The outcome of neutrophil gelatinase-associated lipocalin-positive subclinical acute kidney injury: a multicenter pooled analysis of prospective studies

The impact of tolvaptan on the incidence of contrast-induced acute kidney injury and long-term prognosis in high-risk patients after coronary intervention

OBJECTIVE

To investigate the effect of low-dose tolvaptan combined with hydration on the incidence of contrast-induced acute kidney injury (CI-AKI) and prognosis in high-risk patients undergoing coronary angiography or intervention.

METHODS

This single-center, randomized controlled clinical trial (ChiCTR2000028834) enrolled 232 patients scheduled for elective coronary angiography or intervention, randomly assigned to the experimental group (low-dose tolvaptan + standard intravenous hydration) or the control group (standard hydration alone). Multivariate logistic regression analysis was performed to explore factors associated with CI-AKI occurrence. Kaplan-Meier survival curve was plotted with major adverse cardiovascular events (MACEs) to compare six-month survival rates between the two groups.

RESULTS

The incidence of CI-AKI in the tolvaptan group was significantly lower than in the control group (10.3% vs. 23.3%, p = 0.008). Abdominal spectral CT at 24 h postoperatively showed that iodine concentration in the renal medulla was significantly lower in the tolvaptan group than in the control group (p < 0.05). The increases in creatinine and Cys-C levels and the decrease in eGFR were also significantly smaller in the tolvaptan group (p < 0.05). Multivariate logistic regression analysis indicated that tolvaptan use reduced the risk of CI-AKI (p = 0.001), while lower preoperative eGFR and higher AGEF scores were independent risk factors for CI-AKI (p < 0.05). Kaplan-Meier analysis showed no significant difference in MACEs incidence between groups over six months (93.9% vs. 88.6%, p = 0.142).

CONCLUSION

Low-dose tolvaptan combined with standard hydration reduces the incidence of CI-AKI in high-risk patients undergoing coronary intervention.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2000028834).

The potential mechanisms of extracellular vesicles in transfusion-related adverse reactions: Recent advances

Blood transfusion is an irreplaceable clinical treatment. Blood components are differentiated and stored according to specific guidelines. Storage temperatures and times vary depending on the blood component, but they all release extracellular vesicles (EVs) during storage. Although blood transfusions can be life-saving, they can also cause many adverse transfusion reactions, among which the effects of EVs are of increasing interest to researchers. EVs are submicron particles that vary in size, composition, and surface biomarkers, are encapsulated by a lipid bilayer, and are not capable of self-replication. EVs released by blood cells are important contributors to pathophysiologic states through proinflammatory, coagulant, and immunosuppressive effects, which in turn promote or inhibit the associated disease phenotype. Therefore, this review explores the potential mechanisms of hematopoietic-derived EVs in transfusion-associated adverse reactions and discusses the potential of the latest proteomics tools to be applied to the analysis of EVs in the field of transfusion medicine with a view to reducing the risk of blood transfusion.

Ten tips on how to reduce iatrogenic acute kidney injury

Acute kidney injury (AKI) is a heterogeneous syndrome associated with worse clinical outcomes. Many treatments and procedures in the hospitalized patient can cause AKI. Hence, the incidence of iatrogenic AKI is expected to be high. In this review we provide 10 practical tips on how to manage and avoid iatrogenic AKI. We cover identification of vulnerable patients by epidemiological data and recommend the usage of renal stress biomarkers for enhanced screening of high-risk patients. Further, we discuss the limitations of current diagnostic criteria of AKI. As a key takeaway, we suggest the implementation of novel damage biomarkers in clinical routine to identify subclinical AKI, which may guide novel clinical management pathways. To further reduce the incidence of procedure-associated AKI, we advocate certain preventive measures. Foremost, this includes improvement of hemodynamics and avoidance of nephrotoxic drugs whenever possible. In cases of severe AKI, we provide tips for the implementation and management of renal replacement therapy and highlight the advantages of regional citrate anticoagulation. The furosemide stress test might be of help in recognizing patients who will require renal replacement therapy. Finally, we discuss the progression of AKI to acute and chronic kidney disease and the management of this growing issue. Both can develop after episodes of AKI and have major implications for patient co-morbidity and long-term renal and non-renal outcomes. Hence, we recommend long-term monitoring of kidney parameters after AKI.

Determination of Urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL) Reference Intervals in Healthy Adult and Pediatric Individuals Using a Particle-Enhanced Turbidimetric Immunoassay

Background: The current gold standards for diagnosing acute kidney injury (AKI) are an increase in serum creatinine and a decrease in urine output, which are inadequate for rapid diagnosis. Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein produced and secreted by injured kidney tubule epithelial cells, and can serve as an early urinary biomarker for AKI. ProNephro AKI (NGAL) is an immunoassay for the quantitative determination of NGAL in urine (uNGAL) that recently received FDA clearance. A multisite, cross-sectional study was conducted to establish reference intervals for uNGAL in apparently healthy individuals. Methods: Urine samples were collected from apparently healthy individuals aged ≥3 months who met all inclusion criteria and no exclusion criteria. Specimens were temporarily stored at room temperature or 2-8 °C, then transferred into urinalysis tubes before being frozen and shipped for testing. uNGAL testing was performed using the ProNephro AKI (NGAL) immunoassay on a Roche cobas c501 analyzer. Results: Of the 688 individuals screened, 677 were eligible, and 629 (91.4%) of those were deemed evaluable. The 95th and 97.5th percentile uNGAL values for all pediatric participants were below the clinical cutoff of 125 ng/mL. uNGAL values were statistically significantly higher for female vs. male participants in both adult (p = 0.003) and pediatric groups (p < 0.001), while differences were not statistically significant for age, site location, race, or ethnicity. Conclusions: This study provides normal reference intervals for uNGAL with the ProNephro AKI (NGAL) clinical chemistry immunoassay that may be useful for interpreting patient results.

Higher intraoperative blood pressure does not reduce acute kidney injury in noncardiac surgery: what do the results of the POISE-3 trial tell us?

Hypotension is a common cause of acute kidney injury (AKI), with strong associations between the duration and magnitude of hypotension seen across a range of situations including major surgery. However, it is less clear whether targeting higher intraoperative MAP results in lower rates of AKI. In a prespecified analysis of the Perioperative Ischemic Evaluation-3 (POISE-3) randomized controlled trial, this question is addressed for noncardiac major surgery. Despite an increase in cessation of antihypertensive medications and higher intraoperative mean arterial blood pressure in the intervention arm, no differences were seen in the rates of postoperative AKI. This commentary discusses the strengths and weaknesses of the trial, as well as providing some interpretation of results and their relevance to clinical practice.

Use of urine neutrophil gelatinase-associated lipocalin for nephrotoxic medication acute kidney injury screening in neonates

BACKGROUND

Daily serum creatinine monitoring protocols for acute kidney injury (AKI) are invasive and may lead to surveillance resistance. We aimed to understand if use of urine neutrophil gelatinase-associated lipocalin (uNGAL) could increase high-risk nephrotoxic medication (NTMx) associated AKI screening adherence in neonates.

METHODS

Statistical process control methods prior to and post implementation were trended. The primary outcome, screening adherence, was defined as either daily serum creatinine or uNGAL assessment through 2 days post high-risk NTMx exposure.

RESULTS

1291 monitoring days from the pre-implementation era (4/2020-6/2021) were compared to1377 monitoring days from the post-era (6/2021-10/2022). AKI screening adherence increased (81 to 92%) following implementation of optional uNGAL screening. Urine NGAL accounted for 35% of screening obtained. Use of uNGAL resulted in a 40% reduction in blood sampling for serum creatinine.

CONCLUSIONS

Incorporation of uNGAL as a complementary screening tool to serum creatinine demonstrated sustained increased AKI surveillance in our Baby NINJA monitoring program.

Renal dysfunction in surgical patients

PURPOSE OF REVIEW

To provide an overview of the current diagnostic criteria for acute kidney injury (AKI) including their limitations and to discuss prevention and treatment approaches in the perioperative setting.

