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

Intravenous versus oral hydration to reduce the risk of postcontrast acute kidney injury after intravenous contrast-enhanced CT in patients with severe chronic kidney disease (ENRICH): a study protocol for a single-centre, parallel-group, open-labelled non-inferiority randomised controlled trial in Denmark

INTRODUCTION

Contrast-enhanced CT (CECT) is widely used for diagnostic purposes. The use of contrast medium carries a risk for postcontrast acute kidney injury (PC-AKI), especially in patients with AKI or chronic kidney disease (CKD). Current guidelines recommend prophylactic intravenous hydration to prevent PC-AKI in high-risk patients. Oral hydration is non-inferior to intravenous hydration in patients with moderate CKD, but it has not been evaluated in high-risk patients.

METHODS AND ANALYSIS

The ENRICH trial will enrol 254 patients with estimated glomerular filtration rate ≤30 mL/min/1.73 m2 undergoing intravenous CECT, who are block randomised (2-4-2) with stratification for CKD stage, diabetes status, and indication for referral to prophylactic treatment with oral or intravenous hydration. PC-AKI is defined as an absolute increase in SCr of >0.3 mg/dL or >1.5 from baseline at 2-5 days. Renal function will also be evaluated <90 days, <7 days and 1-3 days before intravenous CECT, and 25-40 days after intravenous CECT. Secondary outcomes include dialysis, renal adverse events, hospitalisation due to hydration-related or contrast-related sequelae, and all-cause mortality ≤30 days postcontrast. Pre- and postcontrast plasma and urinary biomarkers will be evaluated for diagnostic and prognostic accuracy of the primary and secondary outcomes.

ETHICS AND DISSEMINATION

Oral hydration is patient-friendly and less costly compared with intravenous hydration. If oral hydration is non-inferior to intravenous hydration in high-risk patients, it could be implemented as new hydration strategy, which will facilitate the clinical diagnosing of elective patients with severe CKD without unnecessary resource utilisation. The protocol is approved by the Regional Scientific Ethical Committee for Southern Denmark (S-20210126), and the Data Protection Agency (21/66779). The study is conducted in accordance with the Declaration of Helsinki. Positive as well as negative findings will be reported in international peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05283512.

Lipocalin-2 as a biomarker for diabetic nephropathy

Diabetes is a major global public health issue. The prevalence of type 1 diabetes is comparatively static, as hereditary and genetic causes are involved, while type 2 diabetes (T2D) prevalence is increasing day by day. T2D is associated with chronic complications, including diabetic neuropathy (DN), nephropathy, retinopathy, and other complications like diabetic foot. DN is the main complication of both types of diabetes. DN can be diagnosed by routine laboratory tests, microalbuminuria > 300 mg/24 h, and a gradual decrease in glomerular filtration rate. As the appearance of microalbuminuria is a late manifestation, an early marker for renal damage is needed. Lipocalin-2, also known as neutrophil gelatinase-associated lipocalin (NGAL), is a small protein purified from neutrophil granules and a good marker for kidney disease. NGAL is a transporter protein responsible for many physiological processes, such as inflammation, generation of the immune response, and metabolic homeostasis. NGAL has been reported to depict the early changes in renal damage when urine microalbumin is still undetecable. Therefore, elucidating the role of NGAL in detecting DN and understanding its mechanism can help establish it as a potential early marker for DN.

Risk factors for acute kidney injury in vancomycin and piperacillin/tazobactam combination therapy: A retrospective study

INTRODUCTION

Combined use of vancomycin (VCM) and piperacillin/tazobactam (PIPC/TAZ) has been reported to increase the incidence of acute kidney injury (AKI). However, the risk factors associated with AKI after VCM and PIPC/TAZ (VPT) administration have not yet been identified. Therefore, we retrospectively assessed patients treated with VPT to investigate the risk factors for AKI development.

METHODS

The study involved patients who were treated with VPT from January 1, 2016 to March 31, 2020. The patients were divided into the AKI or non-AKI group. The clinical characteristics of patients and antimicrobial therapy were compared between the groups. Their association with AKI risk was evaluated using multivariate logistic regression analysis.

RESULTS

In total, 182 patients were included, with 118 in the non-AKI group and 64 in the AKI group. Therefore, the incidence of AKI was 35.2 %. The initiation of VPT combination therapy on the same day and concomitant use of vasopressors were associated with an increased risk of AKI (odds ratio [OR] 2.55, 95 % confidential interval [CI] 1.20-5.44 and OR 3.22, 95 % CI 1.31-7.89, respectively).

CONCLUSION

Our findings suggest that the concomitant use of vasopressors and initiating VPT combination therapy on the same day are likely risk factors for AKI development.

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.

Laboratory Predictors of Contrast-Induced Nephropathy After Neurointervention: A Prospective 3-Year Observational Study

OBJECTIVE

The purpose of this study was to assess the natural course of contrast-induced nephropathy (CIN) and to determine the predictive abilities of preprocedural high-sensitivity C-reactive protein (hs-CRP) and urine neutrophil gelatinase-associated lipocalin for CIN after neurointervention procedures.

