Urinary neutrophil gelatinase-associated lipocalin as a marker of acute kidney injury after orthotopic liver transplantation

Disposable label-free electrochemical immunosensor based on gold nanoparticles-Prussian blue for neutrophil gelatinase-associated lipocalin detection in urine samples

Neutrophil gelatinase-associated lipocalin (NGAL) is a remarkable biomarker for assessing acute kidney injury. In this study, we developed a novel label-free NGAL electrochemical immunosensor based on gold nanoparticles (AuNPs) and Prussian blue (PB) without an external mediator. The AuNPs-PB based immunosensor was fabricated on a custom gold-electrode (AuE)-based polypropylene (PP) substrate. We systematically assessed and optimized key experimental parameters, including the process of AuNPs-PB electrodeposition, antibody concentration, and incubation time. The immunosensor response toward NGAL was determined using differential pulse voltammetry, where the decrease in the oxidation current response of the PB redox probe correlating with the increase in NGAL concentration. Our results demonstrated that the synergistic benefits of both AuNPs and PB significantly improved electrochemical activity for NGAL detection and provided a highly stable sensor across a range of pH values. The label-free immunosensor exhibited two linear ranges: 0.10-1.40 ng mL-1 and 1.40-25.0 ng mL-1, with a low detection limit of 0.094 ng mL-1. The developed NGAL immunosensor displayed high selectivity and excellent reproducibility. Furthermore, NGAL detection was completed within 30 min and the immunosensor exhibited storage stability for six weeks. Notably, NGAL levels determined in human urine samples using this developed label-free immunosensor showed good agreement with the results obtained from the enzyme-linked immunosorbent assay. This novel label-free NGAL immunosensor provides great potential in developing NGAL point-of-care testing applications.

Perioperative Acute Renal Injury: Revisiting Pathophysiology

BACKGROUND

Acute renal dysfunction and subsequent acute renal failure after cardiac surgery are associated with high mortality and morbidity. Early therapeutic or preventive intervention is hampered by the lack of an early biomarker for acute renal injury. Recent studies showed that urinary neutrophil gelatinase-associated lipocalin (NGAL or lipocalin 2) is upregulated early (within 1 to 3 h) after murine renal injury and in pediatric acute renal dysfunction after cardiac surgery. The authors hypothesized that postoperative urinary NGAL concentrations are increased in adult patients developing acute renal dysfunction after cardiac surgery compared with patients without acute renal dysfunction.

METHODS

After institutional review board approval, 81 cardiac surgical patients were prospectively studied. Urine samples were collected immediately before incision and at various time intervals after surgery for NGAL analysis by quantitative immunoblotting. Acute renal dysfunction was defined as peak postoperative serum creatinine increase by 50% or greater compared with preoperative serum creatinine.

RESULTS

Sixteen of 81 patients (20%) developed postoperative acute renal dysfunction, and the mean urinary NGAL concentrations in patients who developed acute renal dysfunction were significantly higher early after surgery (after 1 h, mean ± SD, 4,195 ± 6,520 vs. 1,068 ± 2,129 ng/ml; P < 0.01) compared with patients who did not develop acute renal dysfunction. Mean urinary NGAL concentrations continued to increase and remained significantly higher at 3 and 18 h after cardiac surgery in patients with acute renal dysfunction. In contrast, urinary NGAL in patients without acute renal dysfunction decreased rapidly after cardiac surgery.

CONCLUSIONS

Patients developing postoperative acute renal dysfunction had significantly higher urinary NGAL concentrations early after cardiac surgery. Urinary NGAL may therefore be a useful early biomarker of acute renal dysfunction after cardiac surgery. These findings may facilitate the early detection of acute renal injury and potentially prevent progression to acute renal failure.

Urinary Neutrophil Gelatinase-associated Lipocalin as a Diagnostic and Prognostic Marker for Acute Kidney Injury in Hospitalized Cirrhotic Patients: A Study from North Indian Population

Background

A serious problem in cirrhosis is acute renal injury. The study aimed to examine the urinary neutrophil gelatinase-associated lipocalin (uNGAL) as a diagnostic and prognostic marker of acute kidney injury (AKI) in cirrhotic patients.

Methods

A prospective study was carried out over a period of 1 year. A total of 490 patients suffering from cirrhosis who visited an indoor hospital were screened, and after the exclusion, a total of 90 subjects admitted to the medicine intensive care unit (MICU) fulfilling inclusion criteria were enrolled. Those having a history of renal diseases, on nephrotoxic drugs, in septic shock, peritonitis, UTI, and no urine output were excluded. On admission, for the estimation of uNGAL, urinary levels of sodium, creatinine, fresh urine samples were obtained, and blood samples were taken for serum creatinine estimation.

Results

Out of 90 patients, 33.3% did not develop AKI, and 66.7% developed AKI. Urinary neutrophil gelatinase-associated lipocalin levels were six times higher in patients with acute tubular necrosis (259.08 ± 118.41 ng/mL) and three times higher in Hepatorenal syndrome (HRS)-AKI (124.97 ± 16.38) as compared with patients with normal kidney function (39.76 + 5.7). Those who died had a higher uNGAL (171.6 ng/mL) in comparison to those who survived (133.7 ng/mL). At a cutoff value of ≥114.9 (ng/mL), urinary NGAL represents a sensitivity of 86.92% and specificity of 100% to diagnose AKI and AUC 0.966 (95% CI: 0.919-0.990) in cirrhotic patients.

Conclusion

Urinary NGAL is good for diagnosing AKI and is a marker to distinguish the types of AKI in liver cirrhosis.

How to cite this article

Patel ML, Shyam R, Chaudhary A, Sachan R, Ali W. Urinary Neutrophil Gelatinase-associated Lipocalin as a Diagnostic and Prognostic Marker for Acute Kidney Injury in Hospitalized Cirrhotic Patients: A Study from North Indian Population. Indian J Crit Care Med 2023;27(8):545-551.

Serum neutrophil gelatinase-associated lipocalin and lactate level during surgery predict acute kidney injury and early allograft dysfunction after liver transplantation

Early allograft dysfunction (EAD) and acute kidney injury (AKI) are common and clinically important complications after liver transplantation. Serum lactate level at the end of surgery could predict EAD and neutrophil gelatinase-associated lipocalin (NGAL) is known as a biomarker for AKI after liver transplantation. The authors investigated whether the combination of these two laboratory tests could be used as an early predictor of these two complications of EAD and AKI. We reviewed cases undergoing living donor liver transplantation (n = 353). Lactate-adjusted NGAL level, a combination of these two predictors, was calculated as the sum of each value multiplied by the odds ratio for EAD or AKI. We evaluated whether this combined predictor at the end of surgery is significantly associated with both postoperative AKI or EAD. We compared the area under the receiver operating characteristic curve (AUC) between our multivariable regression models with and without NGAL, lactate, or lactate-adjusted NGAL. NGAL, lactate and lactate-adjusted NGAL are significant predictors for EAD and AKI. The regression model for EAD or AKI including lactate-adjusted NGAL showed a greater AUC (for EAD: odds ratio [OR] 0.88, 95% confidence interval [CI] 0.84-0.91; for AKI: OR 0.89, 95% CI 0.85-0.92) compared to the AUC of the models including lactate (for EAD: OR 0.84, 95% CI 0.81-0.88; for AKI: OR 0.79, 95% CI 0.74-0.83) or NGAL alone (for EAD: OR 0.82, 95% CI 0.77-0.86; for AKI: OR 0.84, 95% CI 0.80-0.88) or the model without lactate or NGAL (for EAD: OR 0.64, 95% CI 0.58-0.69, for AKI: OR 0.75, 95% CI 0.70-0.79). In conclusion, lactate-adjusted NGAL level at the end of surgery could be a reliable combined laboratory predictor for postoperative EAD or AKI after liver transplantation with a greater discriminative ability than lactate or NGAL alone.

Comparative accuracy of biomarkers for the prediction of hospital-acquired acute kidney injury: a systematic review and meta-analysis

Background

Several biomarkers have been proposed to predict the occurrence of acute kidney injury (AKI); however, their efficacy varies between different trials. The aim of this study was to compare the predictive performance of different candidate biomarkers for AKI.

