NGAL is an early predictive biomarker of contrast-induced nephropathy in children

Pediatric Considerations in Computed Tomographic Angiography

Cardiovascular disease in children comprises a diverse collection of diseases involving multiple organ systems. Abnormality in children is predominately congenital but also may be acquired. Although noninvasive vascular imaging modalities such as magnetic resonance angiography and ultrasound lack ionizing radiation, with improving technology and an increased focus on radiation dose reduction, computed tomographic angiography (CTA) continues to have a role in evaluating cardiovascular disease in pediatric patients. This review focuses on specific considerations of CTA that the radiologist or ordering provider should consider when imaging the pediatric cardiovascular system.

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.

Neutrophil Gelatinase-associated Lipocalin in the Prediction of Contrast-induced Nephropathy: A Systemic Review and Meta-analysis

OBJECTIVE

The aim of this study was to investigate the predictive value of neutrophil gelatinase-associated lipocalin (NGAL) in the early diagnosis of contrast-induced nephropathy (CIN).

METHODS

We searched MEDLINE and Embase until December 2014 for articles evaluating the diagnostic accuracy of plasma/serum and urinary NGAL levels to predict CIN. The primary analysis was based on a hierarchical, bivariate, generalized, linear, mixed model. Diagnostic odds ratio (DOR) and sample size-weighted area under the curve for the receiver operating characteristic (AUROC) were calculated.

RESULTS

Ten studies involving 1310 patients were analyzed. Overall, the DOR/AUROC for NGAL level to predict CIN was 20.56 [95% confidence interval (CI), 9.67-43.74]/0.87 (95% CI, 0.84-0.90), with sensitivity and specificity of 0.80 (95% CI, 0.74-0.85) and 0.83 (95% CI, 0.73-0.90), respectively. Subgroup analysis showed that the diagnostic performance of the DOR/AUROC of urinary NGAL [29.48 (95% CI, 12.19-71.27)/0.87 (95% CI, 0.84-0.90)] was better than that of plasma/serum NGAL [14.63 (95% CI, 4.51-47.38)/0.85 (95% CI, 0.82-0.88)] (DOR, P = 0.005, and AUROC, P = 0.04, respectively).

CONCLUSIONS

Plasma/serum and urinary NGAL levels seem to be useful biomarkers in the early prediction of CIN. Moreover, urinary NGAL levels perform better than plasma/serum NGAL.

Detection of early renal injury in children with solid tumors undergoing chemotherapy by urinary neutrophil gelatinase-associated lipocalin

Acute kidney injury (AKI) is a complication in children with solid tumors undergoing chemotherapy, as it may prevent the use of therapy protocols and also hinder the supportive and diagnostic procedures. Thus, there is an urgent requirement for early predictive biomarkers of AKI. The most promising novel AKI biomarker is neutrophil gelatinase-associated lipocalin (NGAL). The aim of the present study was to compare the predictability of NGAL as a biomarker of AKI with creatinine as a traditional biomarker in children with solid tumors under chemotherapy. The study was performed on 30 patients with different types of solid tumors (reuroblastoma, Wilms tumor, medulloblastoma, rhabdomyosarcoma and Ewing sarcoma) and 20 control subjects. Urinary NGAL (uNGAL) and serum creatinine samples were taken three times: Baseline before the beginning of the treatment, one week after chemotherapy and at the end of the chemotherapy protocol. AKI is defined as a change in creatinine level by >50% of the baseline. The creatinine level only rises to this level in the third sample, while uNGAL increases significantly in the second and third samples with percentage of change 376.8 and 698.2%, respectively, which is highly significant (P<0.001). When comparing the predictive value of serum creatinine for AKI depending on the receiver operating characteristic curve with that of uNGAL, the area under the curve (AUC) for creatinine was 0.60 with a standard error (SE) of 0.086 and 95% confidence interval (CI) between 0.432 and 0.768, while that of uNGAL was highly predictive with an AUC of 0.847, SE 0.55 and 95% CI between 0.739 and 0.955. Depending only on the creatinine level for detecting the AKI will markedly delay the diagnosis; however, uNGAL is detected earlier, and is easier and more reliable as a marker for AKI in children with solid tumors undergoing chemotherapy.

Sepsis and AKI in Clinical Emergency Room Patients: The Role of Urinary NGAL

BACKGROUND

Few studies have investigated the predictive properties of urinary (u) NGAL as an AKI marker in septic population.

OBJECTIVES

This study evaluated the efficacy of uNGAL as predictor of AKI and death in septic patients admitted to the clinical emergency room (ER).

METHODOLOGY

We prospectively studied patients with sepsis admitted to the ER. Urine was analyzed for NGAL within the first 24 hours after admission (classified as NGAL1), between 24 and 48 h (NGAL2), and at moment of AKI diagnosis (NGAL3).

RESULTS

Among 168 septic patients admitted to ER, 72% developed AKI. The uNGAL and its relationship with creatinine (Cr) were high in septic patients but statistically higher in those with sepsis and AKI. The uNGAL1 and uNGAL2, as well as uNGAL1/uCr1 and uNGAL2/uCr2, were good predictors for AKI (AUC-ROC 0.73, 0.70, 0.77, and 0.84, resp.). The uNGAL1 and uNGAL1/uCr1 were poor predictors for death (AUC-ROC 0.66 and 0.68, resp.), whereas uNGAL2 and uNGAL2/uCr2 were better predictors (AUC-ROC 0.70 and 0.81, resp.).

CONCLUSION

The uNGAL is highly sensitive but nonspecific predictor of AKI and death in septic patients admitted into ER.

From the periphery to the brain: Lipocalin-2, a friend or foe?

Lipocalin-2 (LCN2) is an acute-phase protein that, by binding to iron-loaded siderophores, acts as a potent bacteriostatic agent in the iron-depletion strategy of the immune system to control pathogens. The recent identification of a mammalian siderophore also suggests a physiological role for LCN2 in iron homeostasis, specifically in iron delivery to cells via a transferrin-independent mechanism. LCN2 participates, as well, in a variety of cellular processes, including cell proliferation, cell differentiation and apoptosis, and has been mostly found up-regulated in various tissues and under inflammatory states, being its expression regulated by several inducers. In the central nervous system less is known about the processes involving LCN2, namely by which cells it is produced/secreted, and its impact on cell proliferation and death, or in neuronal plasticity and behaviour. Importantly, LCN2 recently emerged as a potential clinical biomarker in multiple sclerosis and in ageing-related cognitive decline. Still, there are conflicting views on the role of LCN2 in pathophysiological processes, with some studies pointing to its neurodeleterious effects, while others indicate neuroprotection. Herein, these various perspectives are reviewed and a comprehensive and cohesive view of the general function of LCN2, particularly in the brain, is provided.