RECENT FINDINGS

AKI is common in the perioperative period and is associated with worse short- and long-term outcomes. Current definitions of AKI have several limitations and lead to delayed recognition of kidney dysfunction which is why novel diagnostic approaches by using renal biomarkers may be helpful. In general, prevention of the development and progression of AKI is vital as a causal treatment for AKI is currently not available. Optimization of kidney perfusion and avoidance of nephrotoxic drugs reduce the occurrence of AKI in surgical patients. Angiotensin II as a new vasopressor, the use of remote ischemic preconditioning, and amino acids may be approaches with a positive effect on the kidneys.

SUMMARY

Evidence suggests that the implementation of supportive measures in patients at high risk for AKI might reduce the occurrence of AKI. Novel biomarkers can help allocating resources by detecting patients at high risk for AKI.

A Highly Sensitive Lateral-Flow Strip Using Latex Microspheres to Detect NGAL in Urine Samples

The incidence of kidney disease is increasing worldwide. Rapid and cost-effective approaches for early detection help prevent this disease. Neutrophil gelatinase-associated lipocalin protein (NGAL) is a novel biomarker for acute kidney injury (AKI) and chronic kidney disease (CKD). We aimed to develop a lateral flow strip (LFS) based on a lateral flow immunoassay method (LFIA), using latex microspheres (LMs) as a color labeling to detect NGAL in urine. The performance and potential of the developed LMs-LFS at a point-of-care (POC) testing were evaluated. The results showed that LMs-LFS successfully detected urinary NGAL within 15 min with high specificity without cross-reactivity to or interference from other endogenous substances in urine. The visual limit of detection (vLOD) was 18.75 ng/mL, and the limit of detection (LOD) was 1.65 ng/mL under the optimum condition. The LMs-LFS developed in this study showed a high correlation with the enzyme-linked immunosorbent assay (ELISA) method (R 2 = 0.973, n = 60 urine specimens) for detecting NGAL in urine. The LMs-LFS remained stable for at least six months at room temperature. The LMs-LFS can be a rapid, sensitive, and specific tool for the diagnosis and follow-up of renal disorders at the POC.

Advancements in Trauma-Induced Acute Kidney Injury: Diagnostic and Therapeutic Innovations

Acute kidney injury following trauma impacts patient recovery critically, necessitating an integrated approach to emergency care and nephrology. This review aims to provide a comprehensive understanding of trauma-induced nephropathy, highlighting recent advancements in pathophysiological insights, diagnostic techniques, and strategic interventions. Our key findings emphasize the role of biomarkers, like Neutrophil Gelatinase-Associated Lipocalin and Liver Fatty Acid-Binding Protein, and imaging techniques, such as contrast-enhanced ultrasound, in early AKI detection. Preventive strategies, including aggressive fluid resuscitation, avoidance of nephrotoxic agents, and hemodynamic optimization, are essential for mitigating AKI progression. Integrating these approaches into trauma care frameworks aims to enhance patient outcomes and set a foundation for future research and clinical improvements.

Biomarkers of acute kidney injury: From discovery to the future of clinical practice

Purpose of this review Acute kidney injury (AKI) is a complex syndrome whose development is associated with an increased morbidity and mortality. Recent studies show that this syndrome is a common complication in critically ill and surgical patients the trajectory of which may differ. As AKI can be induced by different triggers, it is complex and therefore challenging to manage patients with AKI. This review strives to provide a brief historical perspective on AKI, elucidate recent developments in diagnosing and managing AKI, and show the current usage of novel biomarkers in both clinical routine and research. In addition, we provide a perspective on potential future developments and their impact of AKI understanding and management. Recent findings/developments Recent studies show the merits of stress and damage biomarkers, highlighting limitations of the current KDIGO definition that only uses the functional biomarkers serum creatinine and urine output. The use of novel biomarkers led to the introduction of the concept of "subclinical AKI". This new classification may allow a more distinct management of affected or at risk patients. Ongoing studies, such as BigpAK-2 and PrevProgAKI, investigate the implementation of biomarker-guided interventions in clinical practice and may demonstrate an improvement in patients' outcome. Summary The ongoing scientific efforts surrounding AKI have deepened our understanding of the syndrome prompting an expansion of existing concepts. A future integration of stress and damage biomarkers in AKI management, may lead to an individualized therapy in this area.

Perinatal asphyxia leads to acute kidney damage and increased renal susceptibility in adulthood

Perinatal asphyxia (PA) poses a significant threat to multiple organs, particularly the kidneys. Diagnosing PA-associated kidney injury remains challenging, and treatment options are inadequate. Furthermore, there is a lack of long-term follow-up data regarding the renal implications of PA. In this study, 7-day-old male Wistar rats were exposed to PA using a gas mixture (4% O2; 20% CO2 in N2 for 15 min) to investigate molecular pathways linked to renal tubular damage, hypoxia, angiogenesis, heat shock response, inflammation, and fibrosis in the kidney. In a second experiment, adult rats with a history of PA were subjected to moderate renal ischemia-reperfusion (IR) injury to test the hypothesis that PA exacerbates renal susceptibility. Our results revealed an increased gene expression of renal injury markers (kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin), hypoxic and heat shock factors (hypoxia-inducible factor-1α, heat shock factor-1, and heat shock protein-27), proinflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1), and fibrotic markers (transforming growth factor-β, connective tissue growth factor, and fibronectin) promptly after PA. Moreover, a machine learning model was identified through random forest analysis, demonstrating an impressive classification accuracy (95.5%) for PA. Post-PA rats showed exacerbated functional decline and tubular injury and more intense hypoxic, heat shock, proinflammatory, and profibrotic response after renal IR injury compared with controls. In conclusion, PA leads to subclinical kidney injury, which may increase the susceptibility to subsequent renal damage later in life. In addition, the parameters identified through random forest analysis provide a robust foundation for future biomarker research in the context of PA.NEW & NOTEWORTHY This article demonstrates that perinatal asphyxia leads to subclinical kidney injury that permanently increases renal susceptibility to subsequent ischemic injury. We identified major molecular pathways involved in perinatal asphyxia-induced renal complications, highlighting potential targets of therapeutic approaches. In addition, random forest analysis revealed a model that classifies perinatal asphyxia with 95.5% accuracy that may provide a strong foundation for further biomarker research. These findings underscore the importance of multiorgan follow-up for perinatal asphyxia-affected patients.

Derivation and Validation of an Optimal Neutrophil Gelatinase-Associated Lipocalin Cutoff to Predict Stage 2/3 Acute Kidney Injury (AKI) in Critically Ill Children

Introduction

Acute kidney injury (AKI) defined by changes in serum creatinine (SCr), or oliguria is associated with increased morbidity and mortality in children who are critically ill. We derived and validated a clinical cutoff value for urine neutrophil gelatinase-associated lipocalin (NGAL), in a prospective multicenter study of children who were critically ill. We report the clinical performance of urine NGAL (uNGAL) to aid in pediatric AKI risk assessment.

Methods

Eligible subjects were aged ≥ 90 days to < 22 years, admitted to an intensive care unit (ICU), and had 1 or more of the following: mechanical ventilation, vasoactive medication administration, solid organ or bone marrow transplantation, or hypotension within 24-hours of admission. uNGAL was assessed within 24-hours of admission. The primary outcome was SCr-based stage 2/3 AKI presence at 48- to 72-hours.

Results

Twenty-five (12.3%) derivation study patients had stage 2/3 AKI at 48- to 72-hours. uNGAL concentration of 125 ng/ml was the optimal cutoff. Forty-seven (9.1%) validation study patients had stage 2/3 AKI at 48- to 72-hours. The area under the curve of a receiver operator characteristics curve (AUC-ROC) for uNGAL performance was 0.83 (95% confidence interval [CI]: 0.77-0.90). Performance characteristics were sensitivity 72.3% (95% CI: 57.4%-84.4%), specificity 86.3% (95% CI: 82.8%-89.3%), positive predictive value 34.7% (95% CI: 28.5%-41.5%), and negative predictive value 96.9% (95% CI: 95.1%-98.0%).

Conclusion

These prospective, pediatric, multicenter studies demonstrate that uNGAL in the first 24-hours performs very well to predict Kidney Disease Improving Global Outcomes (KDIGO) stage 2/3 AKI at 48- to 72-hours into an ICU course. We suggest that a uNGAL cut point of 125 ng/ml can aid in the risk assessment for stage 2/3 AKI persistence or development.