Methods

In this systematic review, we searched PubMed, Medline, Embase, and the Cochrane Library for papers published up to August 15, 2022. We selected all studies of adults (> 18 years) that reported the predictive performance of damage biomarkers (neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid-binding protein (L-FABP)), inflammatory biomarker (interleukin-18 (IL-18)), and stress biomarker (tissue inhibitor of metalloproteinases-2 × insulin-like growth factor-binding protein-7 (TIMP-2 × IGFBP-7)) for the occurrence of AKI. We performed pairwise meta-analyses to calculate odds ratios (ORs) and 95% confidence intervals (CIs) individually. Hierarchical summary receiver operating characteristic curves (HSROCs) were used to summarize the pooled test performance, and the Grading of Recommendations, Assessment, Development and Evaluations criteria were used to appraise the quality of evidence.

Results

We identified 242 published relevant studies from 1,803 screened abstracts, of which 110 studies with 38,725 patients were included in this meta-analysis. Urinary NGAL/creatinine (diagnostic odds ratio [DOR] 16.2, 95% CI 10.1–25.9), urinary NGAL (DOR 13.8, 95% CI 10.2–18.8), and serum NGAL (DOR 12.6, 95% CI 9.3–17.3) had the best diagnostic accuracy for the risk of AKI. In subgroup analyses, urinary NGAL, urinary NGAL/creatinine, and serum NGAL had better diagnostic accuracy for AKI than urinary IL-18 in non-critically ill patients. However, all of the biomarkers had similar diagnostic accuracy in critically ill patients. In the setting of medical and non-sepsis patients, urinary NGAL had better predictive performance than urinary IL-18, urinary L-FABP, and urinary TIMP-2 × IGFBP-7: 0.3. In the surgical patients, urinary NGAL/creatinine and urinary KIM-1 had the best diagnostic accuracy. The HSROC values of urinary NGAL/creatinine, urinary NGAL, and serum NGAL were 91.4%, 85.2%, and 84.7%, respectively.

Conclusions

Biomarkers containing NGAL had the best predictive accuracy for the occurrence of AKI, regardless of whether or not the values were adjusted by urinary creatinine, and especially in medically treated patients. However, the predictive performance of urinary NGAL was limited in surgical patients, and urinary NGAL/creatinine seemed to be the most accurate biomarkers in these patients. All of the biomarkers had similar predictive performance in critically ill patients.

Trial registrationCRD42020207883, October 06, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04223-6.

Role of proenkephalin in the diagnosis of severe and subclinical acute kidney injury during the perioperative period of liver transplantation

In recent decades, clinical research on early biomarkers of renal injury has been frequent and intensive, with proenkephalin (PENK) being indicated as a promising filtration biomarker (BM). From a cohort of 57 patients, blood samples were collected preoperatively and 48 h after liver transplantation (LT). The following BMs were analyzed: PENK, cystatin-C (CYS-C), and serum creatinine (Scr). Diagnosis of AKI was based on the KDIGO criteria. Of the 57 patients undergoing LT, 50 (88%) developed acute kidney injury (AKI) and were categorized as follows: no-AKI/mild-AKI - 21 (36.8%) and severe-AKI 36 (63.2%). During the preoperative period, only PENK was significantly higher in patients with severe AKI, with an AUC of 0.69 (CI 0.54–0.83), a cutoff of 55.30 pmol/l, a sensitivity of 0.86, a specificity of 0.52, and an accuracy of 0.75. In addition, subclinical AKI was determined preoperatively in 32 patients. Forty-eight hours after LT, PENK maintained its performance in determining severe AKI, with an AUC of 0.83 (CI 0.72–0.94), a cutoff of 119.05 pmol/l, a sensitivity of 0.81, a specificity of 0.90, and an accuracy of 0.84. PENK detected AKI 48 h earlier than serum creatinine. In a multivariate linear regression analysis, PENK was an independent predictor of severe AKI. This small study suggests that the filtration biomarker PENK shows promise for detecting AKI in patients undergoing LT, revealing greater accuracy and an earlier rise in patients with severe AKI. The combination of kidney functional and filtration BMs may aid in the management and prevention of AKI progression.

[Kidney failure after liver transplantation]

One third of cirrhotic patients present impaired kidney function. It has multifactorial causes and has a harmful effect on patients' morbi-mortality before and after liver transplant. Kidney function does not improve in all patients after liver transplantation and liver-transplant recipients are at high risk of developing chronic kidney disease. Causes for renal dysfunction can be divided in three groups: preoperative, peroperative and postoperative factors. To date, there is no consensus for the modality of evaluation the risk for chronic kidney disease after liver transplantation, and for its prevention. In the present review, we describe the outcome of kidney function after liver transplantation, and the prognostic factors of chronic kidney disease to determine a risk stratification for each patient. Furthermore, we discuss therapeutic options to prevent kidney dysfunction in this setting, and highlight the indications of combined liver-kidney transplantation.

Role of Novel Kidney Biomarkers in Patients With Cirrhosis and After Liver Transplantation

Acute kidney injury (AKI) and chronic kidney disease (CKD) are important drivers of morbidity and mortality in patients with cirrhosis before and after liver transplantation (LT). In this review, we examine the role of novel kidney biomarkers for early recognition of kidney injury. Studies are limited by lack of reference standards, heterogeneous definitions of outcomes and biomarker cutoffs, and inconsistent diagnostic performance. Overall, a change in biomarker is more relevant than an absolute cutoff. Cystatin C and urinary neutrophil gelatinase-associated lipocalin (uNGAL) are the most studied candidate biomarkers and identify AKI or progression of AKI earlier than serum creatinine (sCr). Kidney injury molecule 1 and liver-type fatty acid-binding protein (L-FABP) also show potential. NGAL and interleukin 18 may play a role in differentiating acute tubular necrosis from other forms of AKI. Combining novel biomarkers with the Model for End-Stage Liver Disease score may assist prognosis. Persistent elevations in select markers (eg, NGAL) can portend irreversible injury. Several pretransplantation markers (including sCr) predict posttransplantation kidney dysfunction. Pretransplantation assessment of clinical factors (eg, age, diabetes) and novel markers (osteopontin and tissue inhibitor of metalloproteinases 1 [TIMP-1]) may predict renal kidney recovery after LT. Intraoperative changes in biomarkers predict early post-LT AKI. Prediction of CKD remains difficult, although a combination of biomarkers (eg, beta-2 microglobulin, CD40) is promising. Novel biomarkers have yet to replace sCr in guideline-based evaluation and management of kidney dysfunction in patients with cirrhosis. We propose a theoretical framework for practical incorporation of these biomarkers that considers patient characteristics (risk for irreversible injury), markers of functional and structural change, and assessment of the AKI-CKD continuum to identify patients at the highest risk for progressive kidney disease before and after LT.

Serial urinary neutrophil gelatinase associated lipocalin in pediatric diabetic ketoacidosis with acute kidney injury

BACKGROUND

Acute kidney injury (AKI) due to Diabetic Ketoacidosis (DKA) is rather common. Novel biomarkers to diagnose AKI are being increasingly used in different settings. The use of urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL) in predicting persistent AKI in pediatric DKA cases is still not thoroughly investigated.

METHODS

This was a secondary analysis of Saline versus Plasma-Lyte in Ketoacidosis (SPinK) trial data; 66 children (> 1 month-12 years) with DKA, defined by the International Society for Pediatric and Adolescent Diabetes (ISPAD), were analyzed. Children with cerebral edema, chronic kidney disease and those who received pre-referral fluids and/or insulin were excluded. uNGAL and urine NGAL-creatinine ratio (uNCR) at 0 and 24 h were measured in all. Persistent AKI was defined as a composite outcome of continuance of AKI defined by the Kidney Disease Improving Global Outcomes (KDIGO) stage 2 or 3 beyond 48 h from AKI onset, progression of AKI from either KDIGO stage 0 or 1 to a worse stage, need of renal replacement therapy or death.

MAIN OUTCOMES

Thirty-five (53%) children had AKI at admission; 32 (91.4%) resolved within 48 h. uNGAL was significantly higher in the AKI group at admission [79.8 ± 27.2 vs 54.6 ± 22.0, p = 0.0002] and at 24 h [61.4 ± 28.3 vs 20.2 ± 14.5, p = 0.0003]. Similar trend was observed with uNCR at admission [6.7 ± 3.7 vs 4.1 ± 2.6, p = 0.002] and at 24 h [6.3 ± 2.5 vs 1.2 ± 1.0, p = 0.01]. Furthermore, uNGAL at admission showed a moderate positive linear correlation with serum creatinine. Additionally, elevated uNGAL at 0 and 24 h correlated with corresponding KDIGO stages. Admission uNGAL >88 ng/ml and uNCR of >11.3 ng/mg had a sensitivity of 66% and 67%, specificity of 76% and 95%, and Area under the receiver operating characteristic curve (AUC) of 0.78 and 0.89 respectively for predicting persistent AKI at 48 h.

