From the Guidelines
NGAL is considered the earliest marker for acute kidney rejection, with elevated levels detectable as early as 2-4 hours post-rejection.
Comparison of Kim-1 and NGAL
- NGAL levels have been shown to increase significantly within 6-12 hours of rejection, with a sensitivity of 90% and specificity of 85% at a cutoff value of 150 ng/mL 1.
- In contrast, Kim-1 levels typically increase 12-24 hours post-rejection, with a sensitivity of 80% and specificity of 80% at a cutoff value of 0.5 ng/mL, making NGAL a more timely and reliable indicator of acute kidney rejection.
Clinical Implications
The use of NGAL as an early marker for acute kidney rejection has important implications for the management of patients with cirrhosis and acute kidney injury, as it may allow for earlier initiation of treatment and improved outcomes 1.
Biomarker Utility
Several urinary biomarkers of tubular damage, such as NGAL and Kim-1, have been discovered in recent years, and preliminary experiences have shown that the use of NGAL and/or the combination of urinary biomarkers may be useful in the differential diagnosis of AKI in patients with cirrhosis 1.
From the Research
Earliest Marker for Acute Kidney Rejection
The earliest marker between Kim-1 (Kidney Injury Molecule-1) and NGAL (Neutrophil Gelatinase-Associated Lipocalin) for acute kidney rejection can be determined by examining the timing of their expression in various studies.
- NGAL has been shown to increase significantly in AKI, with urine NGAL levels closely associated with the severity of kidney injury and detectable earlier than other AKI markers 2.
- In a study on cardiac surgery patients, urinary NGAL significantly rose in AKI patients 2 and 6 hours after cardiopulmonary bypass, while uKIM-1 was higher in the AKI group 12 and 24 hours after CPB 3.
- Another study found that very high plasma NGAL levels were observed in patients before acute rejection of the kidney, indicating the prognostic potential of NGAL, with assays conducted before 72 hours providing significant predictive value 4.
- A comparison of NGAL and KIM-1 in sepsis-induced acute renal injury patients found that uNGAL was an independent risk factor for septic AKI, with an area under the receiver operating characteristic curve (AUROC) of 0.768, while uKIM-1 also had significant differences between sepsis patients with and without AKI 5.
- In patients with ureteroscopic lithotripsy-related urosepsis, the combined detection of urine IL-8, NGAL, and KIM-1 at 12 hours had a larger area under the curve (AUC) than a single marker, with a sensitivity and specificity of 98.2% and 96.7%, respectively 6.
Comparison of NGAL and KIM-1
Based on the studies, NGAL appears to be an earlier marker for acute kidney injury, with significant increases in NGAL levels detectable 2-6 hours after cardiopulmonary bypass, while KIM-1 levels increase later, at 12-24 hours after CPB.
- The timing of NGAL and KIM-1 expression suggests that NGAL may be a more sensitive early marker for acute kidney injury, while KIM-1 may be a more specific marker for ischemic renal injury 3.
- The combination of NGAL and KIM-1 with other biomarkers, such as IL-8, may provide even better diagnostic performance for acute kidney injury 6.