Urinary Biomarker of Kidney Tubular Function, Risk of Acute Kidney Injury, and Mortality in Acute Stroke Patients

Background and Purpose: Urinary liver-type fatty-acid binding protein (L-FABP), which is a biomarker of kidney tubule injury, has been studied extensively and established as a risk marker of acute kidney injury (AKI) and cardiovascular disease outcomes. However, no evidence to date has indicated whether kidney tubule injury has any potential for predictor of AKI and mortality in acute stroke patients. The aim of the present study was to accurately determine the prevalence of AKI and effect on clinical outcome of acute stroke patients assessed by urinary L-FABP. Methods: Acute ischemic stroke and intracerebral hemorrhage patients hospitalized in the stroke care unit (SCU) within 24 h after symptom onset were prospectively investigated. AKI was defined on the basis of Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We evaluated the association among urinary L-FABP, AKI, and 3-months mortality using multivariate logistic analysis adjusted for baseline estimated glomerular filtration rate (eGFR), albuminuria, stroke risk factors, and neurological severity. Results: In total, 601 acute stroke patients (390 males; median age 72 years, ischemic stroke 476 cases and intracranial hemorrhage 125 cases) were enrolled to the study. AKI occurred in 32 acute stroke patients (5.3%). In the univariate analysis, high urinary L-FABP level had positive associations with AKI (25.4 μg/g Cr vs. 3.6 μg/g Cr, P<0.001) and 3 months mortality (13.4 μg/g Cr vs. 3.8 μg/g Cr, P<0.001). In the multivariate analysis, elevated urinary L-FABP level was independently associated with AKI (OR 1.015; 95% CI, 1.008-1.023, P<0.001) and 3-months mortality (OR 1.012; 95% CI, 1.001-1.023, P=0.032). Moreover, AKI also increased the risk of 3-months mortality after stroke (OR 7.053, 95% CI, 1.771-28.087, P=0.006). Conclusion: Biomarker of tubular dysfunction is independent predictor of AKI and mortality in acute stroke patients.