The Road to Precision Medicine for Acute Kidney Injury

OBJECTIVES

Acute kidney injury (AKI) is a common form of organ dysfunction in the ICU. AKI is associated with adverse short- and long-term outcomes, including high mortality rates, which have not measurably improved over the past decade. This review summarizes the available literature examining the evidence of the need for precision medicine in AKI in critical illness, highlights the current evidence for heterogeneity in the field of AKI, discusses the progress made in advancing precision in AKI, and provides a roadmap for studying precision-guided care in AKI.

DATA SOURCES

Medical literature regarding topics relevant to precision medicine in AKI, including AKI definitions, epidemiology, and outcomes, novel AKI biomarkers, studies of electronic health records (EHRs), clinical trial design, and observational studies of kidney biopsies in patients with AKI.

STUDY SELECTION

English language observational studies, randomized clinical trials, reviews, professional society recommendations, and guidelines on areas related to precision medicine in AKI.

DATA EXTRACTION

Relevant study results, statements, and guidelines were qualitatively assessed and narratively synthesized.

DATA SYNTHESIS

We synthesized relevant study results, professional society recommendations, and guidelines in this discussion.

CONCLUSIONS

AKI is a syndrome that encompasses a wide range of underlying pathologies, and this heterogeneity has hindered the development of novel therapeutics for AKI. Wide-ranging efforts to improve precision in AKI have included the validation of novel biomarkers of AKI, leveraging EHRs for disease classification, and phenotyping of tubular secretory clearance. Ongoing efforts such as the Kidney Precision Medicine Project, identifying subphenotypes in AKI, and optimizing clinical trials and endpoints all have great promise in advancing precision medicine in AKI.

Trajectory pattern of serially measured acute kidney injury biomarkers in critically ill patients: a prospective observational study

BACKGROUND

The clinical value of the trajectory of temporal changes in acute kidney injury (AKI) biomarkers has not been well established among intensive care unit (ICU) patients.

METHODS

This is a single-center, prospective observational study, performed at a mixed ICU in a teaching medical institute in Tokyo, Japan. Adult ICU patients with an arterial line and urethral catheter were enrolled from September 2014 to March 2015. Patients who stayed in the ICU for less than 48 h and patients with known end-stage renal disease were excluded from the study. Blood and urine samples were collected for measurement of AKI biomarkers at 0, 12, 24, and 48 h after ICU admission. The primary outcome was major adverse kidney events (MAKE) at discharge, defined as a composite of death, dialysis dependency, and persistent loss of kidney function (≥ 25% decline in eGFR).

RESULTS

The study included 156 patients. Serum creatinine-based estimated glomerular filtration rate (eGFR), plasma neutrophil gelatinase-associated lipocalin (NGAL), and urinary liver-type fatty acid-binding protein (uL-FABP) were serially measured and each variable was classified into three groups based on group-based trajectory modeling analysis. While the trajectory curves moved parallel to each other (i.e., "low," "middle," and "high") for eGFR and plasma NGAL, the uL-FABP curves showed distinct trajectory patterns and moved in different directions ("low and constant," "high and exponential decrease," and "high and exponential increase"). These trajectory patterns were significantly associated with MAKE. MAKE occurred in 16 (18%), 16 (40%), and 9 (100%) patients in the "low and constant," "high and exponential decrease," and "high and exponential increase" groups, respectively, based on uL-FABP levels (p-value < 0.001). The initial value and the 12-h change in uL-FABP were both significantly associated with MAKE, even after adjusting for eGFR [Odds ratio (95% confidence interval): 1.45 (1.17-1.83) and 1.43 (1.12-1.88) for increase of initial value and 12-h change of log-transformed uL-FABP by 1 point, respectively].

CONCLUSIONS

Trajectory pattern of serially measured urinary L-FABP was significantly associated with MAKE in ICU patients.

A longitudinal study of the blood and urine metabolome of Vipera berus envenomated dogs

Envenomation of dogs by the common European adder (Vipera berus) is associated with high morbidity. The cytotoxic venom of Vipera berus contains enzymes with the potential to cause acute kidney injury, among other insults, however robust biomarkers for such effects are lacking. A prospective observational follow-up study of naturally envenomated dogs and controls was conducted to fill knowledge gaps regarding canine Vipera berus envenomation, attempt to identify novel biomarkers of envenomation and related kidney injury, and elucidate potential long-term effects. Blood and urine samples were analyzed with a global metabolomics approach using liquid chromatography-mass spectrometry, uncovering numerous features significantly different between cases and controls. After data processing and feature annotation, eight features in blood and 24 features in urine were investigated in order to elucidate their biological relevance. Several of these are associated with AKI, while some may also originate from disturbed fatty acid β-oxidation and soft tissue damage. A metabolite found in both blood and a venom reference sample may represent identification of a venom component in case dogs. Our findings suggest that envenomated dogs treated according to current best practice are unlikely to suffer permanent injury.

[Recent developments in acute kidney injury : Definition, biomarkers, subphenotypes, and management]

Acute kidney injury (AKI) is a common problem in critically ill patients and is associated with increased morbidity and mortality. Since 2012, AKI has been defined according to the KDIGO (Kidney Disease Improving Global Outcome) guidelines. As some biomarkers are now available that can provide useful clinical information, a new definition including a new stage 1S has been proposed by an expert group of the Acute Disease Quality Initiative (ADQI). At this stage, classic AKI criteria are not yet met, but biomarkers are already positive defining subclinical AKI. This stage 1S is associated with a worse patient outcome, regardless of the biomarker chosen. The PrevAKI and PrevAKI-Multicenter trial also showed that risk stratification with a biomarker and implementation of the KDIGO bundle (in the high-risk group) can reduce the rate of moderate and severe AKI. In the absence of a successful clinical trial, conservative management remains the primary focus of treatment. This mainly involves optimization of hemodynamics and an individualized (restrictive) fluid management. The STARRT-AKI trial has shown that there is no benefit from accelerated initiation of renal replacement therapy. However, delaying too long might be associated with potential harm, as shown in the AKIKI2 study. Prospective studies are needed to determine whether artificial intelligence will play a role in AKI in the future, helping to guide treatment decisions and improve outcomes.

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

Evaluation of diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin in patients with symptoms of urinary tract infections: a meta-analysis

Introduction

Early and accurate diagnosis of urinary tract infection (UTI) can prevent serious sequelae including chronic kidney disease. Multiple individual studies have identified urine neutrophil gelatinase-associated lipocalin (uNGAL) as a promising biomarker for early diagnosis of UTI. We sought to understand the distribution and diagnostic accuracy of uNGAL values in patients presenting with UTI symptoms.

Methods

Our systematic literature reviews in PubMed, Embase, and Cochrane Reviews up to March 2024, identified 25 studies reporting mean/median, standard deviation/quartiles, and detection limits of uNGAL in symptomatic patients with and without culture-confirmed UTI. Seventeen studies were in children. Meta-analyses were performed using the quantile estimation (QE) method estimating the distributions of uNGAL, which were then compared between the UTI and non-UTI groups for identifying the best cut-off points maximizing the Youden index. Sensitivity analyses were performed on all 25 studies including adult patients.

Results

We found that uNGAL levels were significantly higher in samples with confirmed UTI compared to those without. In pediatric studies, median and 95% confidence interval (CI) of uNGAL values were 22.41 (95% CI of 9.94, 50.54) ng/mL in non-UTI group vs. 118.85 (95% CI of 43.07, 327.97) ng/mL in UTI group. We estimated the cut-off point of 48.43 ng/mL with highest sensitivity (96%) and specificity (97%) in children. Sensitivity analysis including both pediatric and adult studies yielded similar results.

Discussion

The level of uNGAL in symptomatic patients with confirmed UTI is much higher than that reported in patients without UTI. It may be used as a diagnostic tool to identify UTI early among symptomatic patients. The range of uNGAL concentrations and cut-off points reported in subjects with UTI is much lower than that reported in patients with acute intrinsic kidney injury.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023370451).

