkers for early determination of acute kidney injury in non-septic and non-asphyxiated critically ill preterm neonates

OBJECTIVE

We designed the present study to test the hypothesis that urinary biomarkers might predict acute kidney injury (AKI) development in non-septic and non-asphyxiated critically ill preterm infants. We evaluated urine (u) sistatin-C (uCys-C), kidney injury molecule-1 (uKIM-1) and neutrophil gelatinase associate lipocaline (uNGAL) as markers of AKI.

METHODS

Sixty-four preterm infants with gestational age between 28 and 32 weeks were included in this study. Biomarkers were measured on day of life (DOL) 1, 3, and 7.

RESULTS

uNGAL levels in the AKI group were significantly higher than in no-AKI group on DOL 1, 3 and 7 (p = 0.016, p = 0.007 and p = 0.0014, respectively).

CONCLUSIONS

uNGAL is sensitive, early, and noninvasive AKI biomarkers, increasing significantly in non-septic and non-asphyxiated critically ill preterm neonates.

Effect of iodinated contrast medium in diabetic rat kidneys as evaluated by blood-oxygenation-level-dependent magnetic resonance imaging and urinary neutrophil gelatinase-associated lipocalin

OBJECTIVES

The objective of this study was to assess whether streptozotocin (STZ)-induced diabetic rats develop iodinated contrast-induced acute kidney injury. The intrarenal R2* (=1/T2*) was evaluated continuously before, during, and after contrast administration. Renal injury was confirmed using urinary neutrophil gelatinase-associated lipocalin measurements.

MATERIALS AND METHODS

Six Sprague-Dawley rats were administered with STZ to induce diabetes (group 1). R2* was measured before, during, and after administration of iodixanol. R2* readings were sampled from 4 renal regions: inner medulla, inner stripe of outer medulla (ISOM), outer stripe of outer medulla, and cortex. Peak R2* and initial upslope of R2* increase after iodinated contrast were calculated. Data from 12 nondiabetic rats pretreated with nitric oxide synthase and prostaglandin inhibitors to induce susceptibility to contrast-induced acute kidney injury (pretreatment model) from a previous study were reanalyzed for peak R2* and initial upslope of R2* increase after contrast. Six of these animals received saline (group 2), and the other 6 received furosemide (group 3) before iodixanol.

RESULTS

Peak R2* and initial upslope of R2* increase were used as blood-oxygenation-level-dependent response parameters. R2* in ISOM was comparable in all 3 groups before administration of furosemide/saline. Except for the furosemide group, ISOM showed a rapid increase in R2* immediately after contrast administration. Unlike the L-NAME- and indomethacin-treated groups, the diabetic group showed a quick reversal of R2* toward baseline measurements after contrast administration. Urinary neutrophil gelatinase-associated lipocalin indicated significant increase in diabetic rats 4 hours after contrast administration. The observed trends with peak R2* and initial upslope of R2* increase in renal ISOM were in agreement with those of urinary neutrophil gelatinase-associated lipocalin.

CONCLUSIONS

The STZ-induced diabetic rat may be suitable for studying the effects of iodinated contrast on renal oxygenation status and may mimic human condition closer than the pretreatment model described before. The peak R2* value and initial upslope of R2* in ISOM appear to be effective magnetic resonance imaging markers to predict renal injury after administration of an iodinated contrast agent.

The efficacy of hemodialysis in interventional therapy in coronary artery disease patients with chronic renal insufficiency

The aim of this study was to explore the efficacy and safety of hemodialysis in interventional therapy for patients with coronary artery disease combined with chronic renal insufficiency. With the aging and social development, the number of coronary artery disease patients with chronic renal insufficiency gradually increased. Total 58 coronary heart disease patients with chronic renal dysfunction were selected. These patients were characterized with typical angina symptoms and typical electrocardiogram (ECG) changes of onset angina. Continuous oral administration of sodium bicarbonate tablets 1 g 3/day × 3 days and slow intravenous input sodium chloride 1000 ∼1500 mL 3-12 h before operation were given. By this way, all patients were treated by hydration and alkalization. After percutaneous coronary intervention (PCI) treatment, patients were immediately transferred to undergo 4 h of dialysis treatment without removing indwelling of femoral artery puncture sheath tube to protect renal function. Changes in renal function including serum creatinine, glomerular filtration rate, and urine were observed and recorded. All patients were successfully underwent PCI treatment. Within one month after PCI, there were no obvious complication and no stent thrombosis occurred. Among of 58 patients, 56 cases showed no significant increase in serum creatinine levels compared with those before operation. However, serum creatinine level of one patient increased to 251 umol/L and one patient still required permanent dialysis. Using hemodialysis in interventional therapy in coronary artery disease patients with chronic renal insufficiency could significantly improve the prognosis of the patients.