Urinary neutrophil gelatinase-associated lipocalin: potential biomarker for late-onset sepsis

BACKGROUND

To assess the ability of urinary neutrophil gelatinase-associated lipocalin (UNGAL) to discriminate between culture-positive vs. culture-negative late-onset sepsis evaluations.

METHODS

This is a prospective observational study of 136 neonates who underwent ≥1 sepsis evaluation at >72 h of age. Urine was obtained at the time of sepsis evaluation to measure UNGAL concentration. Using generalized estimating equations controlling for gender, gestational and postnatal age, acute kidney injury, and within-patient correlations, pair-wise contrasts between mean log UNGAL concentrations of infants with negative sepsis evaluations vs. culture-positive sepsis and presumed sepsis were assessed. Discrimination characteristics at several UNGAL cutoff concentrations were assessed using receiver-operating characteristic curves.

RESULTS

The predicted mean log UNGAL values of culture-positive sepsis and presumed sepsis vs. negative sepsis evaluations differed significantly (P < 0.001 and P = 0.02, respectively). At a cutoff ≥ 50 ng/ml, UNGAL discriminated between culture-positive sepsis and culture-negative sepsis evaluations with sensitivity = 86%, specificity = 56%, positive predictive value = 41%, negative predictive value = 92%, and number needed to treat = 3.

CONCLUSION

UNGAL is a noninvasive biomarker with high negative predictive value at the time of late-onset sepsis evaluation in neonates and could be a useful adjunct to traditional components of sepsis evaluations.

Biomarkers of Renal Disease and Progression in Patients with Diabetes

Diabetes prevalence is increasing worldwide, mainly due to the increase in type 2 diabetes. Diabetic nephropathy occurs in up to 40% of people with type 1 or type 2 diabetes. It is important to identify patients at risk of diabetic nephropathy and those who will progress to end stage renal disease. In clinical practice, most commonly used markers of renal disease and progression are serum creatinine, estimated glomerular filtration rate and proteinuria or albuminuria. Unfortunately, they are all insensitive. This review summarizes the evidence regarding the prognostic value and benefits of targeting some novel risk markers for development of diabetic nephropathy and its progression. It is focused mainly on tubular biomarkers (neutrophil-gelatinase associated lipocalin, kidney injury molecule 1, liver-fatty acid-binding protein, N-acetyl-beta-d-glucosaminidase), markers of inflammation (pro-inflammatory cytokines, tumour necrosis factor-α and tumour necrosis factor-α receptors, adhesion molecules, chemokines) and markers of oxidative stress. Despite the promise of some of these new biomarkers, further large, multicenter prospective studies are still needed before they can be used in everyday clinical practice.

Opinion paper on utility of point-of-care biomarkers in the emergency department pathways decision making

Overcrowding of the emergency department (ED) is rapidly becoming a global challenge and a major source of concern for emergency physicians. The evaluation of cardiac biomarkers is critical for confirming diagnoses and expediting treatment decisions to reduce overcrowding, however, physicians currently face the dilemma of choosing between slow and accurate central-based laboratory tests, or faster but imprecise assays. With improvements in technology, point-of-care testing (POCT) systems facilitate the efficient and high-throughput evaluation of biomarkers, such as troponin (cTn), brain natriuretic peptide (BNP) and neutrophil gelatinase-associated lipocalin (NGAL). In this context, POCT may help ED physicians to confirm a diagnosis of conditions, such as acute coronary syndrome, heart failure or kidney damage. Compared with classic laboratory methods, the use of cTn, BNP, and NGAL POCT has shown comparable sensitivity, specificity and failure rate, but with the potential to provide prompt and accurate diagnosis, shorten hospital stay, and alleviate the burden on the ED. Despite this potential, the full advantages of rapid delivery results will only be reached if POCT is implemented within hospital standardized procedures and ED staff receive appropriate training.

Identification of drug-induced toxicity biomarkers for treatment determination

Drug-induced organ toxicity (DIOT) that leads to the removal of marketed drugs or termination of candidate drugs has been a leading concern for regulatory agencies and pharmaceutical companies. In safety studies, the genomic assays are conducted after the treatment so that drug-induced adverse effects can occur. Two types of biomarkers are observed: biomarkers of susceptibility and biomarkers of response. This paper presents a statistical model to distinguish two types of biomarkers and procedures to identify susceptible subpopulations. The biomarkers identified are used to develop classification model to identify susceptible subpopulation. Two methods to identify susceptibility biomarkers were evaluated in terms of predictive performance in subpopulation identification, including sensitivity, specificity, and accuracy. Method 1 considered the traditional linear model with a variable-by-treatment interaction term, and Method 2 considered fitting a single predictor variable model using only treatment data. Monte Carlo simulation studies were conducted to evaluate the performance of the two methods and impact of the subpopulation prevalence, probability of DIOT, and sample size on the predictive performance. Method 2 appeared to outperform Method 1, which was due to the lack of power for testing the interaction effect. Important statistical issues and challenges regarding identification of preclinical DIOT biomarkers were discussed. In summary, identification of predictive biomarkers for treatment determination highly depends on the subpopulation prevalence. When the proportion of susceptible subpopulation is 1% or less, a very large sample size is needed to ensure observing sufficient number of DIOT responses for biomarker and/or subpopulation identifications.

Cardiovascular biomarkers in chronic kidney disease: state of current research and clinical applicability

The high incidence of cardiovascular events in chronic kidney disease (CKD) warrants an accurate evaluation of risk aimed at reducing the burden of disease and its consequences. The use of biomarkers to identify patients at high risk has been in use in the general population for several decades and has received mixed reactions in the medical community. Some practitioners have become staunch supporters and users while others doubt the utility of biomarkers and rarely measure them. In CKD patients numerous markers similar to those used in the general population and others more specific to the uremic population have emerged; however their utility for routine clinical application remains to be fully elucidated. The reproducibility and standardization of the serum assays are serious limitations to the broad implementation of these tests. The lack of focused research and validation in randomized trials rather than ad hoc measurement of multiple serum markers in observational studies is also cause for concern related to the clinical applicability of these markers. We review the current literature on biomarkers that may have a relevant role in field of nephrology.