METHODS

We prospectively enrolled 176 patients who underwent an elective neurointervention procedure (diagnostic angiography or endovascular surgery). CIN was defined as an increase in serum creatinine of more than 0.5 mg/dL or an increase of at least 25% from the baseline value within 48 hours of contrast media exposure. The predictive value of hs-CRP and serial urine NGAL (baseline, 6, 24, and 48 hours) for the risk of CIN was assessed using multivariate logistic regression.

RESULTS

CIN occurred in 17 patients (9.46%). Multivariate analysis revealed that the CIN incidence was significantly associated with high baseline hs-CRP. All patients with CIN had creatinine return to baseline levels within 7 days. No patients required dialysis or suffered permanent sequelae as a result of a creatinine increase. During the 3-year follow-up period, no cerebro- or cardiovascular events occurred in the CIN group. However, 3 patients in the non-CIN group suffered a vascular event. One was a myocardial infarction, and 2 were ischemic strokes.

CONCLUSIONS

The incidence of CIN after neurointervention procedures was relatively high (9.46%). The natural course of CIN was favorable, however, and did not affect cerebrovascular events. Additionally, patients with CIN typically recovered with supportive care within 7 days. Elevated preprocedural hs-CRP levels (>5 mg/dL) were a significant and independent predictor of CIN after neurointervention procedures.

Optimal cut points of plasma and urine neutrophil gelatinase-associated lipocalin for the prediction of acute kidney injury among critically ill adults: retrospective determination and clinical validation of a prospective multicentre study

OBJECTIVES

To determine the optimal threshold of blood and urine neutrophil gelatinase-associated lipocalin (NGAL) to predict moderate to severe acute kidney injury (AKI) and persistent moderate to severe AKI lasting at least 48 consecutive hours, as defined by an adjudication panel.

METHODS

A multicentre prospective observational study enrolled intensive care unit (ICU) patients and recorded daily ethylenediaminetetraacetic acid (EDTA) plasma, heparin plasma and urine NGAL. We used natural log-transformed NGAL in a logistic regression model to predict stage 2/3 AKI (defined by Kidney Disease International Global Organization). We performed the same analysis using the NGAL value at the start of persistent stage 2/3 AKI.

RESULTS

Of 245 subjects, 33 (13.5%) developed stage 2/3 AKI and 25 (10.2%) developed persistent stage 2/3 AKI. Predicting stage 2/3 AKI revealed the optimal NGAL cutoffs in EDTA plasma (142.0 ng/mL), heparin plasma (148.3 ng/mL) and urine (78.0 ng/mL) and yielded the following decision statistics: sensitivity (SN)=78.8%, specificity (SP)=73.0%, positive predictive value (PPV)=31.3%, negative predictive value (NPV)=95.7%, diagnostic accuracy (DA)=73.8% (EDTA plasma); SN=72.7%, SP=73.8%, PPV=30.4%, NPV=94.5%, DA=73.7% (heparin plasma); SN=69.7%, SP=76.8%, PPV=32.9%, NPV=94%, DA=75.8% (urine). The optimal NGAL cutoffs to predict persistent stage 2/3 AKI were similar: 148.3 ng/mL (EDTA plasma), 169.6 ng/mL (heparin plasma) and 79.0 ng/mL (urine) yielding: SN=84.0%, SP=73.5%, PPV=26.6%, NPV=97.6, DA=74.6% (EDTA plasma), SN=84%, SP=76.1%, PPV=26.8%, NPV=96.5%, DA=76.1% (heparin plasma) and SN=75%, SP=75.8%, PPV=26.1, NPV=96.4%, DA=75.7% (urine).

CONCLUSION

Blood and urine NGAL predicted stage 2/3 AKI, as well as persistent 2/3 AKI in the ICU with acceptable decision statistics using a single cut point in each type of specimen.

Histopathological Evaluation of Contrast-Induced Acute Kidney Injury Rodent Models

Contrast-induced acute kidney injury (CI-AKI) can occur in 3–25% of patients receiving radiocontrast material (RCM) despite appropriate preventive measures. Often patients with an atherosclerotic vasculature have to receive large doses of RCM. Thus, animal studies to uncover the exact pathomechanism of CI-AKI are needed. Sensitive and specific histologic end-points are lacking; thus in the present review we summarize the histologic appearance of different rodent models of CI-AKI. Single injection of RCM causes overt renal damage only in rabbits. Rats and mice need an additional insult to the kidney to establish a clinically manifest CI-AKI. In this review we demonstrate that the concentrating ability of the kidney may be responsible for species differences in sensitivity to CI-AKI. The most commonly held theory about the pathomechanism of CI-AKI is tubular cell injury due to medullary hypoxia. Thus, the most common additional insult in rats and mice is some kind of ischemia. The histologic appearance is tubular epithelial cell (TEC) damage; however severe TEC damage is only seen if RCM is combined by additional ischemia. TEC vacuolization is the first sign of CI-AKI, as it is a consequence of RCM pinocytosis and lysosomal fusion; however it is not sensitive as it does not correlate with renal function and is not specific as other forms of TEC damage also cause vacuolization. In conclusion, histopathology alone is insufficient and functional parameters and molecular biomarkers are needed to closely monitor CI-AKI in rodent experiments.