Long-term verification of functional and structural renal damage after renal sympathetic denervation

Previous studies of renal sympathetic denervation (RSD) excluded patients with impaired renal function to avoid potential RSD-related renal damage. Measurement of the highly sensitive biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) has shown that RSD does not aggravate renal damage during the early post-procedural period. The aim of the present study was to examine the effect of RSD on blood pressure (BP) reduction and renal function after a long-term follow-up. A total of 62 consecutive patients undergoing RSD were included in this study. Serum NGAL and KIM-1 were collected prior to RSD and at 24 hr, 48 hr, and 3 months after RSD. BP measurements, antihypertensive medication use, and safety events were followed over a three-year period. Follow-up data were available over 36.9[±3.4] months in 47 of 62 (75.8%) of the initially included patients. At this time point a significant systolic BP reduction of 23 mm Hg (P > 0.001) was documented, and there were no significant changes in serum creatinine (P = 0.14), blood urea nitrogen (P = 0.33), or estimated glomerular filtration rate (eGFR) (P = 0.2) values. There were also no significant changes documented in patients with impaired renal function (eGFR < 45 mL/min) during the early post- procedural period or the long-term follow-up (P = 0.34). The results of the present study show a sustained effect of RSD on BP reduction after a three-year follow-up, and there was no evidence of renal failure. These results provide verification of the long-term safety and effectiveness of RSD, even in patients with impaired renal function. © 2015 Wiley Periodicals, Inc.

Predictive role of neutrophil gelatinase-associated lipocalin in early diagnosis of platin-induced renal injury

BACKGROUND

Acute kidney injury is an important issue in chemotherapy receiving patients an neutrophil gelatinase-associated lipocalin has been proposed as a novel marker. We here aimed to assess the role of urinary levels for assessment after platin exposure.

MATERIALS AND METHODS

Patients who had treated with cisplatin or carboplatin or oxaliplatin containg regimens were included in this study. Baseline and postchemotherapy serum urea, creatinine, urine neutrophil gelatinase-associated lipocalin and urine creatinine levels were determined. To avoid the effects of hydration during chemotherapy infusion the urinary neutrophil gelatinase-associated lipocalin/urine creatinine ratio was used to determine acute kidney injury.

RESULTS

Of a total of 42 patients receiving platin compounds,14 (33.3%) received cisplatin containing regimens, 14 (33.3%) received carboplatin and 14 (33.3%) oxaliplatin. The median age was 60 (37-76) years. Nineteen of the patients (45.2%) had lung cancer, 12 (28.6%) colorectal cancer and 11 (26.2%) others. The median pre and post chemotherapy urine neutrophil gelatinase-associated lipocalin/urine creatinin ratio was 15.6 ng/mg and 35.8 ng/mg (p=0.041) in the cisplatin group, 32.5 ng/mg and 86.3 ng/mg (p=0.004) in the carboplatin group and 40.9 ng/mg and 62.3 ng/ mg (p=0.243) in the oxaliplatin group.

CONCLUSIONS

Nephrotoxicity is a serious side effect of chemotherapeutic agentslike cisplatin and carbopaltin, but only to a lower extent oxaliplatin. All platin compounds must be used carefully and urine neutrophil gelatinase-associated lipocalin measurement seems to be promising in detecting acute kidney injury earlier than with creatinine.

Predictive Value of Neutrophil Gelatinase-Associated Lipocalin for Contrast-Induced Acute Kidney Injury After Cardiac Catheterization: A Meta-analysis

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) accumulates in cortical tubules in acute kidney injury (AKI) patients, with its levels associated with serum creatinine. However, the predictive value of NGAL level for contrast-induced acute kidney injury (CI-AKI) remains unclear.

METHODS

A total of 1520 patients from 14 relevant studies retrieved from PUBMED, MEDLINE, EMBASE, Web of Science, ClinicalTrials.gov, Cochrane Library, and Google Scholar from the inception to November 2014 and 15 data sets were included.

RESULTS

The pooled area under the curve of receiver operating characteristic analysis of NGAL for predicting CI-AKI was 0.93, and the diagnostic odds ratio, sensitivity, specificity, and median cutoff value were 42.54, 83.98%, 89.03%, and 52.4 ng/mL, respectively. Urine and serum/plasma NGAL levels performed similarly well in predicting CI-AKI, with somewhat better results obtained when the NGAL level was determined within 4 hours after exposure to contrast medium.

CONCLUSIONS

Patient nationality and definition of CI-AKI were important factors that affected the efficiency of NGAL level in predicting CI-AKI. Urine and serum/plasma NGAL levels appear to be promising biomarkers for early detection of CI-AKI after percutaneous coronary intervention or coronary angiography.

No increase in Kidney Injury Molecule-1 and Neutrophil Gelatinase-Associated Lipocalin excretion following intravenous contrast enhanced-CT

Objectives

To analyze kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (N-GAL) excretion post-intravenous contrast enhanced-CT (CE-CT) in patients with chronic kidney disease (CKD).