Pre-clinical evaluation of biomarkers for the early detection of nephrotoxicity following alpha-particle radioligand therapy

PURPOSE

Cancer treatment with alpha-emitter-based radioligand therapies (α-RLTs) demonstrates promising tumor responses. Radiolabeled peptides are filtered through glomeruli, followed by potential reabsorption of a fraction by proximal tubules, which may cause acute kidney injury (AKI) and chronic kidney disease (CKD). Because tubular cells are considered the primary site of radiopeptides' renal reabsorption and potential injury, the current use of kidney biomarkers of glomerular functional loss limits the evaluation of possible nephrotoxicity and its early detection. This study aimed to investigate whether urinary secretion of tubular injury biomarkers could be used as an additional non-invasive sensitive diagnostic tool to identify unrecognizable tubular damage and risk of long-term α-RLT nephrotoxicity.

METHODS

A bifunctional cyclic peptide, melanocortin 1 ligand (MC1L), labeled with [203Pb]Pb-MC1L, was used for [212Pb]Pb-MC1L biodistribution and absorbed dose measurements in CD-1 Elite mice. Mice were treated with [212Pb]Pb-MC1L in a dose-escalation study up to levels of radioactivity intended to induce kidney injury. The approach enabled prospective kidney functional and injury biomarker evaluation and late kidney histological analysis to validate these biomarkers.

RESULTS

Biodistribution analysis identified [212Pb]Pb-MC1L reabsorption in kidneys with a dose deposition of 2.8, 8.9, and 20 Gy for 0.9, 3.0, and 6.7 MBq injected [212Pb]Pb-MC1L doses, respectively. As expected, mice receiving 6.7 MBq had significant weight loss and CKD evidence based on serum creatinine, cystatin C, and kidney histological alterations 28 weeks after treatment. A dose-dependent urinary neutrophil gelatinase-associated lipocalin (NGAL, tubular injury biomarker) urinary excretion the day after [212Pb]Pb-MC1L treatment highly correlated with the severity of late tubulointerstitial injury and histological findings.

CONCLUSION

Urine NGAL secretion could be a potential early diagnostic tool to identify unrecognized tubular damage and predict long-term α-RLT-related nephrotoxicity.

Plasma neutrophil gelatinase-associated lipocalin independently predicts dialysis need and mortality in critical COVID-19

Neutrophil gelatinase-associated lipocalin (NGAL) is a novel kidney injury and inflammation biomarker. We investigated whether NGAL could be used to predict continuous renal replacement therapy (CRRT) and mortality in critical coronavirus disease 2019 (COVID-19). This prospective multicenter cohort study included adult COVID-19 patients in six intensive care units (ICUs) in Sweden between May 11, 2020 and May 10, 2021. Blood was sampled at admission, days two and seven in the ICU. The samples were batch analyzed for NGAL, creatinine, and cystatin c after the end of the study period. Initiation of CRRT and 90-day survival were used as dependent variables in regression models. Of 498 included patients, 494 were analyzed regarding CRRT and 399 were analyzed regarding survival. Seventy patients received CRRT and 154 patients did not survive past 90 days. NGAL, in combination with creatinine and cystatin c, predicted the subsequent initiation of CRRT with an area under the curve (AUC) of 0.95. For mortality, NGAL, in combination with age and sex, had an AUC of 0.83. In conclusion, NGAL is a valuable biomarker for predicting subsequent initiation of CRRT and 90-day mortality in critical COVID-19. NGAL should be considered when developing future clinical scoring systems.

Acute kidney injury after cardiac surgery

PURPOSE OF REVIEW

Patients undergoing cardiac surgery are at high risk to develop cardiac surgery-associated acute kidney injury (CS-AKI) postoperatively. CS-AKI is associated with an increased risk for persistent renal dysfunction, morbidity and mortality. This review summarizes the epidemiology and pathophysiology of CS-AKI, as well as current treatment and prevention strategies.

RECENT FINDINGS

As AKI is a syndrome with complex pathophysiology, no causative treatment strategies exist. Recent advances in the field of AKI biomarkers offer new perspectives on the issue and the implementation of biomarker-guided preventive strategies may reduce rates of CS-AKI. Finally, nephroprotective treatments and angiotensin II as a novel vasopressor may offer new opportunities for high-risk patients undergoing cardiac surgery.

SUMMARY

Based on the described novel approaches for early detection, prevention and management of CS-AKI, a precision-medicine approach should be implemented in order to prevent the development of AKI in patients undergoing cardiac surgery.

Renal Biomarkers in Heart Failure: Systematic Review and Meta-Analysis

Background

Cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule (KIM)-1 are renal biomarkers increasingly appreciated for their role in the risk stratification and prognostication of heart failure (HF) patients. However, very few have been adopted clinically, owing to the lack of consistency.

Objectives

The authors aimed to study the association between cystatin C, NGAL, and KIM-1 and outcomes, mortality, hospitalizations, and worsening renal function (WRF) in patients with acute and chronic HF.

Methods

We included peer-reviewed English-language articles from PubMed and EMBASE published up to December 2021. We analyzed the above associations using random-effects meta-analysis. Publication bias was assessed using funnel plots.

Results

Among 2,631 articles, 100 articles, including 45,428 patients, met the inclusion criteria. Top-tertile of serum cystatin C, when compared to the bottom-tertile, carried a higher pooled hazard ratio (pHR) for mortality (pHR: 1.59, 95% CI: 1.42-1.77) and for the composite outcome of mortality and HF hospitalizations (pHR: 1.49, 95% CI: 1.23-1.75). Top-tertile of serum NGAL had a higher hazard for mortality (pHR: 2.91, 95% CI: 1.49-5.67) and composite outcome (HR: 4.11, 95% CI: 2.69-6.30). Serum and urine NGAL were significantly associated with WRF, with pHRs of 2.40 (95% CI: 1.48-3.90) and 2.01 (95% CI: 1.21-3.35). Urine KIM-1 was significantly associated with WRF (pHR: 1.60, 95% CI: 1.24-2.07) but not with other outcomes. High heterogeneity was noted between studies without an obvious explanation based on meta-regression.

Conclusions

Serum cystatin C and serum NGAL are independent predictors of adverse outcomes in HF. Serum and urine NGAL are important predictors of WRF in HF.

Designing acute kidney injury clinical trials

Acute kidney injury (AKI) is a common clinical condition with various causes and is associated with increased mortality. Despite advances in supportive care, AKI increases not only the risk of premature death compared with the general population but also the risk of developing chronic kidney disease and progressing towards kidney failure. Currently, no specific therapy exists for preventing or treating AKI other than mitigating further injury and supportive care. To address this unmet need, novel therapeutic interventions targeting the underlying pathophysiology must be developed. New and well-designed clinical trials with appropriate end points must be subsequently designed and implemented to test the efficacy of such new interventions. Herein, we discuss predictive and prognostic enrichment strategies for patient selection, as well as primary and secondary end points that can be used in different clinical trial designs (specifically, prevention and treatment trials) to evaluate novel interventions and improve the outcomes of patients at a high risk of AKI or with established AKI.

PAI-1 as a critical factor in the resolution of sepsis and acute kidney injury in old age

Elevated plasma levels of plasminogen activator inhibitor type 1 (PAI-1) are documented in patients with sepsis and levels positively correlate with disease severity and mortality. Our prior work demonstrated that PAI-1 in plasma is positively associated with acute kidney injury (AKI) in septic patients and mice. The objective of this study was to determine if PAI-1 is causally related to AKI and worse sepsis outcomes using a clinically-relevant and age-appropriate murine model of sepsis. Sepsis was induced by cecal slurry (CS)-injection to wild-type (WT, C57BL/6) and PAI-1 knockout (KO) mice at young (5-9 months) and old (18-22 months) age. Survival was monitored for at least 10 days or mice were euthanized for tissue collection at 24 or 48 h post-insult. Contrary to our expectation, PAI-1 KO mice at old age were significantly more sensitive to CS-induced sepsis compared to WT mice (24% vs. 65% survival, p = 0.0037). In comparison, loss of PAI-1 at young age had negligible effects on sepsis survival (86% vs. 88% survival, p = 0.8106) highlighting the importance of age as a biological variable. Injury to the kidney was the most apparent pathological consequence and occurred earlier in aged PAI-1 KO mice. Coagulation markers were unaffected by loss of PAI-1, suggesting thrombosis-independent mechanisms for PAI-1-mediated protection. In summary, although high PAI-1 levels are clinically associated with worse sepsis outcomes, loss of PAI-1 rendered mice more susceptible to kidney injury and death in a CS-induced model of sepsis using aged mice. These results implicate PAI-1 as a critical factor in the resolution of sepsis in old age.