Is plasma neutrophil gelatinase-associated lipocalin a predictive biomarker for acute kidney injury in sepsis patients? A systematic review and meta-analysis

PURPOSE

Neutrophil gelatinase-associated lipocalin (NGAL) is a useful biomarker for early diagnosis of acute kidney injury (AKI). However, the diagnostic value of NGAL for predicting AKI in sepsis patients is unclear.

METHODS

MEDLINE, EMBASE, and Cochrane Library databases were searched to identify research publications.

RESULTS

Twelve studies from 9 countries including a total of 1582 patients, of whom 315 (19.9%) developed AKI, were included in the study; plasma NGAL levels were significantly higher in adult sepsis patients with AKI than in those without AKI (mean difference, 274.65; 95% confidence interval [CI], 106.16-443.15; I(2) = 94%). Urine NGAL levels were not significantly different. The diagnostic odds ratio of plasma NGAL for predicting AKI in sepsis patients was 6.64 (95% CI, 3.80-11.58). The diagnostic accuracy of plasma NGAL was 0.881 (95% CI, 0.819-0.923) for sensitivity, 0.474 (95% CI, 0.367-0.582) for specificity, 0.216 (95% CI, 0.177-0.261) for positive predictive value and 0.965 (95% CI, 0.945-0.977) for negative predictive value.

CONCLUSION

Plasma NGAL has a high sensitivity and a high negative predictive value for detection of AKI in adult sepsis patients. However, its low specificity and low positive predictive value could limit its clinical utility. The usefulness of urine NGAL was not revealed in this study.

The potential of lipocalin-2/NGAL as biomarker for inflammatory and metabolic diseases

Lipocalin-2 (LCN2), also known as neutrophil gelatinase-associated lipocalin (NGAL), is a secreted glycoprotein that belongs to a group of transporters of small lipophilic molecules in circulation. LCN2 has been recently characterized as an adipose-derived cytokine. This adipokine is believed to bind small substances, such as steroids and lipopolysaccharides, and has been reported to have roles in the induction of apoptosis in hematopoietic cells, transport of fatty acids and iron, modulation of inflammation, and metabolic homeostasis. Recently, LCN2 has emerged as a useful biomarker and rheumatic diseases. This review provides an overview of LCN2 in inflammation, immunity, and metabolism.

Serum neutrophil gelatinase-associated lipocalin is associated with cardiovascular events in patients with chronic kidney disease

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a member of the lipocalin family best known as a novel and early marker of acute kidney injury (AKI). Recent data suggest that NGQueryAL is not only a marker of AKI, but also an important player in the vascular remodeling, atherosclerotic plaque stability and thrombus formation. We conducted this study to investigate the association of serum NGAL levels with fatal and composite (fatal and non-fatal) cardiovascular events (CVE) in a cohort of patients with stage 1-5 CKD.

METHODS

This was an observational cohort study in which serum NGAL was obtained from 298 CKD (stages 1-5) patients. Fatal and composite CVE were recorded for a median 41 months. We examined alteration of serum NGAL through CKD groups as well as association with inflammatory markers. We also performed a Cox regression analysis to determine the association of NGAL with predefined clinical outcomes.

RESULTS

The median value of NGAL was 50.5 ng/mL (IR 47.6-54.9 ng/mL), and higher NGAL values were recorded in diabetic patients. In a multiple linear regression model, including all univariate associates of NGAL, only log eGFR, log hs-CRP and log HDL cholesterol maintained an independent association with log NGAL. During the observational period, 30 patients died due to cardiovascular causes and 69 non-fatal CVE were registered. In the fully adjusted model, we observed a 2.08-fold increase in the risk of fatal CVE and a 1.50-fold increase in the risk of fatal and non-fatal CVE for each increment of 1 SD in log NGAL values.

CONCLUSIONS

This is the first study that shows that serum NGAL is associated with cardiovascular events (fatal and non-fatal) in patients with CKD, independently of traditional risk factors, renal function and inflammation.

Contrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) represents an important adverse effect of contrast media (CM) administration. Contrast-induced nephropathy is associated with prolonged hospitalization as well as increased cardiovascular morbidity, renal morbidity, and all-cause mortality. Several risk factors may predict CIN incidence, and various scores and ratios have been proposed to identify high-risk patients. Novel biomarkers may provide an earlier diagnosis of CIN. A multifactorial approach is required for CIN prevention including hydration, administration of low- or iso-osmolar CM, minimizing CM volume, and statin administration. Renal function may deteriorate after CM administration, even in the absence of CIN. Therefore, this deterioration may not be an “all or none” phenomenon; it may well occur in many patients receiving CM, with/without CIN, and may prove to be an underestimated risk factor. Patients should be followed up for longer periods as outpatients after CM exposure to assess kidney function and predict subsequent increased morbidity and mortality.