Methods

Patients were enrolled in a trial on hydration regimes to prevent contrast-induced acute kidney injury (CI-AKI). Blood and urine samples were taken at baseline, 4 – 6, and 48 – 96 h post CE-CT. Urinary KIM-1 and N-GAL values were normalized for urinary creatinine levels, presented as medians with 2.5 – 97.5 percentiles.

Results

Of the enrolled 511 patients, 10 (2 %) were lost to follow-up. CI-AKI occurred in 3.9 % of patients (20/501). Median KIM-1 values were 1.2 (0.1 – 7.7) at baseline, 1.3 (0.1 – 8.6) at 4 – 6 h, and 1.3 ng/mg (0.1 – 8.1) at 48 – 96 h post CE-CT (P = 0.39). Median N-GAL values were 41.0 (4.4 – 3,174.4), 48.9 (5.7 – 3,406.1), and 37.8 μg/mg (3.5 – 3,200.4), respectively (P = 0.07). The amount of KIM-1 and N-GAL excretion in follow-up was similar for patients with and without CI-AKI (P-value KIM-1 0.08, P-value N-GAL 0.73). Neither patient characteristics at baseline including severe CKD, medication use, nor contrast dose were associated with increased excretion of KIM-1 or N-GAL during follow-up.

Conclusion

KIM-1 and N-GAL excretion were unaffected by CE-CT both in patients with and without CI-AKI, suggesting that CI-AKI was not accompanied by tubular injury.

Key Points

• KIM-1 and N-GAL excretion were unaffected by intravenous contrast-enhanced CT (CE-CT).

• Patient or procedure characteristics were not associated with increased KIM-1 or N-GAL excretion.

• Performance of CE-CT in CKD patients is likely to be safe.

Urinary KIM-1, NGAL and L-FABP for the diagnosis of AKI in patients with acute coronary syndrome or heart failure undergoing coronary angiography

Acute kidney injury (AKI) is a common complication after coronary angiography. Early biomarkers of this disease are needed since increase in serum creatinine levels is a late marker. To assess the usefulness of urinary kidney injury molecule-1 (uKIM-1), neutrophil gelatinase-associated lipocalin (uNGAL) and liver-type fatty acid-binding protein (uL-FABP) for early detection of AKI in these patients, comparing their performance with another group of cardiac surgery patients. Biomarkers were measured in 193 patients, 12 h after intervention. In the ROC analysis, AUC for KIM-1, NGAL and L-FABP was 0.713, 0.958 and 0.642, respectively, in the coronary angiography group, and 0.716, 0.916 and 0.743 in the cardiac surgery group. Urinary KIM-1 12 h after intervention is predictive of AKI in adult patients undergoing coronary angiography, but NGAL shows higher sensitivity and specificity. L-FABP provides inferior discrimination for AKI than KIM-1 or NGAL in contrast to its performance after cardiac surgery. This is the first study showing the predictive capacity of KIM-1 for AKI after coronary angiography. Further studies are still needed to answer relevant questions about the clinical utility of biomarkers for AKI in different clinical settings.

Biomarkers of Contrast-Induced Nephropathy: Which Ones and What Is Their Clinical Relevance?

Contrast-induced nephropathy, or contrast-induced acute kidney injury (AKI), is an acute impairment of renal function as manifested by an increase in serum creatinine. Different urinary and serum proteins have been intensively investigated as possible biomarkers for the early diagnosis of AKI. Promising candidate biomarkers have the ability to detect an early and graded increase in tubular epithelial cell injury and to distinguish prerenal causes of AKI from acute tubular necrosis. In this article new, emerging biomarkers of contrast-induced AKI are presented and described, of which serum neutrophil gelatinase-associated lipocalin appears to be the most promising.

α-Intercalated cells defend the urinary system from bacterial infection

α-Intercalated cells (A-ICs) within the collecting duct of the kidney are critical for acid-base homeostasis. Here, we have shown that A-ICs also serve as both sentinels and effectors in the defense against urinary infections. In a murine urinary tract infection model, A-ICs bound uropathogenic E. coli and responded by acidifying the urine and secreting the bacteriostatic protein lipocalin 2 (LCN2; also known as NGAL). A-IC-dependent LCN2 secretion required TLR4, as mice expressing an LPS-insensitive form of TLR4 expressed reduced levels of LCN2. The presence of LCN2 in urine was both necessary and sufficient to control the urinary tract infection through iron sequestration, even in the harsh condition of urine acidification. In mice lacking A-ICs, both urinary LCN2 and urinary acidification were reduced, and consequently bacterial clearance was limited. Together these results indicate that A-ICs, which are known to regulate acid-base metabolism, are also critical for urinary defense against pathogenic bacteria. They respond to both cystitis and pyelonephritis by delivering bacteriostatic chemical agents to the lower urinary system.

