Urinary neutrophil gelatinase-associated lipocalin as biomarker in the differential diagnosis of impairment of kidney function in cirrhosis.

BACKGROUND & AIMS: Impairment of kidney function is common in cirrhosis but differential diagnosis remains a challenge. We aimed at assessing the usefulness of neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of tubular damage, in the differential diagnosis of impairment of kidney function in cirrhosis.

METHODS: Two-hundred and forty-one patients with cirrhosis, 72 without ascites, 85 with ascites, and 84 with impaired kidney function, were studied. Urinary levels of NGAL were measured by ELISA.

RESULTS: Patients with impaired kidney function had higher urinary NGAL levels compared to patients with and without ascites. Patients with urinary tract infection (n=25) had higher uNGAL values than non-infected patients. Patients with acute tubular necrosis (ATN) had uNGAL levels markedly higher (417μg/g creatinine (239-2242) median and IQ range) compared to those of patients with pre-renal azotemia due to volume depletion 30 (20-59), chronic kidney disease (CKD) 82 (34-152), and hepatorenal syndrome (HRS) 76 (43-263) μg/g creatinine (p<0.001 for all). Among HRS patients, the highest values were found in HRS-associated with infections, followed by classical (non-associated with active infections) type-1 and type-2 HRS (391 (72-523), 147 (83-263), and 43 (31-74) μg/g creatinine, respectively; p<0.001). Differences in uNGAL levels between classical type 1 HRS and ATN on the one hand and classical type 1 HRS and CKD and pre-renal azotemia on the other were statistically significant (p<0.05).

CONCLUSIONS: uNGAL levels may be useful in the differential diagnosis of impairment of kidney function in cirrhosis. Urinary tract infections should be ruled out because they may increase uNGAL excretion.