Analytical validation of Gentian NGAL particle-enhanced enhanced turbidimetric immunoassay (PETIA)

Plasma Neutrophil Gelatinase-Associated Lipocalin Associates with New-Onset Chronic Kidney Disease in the General Population

Circulating levels of neutrophil gelatinase-associated lipocalin (NGAL) have been associated with acute kidney injury and the severity and progression of chronic kidney disease (CKD). This study investigated its potential utility as a biomarker for the risk of new-onset CKD in a population-based cohort study. Individuals without CKD at baseline (n = 4660) who participated in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) prospective population-based cohort study in the Netherlands were included. Baseline plasma NGAL concentrations were investigated for their associations with new-onset CKD, defined as a composite outcome of an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², urinary albumin excretion (UAE) > 30 mg/24-h, or both. Mean (±SD) plasma NGAL concentrations were 104.0 (±34.7) μg/L and median eGFR was 96 [IQR: 85.3-105.8] mL/min/1.73 m². After median follow-up of 8.3 [IQR: 7.8-8.9] years, 467 participants developed new-onset CKD. Plasma NGAL concentrations were significantly associated with an increased risk of new-onset CKD (hazard ratio [HR] per doubling 1.35 [95% CI: 1.11-1.63], p = 0.002), even after adjustment for potentially confounding factors (1.37 [1.09-1.73], p = 0.007) except baseline eGFR (1.09 [0.86-1.37], p = 0.490). In secondary analyses, plasma NGAL concentrations were significantly associated with new-onset CKD as defined by eGFR < 60 mL/min/1.73 m² alone (adjusted HR per doubling 2.54 [1.69-3.80], p < 0.001), which was abrogated after adjustment for eGFR (1.05 [0.69-1.59], p = 0.828), also when UAE > 30 mg/24-h was set as individual outcome (1.05 [0.82-1.35], p = 0.705). Higher plasma NGAL concentrations are associated with an increased risk of developing CKD in the general population. This association is dependent on renal function, and mainly driven by new-onset CKD as defined by renal function decline.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in Peritoneal Dialytic Effluent: Preliminary Results on the Comparison between Two Different Methods in Patients with and without Peritonitis

Neutrophil gelatinase-associated lipocalin (NGAL) is a lipocalin involved in the immune response and is significantly high in the peritoneal dialytic effluent (PDE) of peritoneal dialysis (PD) patients with inflammation of the peritoneum membrane (peritonitis). The focus of this study was to match two different techniques for peritoneal NGAL evaluation: NGAL point-of-care test-POCT (NGAL Dipstick—NGALds) versus the laboratory-based NGAL assay and with the white cell count in PDE. In this study, we included 30 PD patients: 17 with peritonitis and 13 without. Peritoneal NGAL was tested by a turbidimetric immunoassay and by NGALds. We noticed a good positive linear correlation between the POCT results and the laboratory-based test and between the peritoneal NGALds and white cell count in PDE (both, p < 0.01). NGALds values resulted in being elevated in patients with peritonitis (300 ng/mL, IQR 300–600) in comparison to patients without (100 ng/mL, IQR 50–150) (p < 0.01). Furthermore, the NGALds test was performed in a median time of 20 mins (IQR 18–21) in comparison with the median time of 65 mins (IQR 55–69) necessary for the laboratory-based test (p < 0.01). The results of the NGALds were coherent with the laboratory-based NGAL and with the white cell count in PDE; furthermore, it was a user-friendly method with real-time findings. NGALds could be an extra tool for the diagnosis of peritonitis, helpful at the bedside of the patient, shortening the length of diagnosis, and if the laboratory-based NGAL test is not accessible.

Plasma neutrophil gelatinase-associated lipocalin and kidney graft outcome

Background

Plasma neutrophil gelatinase-associated lipocalin (pNGAL) has been investigated extensively in acute kidney injury. This study investigated its pathophysiological significance and utility as marker for graft failure and mortality in stable kidney transplant recipients (KTR).

Methods

Baseline pNGAL was measured in 698 KTR (58% male, age 53 ± 13 years, estimated glomerular filtration rate 52.4 ± 20.4 mL/min/1.73 m²) at median 5.4 (interquartile range 1.8–12.0) years after transplantation, enrolled in the prospective TransplantLines Food and Nutrition Biobank and Cohort Study.