Response of urinary liver-type fatty acid-binding protein to contrast media administration has a potential to predict one-year renal outcome in patients with ischemic heart disease

Urinary liver-type fatty acid-binding proteins (uL-FABP) have recently been recognized as a useful biomarker for predicting contrast-induced nephropathy. Although accumulating studies have evaluated short-term outcomes, its prognostic value for long-term renal prognosis in patients undergoing coronary angiography (CAG) has not been fully examined. This study aimed to evaluate the predictive value of uL-FABP for long-term renal outcome in patients with ischemic heart disease (IHD). Consecutive 24 patients with impaired renal function (serum creatinine >1.2 mg/dL) who underwent CAG were enrolled. uL-FABP was measured before CAG, 24 and 48 h after CAG. The changes in estimated glomerular filtration rate (eGFR) throughout CAG and at 1 year later were compared with the uL-FABP levels. The patients with a greater decrease in eGFR 1 year later had higher uL-FABP levels at all points, but only the value at 48 h after CAG reached statistical significance (lower vs. higher decreased eGFR group, 4.61 ± 3.87 vs. 17.71 ± 12.96; P < 0.01). Measurement of uL-FABP at 48 h after CAG (48h-uL-FABP) showed better correlation with the change in eGFR (pre-CAG uL-FABP vs. 48h-uL-FABP: R = 0.27, P = 0.20 vs. R = 0.65, P < 0.01). Moreover, the high-pre and high-48h-uL-FABP group showed a significantly larger decrease in eGFR compared with the high-pre and low-48h-uL-FABP group (change in eGFR; 8.12 ± 4.06 vs. 1.25 ± 2.23 mL/min/1.73 m2, P < 0.01), although the baseline eGFR levels were similar between these two groups. In this pilot study, measurement of uL-FABP levels at 48 h after CAG may be useful in detecting renal damage, and in predicting 1-year renal outcome in IHD patients undergoing CAG.

Cardiorenal syndrome

Cardiorenal syndrome (CRS) includes a broad spectrum of diseases within which both the heart and kidneys are involved, acutely or chronically. An effective classification of CRS in 2008 essentially divides CRS in two main groups, cardiorenal and renocardiac CRS, based on primum movens of disease (cardiac or renal); both cardiorenal and renocardiac CRS are then divided into acute and chronic, according to onset of disease. The fifth type of CRS integrates all cardiorenal involvement induced by systemic disease. This article addresses the pathophysiology, diagnosis, treatment, and outcomes of the 5 distinct types of CRS.

Urine neutrophil gelatinase-associated lipocalin to predict acute kidney injury in preterm neonates. A pilot study

BACKGROUND

The efficacy of urine neutrophil gelatinase-associated lipocalin (uNGAL) as an early acute kidney injury (AKI) biomarker in preterm neonates was evaluated.

METHODS

Thirty-five preterm neonates were prospectively evaluated for serum creatinine (sCre)-documented AKI during the first 14 days of life. Urine samples were collected daily throughout the study period. Of the neonates evaluated, we analyzed 11 who developed AKI (cases) and an equal number of neonates without AKI (controls) matched for gestational and postnatal age (case-control study). uNGAL was measured on the day of AKI occurrence (day 0) and on the 2 days preceding the event (day -1 and day -2, respectively) using an enzyme-linked immunosorbent assay.

RESULTS

Cases had significantly higher sCre levels than controls on day 0 (1.21 ± 0.48 vs. 0.83 ± 0.16 mg/dL, p =0.031) but not on days -1 and -2. Similarly, uNGAL levels (ng/mL) were significantly higher in cases than in controls only on day 0 (19.1 ± 3.5 vs. 13.3 ± 7.3, p=0.017) and not on days -1 (18.8 ± 3.4 vs. 16.3 ± 5.9, p=0.118) and -2 (19.3 ± 1.8 vs. 19.4 ± 0.8, p =0.979). The receiver operating characteristic curve analysis showed no significant ability of uNGAL to predict AKI on days -2 and -1.

CONCLUSIONS

In this pilot study in preterm neonates, although uNGAL detected sCre-based AKI upon its documentation, it failed to predict its development 1-2 days earlier.