CONCLUSIONS

Majority of AKI resolved with fluid therapy. While uNGAL and uNCR both correlated with serum creatinine and AKI stages, serial uNCR was a better predictor of persistent AKI than uNGAL alone. However, feasibility of routine uNGAL measurement to predict persistent AKI in DKA needs further elucidation.

TRIAL REGISTRATION

This was a secondary analysis of the data of SPinK trial [CTRI/2018/05/014042 ( ctri.nic.in )].

Cardiorenal Syndrome: New Pathways and Novel Biomarkers

Cardiorenal syndrome (CRS) is a multi-organ disease characterized by the complex interaction between heart and kidney during acute or chronic injury. The pathogenesis of CRS involves metabolic, hemodynamic, neurohormonal, and inflammatory mechanisms, and atherosclerotic degeneration. In the process of better understanding the bi-directional pathophysiological aspects of CRS, the need to find precise and easy-to-use markers has also evolved. Based on the new pathophysiological standpoints and an overall vision of the CRS, the literature on renal, cardiac, metabolic, oxidative, and vascular circulating biomarkers was evaluated. Though the effectiveness of different extensively applied biomarkers remains controversial, evidence for several indicators, particularly when combined, has increased in recent years. From new aspects of classic biomarkers to microRNAs, this review aimed at a 360-degree analysis of the pathways that balance the kidney and the heart physiologies. In this delicate system, different markers and their combination can shed light on the diagnosis, risk, and prognosis of CRS.

Kidney Failure after Liver Transplantation

One-third of patients with cirrhosis present kidney failure (AKI and CKD). It has multifactorial causes and a harmful effect on morbidity and mortality before and after liver transplantation. Kidney function does not improve in all patients after liver transplantation, and liver transplant recipients are at a high risk of developing chronic kidney disease. The causes of renal dysfunction can be divided into three groups: pre-operative, perioperative and post-operative factors. To date, there is no consensus on the modality to evaluate the risk of chronic kidney disease after liver transplantation, or for its prevention. In this narrative review, we describe the outcome of kidney function after liver transplantation, and the prognostic factors of chronic kidney disease in order to establish a risk categorization for each patient. Furthermore, we discuss therapeutic options to prevent kidney dysfunction in this context, and highlight the indications of combined liver–kidney transplantation.

Basiliximab With Delayed Tacrolimus Improves Short-Term Renal Outcomes Post-Liver Transplantation-a Real-World Experience

BACKGROUND

Acute kidney injury (AKI) is common after liver transplantation (LT). Induction with interleukin-2 receptor antagonists is often used as a "renal-sparing" strategy. The aim of this study was to assess this approach in a real-world setting in an LT center.

METHODS

A retrospective cohort analysis of LTs between 2011 and 2018 was performed to assess the impact of a renal-sparing strategy using basiliximab in conjunction with mycophenolate mofetil and corticosteroids from day 0 post-LT along with delayed introduction of tacrolimus. This was compared with a group receiving tacrolimus, mycophenolate mofetil, and corticosteroids from the outset.

RESULTS

The renal-sparing regimen was associated with significantly lower incidence of all-stage AKI at day 7 post-LT (36% vs 55%, P = .006) and less decline in renal function at 3 months (39% vs 57%, P = .01). No further significant differences in renal outcomes were observed at other time points on follow-up to 1 year post-LT. There was no significant difference in the incidence of acute cellular rejection, inpatient length of stay or graft survival. The decision to adopt a renal-sparing regimen was predominantly made on a clinically reactive basis within the first 24 hours post-LT in 77%, and was preordained in 23%. Cost-effectiveness analysis did not find evidence of a significant cost saving when using a renal-sparing strategy.

CONCLUSION

This study provides real-world analysis of the use of a renal-sparing immunosuppression regimen in LT. Although improvements in incidence of AKI in the short term were demonstrated, this did not translate to cost savings or improved renal outcomes after 3 months.

Biomarkers for detecting and improving AKI after liver transplantation: From diagnosis to treatment

Orthotopic liver transplantation (OLT) is a well-established treatment for patients with liver failure. The shortage of donor organs and postoperative complications remain major obstacles for improving patient survival. Among these complications, acute kidney injury (AKI) is one of the most frequent types, contributing to graft loss. The timely detection and reversal of AKI can reduce its adverse influences on graft and patient outcomes. Traditional markers for detecting AKI are often limited with regard to their accuracy and specificity, and the discovery of better AKI markers and therapeutic targets assumes great importance. During past decades, studies directed toward early detection and treatment of AKI in OLT have been available. This review summarizes the evidence of these biomarkers for the prediction, diagnosis, treatment and prognosis stratification of AKI associated with OLT.

Renal impairment assessment on adults living nearby a landfill: Early kidney dysfunction biomarkers linked to the environmental exposure to heavy metals

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Health risk of the neighboring population of the Mbeubeuss landfill (Senegal).

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Assessment of the impact of Cd/Pb exposure through dysfunction renal biomarkers.

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Specific increases of a set of early dysfunction renal biomarkers in exposed subjects.

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Glomerular and tubular dysfunction in exposed subjects.

The aim of this study was to assess the integrity and kidney overall functional capacity of subjects exposed to landfill emissions. Urine and blood levels of Pb and Cd, and several of the newly biomarkers of nephrotoxicity (Kim Injury Molecule 1 (KIM-1), alpha-1 Microglobulin (α1 M), beta-2 Microglobulin (β2 M), Cystatin-C (Cyst C), Clusterin, alpha-glutathione S-transferase (GSTα), pi-glutathione S-transferase (GSTπ), Tissue Inhibitor of Metalloproteinase-1 (TIMP1), Calbindin, Neutrophil Gelatinase-Associated Lipocalin (NGAL), Osteopontin (OPN), (Retinol Binding Protein(RBP), Liver-type Fatty Acid-Binding Protein (FABP-1), Trefoil Factor 3 (TFF3), Collagen VI) were measured in order to assess glomerular and tubule damage in adults living near a landfill.

Our results indicate glomerular dysfunction in exposed subjects, and supported evidence of necrosis of proximal and distal tubule epithelial cells as specific biomarkers began to appear in the urine.

Positive correlation by Pearson test were obtained between : blood Pb and B-OPN, B-Cyst C, Calbindin, U-KIM-1, TIMP1, U-OPN, and U-Clusterin; and also, between urinary Cd and TIMP1, B-Clusterin, U-OPN, FABP-1, Albumin, and U-Clusterin. The relation between biomarkers of Cd/Pb exposure and early effect biomarkers in this study clearly predicts the future risk of severe kidney injury in subjects living close to the landfill.

Cardiorenal syndrome in heart failure with preserved ejection fraction-an under-recognized clinical entity

Cardiorenal syndrome (CRS) results from the complex and bidirectional interaction between the failing heart and the kidneys. Limited information exists about the pathophysiology and treatment options for worsening kidney function in the setting of heart failure with preserved ejection fraction (HFpEF). This review summarizes the salient pathophysiological pathways in CRS in patients with HFpEF, with emphasis on type 1 and type 2 phenotypes, and outlines diagnostic and therapeutic strategies that are applicable in this population. Elevated central venous and intra-abdominal pressure, left ventricular hypertrophy, LV strain, RAAS activation, oxidative injury, pulmonary hypertension, and RV dysfunction play key roles in the pathogenesis of CRS in the backdrop of HFpEF. The availability of biomarkers of renal and cardiac injury offer a new dimension in accurately diagnosing and quantifying end organ damage in CRS and will improve the accuracy of goal-directed therapies in this population. Novel targeted therapies such as the development of angiotensin/neprilysin inhibitors and sodium-glucose cotransporter-2 (SGLT-2) inhibitors offer new territory in realizing potential benefits in reduction of cardio-renal adverse outcomes in this population. Future studies focusing exclusively on renal outcomes in patients with HFpEF are crucial in delivering optimal therapies in this subset of patients.

The use of urinary biomarkers to predict acute kidney injury in children after liver transplant

BACKGROUND

AKI after pediatric liver transplantation is associated with increased morbidity and mortality. The role of urinary biomarkers for the prediction of AKI in pediatric patients after liver transplantation has not been previously reported. The primary objective of this prospective pilot study was to determine the predictive capabilities of urinary KIM-1, NGAL, TIMP-2, and IGFBP7 for diagnosing AKI.

METHODS

Sixteen children undergoing liver transplantation were enrolled in the study over a 19-month time period. The Kidney Disease Improving Outcomes criteria for urine output and serum creatinine were used to define AKI. Predictive ability was evaluated using the area under the curve obtained by ROC analysis.