Plasma neutrophil gelatinase-associated lipocalin and kidney function decline and kidney disease-related clinical events in older women

BACKGROUND

It is still unclear whether serum neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of renal tubular injury, is a prognostic marker for the progression of chronic kidney disease (CKD) in the general population.

METHODS

A prospective-cohort study of 1,245 women aged ≥70 from the general population. Associations between plasma NGAL and change in 5-year estimated glomerular filtration rate (eGFR), rapid renal decline and 10-year risk of acute or chronic renal disease-related hospitalisations and/or mortality were examined.

RESULTS

Compared to women with above-median plasma NGAL of 76.5 ng/l, women with below-median plasma NGAL had a 9.3% reduction in eGFR over a 5-year period. Among women with above-median plasma NGAL, there was over a 1.7-fold increased risk of rapid renal decline (eGFR decline of >3 ml/min/year) (adjusted odds ratio 1.76, 95% CI 1.003, 3.102, p = 0.049). Compared to women with baseline eGFR of <60 ml/min/1.73 m(2), women with above-median plasma NGAL experienced over a 2.5-fold increased risk of renal disease events at 10 years (hazard ratio 2.55, 95% CI 1.13, 5.78, p = 0.025) after adjustment of age, hypertension and diabetes. Addition of plasma NGAL in participants with eGFR of <60 ml/min/1.73 m(2) significantly improved the accuracy in predicting the 10-year risk of renal disease events (adjusted area-under-curve receiver operator characteristics without and with NGAL 0.64 and 0.71, respectively; p = 0.027) and reclassified 13% of women who experienced renal disease events into the higher risk categories (p = 0.03).

CONCLUSION

Plasma NGAL is of modest clinical utility in predicting the renal function decline and risk of renal disease-related clinical events, particularly those with mild to moderate CKD.

Relative and absolute changes in urinary neutrophil gelatinase-associated lipocalin and correlation with small increases in serum creatinine levels after coronary angiography: an observational study

INTRODUCTION/AIMS

The Acute Kidney Injury Network classification is based on small increases in serum creatinine (sCr) for stage 1. This study investigated whether changes in the urinary concentration of neutrophil gelatinase-associated lipocalin (uNGAL) could predict small increases in sCr in patients undergoing coronary angiography.

METHODS

The uNGAL was measured before contrast infusion and 2 and 4 h afterwards. Patients were divided into 2 subgroups: G1 (n = 103), where sCr increased by <0.3 mg/dl, and G2 (n = 22), where sCr increased by ≥0.3 mg/dl 48 h after the angiography. To determine the sensitivity and specificity for the absolute and relative variations of uNGAL, a receiver operating characteristic curve analysis was performed.

RESULTS

In G2, the uNGAL concentration increased over baseline values (15.9 vs. 9.2 ng/dl; p < 0.05), and it was also 2-fold higher in G2 versus G1 (15.9 vs. 8.0 ng/dl; p < 0.001). The uNGAL remains an independent predictor of the small increases in sCr, and, for an increase of 50% over baseline levels, it showed 60% sensitivity and 81% specificity.

CONCLUSION

Changes in uNGAL concentration 2 h after the infusion of contrast media showed marginal sensitivity to predict small increases in sCr.

Normalisation of urinary biomarkers to creatinine for clinical practice and research--when and why

Acute kidney injury (AKI) and chronic kidney disease (CKD) are major health problems. Urinary biomarkers have both diagnostic and prognostic utility in AKI and CKD. However, how biomarker excretion rates should be reported, especially whether they should be normalised to urinary creatinine concentration (uCr), is controversial. Some studies suggest that normalisation to uCr may be inappropriate at times, as urinary creatinine excretion rate may vary greatly, depending on the situation. Notably, recent studies suggest that while normalisation of values to UCr may be valid for the evaluation of CKD and prediction of AKI sequelae and occurrences, it could be inappropriate for the diagnosis of AKI, or in the presence of certain acute kidney disease states.

Comparative assessment of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C as early biomarkers for early detection of renal failure in patients with hypertension

BACKGROUND

Hypertension is one the most common causes of chronic kidney disease (CKD). One of the major concerns in hypertensive patients is early detection of renal disorders. In the past, serum creatinine (Scr) concentration was used as a marker of kidney function, but it proffers a late reflection of reduced glomerular filtration rate. Cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) have been recently proven to be useful for quantification of CKD. Therefore, we compared the diagnostic value of NGAL with cystatin C and creatinine to evaluate kidney function in hypertensive patients.

METHODS

In this study, 42 hypertensive patients and 30 healthy volunteers were recruited. Serum cystatin C (Scys C) and plasma NGAL were measured using ELISA method. Creatinine, urea, hemoglobin, fibrinogen, and C-reactive protein were measured according to the routine methods. Estimated glomerular filtration rate (eGFR) was considered as the gold standard method (cut-off value of < 78 ml/min/1.73 m².

RESULTS

In the patient group, plasma NGAL, cystatin C, and creatinine were all significantly correlated with eGFR, and plasma NGAL correlated best with eGFR. Receiver-operating characteristics analysis indicated that plasma NGAL was a better indicator than creatinine and cystatin C for predicting a GFR < 78 ml/min/1.73 m2. The sensitivity and specificity for NGAL were 96% and 100%, for cystatin C were 92% and 60% and for creatinine were 76% and 47%, respectively.

CONCLUSION

Plasma NGAL demonstrated a higher diagnostic value to detect kidney impairment in the early stages of CKD as compared to Scys C and Scr in hypertensive patients.

Systemic and renal hemodynamic effects of intra-arterial radiocontrast

Background

Decreased renal blood flow (RBF) and vasoconstriction are considered major mechanisms of contrast-induced acute kidney injury (CIAKI). To understand the severity and duration of such putative effects, we measured systemic and renal hemodynamics after intra-arterial radiocontrast administration. The subjects were six Merino ewes. The setting was a university-affiliated research institute. This is a randomized cross-over experimental study.

Methods

Transit-time flow probes were implanted on the pulmonary and left renal arteries 2 weeks before experimentation. We simulated percutaneous coronary intervention by administering five intra-arterial boluses of 0.5 mL/kg saline (control) or radiocontrast (iodixanol) to a total of 2.5 mL/kg over 1 h. Cardiac output (CO), heart rate, mean arterial pressure (MAP), RBF, renal vascular conductance (RVC), urine output (UO), creatinine clearance (CrCl), and fractional excretion of sodium (FENa) were measured.