New biomarkers in acute kidney injury

Acute kidney injury (AKI) is a commonly encountered clinical syndrome. Although it often complicates community acquired illness, it is more common in hospitalized patients, particularly those who are critically ill or who have undergone major surgery. Approximately 20% of hospitalized adult patients develop an AKI during their hospital care, and this rises to nearly 60% in the critically ill, depending on the population being considered. In general, AKI is more common in older adults, in those with preexisting chronic kidney disease and in those with known risk factors for AKI (including diabetes and hypertension). The development of AKI is associated with an increase in both mortality and morbidity, including the development of post-AKI chronic kidney disease. Currently, AKI is defined by a rise in serum creatinine from either a known or derived baseline value and/or oliguria or anuria. However, clinicians may fail to recognize the initial development of AKI because of a delay in the rise of serum creatinine or because of inaccurate urine output monitoring. This, in turn, delays any putative measures to treat AKI or to limit its degree. Consequently, efforts have focused on new biomarkers associated with AKI that may allow early recognition of this syndrome with the intent that this will translate into improved patient outcomes. Here we outline current biomarkers associated with AKI and explore their potential in aiding diagnosis, understanding the pathophysiology and directing therapy.

Real-Time Acute Kidney Injury Risk Stratification-Biomarker Directed Fluid Management Improves Outcomes in Critically Ill Children and Young Adults

Introduction

Critically ill admitted patients are at high risk of acute kidney injury (AKI). The renal angina index (RAI) and urinary biomarker neutrophil gelatinase-associated lipocalin (uNGAL) can aid in AKI risk assessment. We implemented the Trial in AKI using NGAL and Fluid Overload to optimize CRRT Use (TAKING FOCUS 2; TF2) to personalize fluid management and continuous renal replacement therapy (CRRT) initiation based on AKI risk and patient fluid accumulation. We compared outcomes pre-TF2 and post-TF2 initiation.

Methods

Patients admitted from July 2017 were followed-up prospectively with the following: (i) an automated RAI result at 12 hours of admission, (ii) a conditional uNGAL order for RAI ≥8, and (iii) a CRRT initiation goal at 10% to 15% weight-based fluid accumulation.

Results

A total of 286 patients comprised 304 intensive care unit (ICU) RAI+ admissions; 178 patients received CRRT over the observation period (2014-2021). Median time from ICU admission to CRRT initiation was 2 days shorter (P < 0.002), and ≥15% pre-CRRT fluid accumulation rate was lower in the TF2 era (P < 0.02). TF2 ICU length of stay (LOS) after CRRT discontinuation and total ICU LOS were 6 and 11 days shorter for CRRT survivors (both P < 0.02). Survival rates to ICU discharge after CRRT discontinuation were higher in the TF2 era (P = 0.001). These associations persisted in each TF2 year; we estimate a conservative $12,500 health care cost savings per CRRT patient treated after TF2 implementation.

Conclusion

We suggest that automated clinical decision support (CDS) combining risk stratification and AKI biomarker assessment can produce durable reductions in pediatric CRRT patient morbidity.

Personalized acute kidney injury treatment

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a complex syndrome that might be induced by different causes and is associated with an increased morbidity and mortality. Therefore, it is a very heterogeneous syndrome and establishing a "one size fits all" treatment approach might not work. This review aims to examine the potential of personalized treatment strategies for AKI.

RECENT FINDINGS

The traditional diagnosis of AKI is based on changes of serum creatinine and urine output, but these two functional biomarkers have several limitations. Recent research identified different AKI phenotypes based on clinical features, biomarkers, and pathophysiological pathways. Biomarkers, such as Cystatin C, NGAL, TIMP2∗IGFBP7, CCL14, and DKK-3, have shown promise in predicting AKI development, renal recovery, and prognosis. Biomarker-guided interventions, such as the implementation of the KDIGO bundle, have demonstrated an improvement in renal outcomes in specific patient groups.

SUMMARY

A personalized approach to AKI treatment as well as research is becoming increasingly important as it allows the identification of distinct AKI phenotypes and the potential for targeted interventions. By utilizing biomarkers and clinical features, physicians might be able to stratify patients into subphenotypes, enabling more individualized treatment strategies. This review highlights the potential of personalized AKI treatment, emphasizing the need for further research and large-scale clinical trials to validate the efficacy of these approaches.

Biomarker Enrichment in Sepsis-Associated Acute Kidney Injury: Finding High-Risk Patients in the Intensive Care Unit

BACKGROUND

Sepsis-associated acute kidney injury (AKI) is a leading comorbidity in admissions to the intensive care unit. While a gold standard definition exists, it remains imperfect and does not allow for the timely identification of patients in the setting of critical illness. This review will discuss the use of biochemical and electronic biomarkers to allow for prognostic and predictive enrichment of patients with sepsis-associated AKI over and above the use of serum creatinine and urine output.

SUMMARY

Current data suggest that several biomarkers are capable of identifying patients with sepsis at risk for the development of severe AKI and other associated morbidity. This review discusses these data and these biomarkers in the setting of sub-phenotyping and endotyping sepsis-associated AKI. While not all these tests are widely available and some require further validation, in the near future we anticipate several new tools to help nephrologists and other providers better care for patients with sepsis-associated AKI.

KEY MESSAGES

Predictive and prognostic enrichment using both traditional biomarkers and novel biomarkers in the setting of sepsis can identify subsets of patients with either similar outcomes or similar pathophysiology, respectively. Novel biomarkers can identify kidney injury in patients without consensus definition AKI (e.g., changes in creatinine or urine output) and can predict other adverse outcomes (e.g., severe consensus definition AKI, inpatient mortality). Finally, emerging artificial intelligence and machine learning-derived risk models are able to predict sepsis-associated AKI in critically ill patients using advanced learning techniques and several laboratory and vital sign measurements.

Diagnostic value and utility of commonly used biomarkers of cardiac and renal function in cardiorenal syndromes: a narrative review

Cardiorenal syndrome (CRS), first defined in 2004 as a consequence of the interactions between the kidneys and other circulatory departments leading to acute heart failure, has since been recognized as a complex clinical entity that is hard to define, diagnose and classify. The framework for the classification of CRS according to pathophysiologic background was laid out in 2008, dividing CRS into five distinct phenotypes. However, determining the timing of individual organ injuries and making a diagnosis of either renal or cardiac failure remains an elusive task. In clinical practice, the diagnosis and phenotyping of CRS is mostly based on using laboratory biomarkers in order to directly or indirectly estimate the degree of end-organ functional decline. Therefore, a well-educated clinician should be aware of the effects that the reduction of renal and cardiac function has on the diagnostic and predictive value and properties of the most commonly used biomarkers (e.g. troponins, N-terminal pro-brain natriuretic peptide, serum creatinine etc). They should also be acquainted, on a basic level, with emerging biomarkers that are specific to either the degree of glomerular integrity (cystatin C) or tubular injury (neutrophil gelatinase-associated lipocalin). This narrative review aims to provide a scoping overview of the different roles that biomarkers play in both the diagnosis of CRS and the prognosis of the disease in patients who have been diagnosed with it, along with highlighting the most important pitfalls in their interpretation in the context of impaired renal and/or cardiac function.

Incidences of and risk factors for clinical and subclinical contrast-associated acute kidney injury in patients who underwent neuroendovascular surgery

BACKGROUND

Contrast-associated acute kidney injury (CA-AKI) can develop after intravascular administration of iodinated contrast media. Neutrophil gelatinase-associated lipocalin (NGAL) is an early marker for AKI that helps to detect subclinical CA-AKI. We investigated the incidence of and risk factors for clinical and subclinical CA-AKI in patients who underwent neuroendovascular surgery.

METHODS

We retrospectively investigated 228 patients who underwent neuroendovascular surgery in 2020. Changes in serum creatinine and urine output were used to detect clinical CA-AKI. Urine NGAL concentration was used to detect subclinical CA-AKI in 67 out of 228 patients.