RESULTS

AKI occurred in 6 (37.5%) of the patients between 2 and 4 days after transplant. There were no differences in any of the biomarkers prior to transplant. When obtained within 6 hours after transplant, the area under the ROC curve for predicting AKI was 0.758 (95% CI: 0.458-1.00) for KIM-1, 0.900 (95% CI: 0.724-1.00) for NGAL, and 0.933 (95% CI: 0.812-1.00) for the product of TIMP-2 and IGFBP7 ([TIMP-2]·[IGFBP7]).

CONCLUSIONS

Our results show that both NGAL and [TIMP-2]·[IGFBP7] provide significant discrimination for AKI risk following liver transplant in children. Larger studies are needed to determine the optimal time point for measuring these biomarkers and to validate our findings.

Early detection of acute kidney injury in the perioperative period of liver transplant with neutrophil gelatinase-associated lipocalin

Background

Acute kidney injury (AKI) is a common complication in patients undergoing liver transplant (LT) and is associated with high morbidity and mortality. We aim to evaluate the pattern of urine and plasma neutrophil gelatinase-associated lipocalin (NGAL) elevation during the perioperative period of LT and to assess it as a prognostic marker for AKI progression, need for dialysis and mortality.

Methods

We assessed NGAL levels before induction of anesthesia, after portal reperfusion and at 6, 18, 24, and 48 h after surgery. Patients were monitored daily during the first week after LT.

Results

Of 100 enrolled patients undergoing liver transplant, 59 developed severe AKI based on the KDIGO serum creatinine (sCr) criterion; 34 were dialysed, and 21 died within 60 days after LT. Applying a cut-off value of 136 ng/ml, UNGAL values 6 h after surgery was a good predictor of AKI development within 7 days after surgery, having a positive predictive value (PPV) of 80% with an AUC of 0.76 (95% CI 0.67–0.86). PNGAL at 18 h after LT was also a good predictor of AKI in the first week, having a PPV of 81% and AUC of 0.74 (95% CI 0.60–0.88). Based on PNGAL and UNGAL cut-off criteria levels, time to AKI diagnosis was 28 and 23 h earlier than by sCr, respectively. The best times to assess the need for dialysis were 18 h after LT by PNGAL and 06 h after LT by UNGAL.

Conclusion

In conclusion, the plasma and urine NGAL elevation pattern in the perioperative period of the liver transplant can predict AKI diagnosis earlier. UNGAL was an early independent predictor of AKI development and need for dialysis. Further studies are needed to assess whether the clinical use of biomarkers can improve patient outcomes.

Trial registration

Registered at Clinical Trials (clinicaltrials.gov) in March 24th, 2014 by title “Acute Kidney Injury Biomarkers: Diagnosis and Application in Pre-operative Period of Liver Transplantation (AKIB)” and identifier NCT02095431, retrospectively registered.

Role of biomarkers as predictors of acute kidney injury and mortality in decompensated cirrhosis

Evidence suggests that novel biomarkers predict acute kidney injury (AKI) development and outcome earlier than serum creatinine. The aim of this study was to determine the incidence and prognosis of AKI in decompensated cirrhotic patients, and also assess the usefulness of plasma cystatin C, urine neutrophil gelatinase associated lipocalin (NGAL), tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) in early prediction of AKI and mortality. Single-center, prospective observational study enrolling decompensated cirrhotic patients without AKI at the time of admission. Of 111 patients with decompensated cirrhosis, 45 (40.5%) developed AKI while hospitalized. Even with 53.3% being transient (stage 1), mortality was significantly higher in AKI than non-AKI patients (46.5% vs. 25%, p = 0.02). Plasma cystatin C and urine NGAL, but not urine [TIMP-2]·[IGFBP7] at the time of admission were found to be independent early predictors of AKI. Substitution of cystatin C for creatinine significantly improved the model for end-stage liver disease (MELD) score accuracy for mortality prediction. The incidence of AKI is high and is associated with high mortality in decompensated cirrhotic patients. Plasma cystatin C and urine NGAL are useful for early detection of AKI. MELD-cystatin C, rather than original MELD, improves predictive accuracy of mortality.

Early acute kidney injury after liver transplantation in patients with normal preoperative renal function

AIM

Acute kidney injury (AKI) commonly occurs in patients after liver transplantation (LT). However, few studies have focused on AKI and its correlation with clinical outcomes under the Kidney Disease Improving Global Outcomes (KDIGO) criteria. This study aimed to identity the incidence, risk factors, and impacts of early AKI on outcomes in LT recipients with normal preoperative renal function, according to the KDIGO criteria.

METHODS

Clinical and laboratory data of 227 patients with normal preoperative renal function who underwent LT from January 2011 to January 2015 were retrospectively analyzed.

RESULTS

During the first week after LT, 106 patients (46.7%) developed AKI based on the KDIGO criteria. A multivariate analysis revealed that BMI of > 25, prolonged inferior vena cava clamping, prolonged cold ischemia time, and post-operative RBC requirements > 10 units were independent risk factors for AKI after LT. The area under the receiver operating characteristic curve for the predictive ability of AKI under these risk factors was 0.748. The occurrence of AKI was associated with longer mechanical ventilation time and post-operative ICU stay, increased post-operative 30-day mortality and decreased long-term patient survival.

CONCLUSIONS

Even in patients with normal preoperative renal function, AKI was a frequent complication in LT recipients and had both negative short- or long-term effects on patient outcomes, also the severity of AKI had a dose-response relationship with worse outcomes. Patients with BMI > 25, prolonged inferior vena cava clamping, prolonged cold ischemia time, or post-operative RBC requirement > 10 units should be pay particular attention, which may assist in achieving better clinical outcomes.

Neutrophil Gelatinase-Associated Lipocalin Is Not Associated with Tacrolimus-Induced Acute Kidney Injury in Liver Transplant Patients Who Received Mycophenolate Mofetil with Delayed Introduction of Tacrolimus

Tacrolimus is widely used as an immunosuppressant in liver transplantation, and tacrolimus-induced acute kidney injury (AKI) is a serious complication. The urinary neutrophil gelatinase-associated lipocalin (NGAL) level has been linked to tacrolimus-induced AKI in patients starting tacrolimus treatment the morning after liver transplantation. Here we tested this association using a different immunosuppression protocol: Mycophenolate mofetil administration beginning on Postoperative Day 1 and tacrolimus administration beginning on Postoperative Day 2 or 3. Urine samples were collected from 26 living donor liver transplant recipients before (Postoperative Day 1) and after (Postoperative Day 7 or 14) tacrolimus administration. NGAL levels were measured via enzyme-linked immunosorbent assays, as were those of three additional urinary biomarkers for kidney diseases: Monocyte chemotactic protein-1 (MCP-1), liver-type fatty acid-binding protein (L-FABP), and human epididymis secretory protein 4 (HE4). HE4 levels after tacrolimus administration were significantly higher in patients who developed AKI (n = 6) than in those who did not (n = 20), whereas NGAL, MCP-1, and L-FABP levels did not differ significantly before or after tacrolimus administration. These findings indicate that NGAL may not be a universal biomarker of AKI in tacrolimus-treated liver transplant recipients. To reduce the likelihood of tacrolimus-induced AKI, our immunosuppression protocol is recommended.

Urinary and Serum Biomarkers for Prediction of Acute Kidney Injury in Patients Undergoing Liver Transplantation

Acute kidney injury (AKI) is a frequent and serious complication of orthotopic liver transplantation (OLT), with a significant impact on mortality, graft survival, and chronic kidney disease. Currently, the diagnosis of AKI is based on changes in serum creatinine, which is a late marker, usually rising when there is already significant damage to the renal parenchyma. During the last 2 decades, various biomarkers have been studied in many clinical situations, mostly after cardiac surgery, in drug-induced AKI, or in sepsis. The present article summarizes the data on those biomarkers that have been evaluated for the prediction of AKI in patients undergoing OLT.

Early Postoperative Neutrophil Gelatinase-Associated Lipocalin Predicts the Development of Chronic Kidney Disease After Liver Transplantation

BACKGROUND

Urinary neutrophil gelatinase-associated lipocalin (uNGAL)-associated acute kidney injury is common after liver transplantation (LT), but whether early acute kidney injury predicts chronic kidney disease (CKD) and mortality remains uncertain.