Results

In the first 8 h after intra-arterial administration of radiocontrast, CO, total peripheral conductance (TPC), and heart rate (HR) increased compared with those after normal saline administration. Thereafter, CO and TPC were similar between the two groups, but HR remained higher with radiocontrast (p < 0.001). After a short (30 min) period of renal vasoconstriction with preserved RBF secondary to an associated increase in MAP, RBF and RVC showed an earlier and greater increase (vasodilatation) with radiocontrast (p < 0.001) and remained higher during the first 2 days. Radiocontrast initially increased urine output (p < 0.001) and FENa (p = 0.003). However, the overall daily urine output decreased in the radiocontrast-treated animals at 2 days (p < 0.001) and 3 days (p = 0.006). Creatinine clearance was not affected.

Conclusions

In healthy animals, intra-arterial radiocontrast increased RBF, induced renal vasodilatation, and caused a delayed period of oliguria. Our findings suggest that sustained reduction in RBF and renal vasoconstriction may not occur in normal large mammals after intra-arterial radiocontrast administration.

Neutrophil gelatinase-associated lipocalin as a marker of acute renal disease

PURPOSE OF REVIEW

Acute renal disease has major prognostic impact in hospitalized patients. Early diagnosis using renal function markers such as serum creatinine or urinary output and effective treatment are currently not possible. This review focuses on recent studies examining the biological characteristics and the diagnostic and prognostic value of a novel biomarker, neutrophil gelatinase-associated lipocalin (NGAL), in patients at risk for acute renal disease.

RECENT FINDINGS

NGAL levels increase early and proportional to the degree of renal injury in the urine and plasma. Here, we report the results of clinical studies where NGAL was measured in 325 patients with autoimmune and infectious diseases, those with cisplatin-associated nephrotoxicity, and more than 4000 patients at risk of acute kidney injury due to sepsis, cardiac surgery, exposure to contrast media, or after renal transplantation. Whenever renal damage occurred, as evidenced by histopathology or subsequent increase in serum creatinine levels, NGAL levels were higher than in patients without acute renal disease. An increase in NGAL substantially preceded clinical diagnosis of acute renal disease.

SUMMARY

NGAL fulfills many characteristics of an appropriate 'real-time' renal biomarker. The data on NGAL could justify re-assessment of the concept and definition of acute kidney injury.

Role of neutrophil gelatinase-associated lipocalin for early detection of acute kidney injury

Acute kidney injury (AKI) is characterized by abrupt or rapid decline of renal function and is usually associated with the development of serious complications as well as an independent risk of mortality in hospitalized patients. Emergency physicians play a critical role in recognizing early AKI, preventing iatrogenic injury, and reversing the course of AKI. Among the various available biomarkers for AKI, reliable and automated assay methods are commercially available for only cystatin-C and neutrophil gelatinase-associated lipocalin (NGAL). NGAL appears to be a promising marker for early detection of AKI and is likely to be adapted for wide-scale clinical use in patient management as a point-of-care test. Use of NGAL along with panel of other renal biomarkers can improve the rate of early detection of AKI. Large, multicenter studies demonstrate the association between biomarkers and hard end points such as need for renal replacement therapy (RRT), cardiovascular events, hospital stay, and death, independent of serum creatinine concentrations.

Urinary neutrophil gelatinase-associated lipocalin: a useful biomarker for tacrolimus-induced acute kidney injury in liver transplant patients

Tacrolimus is widely used as an immunosuppressant in liver transplantation, and tacrolimus-induced acute kidney injury (AKI) is a serious complication of liver transplantation. For early detection of AKI, various urinary biomarkers such as monocyte chemotactic protein-1, liver-type fatty acid-binding protein, interleukin-18, osteopontin, cystatin C, clusterin and neutrophil gelatinase-associated lipocalin (NGAL) have been identified. Here, we attempt to identify urinary biomarkers for the early detection of tacrolimus-induced AKI in liver transplant patients. Urine samples were collected from 31 patients after living-donor liver transplantation (LDLT). Twenty recipients developed tacrolimus-induced AKI. After the initiation of tacrolimus therapy, urine samples were collected on postoperative days 7, 14, and 21. In patients who experienced AKI during postoperative day 21, additional spot urine samples were collected on postoperative days 28, 35, 42, 49, and 58. The 8 healthy volunteers, whose renal and liver functions were normal, were asked to collect their blood and spot urine samples. The urinary levels of NGAL, monocyte chemotactic protein-1 and liver-type fatty acid-binding protein were significantly higher in patients with AKI than in those without, while those of interleukin-18, osteopontin, cystatin C and clusterin did not differ between the 2 groups. The area under the receiver operating characteristics curve of urinary NGAL was 0.876 (95% confidence interval, 0.800–0.951; P<0.0001), which was better than those of the other six urinary biomarkers. In addition, the urinary levels of NGAL at postoperative day 1 (p = 0.0446) and day 7 (p = 0.0006) can be a good predictive marker for tacrolimus-induced AKI within next 6 days, respectively. In conclusion, urinary NGAL is a sensitive biomarker for tacrolimus-induced AKI, and may help predict renal event caused by tacrolimus therapy in liver transplant patients.

Evaluation of the optimal neutrophil gelatinase-associated lipocalin value as a screening biomarker for urinary tract infections in children

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker in the detection of kidney injury. Early diagnosis of urinary tract infection (UTI), one of the most common infections in children, is important in order to avert long-term consequences. We assessed whether serum NGAL (sNGAL) or urine NGAL (uNGAL) would be reliable markers of UTI and evaluated the appropriate diagnostic cutoff value for the screening of UTI in children.

Methods

A total of 812 urine specimens and 323 serum samples, collected from pediatric patients, were analyzed. UTI was diagnosed on the basis of culture results and symptoms reported by the patients. NGAL values were measured by using ELISA.

Results

NGAL values were more elevated in the UTI cases than in the non-UTI cases, but the difference between the values were not statistically significant (P=0.190 for sNGAL and P=0.064 for uNGAL). The optimal diagnostic cutoff values of sNGAL and uNGAL for UTI screening were 65.25 ng/mL and 5.75 ng/mL, respectively.

Conclusions

We suggest that it is not appropriate to use NGAL as a marker for early diagnosis of UTI in children.

