From the Guidelines
Neutrophil gelatinase-associated lipocalin (NGAL) is a recommended biomarker for acute tubular injury. According to the most recent study 1, NGAL is the most studied biomarker and urinary NGAL performs better than serum NGAL when measured 2 days following a fluid challenge. The level of NGAL in patients with hepatorenal syndrome-acute kidney injury (HRS-AKI) is always much lower than that in patients with acute tubular necrosis (ATN), even if the HRS-AKI has not responded to treatment.
Key Points
- NGAL rises rapidly in the urine and serum following tubular injury, typically within 2-4 hours after the insult, making it significantly more sensitive for early detection than traditional markers like serum creatinine 1.
- A cutoff value of 220–244 mg/g of creatinine has been reported as best for differentiating ATN from prerenal azotemia or HRS and may predict 90-day mortality 1.
- Other biomarkers such as a1-microglobulin, b2-microglobulin, and retinol binding protein have also been used to detect renal tubular cell damage 1.
- The primary advantage of NGAL is its ability to detect kidney injury before functional decline occurs, potentially allowing earlier intervention and improved patient outcomes.
Comparison with Other Biomarkers
- While other biomarkers like kidney injury molecule-1 (KIM-1), interleukin-18 (IL-18), and liver-type fatty acid binding protein (L-FABP) are useful, NGAL currently has the strongest evidence base for clinical use 1.
- Cystatin-C is a marker of glomerular filtration rate that is not affected by body mass or protein intake, but recent data do not suggest that it is superior to more traditional measures such as blood urea nitrogen and creatinine in risk stratification 1.
From the Research
Acute Tubular Injury Biomarker
- Neutrophil gelatinase-associated lipocalin (NGAL) is a recommended biomarker for acute tubular injury, as it is produced and secreted by kidney tubule cells at low levels, but increases dramatically after ischemic, septic, or nephrotoxic injury of the kidneys 2, 3.
- NGAL has been found to be an early predictor for acute kidney injury (AKI) in clinical studies, with urine NGAL being a sensitive and specific biomarker for AKI detection 4, 5.
- The average sensitivity and specificity of NGAL for AKI detection was 76 and 77% respectively for cardiac surgery patients and 73 and 80% respectively for patients admitted to the intensive care unit 3.
- NGAL is emerging as an excellent stand-alone troponin-like structural biomarker in the plasma and urine for the early diagnosis of AKI, and for the prediction of clinical outcomes such as dialysis requirement and mortality in several common clinical scenarios 5.
- Newer devices for early bedside detection of NGAL are now available, which may soon emerge as a troponin-like early marker for AKI, replacing serum creatinine as a late and inadequate marker 6.