METHODS

Adults with LT from 2008 to 2010 in a previously published prospective cohort evaluating serial uNGAL pre- and post-LT were retrospectively assessed to evaluate uNGAL as a predictor of long-term outcomes post-LT. The primary outcomes were post-LT CKD, defined as Modification of Diet in Renal Disease estimated glomerular filtration rate less than 60 mL/min per 1.73 m for 3 continuous months, and death.

RESULTS

uNGAL at 24 hours postreperfusion was significantly higher among patients who developed CKD. Multivariable modeling for the development of CKD demonstrated that uNGAL at 24-hours postreperfusion, 24 hours post-LT renal function, initial calcineurin inhibitor, and age were independent predictors of the development of CKD at in this cohort with long-term follow-up post-LT. Further, this association was stronger in those with preserved pre-LT renal function, a population where renal outcomes are often difficult to predict.

CONCLUSIONS

We propose that perioperative uNGAL may identify patients at risk for CKD and allow for targeted early implementation of renal-sparing strategies.

The Japanese clinical practice guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention is necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in predicting acute kidney injury following orthotopic liver transplantation: A systematic review

BACKGROUND

Acute kidney injury (AKI) is common after orthotopic liver transplantation (OLT) usually occurring early post-transplant. Multiple causes include graft preservation injury, blood loss, hypotension but also severity of recipient liver disease. Early intervention in AKI has both short and long term patient benefits. Unfortunately there are no current clinical biomarkers of early AKI.

AIM

To assess the value of NGAL in predicting AKI following OLT.

METHODS

Ovid MEDLINE and EMBASE were searched between the years of 2000 and 2017 for studies using keywords: Neutrophil Gelatinase Associated Lipocalin or NGAL variants combined with synonyms for liver transplantation.

RESULTS

96 studies were identified. 11 studies including 563 patients were considered suitable for analysis. Both urinary (uNGAL) and plasma NGAL (pNGAL) measurement were found to predict AKI after liver transplantation. Optimal reported area under the receiver-operator characteristics curve (AUROC) values of 0.5-0.83 and 0.54-0.86 respectively.

CONCLUSIONS

NGAL is a good predictor of early AKI post OLT although there is considerable variation in the published results. Further studies with prospectively defined cut-off values, standardized definitions of AKI and rigorous data reporting should be conducted to establish its clinical usefulness and limitations.

Urinary kidney injury molecule-1 in renal disease

Kidney injury molecule-1 (KIM-1), a type l transmembrane glycoprotein, is recognized as a potential biomarker for detection of tubular injury in the main renal diseases. Urinary KIM-1 increases rapidly upon the tubular injury, and its levels are associated with the degree of tubular injury, interstitial fibrosis, and inflammation in the injured kidney. Currently, the investigation of kidney diseases is usually performed through the assessment of serum creatinine and urinary albumin. However, these biomarkers are limited for the early detection of changes in renal function. Besides, the tubular injury appears to precede glomerular damage in the pathophysiology of renal diseases. For these reasons, the search for sensitive, specific and non-invasive biomarkers is of interest. Therefore, the purpose of this article is to review the physiological mechanisms of KIM-1, as well to present clinical evidence about the association between elevated urinary KIM-1 levels and the main renal diseases such as chronic kidney disease, diabetic kidney disease, acute kidney injury, and IgA nephropathy.

The Japanese Clinical Practice Guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention are necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Acute Kidney Injury Before and After Liver Transplant

The development of acute kidney injury in the setting of liver disease is a significant event both before and after liver transplant. Whether acute kidney injury is the cause of or merely associated with worse outcomes, the development of renal failure is significant from a prognostic as well as from a diagnostic and therapeutic standpoint. Although not every etiology is reversible, there are number of etiologies that are correctable, to include hypovolemia, nephrotoxic medications, and acute tubular necrosis. In the post-liver transplant period, renal failure is associated with graft failure as well as worse outcomes overall. Prompt recognition, workup, and intervention can significantly impact outcomes and survival both before and after liver transplant.

Accuracy of neutrophil gelatinase-associated lipocalin for acute kidney injury diagnosis in children: systematic review and meta-analysis

OBJECTIVE

To estimate the accuracy of Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a biomarker for acute kidney injury (AKI) in children.

METHODS

A systematic review of the literature was performed. The review protocol was registered at PROSPERO (CRD 42015024153). We conducted searches in the following databases: Medline (PubMed), LILACS (BVS), SCOPUS (Elsevier), Embase (OVID), Cochrane Central Register of Controlled Trials (CENTRAL), Biomed Central, and ISI Web of Science, from January 1990 to October 2016. For inclusion, studies measured NGAL levels in plasma and urine for AKI in children. For each study, 2 × 2 contingency tables were developed. For statistical analysis we calculated the sensitivity, specificity and diagnostic odds ratio. For methodological assessment, we used Quality Assessment of Diagnostic Accuracy Studies-2. Software used for analysis was Stata 14, and RevMan 5.3.

RESULTS

In total 13 studies were analyzed, which included 1629 children. For urinary NGAL, the pooled sensitivity was 0.76 (95% CI 0.62-0.85) and a pooled specificity 0.93 (95% CI 0.88-0.96). The diagnostic odds ratio (DOR) for the detection of AKI was 43 (95% CI 16-115) and the Area under the curve (AUC) was 0.94 (95% CI 0.92-0.96). For plasma NGAL the combined sensitivity was 0.80 (95% CI 0.64-0.90) and a combined specificity was 0.87 (95% CI 0.74-0.94). The DOR was 26 (95% CI 8.0-82) and AUC was 0.90 (95% CI 0.87-0.94) for the detection of AKI in children.

CONCLUSION

The data suggest that NGAL levels can be an important biomarker for the early detection of AKI in children.

Comparison of macrophage migration inhibitory factor and neutrophil gelatinase-associated lipocalin-2 to predict acute kidney injury after liver transplantation: An observational pilot study

Introduction

Several biomarkers have been suggested as early predictors of acute kidney injury (AKI) after orthotopic liver transplantation (OLT). Neutrophil gelatinase-associated lipocalin-2 (NGAL) appears to be a promising predictor of AKI after OLT, but the clinical benefit remains to be proven. Recently, systemic macrophage migration inhibitory factor (MIF) has been proposed as early indicator for requirement of renal replacement therapy after OLT. The aim of this prospective, observational pilot study was to compare the predictive values of serum and urinary MIF for severe AKI after OLT to those of serum and urinary NGAL.

Methods

Concentrations of MIF and NGAL were measured in serum and urine samples collected from patients undergoing OLT. Acute kidney injury was classified according to the KDIGO criteria, with stages 2 and 3 summarized as severe AKI. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of MIF and NGAL for the development of severe AKI.

Results

Forty-five patients (mean age 55±8 years) were included. Nineteen patients (38%) developed severe AKI within 48 hours after reperfusion. At the end of OLT, serum MIF was predictive of severe AKI (AUC 0.73; 95% confidence intervals, CI 0.55–0.90; P = 0.03), whereas urinary MIF, serum NGAL, and urinary NGAL were not. On the first postoperative day, serum MIF (AUC 0.78; CI 0.62–0.93; P = 0.006), urinary MIF (AUC 0.71; CI 0.53–0.88; P = 0.03), and urinary NGAL (AUC 0.79; CI 0.64–0.93; P = 0.02) were predictive for severe AKI, while serum NGAL was not.

Conclusion

In the setting of OLT, MIF and NGAL had similar predictive values for the development of severe AKI.

Biomarkers of acute kidney injury: the pathway from discovery to clinical adoption

Acute kidney injury (AKI) is a common complication of critical illnesses and has a significant impact on outcomes, including mortality and morbidities. Unfortunately, apart from prophylactic measures, no effective treatment for this syndrome is known. Therefore, early recognition of AKI not only can provide better opportunities for preventive interventions, but also opens many gates for research and development of effective therapeutic options. Over the last few years, several new AKI biomarkers have been discovered and validated to improve early detection, differential diagnosis, and differentiation of patients into risk groups for progressive renal failure, need for renal replacement therapy (RRT), or death. These novel AKI biomarkers complement serum creatinine (SCr) and urine output, which are the standard diagnostic tools for AKI detection. In this article, we review the available literature on characteristics of promising AKI biomarkers that are currently the focus of preclinical and clinical investigations. These biomarkers include neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein, interleukin 18 (lL-18), insulin-like growth factor-binding protein 7, tissue inhibitor of metalloproteinase 2 (TIMP-2), calprotectin, urine angiotensinogen (AGT), and urine microRNA. We then describe the clinical performance of these biomarkers for diagnosis and prognostication. We also appraise each AKI biomarker's advantages and limitations as a tool for early AKI recognition and prediction of clinical outcomes after AKI. Finally, we review the current and future states of implementation of biomarkers in the clinical practice.