Pediatric acute kidney injury: A syndrome under paradigm shift

The recent standardization and validation of definitions of pediatric acute kidney injury (pAKI) has ignited new dimensions of pAKI epidemiology and its risk factors. pAKI causes increased morbidity and mortality in critically ill-children. Among the hospitalized patients incidence of pAKI ranges from 1% to 31%, while mortality ranges from 28% to 82%, presenting a broad range due to lack of uniformly acceptable pAKI definition. In addition, cumulative data regarding the progression of pAKI to chronic kidney disease in children is rising. Despite these alarming figures, treatment modalities have failed to deliver significantly. In this review, we will summarize the latest developments of pAKI and highlight important aspects of pAKI management.

Acute kidney injury after using contrast during cardiac catheterization in children with heart disease

Acute kidney injury (AKI) is closely associated with the mortality of hospitalized patients and long-term development of chronic kidney disease, especially in children. The purpose of our study was to assess the evidence of contrast-induced AKI after cardiac catheterization in children with heart disease and evaluate the clinical usefulness of candidate biomarkers in AKI. A total of 26 children undergoing cardiac catheterization due to various heart diseases were selected and urine and blood samples were taken at 0 hr, 6 hr, 24 hr, and 48 hr after cardiac catheterization. Until 48 hr after cardiac catheterization, there was no significant increase in serum creatinine level in all patients. Unlike urine kidney injury molecule-1, IL-18 and neutrophil gelatinase-associated lipocalin, urine liver-type fatty acid-binding protein (L-FABP) level showed biphasic pattern and the significant difference in the levels of urine L-FABP between 24 and 48 hr. We suggest that urine L-FABP can be one of the useful biomarkers to detect subclinical AKI developed by the contrast before cardiac surgery.

Biomarkers in cardiorenal syndromes

Cardiac and renal diseases often coexist and patients with cardiac and renal failure have high morbidity and mortality. Cardiorenal syndromes (CRSs) are disorders of the heart and kidneys whereby dysfunction in one organ may induce dysfunction in the other organ. Five subtypes of CRSs have been defined by the Acute Dialysis Quality Initiative Consensus Group. There is a need for early detection and monitoring of patients with CRSs. Biomarkers play a key role in the diagnosis and monitoring of acute myocardial infarction, chronic heart failure, and chronic kidney disease. In recent years, new biomarkers have been identified that may play a role in the early diagnosis of acute kidney injury. Herein, we review the use of serum and urine biomarkers in the diagnosis and management of CRSs. The established cardiac and renal biomarkers such as the cardiac troponins, natriuretic peptides, urine albumin, and creatinine, as well as the new renal biomarkers cystatin C and neutrophil gelatinase-associated lipocalin are reviewed in detail. The recent advances in assay methods, clinical studies, and recommendations in clinical guidelines are discussed. With advances in biomarker research, in future, perhaps a multimarker approach will become feasible to stratify the diagnosis of CRS for individualized treatment and prognosis.

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.

Emerging biomarkers and metabolomics for assessing toxic nephropathy and acute kidney injury (AKI) in neonatology

Identification of novel drug-induced toxic nephropathy and acute kidney injury (AKI) biomarkers has been designated as a top priority by the American Society of Nephrology. Increasing knowledge in the science of biology and medicine is leading to the discovery of still more new biomarkers and of their roles in molecular pathways triggered by physiological and pathological conditions. Concomitantly, the development of the so-called "omics" allows the progressive clinical utilization of a multitude of information, from those related to the human genome (genomics) and proteome (proteomics), including the emerging epigenomics, to those related to metabolites (metabolomics). In preterm newborns, one of the most important factors causing the pathogenesis and the progression of AKI is the interaction between the individual genetic code, the environment, the gestational age, and the disease. By analyzing a small urine sample, metabolomics allows to identify instantly any change in phenotype, including changes due to genetic modifications. The role of liquid chromatography-mass spectrometry (LC-MS), proton nuclear magnetic resonance (1H NMR), and other emerging technologies is strategic, contributing basically to the sudden development of new biochemical and molecular tests. Urine neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (KIM-1) are closely correlated with the severity of kidney injury, representing noninvasive sensitive surrogate biomarkers for diagnosing, monitoring, and quantifying kidney damage. To become routine tests, uNGAL and KIM-1 should be carefully tested in multicenter clinical trials and should be measured in biological fluids by robust, standardized analytical methods.

Novel biomarkers for contrast-induced acute kidney injury

Biomarkers of acute kidney injury (AKI) may be classified in 2 groups: (1) those representing changes in renal function (e.g., serum creatinine or cystatin C and urine flow rate) and (2) those reflecting kidney damage (e.g., kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18, etc.). According to these 2 fundamental criteria, 4 subgroups have been proposed: (1) no marker change; (2) damage alone; (3) functional change alone; and (4) combined damage and functional change. Therefore, a new category of patients with “subclinical AKI” (that is, an increase in damage markers alone without simultaneous loss of kidney function) has been identified. This condition has been associated with higher risk of adverse outcomes (including renal replacement therapy and mortality) at followup. The ability to measure these physiological variables may lead to identification of patients at risk for AKI and early diagnosis of AKI and may lead to variables, which may inform therapeutic decisions.

Serum neutrophil gelatinase associated lipocalin (NGAL) and cystatin C as early predictors of contrast-induced acute kidney injury in patients undergoing percutaneous coronary intervention

BACKGROUND

Contrast-induced acute kidney injury (AKI) is diagnosed by estimating serum creatinine at 48-72h after diagnostic or interventional coronary angiography. It is too late for an early intervention. Neutrophil gelatinase associated lipocalin (NGAL) and cystatin C are novel markers of AKI. We determined the optimum cut-off level of NGAL and cystatin C in early diagnosis and prediction of AKI in patients undergoing coronary angiography followed by angioplasty.

METHODS

In a nested case control study, serum NGAL, cystatin C by ELISA and serum creatinine by Jaffe's kinetic method were estimated at 0, 4, 24 and 48h of coronary angiography followed by angioplasty in 30 cases who developed contrast-induced AKI and 30 subjects who did not develop AKI. eGFR was estimated for both cases and controls by the MDRD equation. ROC was used to determine the optimum cut-off.

RESULTS

Serum NGAL increased sharply at 4h after the procedure and then gradually declined to near normal level at 48h in AKI cases. The rise in cystatin C peaked at 24h and then declined but remained high till 48h. In controls, they remained static. The optimum cut-off of serum NGAL and cystatin C was 155.2ng/ml and 0.517mg/l respectively at 4h and 89.5ng/ml and 0.99mg/l respectively at 24h of angiography. Odds ratio for hypertensives to develop AKI was 3.57 (CI: 1.2-11.1, p=0.03).