Decreased renal function in hypertensive emergencies

Data about acute renal function in hypertensive crises are scarce. We hypothesised that acute kidney damage could result from hypertensive emergency (HE), as indicated by the earliest biomarker of kidney injury, neutrophil gelatinase-associated lipocalin (NGAL). Thus, we compared renal function between patients with HE, patients with urgencies and normotensive controls. Sixty emergency department patients were enroled in a prospective, cross-sectional study. Creatinine, blood urea nitrogen (BUN), NGAL and cystatin C were measured and estimated glomerular filtration rate was calculated (eGFR). Creatinine and BUN were significantly higher and eGFR was significantly lower in HE as compared with urgencies or controls (P < 0.01). Similarly, cystatin C and NGAL levels were significantly higher in emergencies compared with the other groups (P < 0.001). All renal function parameters were similar between urgencies and controls. Among HE, NGAL was significantly higher (61%) in patients with pulmonary oedema than in those with cerebral events (P = 0.008), whereas the other parameters were not significantly different. In conclusion, this cross-sectional investigation showed that markers of acute and chronic kidney injury were higher in patients with HE than in urgencies or controls. These results should encourage further studies to better characterise the role of acute kidney damage in hypertensive pulmonary oedema, and HE in general.

Neutrophil gelatinase associated lipocalin in acute kidney injury

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a member of the lipocalin family of proteins. Usually, NGAL is produced and secreted by kidney tubule cells at low levels, but the amount produced and secreted into the urine and serum increases dramatically after ischemic, septic, or nephrotoxic injury of the kidneys. The purpose of our review article is to summarize the role of NGAL in acute kidney injury (AKI), emergent, and intensive care.

METHODS

A PubMed search was performed (only English-language articles concerning human subjects were considered) using each of the following search term combinations: neutrophil gelatinase-associated lipocalin OR NGAL and acute kidney injury OR AKI; cardiac surgery; heart failure OR cardiology; intensive care; emergency department OR emergency medicine; nephropathy OR nephrotoxicity and transplantation.

RESULTS

The results of our search yielded 339 articles. Of the 339 articles, 160 were eligible for review based on the predefined criteria for inclusion.

CONCLUSION

Based on the evidence reviewed, it is clear that patient NGAL level is an appropriate, sensitive, and specific early biomarker of AKI caused by a variety of different etiologies. It is advised that a multidisciplinary group of experts come together to make recommendations and propose a consensus of clinical procedures to advance the most efficacious NGAL monitoring protocol for early detection and treatment of patients with AKI.

Remote ischemic pre-conditioning alleviates contrast-induced acute kidney injury in patients with moderate chronic kidney disease

BACKGROUND

Although remote ischemic preconditioning (RIPC) is shown to preserve kidney function in patients at high risk of contrast-induced acute kidney injury (CI-AKI), the effect in patients at low-moderate risk remains unknown. The preventive effects of RIPC in patients not at high risk of CI-AKI were examined, and biomarkers with anticipated roles in renal protection via RIPC investigated.

METHODS AND RESULTS

Sixty patients who had moderate chronic kidney disease and who underwent angiography were randomly assigned to the control (n=30) or RIPC (intermittent arm ischemia, n=30) group. The baseline characteristics in the 2 groups did not differ significantly. CI-AKI was evaluated by measuring urinary liver-type fatty acid-binding protein (L-FABP). Biomarkers were measured before and 24 and 48 h after angiography. Twenty-four hours after angiography, the percent change in urinary L-FABP level in the RIPC group was significantly smaller than in the control group (41.3±15.6 vs. 159±34.1%, P=0.003). L-FABP-based CI-AKI developed in 8 control patients (26.9%) vs. only 2 patients in the RIPC group (7.7%), suggesting that RIPC prevents CI-AKI. Factors contributing to CI-AKI were analyzed. Neither high-sensitivity C-reactive protein nor pentraxine-3 level differed significantly between the 2 groups, while the percent change in asymmetrical dimethy larginine (ADMA) level and blood derivatives of reactive oxidative metabolite levels were significantly smaller in the RIPC group.

CONCLUSIONS

RIPC alleviates CI-AKI in patients at low-moderate risk. This effect might be mediated partly by decreasing oxidative stress and plasma ADMA level.

Bicarbonates for the prevention of postoperative renal failure in endovascular aortic aneurysm repair: a randomized pilot trial

Purpose. Contrast-induced nephropathy (CIN) can contribute to acute kidney injury (AKI) in patients undergoing endovascular aortic aneurysm surgery. We evaluated the incidence of AKI together with the evolution of early biomarkers of renal injury in patients receiving bicarbonates or NaCl 0.9%. Methods. This study involved endovascular aortic aneurysm surgery patients. Group A (n = 17) received bicarbonates 3 mL/kg/h for 1 h before the procedure and then 1 mL/kg/h until 6 h after surgery, whereas group B (n = 17) received NaCl 0.9% using the same protocol. Biomarkers of renal injury from urine (interleukin-18 (IL-18), neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-β-D-glucosaminidase (NAG), and kidney injury molecule 1 (KIM-1)) and blood (NGAL, cystatin C) were measured at baseline and 3, 24, and 48 h postoperatively. Results. AKI occurred in 1 patient (2.9%), in the bicarbonates group. IL-18, NAG, NGAL, and KIM-1 significantly rose in both groups after the surgery. There was a greater rise in NGAL and IL-18 after 3 h in the bicarbonates versus NaCl 0.9% group: 1115% versus 240% increase (P = 0.03) and 338% increase versus 1.4% decrease (P = 0.01). Conclusions. Despite significant elevation in biomarkers of renal injury, we demonstrated a low rate of AKI following endovascular aortic surgery.