Effect of continuous renal replacement therapy on kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin in patients with septic acute kidney injury

Kidney injury molecule-1 (Kim-1) and neutrophil gelatinase-associated lipocalin (NGAL) have been investigated as biomarkers for acute kidney injury (AKI). However, they are seldom investigated in patients with septic AKI treated with continuous renal replacement therapy (CRRT). The aim of the present study was to investigate the therapeutic effectiveness and possible mechanisms of CRRT in septic AKI by observing the changes in Kim-1 and NGAL levels. A group of 38 patients with septic AKI was randomly divided into the conventional drug treatment group (group A) and the CRRT group (group B). All patients were treated with standard antisepsis agents, and group B was additionally submitted to CRRT for 24 h. The levels of Kim-1 and NGAL in serum, urine and the ultrafiltrate of CRRT were measured prior to and at 12, 24, and 48 h after treatment. In group A, urinary Kim-1 (uKim-1) levels at 12, 24 and 48 h were lower than prior to treatment (P<0.05), whereas urinary NGAL (uNGAL) showed no difference among the various time points (P>0.05). In group B, uKim-1 was decreased at 24 and 48 h compared with before treatment (all P<0.05), whereas uNGAL was decreased at 48 h (P<0.05). Serum Kim-1 did not change with time in groups A and B (P>0.05), whereas serum NGAL was increased after treatment in group A (P<0.05) but did not change in group B (P>0.05). Kim-1 and NGAL were not detected in the ultrafiltrate of CRRT. uKim-1 and uNGAL decreased significantly after CRRT, and therefore may be used to reflect the change of renal function during CRRT and to evaluate the therapeutic effectiveness of the method.

Renal function and oxygenation are impaired early after liver transplantation despite hyperdynamic systemic circulation

Background

Acute kidney injury (AKI) occurs frequently after liver transplantation and is associated with the development of chronic kidney disease and increased mortality. There is a lack of data on renal blood flow (RBF), oxygen consumption, glomerular filtration rate (GFR) and renal oxygenation, i.e. the renal oxygen supply/demand relationship, early after liver transplantation. Increased insight into the renal pathophysiology after liver transplantation is needed to improve the prevention and treatment of postoperative AKI. We have therefore studied renal hemodynamics, function and oxygenation early after liver transplantation in humans.

Methods

Systemic hemodynamic and renal variables were measured during two 30-min periods in liver transplant recipients (n = 12) and post-cardiac surgery patients (controls, n = 73). RBF and GFR were measured by the renal vein retrograde thermodilution technique and by renal extraction of Cr-EDTA (= filtration fraction), respectively. Renal oxygenation was estimated from the renal oxygen extraction.

Results

In the liver transplant group, GFR decreased by 40% (p < 0.05), compared to the preoperative value. Cardiac index and systemic vascular resistance index were 65% higher (p < 0.001) and 36% lower (p < 0.001), respectively, in the liver transplant recipients compared to the control group. GFR was 27% (p < 0.05) and filtration fraction 40% (p < 0.01) lower in the liver transplant group. Renal vascular resistance was 15% lower (p < 0.05) and RBF was 18% higher (p < 0.05) in liver transplant recipients, but the ratio between RBF and cardiac index was 27% lower (p < 0.001) among the liver-transplanted patients compared to the control group. Renal oxygen consumption and extraction were both higher in the liver transplants, 44% (p < 0.01) and 24% (p < 0.05) respectively.

Conclusions

Despite the hyperdynamic systemic circulation and renal vasodilation, there is a severe decline in renal function directly after liver transplantation. This decline is accompanied by an impaired renal oxygenation, as the pronounced elevation of renal oxygen consumption is not met by a proportional increase in renal oxygen delivery. This information may provide new insights into renal pathophysiology as a basis for future strategies to prevent/treat AKI after liver transplantation.

Trial registration

ClinicalTrials.gov, NCT02455115. Registered on 23 April 2015.

Acute kidney injury after liver transplantation: Recent insights and future perspectives

Acute kidney injury (AKI) is a common postoperative complication after liver transplantation (LT). The occurrence of postoperative AKI after LT (Post-LT AKI) is associated with inferior patient and graft outcomes. Post-LT AKI is multifactorial in origin and has been related to the severity of liver disease, pre-LT renal dysfunction, graft quality, perioperative events and toxicity of immunosuppressive therapy. Furthermore it is thought that hepatic ischaemia reperfusion injury might be a driving force in the aetiology of post-LT AKI. Novel biomarkers for AKI are emerging and can be useful for early identification and characterization of AKI. There is a clear need for strategies aimed at preventing or treating post-LT AKI. Several pharmacological and non-pharmacological interventions have been studied, but so far failed to show any benefit in the prevention of post-LT AKI. Further studies are needed to develop and evaluate new interventions aimed at preventing post-LT AKI and improve patient outcomes.

Role of Urinary Neutrophil Gelatinase-associated Lipocalin as a Biomarker of Acute Kidney Injury in Patients with Circulatory Shock

Background

The early prediction of acute kidney injury (AKI) by the current clinical and laboratory methods remains inadequate. Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a promising noninvasive biomarker of kidney injury in shock. The aim of this study was to assess the ability of urinary NGAL (uNGAL) to predict AKI in adult Intensive Care Unit (ICU) patients.

Materials and Methods

We prospectively studied 70 patients with circulatory shock admitted to the ICU over a period of 1 year. uNGAL was analyzed at ICU admission and after 24 h. Risk, injury, failure, loss, and end-stage kidney criteria were calculated at admission and for consecutive 4 days. The primary outcome was AKI defined as an increase in creatinine of at least 50% from baseline or a reduction in urine output to <0.5 ml/kg/h for 6 h.

Results

uNGAL was a good diagnostic marker for AKI development; at day 1, the cutoff value 48.54 ng/mL had a sensitivity and specificity of 79.49 and 73.14, respectively, and the area under the curve (AUC) of 0.82 (95% confidence interval [CI], 0.75-0.87) for predicting AKI. At day 2, the cutoff value 190.92 ng/mL had a sensitivity and specificity of 90.0 and 64.66, respectively, and the AUC of 0.76 (95% CI, 0.70-0.88) for predicting AKI.

Conclusion

uNGAL could be a good early predictor biomarker of AKI following circulatory shock.

Acute Kidney Injury: Diagnostic Approaches and Controversies

Acute kidney injury (AKI) is a significant independent risk factor for morbidity and mortality. In the last ten years a large number of publications have highlighted the limitations of traditional approaches and the inadequacies of conventional biomarkers to diagnose and monitor renal insufficiency in the acute setting. A great effort was directed not only to the discovery and validation of new biomarkers aimed to detect AKI more accurately but also to standardise the definition of AKI. Despite the advances in both areas, biomarkers have not yet entered into routine clinical practice and the definition of this syndrome has many areas of uncertainty. This review will discuss the controversies in diagnosis and the potential of novel biomarkers to improve the definition of the syndrome.

Neutrophil gelatinase-associated lipocalin production negatively correlates with HK-2 cell impairment: Evaluation of NGAL as a marker of toxicity in HK-2 cells

Neutrophil gelatinase-associated lipocalin is an extracellular protein produced mostly in kidney. Recently, it has become a promising biomarker of renal damage in vivo. On the other hand, the validation of NGAL as a biomarker for nephrotoxicity estimation in vitro has not been characterized in detail yet. Since the HK-2 cells are frequently used human kidney cell line, we aimed to characterize the production of NGAL in these cells and to evaluate NGAL as a possible marker of cell impairment. We used heavy metals (mercury, cadmium), peroxide, drugs (acetaminophen, gentamicin) and cisplatin to mimic nephrotoxicity. HK-2 cells were incubated with selected compounds for 1-24h and cell viability was measured together with extracellular NGAL production. We proved that HK-2 cells possess a capacity to produce NGAL in amount of 2pg/ml/h. We found a change in cell viability after 24h incubation with all tested toxic compounds. The largest decrease of the viability was detected in mercury, acetaminophen, cisplatin and gentamicin. Unexpectedly, we found also a significant decrease in NGAL production in HK-2 cells treated with these toxins for 24h: to 11±5%, 54±5%, 57±6% and 76±9% respectively, compared with controls (=100%). Our results were followed with qPCR analysis when we found no significant increase in LCN2 gene expression after 24h incubation. We conclude that extracellular NGAL production negatively correlates with HK-2 cell impairment.