CONCLUSION

Serum NGAL and cystatin C may act as early markers of contrast-induced AKI in patients undergoing percutaneous coronary intervention. Patients with hypertension are susceptible to develop contrast-induced AKI.

The effects of dexmedetomidine on early stage renal functions in pediatric patients undergoing cardiac angiography using non-ionic contrast media: a double-blind, randomized clinical trial

BACKGROUND

In this study we aimed to investigate the effects of dexmedetomidine on early stage renal function in pediatric patients undergoing cardiac angiography.

METHODS

60 pediatric patients between 6 and 72 months of age undergoing cardiac angiography were included in the study. Patients were divided into two groups. The patients in both groups were administered 1 mg · kg(-1) ketamine, 1 mg · kg(-1) propofol as bolus and followed by 1 mg · kg(-1) · h(-1) ketamine and 50 μg · kg(-1) · min(-1) propofol infusion. Additionally, a loading dose of 1 μg · kg(-1) dexmedetomidine given over 10 min followed by 0.5 μg · kg(-1) · h(-1) dexmedetomidine infusion to patients in group D. The patients were evaluated for NGAL, creatinine, renin, endothelin-1, TAS and TOS blood levels before the procedure and 6th and 24th h after the procedure. pRIFLE criteria were used to define CIN and its incidence in the study.

RESULTS

According to pRIFLE criteria contrast-induced acute kidney injury developed in 3 (10%) of the patients in group D and 11 (36.7%) of the patients in group C (P = 0.029, risk ratio = 0.27; 95% CI: 0.084-0.88). In patients who developed CIN, Endothelin-1 levels in groups C and D were significantly higher than baseline levels at 6th, 24th and 6th h, respectively. Renin levels were significantly increased at 6th and 24 th( ) h in patients with CIN in both groups.

CONCLUSIONS

Dexmedetomidine may be beneficial in protecting against contrast-induced nephropathy during pediatric angiography by preventing the elevation of vasoconstrictor agents such as plasma endothelin-1 and renin.

Neutrophil gelatinase-associated lipocalin (NGAL): a promising biomarker of contrast-induced nephropathy after computed tomography

Contrast-induced nephropathy (CIN) is a common cause of hospital-acquired acute kidney injury (AKI) and a source of significantly increased short- and long-term mortality. Studies of large cohorts have revealed that more than half of these cases are in subjects undergoing cardiac catheterization and intra-arterial coronary angiography, and nearly a third follow computed tomography (CT) scans. Neutrophil gelatinase-associated lipocalin (NGAL) represents an early predictive troponin-like biomarker for AKI. Its role in the timely diagnosis of CIN has already been examined in adults and children undergoing coronary angiography and a meta-analysis revealed a very good performance of plasma or urine NGAL in the prediction of CIN. Much of these data have been extrapolated to patients receiving intravenous (IV) contrast agent for CT scans, although major differences in patient populations, contrast volume administered and intra-procedural complications between the two settings exist. In this context, a recent prospective study by our group evaluated plasma NGAL, measured using standardized Τriage® NGAL test (Biosite Incorporated, San Diego, CA) at baseline and 6-h post-procedure, for early detection of CIN among hospitalized patients undergoing elective contrast-enhanced CT. CIN, defined as an increase in serum creatinine (SCr) of >25% or >0.5 mg/dL from baseline within 48-h post-procedure, was found in 8.51% of subjects. In contrast, significant elevation of plasma NGAL was found at 6-h post-procedure with excellent performance characteristics. This review presents the current status of NGAL in the prediction of CIN after IV contrast administration among hospitalized patients undergoing elective contrast-enhanced CT.

Renal neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 expression in children with acute kidney injury and Henoch-Schönlein purpura nephritis

The aim of this study was to investigate the expression of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in the serum, urine and renal tissues of children with acute kidney injury (AKI) and Henoch-Schönlein purpura nephritis (A-on-C). A prospective single-center evaluation of the serum, urine and renal NGAL and KIM-1 levels was performed in a cohort of children. Blood and 5-ml urine samples were collected from each patient for the analysis of NGAL and KIM-1 levels using an ELISA. In addition, the expression of NGAL and KIM-1 in the kidney was examined using immunohistochemistry in patients with A-on-C and HSPN. The expression of serum cystatin C, β2-macroglobulin and serum creatinine (SCr), as well as urinary β2-MG and SCr, in the patients with A-on-C was significantly higher than that of HSPN patients, and the expression of NGAL and KIM-1 in the serum and urine in the A-on-C patients was also significantly higher than that of HSPN patients. However, there were no significant differences in the urine protein levels between the two groups. NGAL and KIM-1 were expressed in renal tubular epithelial cells, and the expression of NGAL and KIM-1 in the A-on-C patients was significantly higher than that in HSPN patients. In addition, the urine NGAL and KIM-1 levels were negatively correlated with glomerular filtration rate, but there was no significant correlation between the urine NGAL/KIM-1 and urine protein levels. The changes in serum and urine NGAL and KIM-1 levels may be applied to the diagnosis of A-on-C.

Hemodynamic and tubular changes induced by contrast media

The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI.

Contrast media induced nephropathy: a literature review of the available evidence and recommendations for practice

BACKGROUND

Contrast media induced nephropathy (CIN) is a sudden compromise of renal function 24-48 h after administering contrast medium during a CT scan or angiography. CIN accounts for 10% of hospital acquired renal failure and is ranked the third cause of acquiring this condition. Identifying patients at risk through proper screening can reduce the occurrence of this condition.

PURPOSE

This review paper aims to critique current evidence, provide a better understanding of CIN, inform nursing practice and make recommendations for bedside nurses and future research.

METHOD

An integrative review of the literature was made using the key terms: "contrast media", "nephritis", "nephropathy", "contrast media induced nephropathy scores", "acute kidney failure", "acute renal failure" and "acute kidney injury". MeSH key terms used in some databases were: "prevention and control", "acute kidney failure" and "treatment". Databases searched included Medline, CINAHL and Academic Search Complete, and references of relevant articles were also assessed. The search included all articles between the years 2000 and 2013.

RESULTS

Sixty-seven articles were obtained as a result of the search, including RCTs, systematic reviews, and retrospective studies.

CONCLUSION

Contrast media induced nephropathy is an iatrogenic complication occurring secondary to diagnostic or therapeutic procedures. At times it is unavoidable but a systematic method of risk assessment should be adopted to identify high risk patients for tailored and targeted approaches to management interventions.