Clinical use of biomarkers for toxicant-induced acute kidney injury

Toxicant-induced acute kidney injury (ToxAKI) causes substantial morbidity and retards drug development. ToxAKI is relatively underexplored compared with ischemia–reperfusion injury in clinical biomarker studies. We highlight the rationale for novel AKI biomarkers in management of ToxAKI, and review the contemporary evidence supporting their clinical use. Directly-acting nephrotoxins, such as cisplatin, aminoglycosides, vancomycin and radiocontrast, remain widely used and highlight how novel biomarkers can either improve the detection of changes in glomerular filtration rate or directly signal cellular injury and structural damage. Serum cystatin C has already improved clinical risk prediction and drug dosing although its clinical use for early diagnosis awaits validation. The use of novel functional and structural biomarkers to stage ToxAKI and aid prognosis requires robust validation and better understanding of the relationship between biomarkers, morbidity and mortality. Biomarkers that illustrate the probable mechanisms and phase of ToxAKI may guide mechanism-specific diagnosis and therapy.

Use of alpha-lipoic acid in prevention of contrast-induced nephropathy in diabetic patients

In this prospective study, we aimed to determine the protective antioxidant role of alpha-lipoic acid (ALA) on development of contrast-induced nephropathy (CIN) in diabetic patients undergoing coronary angiography. Seventy-eight diabetic patients undergoing coronary angiography were included. Thirty-nine patients were randomized to control group and 39 patients to ALA group. Both groups were hydrated on the day of angiography, and the ALA group had also received three doses of "Thioctacid 600 mg HR, MEDA Manufacturing GmbH" in pill form. Serum creatinine clearance, cystatin C, and urinary neutrophil gelatinase-associated lipocalin (NGAL) were studied before and after angiography. We defined CIN as either ≥25% or ≥0.5 mg/dL increase in serum creatinine at 48th hour after angiography. Baseline clinical characteristics were similar in both groups. Mehran risk score and creatinine clearance were comparable in control and therapy groups (5.59 ± 1.96 vs. 5.49 ± 1.73, p = 0.54 and 89 ± 21 vs. 96 ± 24, p = 0.13, respectively). The volumes of contrast media (median values of 80 mL vs. 75 mL) and hydration with saline (2862 ± 447 mL vs. 2637 ± 592 mL) were also similar (p > 0.05). The incidence of CIN was the same (8%) in both the groups. Alterations in serum creatinine, cystatin C, and urinary NGAL levels before and after the procedure were comparable between the ALA and control groups (group p-values were >0.05 in two-way repeated measures analysis of variance). We presented for the first time that ALA therapy added to hydration does not decrease the risk of CIN development in diabetic patients undergoing coronary angiography.

Cystatin C: a step forward in assessing kidney function and cardiovascular risk

The cardiorenal syndrome is a clinical manifestation of the bidirectional interaction between the heart and kidneys. Evaluating renal function is an essential part of the assessment of every cardiac patient. It has become clear that serum creatinine is not an accurate enough marker of glomerular filtration rate (GFR) and should not be used to evaluate kidney dysfunction. Creatinine-based estimates of GFR are preferred, but require renal function to be stable and are not suitable when changes in kidney function occur. Cystatin C (CysC) has been the target of much interest in the search for an alternative measure of GFR. As an endogenous biomarker, CysC possesses many of the properties required of a good marker of renal function. Compared with that of creatinine, plasma concentrations of CysC are less influenced by factors other than GFR. Consequently, CysC correlates with true GFR more accurately than creatinine. Equations for estimating GFR from CysC values have also been developed, which makes values easier to interpret and facilitates the clinical use of this new marker. The use of CysC in acute kidney injury has also shown promising results. CysC has been studied as a risk marker for prognosis in cardiovascular disease. This effect is attributed to the strong impact of renal dysfunction on progressive cardiovascular disease and impaired survival. Higher levels of CysC have consistently been predictive of incident or recurrent cardiovascular events and adverse outcomes. CysC is a predictor of the development of heart failure and increased levels of CysC have an independent association with higher mortality in both chronic and acute heart failure. In conclusion, CysC appears to be an interesting marker of renal function and is useful for risk stratification in heart failure.

Accuracy of plasma neutrophil gelatinase-associated lipocalin in the early diagnosis of contrast-induced acute kidney injury in critical illness

PURPOSE

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for acute kidney injury (AKI). We evaluated the diagnostic and prognostic accuracies of plasma NGAL (pNGAL) for contrast-induced AKI (CI-AKI) in critically ill patients.