RESULTS

In 228 patients, serum creatinine, hemoglobin, hematocrit, total protein, and blood urea nitrogen (BUN) decreased significantly (p < 0.001) after surgery. However, serum creatinine decreased less significantly (p < 0.05) than hemoglobin, hematocrit, total protein, and BUN on postoperative Day 3. Two patients out of 228 developed clinical CA-AKI, and seven patients out of 67 with urine NGAL measurements developed subclinical CA-AKI. Multivariate regression analysis revealed that diabetes mellitus and carotid artery stenosis were significantly (p < 0.05) associated with the development of clinical and/or subclinical CA-AKI.

CONCLUSION

There was a large difference between the incidences of clinical CA-AKI (0.88%) and subclinical CA-AKI (10.4%). The difference might have primarily resulted from the different sensitivities between serum creatinine and urine NGAL and possibly from underestimation of the incidence of clinical AKI due to a postoperative decrease in serum creatinine caused by hemodilution. In addition to diabetes mellitus, carotid artery stenosis could also be a risk factor for CA-AKI.

Subclinical and clinical acute kidney injury share similar urinary peptide signatures and prognosis

PURPOSE

Acute kidney injury (AKI) is a frequent and severe condition in intensive care units (ICUs). In 2020, the Acute Dialysis Quality Initiative (ADQI) group proposed a new stage of AKI, referred to as stage 1S, which represents subclinical disease (sAKI) defined as a positive biomarker but no increase in serum creatinine (sCr). This study aimed to determine and compare the urinary peptide signature of sAKI as defined by biomarkers.

METHODS

This is an ancillary analysis of the prospective, observational, multinational FROG-ICU cohort study. AKI was defined according to the Kidney Disease Improving Global Outcome definition (AKIKDIGO). sAKI was defined based on the levels of the following biomarkers, which exceeded the median value: neutrophil gelatinase-associated lipocalin (pNGAL, uNGAL), cystatin C (pCysC, uCysC), proenkephalin A 119-159 (pPENKID) and liver fatty acid binding protein (uLFABP). Urinary peptidomics analysis was performed using capillary electrophoresis-mass spectrometry. Samples were collected at the time of study inclusion.

RESULTS

One thousand eight hundred eighty-five patients had all biomarkers measured at inclusion, which included 1154 patients without AKI (non-AKIKDIGO subgroup). The non-AKIKDIGO subgroup consisted of individuals at a median age of 60 years [48, 71], among whom 321 (27.8%) died. The urinary peptide signatures of sAKI, regardless of the biomarkers used for its definition, were similar to the urinary peptide signatures of AKIKDIGO (inflammation, haemolysis, and endothelial dysfunction). These signatures were also associated with 1-year mortality.

CONCLUSION

Biomarker-defined sAKI is a common and severe condition observed in patients within intensive care units with a urinary peptide signature that is similar to that of AKI, along with a comparable prognosis.

The effects of perioperative goal-directed therapy on acute kidney injury after cardiac surgery in the early period

Background: This study aims to investigate the effects of goaldirected fluid therapy on the development of acute kidney injury in the perioperative period in patients undergoing cardiopulmonary bypass. Methods: Between November 2019 and May 2021, a total of 60 patients (46 males, 14 females; mean age: 62.5±9.6 years; range, 44 to 76 years) who were scheduled for elective coronary artery bypass grafting or valve surgery under cardiopulmonary bypass were included in the study. The patients were divided into two groups as the study group (Group S, n=30) and control group (Group C, n=30). The patients in Group C were treated with standard therapy, while the patients in Group S were treated with goal-directed fluid therapy. The Kidney Disease: Improving Global Outcomes (KDIGO) classification and renal biomarkers were used for the evaluation of acute kidney injury. Results: Acute kidney injury rates were similar in both groups (30%). Postoperative fluid requirement, intra-, and postoperative erythrocyte suspension requirements were significantly lower in Group S than Group C (p=0.002, p=0.02, and p=0.002, respectively). Cystatin-C was lower in Group S (p<0.002). The kidney injury molecule-1, glomerular filtration rate, and creatinine levels were similar in both groups. The length of hospital stay was longer in Group C than Group S (p<0.001). Conclusion: Although goal-directed fluid therapy does not change the incidence of acute kidney injury in patients undergoing cardiac surgery, it can significantly decrease Cystatin-C levels. Goal-directed fluid therapy can also decrease fluid and erythrocyte requirements with shorter length of hospital stay.

Pre-clinical Evaluation of Biomarkers for Early Detection of Nephrotoxicity Following Alpha-particle Radioligand Therapy

Purpose

Cancer treatment with alpha-emitter-based radioligand therapies (α-RLTs) demonstrates promising tumor responses. Radiolabeled peptides are filtered through glomeruli, followed by potential reabsorption of a fraction by proximal tubules, which may cause acute kidney injury (AKI) and chronic kidney disease (CKD). Because tubular cells are considered the primary site of radiopeptides' renal reabsorption and potential injury, the current use of kidney biomarkers of glomerular functional loss limits the evaluation of possible nephrotoxicity and its early detection. This study aimed to investigate whether urinary secretion of tubular injury biomarkers could be used as additional non-invasive sensitive diagnostic tool to identify unrecognizable tubular damage and risk of long-term α-RLTs nephrotoxicity.

Methods

A bifunctional cyclic peptide, melanocortin ligand-1(MC1L), labeled with [ 203 Pb]Pb-MC1L, was used for [ 212 Pb]Pb-MC1L biodistribution and absorbed dose measurements in CD-1 Elite mice. Mice were treated with [ 212 Pb]Pb-MC1L in a dose escalation study up to levels of radioactivity intended to induce kidney injury. The approach enabled prospective kidney functional and injury biomarker evaluation and late kidney histological analysis to validate these biomarkers.

Results

Biodistribution analysis identified [ 212 Pb]Pb-MC1L reabsorption in kidneys with a dose deposition of 2.8, 8.9, and 20 Gy for 0.9, 3.0, and 6.7 MBq injected [ 212 Pb]Pb-MC1L doses, respectively. As expected, mice receiving 6.7 MBq had significant weight loss and CKD evidence based on serum creatinine, cystatin C, and kidney histological alterations 28 weeks after treatment. A dose-dependent urinary Neutrophil gelatinase-associated lipocalin (NGAL, tubular injury biomarker) urinary excretion the day after [ 212 Pb]Pb-MC1L treatment highly correlated with the severity of late tubulointerstitial injury and histological findings.

Conclusion

urine NGAL secretion could be a potential early diagnostic tool to identify unrecognized tubular damage and predict long-term α-RLT-related nephrotoxicity.

Early recognition and prevention of acute kidney injury in hospitalised children

Acute kidney injury is common in hospitalised children and is associated with poor patient outcomes. Once acute kidney injury occurs, effective therapies to improve patient outcomes or kidney recovery are scarce. Early identification of children at risk of acute kidney injury or at an early injury stage is essential to prevent progression and mitigate complications. Paediatric acute kidney injury is under-recognised by clinicians, which is a barrier to optimisation of inpatient care and follow-up. Acute kidney injury definitions rely on functional biomarkers (ie, serum creatinine and urine output) that are inadequate, since they do not account for biological variability, analytical issues, or physiological responses to volume depletion. Improved predictive tools and diagnostic biomarkers of kidney injury are needed for earlier detection. Novel strategies, including biomarker-guided care algorithms, machine-learning methods, and electronic alerts tied to clinical decision support tools, could improve paediatric acute kidney injury care. Clinical prediction models should be studied in different paediatric populations and acute kidney injury phenotypes. Research is needed to develop and test prevention strategies for acute kidney injury in hospitalised children, including care bundles and therapeutics.

