Serum neutrophil gelatinase-associated lipocalin as a predictor of organ recovery from delayed graft function after kidney transplantation from donors after cardiac death

Serum neutrophil gelatinase-associated lipocalin correlates with kidney function in renal allograft recipients

The value of neutrophil gelatinase-associated lipocalin (NGAL) as a novel marker for early detection of acute renal failure has been highlighted recently. The aim of this study was to assess whether serum NGAL correlates with kidney function in kidney allograft recipients. Serum NGAL, creatinine, and estimated glomerular filtration rate (GFR) were evaluated in 100 kidney allograft recipients on triple therapy: calcineurin inhibitor, mycophenolate mofetil or azathioprine, prednisone and healthy volunteers. Kidney transplant recipients had significantly higher NGAL than the control group. Serum NGAL in univariate analysis was strongly correlated with serum creatinine (r = 0.78). Estimated GFR (r = -0.69), on the other hand, was moderately correlated with white blood cell count (r = 0.43) and only weakly with other parameters. In multiple regression analysis, the best predictor of serum NGAL was eGFR (beta -0.69), with other predictors being white blood cell count (beta 0.25) and high sensitivity C-reactive protein (hsCRP) (beta 0.23) explaining 82% of NGAL concentration. Even a successful kidney transplantation is associated with kidney injury as reflected by elevated serum NGAL and lowered eGFR. Therefore, NGAL needs to be investigated as a potential early marker for impaired kidney function/kidney injury, especially in patients with other risk factor for kidney damage, i.e., hypertension or diabetes.

Serum neutrophil gelatinase-associated lipocalin (NGAL) in predicting worsening renal function in acute decompensated heart failure

BACKGROUND

The development of worsening renal function (WRF, defined as creatinine rise >or=0.3mg/dL) occurs frequently in the setting of acute decompensated heart failure (ADHF) and strongly predicts adverse clinical outcomes. Neutrophil gelatinase-associated lipocalin (NGAL) is produced by the nephron in response to tubular epithelial damage and serves as an early marker for acute renal tubular injury. We sought to determine the relationship between admission serum NGAL levels and WRF in the setting of ADHF.

METHODS AND RESULTS

We measured serum NGAL levels in 91 patients admitted to the hospital with ADHF. Patients were adjudicated by independent physician into those that did or did not develop WRF over the ensuing 5 days of in-hospital treatment. In our study cohort (68% male, mean age 61+/-15 years, mean left ventricular ejection fraction 31+/-14%), median admission serum NGAL level was 165 ng/mL (interquartile range [IQR] 108-235 ng/mL). Thirty-five patients (38%) developed WRF within the 5-day follow-up. Patients who developed WRF versus those without WRF had significantly higher median admission serum NGAL levels (194 [IQR 150-292] ng/mL vs. 128 [IQR 97-214] ng/mL, P=.001). High serum NGAL levels at admission were associated with greater likelihood of developing WRF (odds ratio: 1.92, 95% confidence interval 1.23-3.12, P=.004). In particular, admission NGAL >or=140 ng/mL had a 7.4-fold increase in risk of developing WRF, with a sensitivity and specificity of 86% and 54%, respectively.

CONCLUSIONS

The presence of elevated admission serum NGAL levels is associated with heightened risk of subsequent development of WRF in patients admitted with ADHF.

NGAL: a biomarker of acute kidney injury and other systemic conditions

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25 kDa protein belonging to the lipocalin superfamily. It was initially found in activated neutrophils, however, many other cells, like kidney tubular cells, may produce NGAL in response to various insults. Recently, it has been found to have a role in iron metabolism by virtue of its binding with siderophores. It has also been found to have a role in kidney development and tubular regeneration after injury. In experimental studies, it was found to be highly expressed in response to tubular injury. In subsequent clinical studies, urine NGAL has been found to be an early predictor for acute kidney injury (AKI). Newer devices for early bedside detection of NGAL are now available. Since serum creatinine is known to be an inadequate and late marker of AKI, NGAL might soon emerge as a troponin-like early marker for AKI. Recent evidence also suggests its role as a biomarker in a variety of other renal and non-renal conditions.