Results

pNGAL concentrations were higher in males, younger patients, patients with a deceased-donor kidney and higher serum creatinine. Independent of these, pNGAL was positively associated with urinary protein excretion, systemic inflammation parameters and calcineurin inhibitor use. During median follow-up of 5.3 (4.5–6.0) years, death-censored graft failure rates were 3.9%, 7.3% and 25.0% across increasing tertiles of pNGAL (P_log-rank < 0.001). Cox-regression analyses showed no independent associations of pNGAL with mortality, but strong associations with graft failure (hazard ratio, per doubling 4.16; 95% confidence interval 3.03–5.71; P < 0.001), which remained independent of adjustment for confounders. These associations were present only in patients with pre-existent proteinuria and poor kidney function.

Conclusions

pNGAL is associated with parameters of kidney graft damage and with graft failure. The latter association is particularly present in KTR with pre-existent poor kidney function and proteinuria.

Trial Registration:  ClinicalTrials.gov NCT02811835.

Enhancing Military Burn- and Trauma-Related Acute Kidney Injury Prediction Through an Automated Machine Learning Platform and Point-of-Care Testing

CONTEXT.—

Delayed recognition of acute kidney injury (AKI) results in poor outcomes in military and civilian burn-trauma care. Poor predictive ability of urine output (UOP) and creatinine contribute to the delayed recognition of AKI.

OBJECTIVE.—

To determine the impact of point-of-care (POC) AKI biomarker enhanced by machine learning (ML) algorithms in burn-injured and trauma patients.

DESIGN.—

We conducted a 2-phased study to develop and validate a novel POC device for measuring neutrophil gelatinase-associated lipocalin (NGAL) and creatinine from blood samples. In phase I, 40 remnant plasma samples were used to evaluate the analytic performance of the POC device. Next, phase II enrolled 125 adults with either burns that were 20% or greater of total body surface area or nonburn trauma with suspicion of AKI for clinical validation. We applied an automated ML approach to develop models predicting AKI, using a combination of NGAL, creatinine, and/or UOP as features.

RESULTS.—

Point-of-care NGAL (mean [SD] bias: 9.8 [38.5] ng/mL, P = .10) and creatinine results (mean [SD] bias: 0.28 [0.30] mg/dL, P = .18) were comparable to the reference method. NGAL was an independent predictor of AKI (odds ratio, 1.6; 95% CI, 0.08-5.20; P = .01). The optimal ML model achieved an accuracy, sensitivity, and specificity of 96%, 92.3%, and 97.7%, respectively, with NGAL, creatinine, and UOP as features. Area under the receiver operator curve was 0.96.

CONCLUSIONS.—

Point-of-care NGAL testing is feasible and produces results comparable to reference methods. Machine learning enhanced the predictive performance of AKI biomarkers including NGAL and was superior to the current techniques.

Synovial neutrophilic gelatinase-associated lipocalin in the diagnosis of periprosthetic joint infection after total knee arthroplasty

BACKGROUND

Periprosthetic joint infection (PJI) is one of the most serious complications following total knee arthroplasty (TKA). However, the diagnosis remains a challenge for clinicians. In 2011, the muscoskeletal infection society (MSIS) criteria provided a consensus which has been updated in 2013, but these criteria are complex and contain tests that are time-consuming. The same is applicable to the pro-Implant guidelines. Therefore, a simpler diagnostic test is desirable.

OBJECTIVES

The value of neutrophil gelatinase-associated lipocalin (NGAL), leucocyte esterase (LE) levels, and the white blood cell (WBC) count in synovial fluid to diagnose PJI after TKA was evaluated.

METHODS

In a retrospective cohort study, we analyzed 89 synovial fluid samples from 86 patients with suspected PJI after TKA. Thirteen and 23 of those samples were classified as PJI according to the MSIS and pro-Implant criteria, respectively. Subsequently, NGAL, LE levels, and the WBC count were determined, the former one using an immunoassay. Using either the MSIS or pro-Implant criteria as the golden standard for PJI, sensitivity and specificity of those markers were determined with ROC curves, and medians were compared with Mann-Whitney U and Pearson Chi-square tests.

RESULTS

When applying the MSIS criteria, NGAL revealed 92% sensitivity and 83% specificity. WBC count showed similar sensitivity (92%) and specificity (84%), whereas sensitivity and specificity for LE were 39% and 88% respectively. When applying the pro-Implant criteria, sensitivity was 95% and specificity was 95% for NGAL. Sensitivity and specificity for WBC count were 100% and 97% and for LE 39% and 92% respectively.

CONCLUSION

NGAL and WBC count in synovial fluid has high accuracy in the diagnosis of PJI after TKA and should seriously be considered as part of PJI diagnostics. Leucocyte esterase can serve as rule-in criterion peroperatively. These conclusions are independent of which criteria set was used as golden standard.