Monitoring Renal Function in HIV Patients Without Kidney Disease Using Endothelial Biomarkers: A Prospective Pilot Study

This study aimed to investigate the association between novel biomarkers and renal injury in people with HIV (PWH). A cohort study was carried out with PWH under chronic use of antiretroviral therapy (ART), followed at a public outpatient service. Clinical and laboratory parameters of the patients were evaluated year by year, from 2015 [at baseline (year 1, Y1)] to 2019 [year 5 (Y5)]. At baseline, biomarkers of renal damage (e.g., neutrophil gelatinase-associated lipocalin-NGAL, monocyte chemoattractant protein-1-MCP-1, and kidney injury molecule-1-KIM-1) and endothelial activation or glycocalyx damage [e.g., intercellular adhesion molecule 1 (ICAM-1), E-selectin, and syndecan-1] were quantified using enzyme-linked immunosorbent assays and their levels were used to classify patients into different groups. However, only syndecan-1 showed a significant correlation with serum creatinine (p < .001) and glomerular filtration rate (GFR) (p = .003) over the years. Moreover, both serum creatinine and GFR in almost 5 years were significantly associated with serum levels of syndecan-1 at baseline. The multivariate linear regression with confounders showed a significant and independent association between GFR and levels of syndecan-1 and CD4 cell count in the beginning of the study, as well as age in Y5. The data reinforce the screening for kidney diseases with novel biomarkers, especially syndecan-1, as an important strategy for a timely diagnostic and therapeutic approach.

Effects of 20% albumin infusion therapy during liver transplantation on plasma neutrophil gelatinase-associated lipocalin level: A randomized controlled trial

The risk of acute kidney injury (AKI) after liver transplantation was lower in patients with serum albumin levels ≥3.0 mg/dL during surgery. We tested whether intraoperative infusion of 20% albumin affects neutrophil gelatinase-associated lipocalin (NGAL) level, a reliable indicator of AKI. We randomly assigned 134 patients undergoing liver transplantation into albumin group (n=70, 20% albumin 200 mL) and the control group (n=66, crystalloid solution 200 mL). The 2 study fluids were infused at 100 mL/h from the start of the anhepatic phase. The primary outcome was plasma NGAL level at 1 hour after graft reperfusion. Albumin level at the start of graft reperfusion was significantly greater in albumin group than in the control group [2.9 (2.4-3.3) g/dL vs. 2.3 (2.0-2.7) g/dL, p <0.001]. The NGAL level at 1 hour after graft reperfusion was not significantly different between the 2 groups [100.2 (66.7-138.8) ng/mL vs. 92.9 (70.8-120.6) ng/mL, p =0.46], and the AKI risk was not either (63.9% vs. 67.8%, adjusted p =0.73). There were no significant differences between the 2 groups regarding hospital readmission within 30 days/90 days after transplantation (32.6% vs. 41.5%, adjusted p =0.19 and 55.0% vs. 55.7%, adjusted p =0.87). Graft survival probability at 30 days/90 days/1 year after transplantation was 90.0%/84.3%/78.6% in albumin group and 97.0%/90.9%/89.4% in the control group [HR=1.6 (0.6-4.0), adjusted p =0.31]. In conclusion, intraoperative infusion of 20% albumin 200 mL increased the albumin level but failed to maintain serum albumin ≥3.0 mg/dL during surgery. The hypertonic albumin therapy did not significantly affect plasma NGAL level and clinical outcomes including AKI.

Risk factors associated with contrast-associated acute kidney injury in ST-segment elevation myocardial infarction patients: a systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis was to evaluate the risk factors for contrast-associated acute kidney injury (CA-AKI) in ST-elevation myocardial infarction patients treated with primary percutaneous coronary intervention.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We searched the databases of PubMed, Embase and Ovid, up to February 2022, for observational studies that investigated the association between risk factors and CA-AKI.

RESULTS

A total of 21 studies were included in the meta-analysis. Of the total 22 015 participants, 2728 developed CA-AKI. Pooled incidence was 11.91% (95% CI 9.69%, 14.14%). Patients with CA-AKI were more likely to be older, female, also had comorbidities (hypertension, diabetes, previous heart failure). Smoking (OR: 0.60; 95% CI 0.52, 0.69) and family history of CAD (coronary artery disease) (OR: 0.76; 95% CI 0.60, 0.95) were associated with lower risk of CA-AKI. Left anterior descending (LAD) artery occlusion (OR: 1.39; 95% CI 1.21, 1.59), left main disease (OR: 4.62; 95% CI 2.24, 9.53) and multivessel coronary disease (OR: 1.33; 95% CI 1.11, 1.60) were risk factors for CA-AKI. Contrast volume (weighted mean difference: 20.40; 95% CI 11.02, 29.79) was associated with increased risk in patients receiving iso-osmolar or low-osmolar non-ionic contrast.

CONCLUSIONS

In addition to the known risk factors, LAD artery infarction, left main disease and multivessel disease are risk factors for CA-AKI. The unexpected favourable association between smoking, as well as family history of CAD, and CA-AKI requires further investigation.

PROSPERO REGISTRATION NUMBER

CRD42021289868.

A risk-stratified assessment of biomarker-based acute kidney injury phenotypes in children

BACKGROUND

The functional acute kidney injury (AKI) diagnostic tests serum creatinine (SCr) and urine output are imprecise and make management challenging. Combining tubular injury biomarkers with functional markers reveal AKI phenotypes that may facilitate personalized care. However, when and in whom to obtain injury biomarkers remains unclear.

METHODS

This was a prospective, observational study of patients admitted to a pediatric intensive care unit (PICU). Using the Renal Angina Index (RAI), subjects were screened for the presence (RAI+) or absence (RAI-) of renal angina 12 h post-admission and assigned an AKI phenotype using urinary NGAL (NGAL+: ≥150 ng/ml) and SCr (SCr+: ≥KDIGO Stage 1). Outcomes for each AKI phenotype were assessed and compared by RAI status.

RESULTS

In all, 200/247 (81%) subjects were RAI+. RAI+ subjects who were NGAL+ had higher risk of Day 3 AKI, renal replacement therapy use, and mortality and fewer ventilator- and PICU-free days, compared to NGAL-, irrespective of Day 0 SCr. Similar findings were not demonstrated in RAI- subjects, though NGAL+/SCr+ was associated with fewer ventilator- and PICU-free days compared to NGAL-/SCr+.

CONCLUSIONS

NGAL- and SCr-based AKI phenotypes provide improved prognostic information in children with renal angina (RAI+) and/or with SCr elevation. These populations may be appropriate for targeted biomarker testing.

IMPACT

New consensus recommendations encourage the integration of kidney tubular injury biomarkers such as urinary NGAL with serum creatinine for diagnosis and staging of acute kidney injury; however, no structured testing framework exists guiding when to test and in whom. Urinary NGAL- and serum creatinine-based acute kidney injury phenotypes increase diagnostic precision in critically ill children experiencing renal angina (RAI+) or serum creatinine-defined acute kidney injury. These data provide preliminary evidence for a proposed framework for directed urinary NGAL assessment in the pediatric intensive care unit.

Biomarkers for acute kidney injury in children - where are we now?

PURPOSE OF REVIEW

Review the literature over the last 2 years on commonly evaluated biomarkers of acute kidney injury (AKI) and highlight the findings of these biomarkers.

RECENT FINDINGS

Among several studied AKI biomarkers, urine neutrophil gelatinase-associated lipocalin (NGAL) and the combination of urine tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) have been recently studied most frequently as diagnostic biomarkers of AKI and for AKI risk stratification. Urine NGAL has continued to show good discriminative value to predict and diagnose AKI in childhood. Urine TIMP-2∗IGFBP7 can provide modest improvement to clinical models of AKI.

SUMMARY

Prior research supports that AKI biomarkers may identify AKI at an earlier time point and indicate clinically meaningful tubular injury. More effort should be made to understand if AKI biomarkers can guide treatments and improve outcomes.

The outcome of acute kidney injury substages based on urinary cystatin C in critically ill children

BACKGROUND

The concept of acute kidney injury (AKI) substages has been recommended to better phenotype AKI and identify high-risk patient groups and therefore improve the diagnostic accuracy of AKI. However, there remains a gap between the recommendation and the clinical application. The study aimed to explore the incidence of AKI substages based on a sensitive AKI biomarker of urinary cystatin C (uCysC), and to determine whether AKI substages were relevant with respect to outcome in critically ill children.