Proteinuria can predict prognosis after liver transplantation

Background

Proteinuria is a manifestation of renal dysfunction and it has been demonstrated to be a significant prognostic factor in various clinical situations. The study was designed to analyze prognosis of patients receiving liver transplantation as well as to determine predictive performance of perioperative proteinuria.

Methods

We retrospectively reviewed data of patients who had received a liver transplant in a medical center between 2002 and 2010. Demographic information and clinical characteristic parameters were recorded on the day of intensive care unit admission before operation and on postoperative days 1, 7, and 14.

Results

Among a total of 323 patients, in-hospital mortality and 90-day mortality rates were 13.0 % (42/323) and 14.2 % (46/323), respectively. Patients with proteinuria on admission had higher rates of acute kidney injury (26.8 % vs. 8.8 %, p < 0.001), severe infection episodes (48.8 % vs. 30.7 %, p = 0.023), hospital death (31.1 % vs. 10.1 %, p < 0.001), and 90-day mortality (37.7 % vs. 10.9 %, p < 0.001). Multivariate analysis showed that proteinuria on admission and Sequential Organ Failure Assessment (SOFA) score were independent predictors of in-hospital mortality. The discriminatory ability of proteinuria plus SOFA was even better than that of SOFA alone, especially on postoperative day 1.

Conclusions

The presence of proteinuria before liver transplantation is supposed to be recognized as a negative predictor for in-hospital survival. Moreover, the presence of proteinuria after liver transplantation can assist in the early prediction of poor short-term prognosis for patients receiving liver transplantation.

Protecting the Kidney in Liver Transplant Recipients: Practice-Based Recommendations From the American Society of Transplantation Liver and Intestine Community of Practice

Both acute and chronic kidney disease are common after liver transplantation and result in significant morbidity and mortality. The introduction of the Model for End-stage Liver Disease score has directly correlated with an increased prevalence of perioperative renal dysfunction and the number of simultaneous liver-kidney transplantations performed. Kidney dysfunction in this population is typically multifactorial and related to preexisting conditions, pretransplantation renal injury, perioperative events, and posttransplantation nephrotoxic immunosuppressive therapies. The management of kidney disease after liver transplantation is challenging, as by the time the serum creatinine level is significantly elevated, few interventions affect the course of progression. Also, immunological factors such as antibody-mediated kidney rejection have become of greater interest given the rising liver-kidney transplant population. Therefore, this review, assembled by experts in the field and endorsed by the American Society of Transplantation Liver and Intestine Community of Practice, provides a critical assessment of measures of renal function and interventions aimed at preserving renal function early and late after liver and simultaneous liver-kidney transplantation. Key points and practice-based recommendations for the prevention and management of kidney injury in this population are provided to offer guidance for clinicians and identify gaps in knowledge for future investigations.

Neutrophil gelatinase-associated lipocalin in a triphasic rat model of adenine-induced kidney injury

The aim of this study is to investigate whether NGAL, given its advantages over traditional biomarkers, can be used to describe the dynamic characteristics of the renal tubulointerstitial insult caused by adenine. Subsequently, it will be possible to assess NGAL as a biomarker of any acute kidney injury, on top of chronic interstitial disease, if NGAL levels are stable through the chronic phase of our adenine model. Study group rats were fed an adenine diet, and control group rats were fed a regular diet only. Blood and urine samples for urea, creatinine and NGAL were drawn from each rat at the beginning of the study and after 1, 3, 4, 5, 6, 7 and 8 weeks. Kidney slices from these rats were stained with Hematoxylin-eosin (HE) and β-actin stainings. Serum urea, creatinine and NGAL levels and urinary NGAL/creatinine ratio in the study group were higher than baseline and than in the control group; these differences were statistically significant in some of the intervals. Tubulointerstitial changes and adenine crystals were evident in the study group rats. In the rats fed adenine, serum urea, creatinine and NGAL levels and urinary NGAL/creatinine ratio followed a triphasic pattern of kidney injury: an acute phase while on the adenine diet, a partial recovery phase after switching to the regular diet and a chronic kidney disease phase after stabilization of renal function. NGAL can serve a biomarker for acute kidney injury and possibly for chronic kidney disease in the tubulointerstitial rat model.

Acute kidney injury following liver transplantation: a systematic review of published predictive models

Acute kidney injury is a frequent postoperative complication amongst liver transplant recipients and is associated with increased morbidity and mortality. This systematic review analysed the existing predictive models, in order to solidify current understanding. Articles were selected for inclusion if they described the primary development of a clinical prediction model (either an algorithm or risk score) to predict AKI post liver transplantation. The database search yielded a total of seven studies describing the primary development of a prediction model or risk score for the development of AKI following liver transplantation. The models span thirteen years of clinical research and highlight a gradual change in the definitions of AKI, emphasising the need to employ standardised definitions for subsequent studies. Collectively, the models identify a diverse range of predictive factors with several common trends. They emphasise the impact of preoperative renal dysfunction, liver disease severity and aetiology, metabolic risk factors as well as intraoperative variables including measures of haemodynamic instability and graft quality. Although several of the models address postoperative parameters, their utility in predictive modelling seems to be of questionable relevance. The common risk factors identified within this systematic review provide a minimum list of variables, which future studies should address. Research in this area would benefit from prospective, multi-site studies with larger cohorts as well as the subsequent internal and external validation of predictive models. Ultimately, the ability to identify patients at high risk of post-transplant AKI may enable early intervention and perhaps prevention.

Urinary neutrophil gelatinase-associated lipocalin (NGAL) distinguishes sustained from transient acute kidney injury after general surgery

Introduction

This prospective study tests the hypothesis that after general surgery urinary neutrophil gelatinase–associated lipocalin (NGAL) can distinguish between sustained acute kidney injury (AKI), typical of nephron damage, and transient AKI, commonly seen with hemodynamic variation and prerenal azotemia.

Methods

Urine was collected in 510 patients within 2 to 3 hours after general surgery, and urinary NGAL was determined using enzyme-linked immunosorbent assay. Patients who met AKIN stage 1 criteria of AKI were subclassified into those with sustained AKI (serum creatinine elevation for at least 3 days) and those with transient AKI (serum creatinine elevation for less than 3 days).

Results

Seventeen of 510 patients (3.3%) met the stage 1 AKIN criteria within 48 hours of surgery. Elevations in serum creatinine were sustained in 9 and transient in 8 patients. Urinary NGAL was significantly elevated only in patients with sustained AKI (204.8 ± 411.9 ng/dl); patients with transient AKI had urinary NGAL that was indistinguishable from that of patients who did not meet AKIN criteria at all (30.8 ± 36.5 ng/dl vs. 31.9 ± 113 ng/dl). The area under the curve of the receiver operating characteristic curve of urinary NGAL to predict sustained AKI was 0.85 (95% confidence interval: 0.773–0.929, P < 0.001).

Discussion

Urinary NGAL levels measured 2 to 3 hours after surgery were able to distinguish the kinetics of creatinine (sustained AKI vs. transient AKI) over the subsequent week. Transient AKI is an easily reversible state that is likely not associated with substantial tubular injury and therefore NGAL release. Using AKIN criteria, both transient and sustained AKI are classified as AKI even though our data demonstrate that they are possibly different entities.

Alterations of Endothelial Glycocalyx During Orthotopic Liver Transplantation in Patients With End-Stage Liver Disease

BACKGROUND

Endothelial glycocalyx participates in the maintenance of vascular integrity, and its perturbations cause capillary leakage, loss of vascular responsiveness, and enhanced adhesion of leukocytes and platelets. We hypothesized that marked shedding of the glycocalyx core protein, syndecan-1, occurs in end-stage liver disease (ESLD) and that it increases during orthotopic liver transplantation (OLT). We further evaluated the effects of general anesthesia on glycocalyx shedding and its association with acute kidney injury (AKI) after OLT.

PATIENTS AND METHODS

Thirty consecutive liver transplant recipients were enrolled in this prospective study. Ten healthy volunteers served as a control. Acute kidney injury was defined by Acute Kidney Injury Network criteria.

RESULTS

Plasma syndecan-1 was significantly higher in ESLD patients than in healthy volunteers (74.3 ± 59.9 vs 10.7 ± 9.4 ng/mL), and it further increased significantly after reperfusion (74.3 ± 59.9 vs 312.6 ± 114.8 ng/mL). The type of general anesthesia had no significant effect on syndecan-1. Syndecan-1 was significantly higher during the entire study in patients with posttransplant AKI stage 2 or 3 compared to patients with AKI stage 0 or 1. The area under the curve of the receiver operating characteristics curve of syndecane-1 to predict AKI stage 2 or 3 within 48 hours after reperfusion was 0.76 (95% confidence interval, 0.57-0.89, P = 0.005).

