Objective: This study is aimed to examine whether urinary L-type fatty acid-binding protein can detect the severity of sepsis with animal sepsis models and septic shock patients complicated with established acute kidney injury.
Design: Experimental animal models and a clinical, prospective observational study.
Setting: University laboratory and tertiary hospital.
Subjects and patients: One hundred fourteen human L-type fatty acid-binding protein transgenic mice and 145 septic shock patients with established acute kidney injury.
Interventions: Animals were challenged by abdominal (cecal ligation and puncture) and pulmonary (intratracheal lipopolysaccharide injection) sepsis models with different severities that were confirmed by survival analysis (n = 24) and bronchoalveolar lavage fluid analysis (n = 38).
Measurements and main results: In animal experiments, significant increases of urinary L-type fatty acid-binding protein levels were induced by sepsis (severe cecal ligation and puncture 399.0 ± 226.8 μg/g creatinine [n = 12], less-severe cecal ligation and puncture 89.1 ± 25.3 [n = 11], sham 13.4 ± 3.4 [n = 10] at 6 hrs, p < .05 vs. sham; 200 μg of lipopolysaccharide 190.6 ± 77.4 μg/g creatinine [n = 6], 50 μg of lipopolysaccharide 145.4 ± 32.6 [n = 8], and saline 29.9 ± 14.9 [n = 5] at 6 hrs, p < .05 vs. saline). Urinary L-type fatty acid-binding protein predicted severity more accurately than blood urea nitrogen, serum creatinine, and urinary N-acetyl-d-glucosaminidase levels. In clinical evaluation, urinary L-type fatty acid-binding protein measured at admission was significantly higher in the nonsurvivors of septic shock with established acute kidney injury than in the survivors (4366 ± 192 μg/g creatinine [n = 68] vs. 483 ± 71 [n = 77], p < .05). Urinary L-type fatty acid-binding protein showed the higher value of area under the receiver operating characteristic curve for mortality compared with Acute Physiology and Chronic Health Evaluation (APACHE) II and Sepsis-related Organ Failure Assessment (SOFA) scores (L-type fatty acid-binding protein 0.994 [0.956-0.999], APACHE II 0.927 [0.873-0.959], and SOFA 0.813 [0.733-0.873], p < .05).
Conclusions: Our results suggest that urinary L-type fatty acid-binding protein can be a useful biomarker for sepsis complicated with acute kidney injury for detecting its severity.