CLINICAL IMPLICATIONS

As the use of contrast media is increasing for diagnostic purposes, it is important that nurses be aware of the risk factors for CIN, identify and monitor high risk patients to prevent deterioration in renal function when possible.

Neutrophil gelatinase-associated lipocalin in dogs with naturally occurring renal diseases

Background

Neutrophil gelatinase–associated lipocalin (NGAL) is released from renal tubular cells after injury and serves in humans as a real‐time indicator of active kidney damage, including acute kidney injury (AKI) and chronic kidney disease (CKD). However, NGAL concentrations in dogs with naturally occurring AKI or CKD rarely have been explored in detail.

Hypothesis/Objectives

The goal of this study was to evaluate whether NGAL can serve as a useful biomarker in dogs with naturally occurring renal disease.

Animals

Client‐owned dogs with renal disease (57) and control dogs without any disease (12) were examined.

Methods

Serum NGAL (sNGAL) and urine NGAL (uNGAL) concentrations were measured in each animal by a newly developed ELISA system. Demographic, hematologic, and serum biochemical data were recorded. Survival attributable to AKI and CKD was evaluated at 30 days and 90 days, respectively.

Results

Serum and urine NGAL concentrations in azotemic dogs were significantly higher than in nonazotemic dogs and were highly correlated with serum creatinine concentration (P < .05). Among CKD dogs, death was associated with significantly higher sNGAL and uNGAL concentrations compared with survivors. Receiver‐operating characteristic curve (ROC) analysis showed that sNGAL was better than serum creatinine concentration when predicting clinical outcomes for CKD dogs (P < .05). The best cutoff point for sNGAL was 50.6 ng/mL, which gave a sensitivity and a specificity of 76.9 and 100%, respectively. Furthermore, dogs that had higher concentrations of sNGAL survived for a significantly shorter time.

Conclusion

sNGAL is a useful prognostic marker when evaluating dogs with CKD.

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.

Urinary Neutrophil Gelatinase-Associated Lipocalin predicts the severity of contrast-induced acute kidney injury in chronic kidney disease patients undergoing elective coronary procedures

Background

Contrast-induced acute kidney injury (CI-AKI) particularly in high risk patients with chronic kidney disease (CKD), increases morbidity and mortality. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein excreted by the kidney during AKI. There are no urine (u) NGAL data as an early CI-AKI marker in CKD patients undergoing coronary procedures.

Methods

This prospective study enrolled 130 patients with estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m² undergoing elective coronary procedures. Serial urine samples, obtained at baseline and 3, 6, 12, 18, and 24 h post contrast administration were analyzed by NGAL ELISA kit. AKI was defined as an increase in serum creatinine (SCr) of ≥ 0.3 mg/dl or ≥ 1.5 times baseline SCr within 48 h per 2012 KDIGO guidelines. Receiver operator characteristic curve analyses identified optimal uNGAL and delta of uNGAL values for diagnosing CI-AKI.

Results

The uNGAL was significantly and inverse correlated with eGFR (R = 0.25, P < 0.005). CI-AKI developed in 16/130 (12.31%) patients: 13 and 3 in CI-AKI stages I and II, respectively. uNGAL and delta of uNGAL were significantly higher in the CI-AKI group when compared with the No CI-AKI group (P < 0.05). The best uNGAL cut-off for optimal sensitivity 94%, specificity 78%, and area under the curve 0.84 for predicting CI-AKI was 117 ng/mL at 6 h, respectively. Corresponding values for predicting CI-AKI stage II were 100%, 87% and 0.9 when using an uNGAL of 264 ng/mL at 6 h.

Conclusions

Monitoring of uNGAL levels not only provide the early detecting CI-AKI but also predict the severity of CI-AKI in CKD patients undergoing elective coronary procedures.

Why is diabetes mellitus a risk factor for contrast-induced nephropathy?

Contrast-induced nephropathy (CIN) remains a leading cause of iatrogenic acute kidney injury, as the usage of contrast media for imaging and intravascular intervention keeps expanding. Diabetes is an important predisposing factor for CIN, particularly in patients with renal functional impairment. Renal hypoxia, combined with the generation of reactive oxygen species, plays a central role in the pathogenesis of CIN, and the diabetic kidney is particularly susceptible to intensified hypoxic and oxidative stress following the administration of contrast media. The pathophysiology of this vulnerability is complex and involves various mechanisms, including a priori enhanced tubular transport activity, oxygen consumption, and the generation of reactive oxygen species. The regulation of vascular tone and peritubular blood flow may also be altered, particularly due to defective nitrovasodilation, enhanced endothelin production, and a particular hyperresponsiveness to adenosine-related vasoconstriction. In addition, micro- and macrovascular diseases and chronic tubulointerstitial changes further compromise regional oxygen delivery, and renal antioxidant capacity might be hampered. A better understanding of these mechanisms and their control in the diabetic patient may initiate novel strategies in the prevention of contrast nephropathy in these susceptible patients.

Serum neutrophil gelatinase-associated lipocalin (NGAL) in patients with Shiga toxin mediated haemolytic uraemic syndrome (STEC-HUS)

Neutrophil gelatinase-associated lipocalin (NGAL) is an increasingly used biomarker for acute kidney injury (AKI). Its utility in adult patients with AKI caused by Shiga toxin producing Escherichia coli infection (STEC)-associated haemolytic-uraemic syndrome (HUS), remains unknown. We aimed to evaluate the prognostic value of serum NGAL admission levels for the need of renal replacement therapy (RRT) in STEC-HUS patients. Baseline serum NGAL was determined by ELISA in 39 patients with STEC O104:H4 infection cared for at Hannover Medical School during the outbreak in Germany through May-July 2011. Patients with HUS had significant higher NGAL levels than healthy controls (379 [248 - 540] vs 39.0 [37.5-45] ng/ml, p < 0.0001). During clinical course, 24 patients required RRT at a median of five days after admission. NGAL admission levels were higher in patients requiring RRT (476 (344-639) ng/ml) compared to patients not requiring RRT (257 (196-426) ng/ml; p < 0.001). Unadjusted and adjusted logistic regression analyses identified NGAL as an independent predictor for need of RRT. In a combined model, a joint NGAL/AKIN classification approach improved the predictive accuracy for need of RRT over either marker alone. The combined categorical cut-off point defined by NGAL ≥ 330 ng/ml and presence of AKI (AKIN ≥ I) on admission correctly identified 20 of 24 patients requiring RRT (odds ratio 20, sensitivity 83%, specificity 80%, negative predictive value 75%, positive predictive value 87%). NGAL may serve as an adjunctive tool to improve risk prediction in patients with STEC-HUS.

