Clinical bottom line
Serum neutrophil gelatinase-associated lipocalin (NGAL) is a promising early biomarker for acute kidney injury (AKI) in patients with liver cirrhosis. It may detect renal injury earlier than traditional markers such as serum creatinine, potentially allowing more timely intervention. However, its clinical utility remains putative and requires further validation in larger, diverse cirrhotic cohorts before routine adoption. Clinicians should interpret NGAL results cautiously alongside clinical context and established diagnostic criteria.
What the evidence shows
AKI is a frequent and serious complication in cirrhotic patients, often portending poor prognosis. Traditional markers like serum creatinine are limited by delayed elevation and confounding by reduced muscle mass and altered volume status in cirrhosis. NGAL, a 25-kDa protein released by injured tubular epithelial cells, has emerged as an early and sensitive biomarker for AKI in various settings (Devarajan et al., 2012; Shemin et al., 2011).
Several studies have evaluated NGAL’s role specifically in cirrhosis-associated AKI. A 2017 study by [Author et al.] demonstrated that urinary NGAL levels were significantly elevated in cirrhotic patients with AKI compared to those without, correlating with AKI severity and predicting short-term prognosis (2017). Similarly, the Egyptian Journal of Hospital Medicine (2023) reported that urinary NGAL distinguished AKI from prerenal azotemia in cirrhotic patients with good sensitivity and specificity, suggesting utility in differential diagnosis.
Khawaja Shabnum et al. (2019) extended these findings to critically ill patients, including those with liver disease, showing that serum NGAL levels rose earlier than creatinine and correlated with AKI severity. Analytical performance evaluations on platforms such as Roche Cobas c502 have confirmed NGAL assays’ reproducibility and feasibility for clinical use (Samara et al., 2023).
Collectively, these data suggest NGAL may serve as an early warning biomarker for AKI in cirrhosis, potentially enabling earlier detection than creatinine and aiding in prognostication. However, most evidence derives from relatively small cohorts or heterogeneous populations, limiting generalizability.
Caveats and uncertainty
Despite promising data, several limitations temper enthusiasm for routine NGAL use in cirrhosis:
- Heterogeneity of AKI etiology: Cirrhotic AKI can result from prerenal causes, hepatorenal syndrome, or intrinsic renal injury. NGAL elevations may not reliably distinguish these subtypes, complicating clinical interpretation (Author et al., 2017).
- Influence of systemic inflammation: NGAL is also produced by neutrophils and can increase in systemic infections or inflammation common in cirrhosis, potentially confounding specificity for renal injury (Khawaja et al., 2019).
- Lack of standardized cutoffs: Studies report variable NGAL thresholds for AKI diagnosis, and no consensus exists on optimal cutpoints tailored to cirrhotic populations.
- Limited prospective validation: Most data are observational or cross-sectional. Large prospective studies assessing NGAL-guided management impact on clinical outcomes are lacking.
- Assay variability: Although analytical platforms show promise, inter-assay variability and cost considerations remain barriers to widespread implementation (Samara et al., 2023).
How this may change practice
If further validated, serum or urinary NGAL measurement could complement traditional renal function tests in cirrhotic patients at risk for AKI. Early NGAL elevation might prompt more aggressive volume management, avoidance of nephrotoxins, or consideration of renal replacement therapy before overt creatinine rise. It may also aid in differentiating AKI subtypes, guiding tailored therapies.
However, given current uncertainties, NGAL should not replace established diagnostic criteria or clinical judgment. Instead, it may serve as an adjunctive tool in specialized centers or research settings. Integration into clinical workflows will require standardized assays, clear interpretation guidelines, and demonstration of outcome benefit.