METHODS

In a prospective observational study in two adult intensive care units in a university hospital, 100 consecutive critically ill patients with stable serum creatinine concentrations up to 48 h before contrast medium (CM) injection were enrolled. Serial blood sampling for pNGAL analysis was performed at enrolment, 2, 6, and 24 h after CM injection. The primary outcome was CI-AKI, defined by AKIN criteria, within the first 72 h following CM injection. Secondary outcomes were the need for renal replacement therapy (RRT) and mortality.

RESULTS

Of the 98 patients analyzed, 30 developed CI-AKI. The pNGAL levels did not differ in patients with or without CI-AKI, and were higher in septic patients compared to nonseptic patients, and in patients with AKI preceding CM injection. The discriminative value of pNGAL to predict CI-AKI and mortality was poor; although, it did predict the need for RRT requirement after CM injection (area under receiver-operating characteristic curve, 0.85, 0.80, 0.83 and 0.86 at H0, H2, H6 and H24, respectively).

CONCLUSION

CI-AKI was common in critically ill patients. pNGAL levels were higher in patients with sepsis or previous AKI, but did not help to diagnose CI-AKI any earlier than serum creatinine after CM injection. However, pNGAL could be of interest to detect patients at risk of subsequent RRT requirement.

Novel Biomarkers for Cardio-renal Syndrome

Cardio-renal syndrome (CRS) is a frequent and life-threatening syndrome. It is a disorder of the heart and kidneys in which acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other organ. Acute kidney injury (AKI) is strongly associated with increased morbidity and mortality in patients with CRS. Early detection of renal dysfunction is not possible using the traditional marker, serum creatinine, and therefore efforts to explore possible biomarkers for early detection of AKI are being made. Apart from predicting AKI, several biomarker studies also identified predictors for poor prognosis such as the need for renal replacement therapy (RRT) or death. It is possible that biomarkers can become risk factors in an improvement of clinical outcomes of CRS. Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with renal dysfunction and the treatment for this disease can be modified based on cardiac biomarkers. In addition to natriuretic peptides, which are established cardiac markers, several new biomarkers have been identified and may play important roles in CRS. In this review, we will briefly summarize the literature on novel renal and cardiac biomarkers and discuss their potential roles in the clinical outcome of CRS.

Performance of urinary liver-type fatty acid-binding protein in acute kidney injury: a meta-analysis

BACKGROUND

Urinary liver-type fatty acid-binding protein (L-FABP) is a proximal tubular injury candidate biomarker for early detection of acute kidney injury (AKI), with variable performance characteristics depending on clinical settings.

STUDY DESIGN

Meta-analysis of diagnostic test studies assessing the performance of urinary L-FABP in AKI.

SETTING & POPULATION

Literature search in MEDLINE, EMBASE, Scopus, Google Scholar, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov using search terms "liver-type fatty acid-binding protein" and "L-FABP."

SELECTION CRITERIA FOR STUDIES

Studies of humans investigating the performance characteristics of urinary L-FABP for the early diagnosis of AKI and AKI-related outcomes, including dialysis requirement and mortality.

PREDICTOR

Urinary L-FABP.

OUTCOMES

Diagnosis of AKI, dialysis requirement, and in-hospital death.

RESULTS

15 prospective cohort and 2 case-control studies were identified. Only 7 cohort studies could be meta-analyzed. The estimated sensitivity of urinary L-FABP level for the diagnosis of AKI was 74.5% (95% CI, 60.4%-84.8%), and specificity was 77.6% (95% CI, 61.5%-88.2%). The estimated sensitivity of urinary L-FABP level for predicting dialysis requirement was 69.1% (95% CI, 34.6%-90.5%), and specificity was 42.7% (95% CI, 3.1%-94.5%); for in-hospital mortality, sensitivity and specificity were 93.2% (95% CI, 66.2%-99.0%) and 78.8% (95% CI, 27.0%-97.4%), respectively.

LIMITATIONS

Paucity and low quality of studies, different clinical settings, and variable definitions of AKI.

CONCLUSIONS

Although urinary L-FABP may be a promising biomarker for early detection of AKI and prediction of dialysis requirement and in-hospital mortality, its potential value needs to be validated in large studies and across a broader spectrum of clinical settings.