RESULTS

The multicenter cohort study enrolled 793 children in pediatric intensive care unit (PICU) of four tertiary hospitals in China. Children were classified as non-AKI, sub-AKI and AKI substages A and B according to uCysC level at PICU admission. Sub-AKI was defined by admission uCysC level ≥ 1.26 mg/g uCr in children not meeting the KDIGO criteria of AKI. In children who fulfilled KDIGO criteria, those with uCysC < 1.26 was defined as AKI substage A, and with ≥ 1.26 defined as AKI substage B. The associations of AKI substages with 30-day PICU mortality were assessed. 15.6% (124/793) of patients met the definition of sub-AKI. Of 180 (22.7%) patients with AKI, 90 (50%) had uCysC-positive AKI substage B and were more likely to have classical AKI stage 3, compared to substage A. Compared to non-AKI, sub-AKI and AKI substages A and B were risk factors significantly associated with mortality, and the association of sub-AKI (adjusted hazard ratio HR = 2.42) and AKI substage B (adjusted HR = 2.83) with mortality remained significant after adjustment for confounders. Moreover, AKI substage B had increased risks of death as compared with sub-AKI (HR = 3.10) and AKI substage A (HR = 3.19).

CONCLUSIONS

Sub-AKI defined/based on uCysC occurred in 20.2% of patients without AKI and was associated with a risk of death close to patients with AKI substage A. Urinary CysC-positive AKI substage B occurred in 50% of AKI patients and was more likely to have classical AKI stage 3 and was associated with the highest risk of mortality.

NGAL as Biomarker of Clinical and Subclinical Damage of Kidney Function after Coronary Angiography

Contrast-induced acute kidney injury (CI-AKI) is a serious complication after angiographic examinations in cardiology. Diagnosis may be delayed based on standard serum creatinine, and subclinical forms of kidney damage may not be detected at all. In our study, we investigate the clinical use in these directions of a “damage”-type biomarker—neutrophil gelatinase-associated lipocalin (NGAL). Among patients with a high-risk profile undergoing scheduled coronary angiography and/or angioplasty, plasma NGAL was determined at baseline and at 4th and 24th h after contrast administration. In the CI-AKI group, NGAL increased significantly at the 4th hour (Me 109.3 (IQR 92.1–148.7) ng/mL versus 97.6 (IQR 69.4–127.0) ng/mL, p = 0.006) and at the 24th hour (Me 131.0 (IQR 81.1–240.8) ng/mL, p = 0.008). In patients with subclinical CI-AKI, NGAL also increased significantly at the 4th hour (Me 94.0 (IQR 75.5–148.2) ng/mL, p = 0.002) and reached levels close to those in patients with CI-AKI. Unlike the new biomarker, however, serum creatinine did not change significantly in this group. The diagnostic power of NGAL is extremely good—AUC 0.847 (95% CI: 0.677–1.000; p = 0.001) in CI-AKI and AUC 0.731 (95% CI: 0.539–0.924; p = 0.024) in subclinical CI-AKI. NGAL may be a reliable biomarker for the early diagnosis of clinical and subclinical forms of renal injury after contrast angiographic studies.

Definitions, phenotypes, and subphenotypes in acute kidney injury-Moving towards precision medicine

The current definition of acute kidney injury (AKI) is generic and, based only on markers of function, is unsuitable for guiding individualized treatment. AKI is a complex syndrome with multiple presentations and causes. Targeted AKI management will only be possible if different phenotypes and subphenotypes of AKI are recognised, based on causation and related pathophysiology. Molecular signatures to identify subphenotypes are being recognised, as specific biomarkers reveal activated pathways. Assessment of individual clinical risk needs wider dissemination to allow identification of patients at high risk of AKI. New and more timely markers for glomerular filtration rate (GFR) are available. However, AKI diagnosis and classification should not be limited to GFR, but include tubular function and damage. Combining damage and stress biomarkers with functional markers enhances risk prediction, and identifies a population enriched for clinical trials targeting AKI. We review novel developments and aim to encourage implementation of these new techniques into clinical practice as a strategy for individualizing AKI treatment akin to a precision medicine-based approach.

The von Hippel-Lindau Tumor Suppressor Gene Mutations Modulate Lipocalin-2 Expression in Ferroptotic-Inflammatory Pathways

A previous study of an animal model with tumor suppressor gene von Hippel-Lindau (VHL) conditional knockdown suggested that tissue inflammation and fibrosis play important roles in the development of clear-cell renal cell carcinoma (ccRCC), which is consistent with the epidemiological evidence linking inflammatory kidney disease and renal cancer. Ferroptosis and inflammation have been linked in a recent study, but the exact mechanism remains unclear. This study is aimed at investigating the mechanism of lipocalin-2- (LCN-2-) mediated ferroptosis and inflammation in vhl-mutated HK-2 cells and mouse primary proximal tubule cells (mRTCs) and the polarization of macrophage RAW 264.7 cells. Based on the levels of lipid reactive oxygen species (ROS) and the expression of glutathione peroxidase 4 (GPX4) in HK-2 cells, we observed that a VHL mutation increased ROS production and depressed GPX4 expression, whereas LCN-2 knockdown reversed these effects. Accordingly, VHL appears to affect ferroptosis in an LCN-2-dependent manner. We also revealed that LCN-2 sensitizes HK-2 cells to inflammation and macrophage RAW 264.7 cells to M1-like polarization. This study provides novel insights into the potential therapeutic target and strategy for attenuating the progression of ccRCC by revealing the role of VHL in regulating chronic inflammation within the LCN-2-ferroptosis pathway.

Renal medicine in the intensive care unit: a narrative review

Kidney disease, both acute and chronic, is commonly encountered on the intensive care unit. Due to the role the kidneys play in whole body homeostasis, it follows that their dysfunction has wide-ranging implications and can affect prescribing and therapeutic management. This narrative review discusses the pathophysiology of acute kidney injury and chronic kidney disease, and how this relates to critically unwell patients. We cover several aspects of the management of renal dysfunction on the critical care unit, exploring some of the recurrent themes within the literature, including type and timing of kidney replacement therapy, management of acute kidney injury, as well as discussing how novel biomarkers for acute kidney injury may help to identify patients suffering from acute kidney injury as well as risk stratifying these patients. We discuss how early involvement of specialist nephrology services can improve outcomes in patients with kidney disease as well as offer valuable diagnostic and specialist management advice, particularly for patients with established end stage kidney disease and patients who are already known to nephrology services. We also explore some of the ongoing research questions that need to be answered within this arena.

Acute Kidney Injury: Medical Causes and Pathogenesis

Acute kidney injury (AKI) is a common clinical syndrome characterized by a sudden decline in or loss of kidney function. AKI is not only associated with substantial morbidity and mortality but also with increased risk of chronic kidney disease (CKD). AKI is classically defined and staged based on serum creatinine concentration and urine output rates. The etiology of AKI is conceptually classified into three general categories: prerenal, intrarenal, and postrenal. Although this classification may be useful for establishing a differential diagnosis, AKI has mostly multifactorial, and pathophysiologic features that can be divided into different categories. Acute tubular necrosis, caused by either ischemia or nephrotoxicity, is common in the setting of AKI. The timely and accurate identification of AKI and a better understanding of the pathophysiological mechanisms that cause kidney dysfunction are essential. In this review, we consider various medical causes of AKI and summarize the most recent updates in the pathogenesis of AKI.

Analytical Study on the Components of Health Products for Lowering Blood Glucose

Apriori algorithm was used to analyze 480 hypoglycemic health products for component association. Meanwhile, plain Bayesian algorithm was used to analyze the properties and flavors according to the Chinese Pharmacopoeia on the former basis. The results showed that chromium pyridinecarboxylate, magnesium stearate and Astragalus single ingredient played an important role on lowering blood glucose. The extracts of huangjing and mulberry leaf as well as coix seed and Chinese yam were highly correlated in the hypoglycemic health products. the The ingredients of health products used to lower blood glucose are mainly pungent, warm and bitter medicines. This paper, can contribute to the research and application of health products and regulate the health products market according to the analysis of the valid ingredients of health products.

Low dimensional nanomaterials for treating acute kidney injury

Acute kidney injury (AKI) is one of the most common severe complications among hospitalized patients. In the absence of specific drugs to treat AKI, hemodialysis remains the primary clinical treatment for AKI patients. AKI treatment has received significant attention recently due to the excellent drug delivery capabilities of low-dimensional nanomaterials (LDNs) and their unique therapeutic effects. Diverse LDNs have been proposed to treat AKI, with promising results and the potential for future clinical application. This article aims to provide an overview of the pathogenesis of AKI and the recent advances in the treatment of AKI using different types of LDNs. In addition, it is intended to provide theoretical support for the design of LDNs and implications for AKI treatment.