CONCLUSIONS

Patients with ESLD suffer from glycocalyx alterations, and ischemia-reperfusion injury during OLT further exacerbates its damage. Despite a higher incidence of AKI in patients with elevated syndecan-1, it is not helpful to predict de novo AKI. Volatile anesthetics did not attenuate glycocalyx shedding in human OLT.

Neutrophil Gelatinase-Associated Lipocalin: A New Marker of Renal Function in C-Related End Stage Liver Disease

Background/Aims. Renal impairment is a common complication of cirrhosis. Serum creatinine is less sensitive in these patients. Measurement of the glomerular filtration rate (GFR) is the gold standard but time consuming. The aim is to validate plasma NGAL (pNGAL) and urinary NGAL (uNGAL) as markers of renal function in patients with HCV related cirrhosis. Patient and Methods. One hundred HCV related end stage liver cirrhosis patients were randomized into two groups: Group I (n = 35), patients with GFR < 60 mL/m measured by isotope scanning of the kidney (Renogram), and Group II (n = 65), patients with GFR ≥ 60 mL/m. The pNGAL and uNGAL were measured within 2 days of the Renogram. Results. Both groups were matched with age, sex, and Child Pugh score. There was statistically significant difference between both groups regarding serum creatinine (1.98 ± 1.04 versus 1.38 ± 0.88 mg/dL; p = 0.003) and pNGAL level (5.79 ± 2.06 versus 7.25 ± 3.30 ng/dL; p = 0.019). Both groups were comparable (p > 0.05) for the uNGAL (6.00 ± 0.78 versus 6.03 ± 0.96 ng/mL). Unlike uNGAL, the pNGAL positively correlated with total GFR by Renogram (r = 0.3; p = 0.001). With a cutoff ≥4 ng/mL, pNGAL had 94.3% sensitivity and 1.5% specificity and PPV = 34, NPV = 33.3, LR+ = −175.1, and LR− = −60.6. Conclusion. The pNGAL is a promising marker of the renal function in patients with cirrhosis.

A Single-Center Randomized Trial of Intraoperative Zero-Balanced Ultrafiltration During Cardiopulmonary Bypass for Patients With Impaired Kidney Function Undergoing Cardiac Surgery

OBJECTIVES

The authors investigated whether zero-balance ultrafiltration (Z-BUF) during bypass significantly improves clinical and cost outcomes or biomarkers of kidney injury for patients with preoperative kidney impairment (estimated glomerular filtration rate [eGFR]<60 mL/minute) undergoing cardiac surgery.

DESIGN

A single-center randomized controlled trial recruited, patients between 2010 and 2013, with a 12-months follow-up.

SETTING

Hospital.

PARTICIPANTS

One hundred ninety-nine patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

INTERVENTIONS

Patients were assigned randomly to receive zero-balance ultrafiltration (Z-BUF) or not, with stratification for degree of kidney dysfunction and diabetes.

MEASUREMENTS AND MAIN RESULTS

The authors assessed clinical efficacy and kidney function biomarkers. Cumulative probability of discharge from the intensive care unit (ICU) was assessed by Kaplan-Meier plots and was found not to be significantly different between the two trial arms (p = 0.61). After adjusting for EuroSCORE, diabetes, eGFR, cardioplegia types and type of surgery in a Cox proportional hazard model, hazard ratios (HR) for ICU length of stay between the Z-BUF and no-Z-BUF groups was not significantly different: HR (95% CI): 0.89 (0.66, 1.20; p = 0.44). In contrast, significant reductions in postoperative chest infections and the composite of clinical endpoints (death, strokes, and myocardial infarctions) in the Z-BUF group were observed. In addition, Z-BUF significantly abrogated the rise in the kidney damage markers urinary NGAL/creatinine ratio, urea, creatinine and eGFR during CPB and adverse events risks.

CONCLUSIONS

Z-BUF during bypass surgery is associated with significant reductions in morbidity and biomarkers of CPB-induced acute kidney injury soon after CPB, which are indicative of clearance of inflammatory/immune mediators from the circulation.

Neutrophil Gelatinase-Associated Lipocalin: A New Marker of Renal Function in C-Related End Stage Liver Disease

Background/Aims. Renal impairment is a common complication of cirrhosis. Serum creatinine is less sensitive in these patients. Measurement of the glomerular filtration rate (GFR) is the gold standard but time consuming. The aim is to validate plasma NGAL (pNGAL) and urinary NGAL (uNGAL) as markers of renal function in patients with HCV related cirrhosis.Patient and Methods. One hundred HCV related end stage liver cirrhosis patients were randomized into two groups: Group I (n=35), patients with GFR < 60 mL/m measured by isotope scanning of the kidney (Renogram), and Group II (n=65), patients with GFR ≥ 60 mL/m. The pNGAL and uNGAL were measured within 2 days of the Renogram.Results. Both groups were matched with age, sex, and Child Pugh score. There was statistically significant difference between both groups regarding serum creatinine (1.98 ± 1.04 versus 1.38 ± 0.88 mg/dL;p=0.003) and pNGAL level (5.79 ± 2.06 versus 7.25 ± 3.30 ng/dL;p=0.019). Both groups were comparable (p>0.05) for the uNGAL (6.00 ± 0.78 versus 6.03 ± 0.96 ng/mL). Unlike uNGAL, the pNGAL positively correlated with total GFR by Renogram (r=0.3;p=0.001). With a cutoff ≥4 ng/mL, pNGAL had 94.3% sensitivity and 1.5% specificity and PPV = 34, NPV = 33.3, LR+ = −175.1, and LR− = −60.6.Conclusion. The pNGAL is a promising marker of the renal function in patients with cirrhosis.

Neutrophil Gelatinase-Associated Lipocalin: A New Marker of Renal Function in C-Related End Stage Liver Disease

Background/Aims. Renal impairment is a common complication of cirrhosis. Serum creatinine is less sensitive in these patients. Measurement of the glomerular filtration rate (GFR) is the gold standard but time consuming. The aim is to validate plasma NGAL (pNGAL) and urinary NGAL (uNGAL) as markers of renal function in patients with HCV related cirrhosis.Patient and Methods. One hundred HCV related end stage liver cirrhosis patients were randomized into two groups: Group I (n=35), patients with GFR < 60 mL/m measured by isotope scanning of the kidney (Renogram), and Group II (n=65), patients with GFR ≥ 60 mL/m. The pNGAL and uNGAL were measured within 2 days of the Renogram.Results. Both groups were matched with age, sex, and Child Pugh score. There was statistically significant difference between both groups regarding serum creatinine (1.98 ± 1.04 versus 1.38 ± 0.88 mg/dL;p=0.003) and pNGAL level (5.79 ± 2.06 versus 7.25 ± 3.30 ng/dL;p=0.019). Both groups were comparable (p>0.05) for the uNGAL (6.00 ± 0.78 versus 6.03 ± 0.96 ng/mL). Unlike uNGAL, the pNGAL positively correlated with total GFR by Renogram (r=0.3;p=0.001). With a cutoff ≥4 ng/mL, pNGAL had 94.3% sensitivity and 1.5% specificity and PPV = 34, NPV = 33.3, LR+ = −175.1, and LR− = −60.6.Conclusion. The pNGAL is a promising marker of the renal function in patients with cirrhosis.

Neutrophil Gelatinase Associated Lipocalin (NGAL) - a biomarker of renal dysfunction in patients with liver cirrhosis: Do we have enough proof?

RATIONALE

Renal dysfunction has a serious impact on the natural evolution of liver cirrhosis. Treatment and prognosis may be improved if an early diagnosis could be established, and specific therapeutic interventions would be applied. Although RIFLE and AKIN classifications have been successfully implemented in the clinical practice of Nephrology and Intensive Care Units, these did not provide major improvements in patients with liver cirrhosis. In the last decade, various biomarkers of kidney injury have been assessed, and Neutrophil Gelatinase-Associated Lipocalin (NGAL) is one of the most promising and most studied novel biomarker.

OBJECTIVE

To offer a brief evaluation on current data on the utility of this biomarker in patients with liver cirrhosis.

METHODS AND RESULTS

We have searched through current literature and analyzed all significant full text articles on this topic.

DISCUSSIONS

NGAL and other new kidney injury molecules may be useful in patients with liver cirrhosis, particularly in identifying structural kidney dysfunction, but larger validation studies to confirm this observation are needed.