Assessment and diagnosis of renal dysfunction in the ICU

Identifying patients with impaired renal function is crucial in the setting of critical illness. Serum creatinine serves as the gold standard for assessing steady-state renal function, helping to define those with chronic kidney disease (CKD). Although these baseline creatinine values are often not available in the setting of critical illness, CKD, whether defined by serum creatinine or proteinuria, increases the risk of developing acute kidney injury (AKI). Despite delays in elevations following renal insults, serum creatinine remains the standard for assessing acute changes in renal function. Standardized definitions of AKI, using changes in serum creatinine and urine output, have informed the epidemiology of ICU-acquired AKI and have helped define the long-term outcomes in patients who experience AKI. A complex cyclical interplay exists between AKI and CKD, in which CKD predisposes patients to an increased risk of AKI, whereas those with AKI, regardless of baseline renal function, are more likely to suffer from post-AKI CKD. The clarification of the AKI-CKD dynamic remains a work in progress and will be aided by the implementation of novel measures of renal function. Several novel biomarkers of renal function have been proposed to augment serum creatinine in the diagnosis of AKI and CKD. These biomarkers, taken with recent clinical investigations, have laid the groundwork for the impending paradigm shift in risk stratifying and in diagnosing changes in renal function in the ICU.

Serum and urine acute kidney injury biomarkers in asphyxiated neonates

BACKGROUND

We evaluated serum (s) cystatin C (CysC) and neutrophil gelatinase-associated lipocalin (NGAL) and urine (u) CysC, NGAL and kidney injury molecule-1 (KIM-1) as markers of acute kidney injury (AKI) in asphyxiated neonates.

METHODS

AKI biomarkers were measured in 13 asphyxiated neonates born at ≥ 36 weeks gestational age (eight with AKI and five without AKI) and 22 controls. AKI was defined as serum creatinine ≥ 1.5 mg/dl for >24 h or rising values >0.3 mg/dl from day of life (DOL) 1. Biomarkers were measured on DOL 1, 3, and 10.

RESULTS

Asphyxiated neonates had significantly higher sCysC on DOL 1 as well as sNGAL and uCysC and uNGAL (standardized to urine creatinine and absolute values) than controls at all time points. Compared to controls, significantly higher sNGAL, uCysC, and uNGAL values were observed in the asphyxia-AKI and asphyxia-no AKI subgroups. Regarding uKIM-1, only the absolute values were significantly higher in asphyxiated neonates (DOL 10). sNGAL, uCyst, and uNGAL had a significant diagnostic performance as predictors AKI on DOL 1.

CONCLUSIONS

sNGAL, uCysC, and uNGAL are sensitive, early AKI biomarkers, increasing significantly in asphyxiated neonates even in those not fulfilling AKI criteria. Their measurement on DOL 1 is predictive of post-asphyxia-AKI.

Intrarenal oxygenation by blood oxygenation level-dependent MRI in contrast nephropathy model: effect of the viscosity and dose

PURPOSE

To compare the effects of osmolality versus viscosity of radio-contrast media on intra-renal oxygenation as determined by blood oxygenation level-dependent (BOLD) MRI in a model of contrast induced nephropathy (CIN).

MATERIALS AND METHODS

Twenty-four Sprague-Dawley rats were divided into five groups. Nitric oxide synthase inhibitor L-NAME (10 mg/kg), cyclooxygenase inhibitor indomethacin (10 mg/kg), or saline, and radio-contrast iodixanol (high viscosity, 784 or 1600 mg I/kg) or iothalamate (high osmolality, 1600 mg I/kg) were administered. BOLD MRI images were acquired on Siemens 3 Tesla (T) scanner using a multiple gradient recalled echo sequence at baseline, following L-NAME (or saline), indomethacin (or saline), and radio-contrast agents. R2* (=1/T2*) was used as the BOLD MRI parameter in renal medulla and cortex. Mixed-effects models with first order auto-regressive variance-covariance models were used to analyze the data.

RESULTS

The magnitude of change in medullary R2* (MR2*) with same dose of iodine was larger with iodixanol compared with iothalalmate both in pretreated groups (303% versus 225.6%, < 0.01) and the control group (191.6% versus -1.8%, P < 0.01). The MR2* change in high dose iodixanol was approximately twice compared with the low dose (303% versus 133%, P < 0.01).

CONCLUSION

The viscosity of radio-contrast seems to play a more significant role than osmolality in terms of renal oxygenation changes as evaluated by BOLD MRI. Additionally, iodixanol induced a dose-dependent increase in renal medullary hypoxia.

Cardio-renal syndrome: new perspective in diagnostics

Chronic heart failure and chronic renal failure are at epidemic proportions. These patients have significantly altered cardiac, renal, and all-cause outcomes. Much of the current research has focused on treating these individual organs in isolation. Although there are positive data on outcomes with neurohormonal modulation, they, however, remain underused. At present, data lacks for novel treatment options, while evidence continues to point at significantly worsened prognosis. Current diagnostic tools that detect acute changes in renal function or renal injury appear retrospective, which often hinder meaningful diagnostic and therapeutic decisions. This review is aimed at exploring the importance of accurate assessment of renal function for the heart failure patient by providing a synopsis on cardio-renal physiology and establishing the possibility of novel approaches in bridging the divide.