title: Comparison of three early biomarkers for acute kidney injury after cardiac surgery under cardiopulmonary bypass.
abstract: BACKGROUND
  Acute kidney injury (AKI) is a serious complication after cardiac surgery, being associated with a high mortality. We assessed three urinary biomarkers, L-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL), and angiotensinogen, which are elevated through different mechanisms, and investigated which of these biomarkers was the earliest and most useful indicator of AKI after cardiac surgery.
  
  
  METHODS
  This study was a prospective observational study conducted at a single-institution university hospital. All patients were adults aged under 80 years who underwent cardiac surgery with cardiopulmonary bypass between November 2013 and January 2015. Perioperatively, urine samples were obtained from all patients at five points. Based on AKI criteria, patients were divided into two groups: AKI group (n = 11) and non-AKI group (n = 39), according to postoperative serum creatinine (Cr) levels.
  
  
  RESULTS
  Urinary L-FABP, NGAL, angiotensinogen, and Cr were measured perioperatively. L-FABP was significantly higher in the AKI group than in the non-AKI group at the end of surgery and 3 h after surgery. L-FABP levels were 601.5 ± 341.7 and 233.8 ± 127.2 μg/g Cr in the AKI and non-AKI groups, respectively. Three hours after surgery, NGAL levels were 950.5 ± 827.9 and 430.0 ± 250.6 μg/g Cr in the AKI and non-AKI groups, respectively, the level being significantly higher in the AKI group than in the non-AKI group. There were no significant differences in urinary angiotensinogen levels between the two groups at any time point.
  
  
  CONCLUSIONS
  We demonstrated the utility of L-FABP and NGAL, but not angiotensinogen in the early recognition of AKI. The problem of the different peak points among biomarkers needs to be resolved for discovery of a panel of biomarkers.
authors.affiliation: Department of Anesthesiology and Intensive Care, Kagoshima University Hospital, Sakuragaoka 8-35-1, Kagoshima, 46201 Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Moriyama
authors.affiliation: Department of Anesthesiology and Intensive Care, Kagoshima University Hospital, Sakuragaoka 8-35-1, Kagoshima, 46201 Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hagihara
authors.affiliation: Department of Anesthesiology and Intensive Care, Kagoshima University Hospital, Sakuragaoka 8-35-1, Kagoshima, 46201 Japan.
authors.forename: Toko
authors.initials: T
authors.lastname: Shiramomo
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Kyusyu University, Maidashi 3-1-1, Higashi-ku, Fukuoka, 46201 Japan.
authors.forename: Misaki
authors.initials: M
authors.lastname: Nagaoka
authors.affiliation: Department of Anesthesiology and Intensive Care, Kagoshima University Hospital, Sakuragaoka 8-35-1, Kagoshima, 46201 Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Iwakawa
authors.affiliation: Department of Anesthesiology and Intensive Care, Kagoshima University Hospital, Sakuragaoka 8-35-1, Kagoshima, 46201 Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kanmura
keywords: Acute kidney injury; Cardiac surgery; L-type fatty acid-binding protein (L-FABP); Neutrophil gelatinase-associated lipocalin (NGAL); Urinary angiotensinogen