Repulsive guidance cue semaphorin 3A in urine predicts the progression of acute kidney injury in adult patients from a mixed intensive care unit

BACKGROUNDS

Predicting the development of acute kidney injury (AKI) in the critical care setting is challenging. Although several biomarkers showed somewhat satisfactory performance for detecting established AKI even in a heterogeneous disease-oriented population, identification of new biomarkers that predict the development of AKI accurately is urgently required.

METHODS

A single-center prospective observational cohort study was undertaken to evaluate for the first time the reliability of the newly identified biomarker semaphorin 3A for AKI diagnosis in heterogeneous intensive care unit populations. In addition to five urinary biomarkers of L-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL), IL-18, albumin and N-acetyl-β-d-glucosaminidase (NAG), urinary semaphorin 3A was measured at intensive care unit (ICU) admission.

RESULTS AND CONCLUSION

Three hundred thirty-nine critically ill adult patients were recruited for this study. Among them, 131 patients (39%) were diagnosed with AKI by the RIFLE criteria and 66 patients were diagnosed as AKI at post-ICU admission (later-onset AKI). Eighty-four AKI patients showed worsening severity during 1 week observation (AKI progression). Although L-FABP, NGAL and IL-18 showed significantly higher area under the curve (AUC)-receiver operating characteristic (ROC) values than semaphorin 3A in detecting established AKI, semaphorin 3A was able to detect later-onset AKI and AKI progression with similar AUC-ROC values compared with the other five biomarkers [AUC-ROC (95% CI) for established AKI 0.64 (0.56-0.71), later-onset AKI 0.71 (0.64-0.78), AKI progression 0.71 (0.64-0.77)]. Urinary semaphorin 3A was not increased in non-progressive established AKI, while the other biomarkers were elevated regardless of further progression. Finally, sepsis did not have any impact on semaphorin 3A while the other urinary biomarkers were increased with sepsis. Semaphorin 3A is a new biomarker of AKI which may have a distinct predictive use for AKI progression when compared with other AKI biomarkers.

Biomarkers in the assessment of acute and chronic kidney diseases in the dog and cat

In both human and veterinary medicine, diagnosing and staging renal disease can be difficult. Measurement of glomerular filtration rate is considered the gold standard for assessing renal function but methods for its assessment can be technically challenging and impractical. The main parameters used to diagnose acute and chronic kidney disease include circulating creatinine and urea concentrations, and urine-specific gravity. However, these parameters can be insensitive. Therefore, there is a need for better methods to diagnose and monitor patients with renal disease. The use of renal biomarkers is increasing in human and veterinary medicine for the diagnosis and monitoring of acute and chronic kidney diseases. An ideal biomarker would identify site and severity of injury, and correlate with renal function, among other qualities. This article will review the advantages and limitations of renal biomarkers that have been used in dogs and cats, as well as some markers used in humans that may be adapted for veterinary use. In the future, measuring a combination of biomarkers will likely be a useful approach in the diagnosis of kidney disorders.

Neutrophil gelatinase-associated lipocalin

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a major clinical problem in hospitalized patients. Effective treatment and early diagnosis of this syndrome are not currently available. This review focuses on recent studies examining the biological characteristics and the diagnostic and prognostic value of a novel biomarker--neutrophil gelatinase-associated lipocalin (NGAL)--in the two major patient populations at risk for AKI.

RECENT FINDINGS

NGAL is one of the most intensively investigated novel renal biomarkers with promising data from animal experiments and clinical studies comprising more than 3500 cardiac surgery or critically ill patients. NGAL was discovered using unbiased transcriptomic approaches and was identified as the gene with the earliest and highest rise of mRNA and protein concentration in renal tissue, urine and plasma following various renal insults. Within minutes to a few hours after a renal insult, NGAL is induced in and released from the injured distal nephron. The average sensitivity and specificity of NGAL--measured 1-3 days prior to current AKI consensus diagnosis--was 76 and 77% respectively for cardiac surgery patients and 73 and 80% respectively for patients admitted to the intensive care unit.

SUMMARY

NGAL appears to fulfill many characteristics of an appropriate 'real-time' biomarker for AKI detection.

Neutrophil gelatinase associated lipocalin as an indicator of acute kidney injury and inflammation in burned children

INTRODUCTION

Neutrophil gelatinase associated lipocalin (NGAL) is a novel predictor of acute kidney injury (AKI), which increases with inflammation. We aimed to assess whether serum NGAL (SNGAL) and urine NGAL (UNGAL) can predict AKI in burned children.

METHODS

Patients were referred within the 12 h of burn to our center. Serum samples for SNGAL, C-reactive protein (CRP), procalcitonin (PCT) and urine for UNGAL, microalbumine (Umalb), creatinine (Ucr) were obtained at both admission and the 5th day after burn. Blood urea nitrogen (BUN) and serum creatinine (Scr) were examined daily.

RESULTS

Twenty-two subjects were enrolled and six (27.2%) of them developed AKI within the 48 h of injury. Burn size and abbreviated burn severity index (ABSI) were significantly increased in patients with AKI. CRP, PCT, SNGAL and UNGAL levels at admission and day 5 were significantly higher in patients with AKI than in those without AKI and controls. Scr was not significant between AKI and non-AKI groups at hospital days 1 and 5. A SNGAL level of 315 ng/ml and a UNGAL level of 100 ng/ml were determined as predictive cut-off values of AKI at admission (sensitivity and specificity: 71.4%, 83.3% and 93.3%, 93.7%, respectively). SNGAL and UNGAL were positively correlated with CRP, PCT, ABSI and Umalb/Ucr.

CONCLUSION

SNGAL and UNGAL are good early predictors of AKI in children with severe burn. NGAL might reflect the severity of burn insult and also could be used as an indicator of inflammation in burn children.

Radiographic contrast-media-induced acute kidney injury: pathophysiology and prophylactic strategies

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topics in cardiovascular medicine. With increasing number of contrast-media- (CM-) enhanced imaging studies being performed and growing octogenarian population with significant comorbidities, incidence of CI-AKI remains high. In this review, pathophysiology of CI-AKI, its relationship with different types of CM, role of serum and urinary biomarkers for diagnosing CI-AKI, and various prophylactic strategies used for nephroprotection against CI-AKI are discussed in detail.