title: Alpha1-microglobulin as an early biomarker of sepsis-associated acute kidney injury: a prospective cohort study.
abstract: BACKGROUND
  Sepsis emerges as the leading risk factor for acute kidney injury (AKI) development in critically ill patients. Much effort has been invested so far on early diagnosis of AKI using promising biomarkers. This study aimed to determine whether urine alpha1-microglobulin (α1m), a lipocaline member previously used as an indicator of proximal tubular dysfunction, can early predict the development of sepsis-associated AKI (SAAKI) in critically ill patients.
  
  
  METHODS
  A prospective, observational study was conducted in a single center Intensive Care Unit (ICU). Patients with normal renal function admitted to the ICU followed for sepsis and AKI development. Urine α1m levels were analyzed in pooled samples from 24-hour urine collections on sepsis onset and at various time points thereafter. The diagnostic performance of urine α1m was assessed using thenonparametriccalculation of the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.
  
  
  RESULTS
  Among 286 critically ill patients admitted to our ICU in a year, 45 patients with sepsis met the inclusion criteria. SAAKI developed in 16 septic patients (35.6%). Urine α1m levels were significantly elevated in all septic patients (average value of all samples on the day of sepsis: 46.02 ± 7.17 mg/l) and showed a trend to increase in patients who finally developed SAAKI. The AUC for SAAKI prediction according to α1m urine levels 24-hours before SAAKI onset was 0.739 (sensitivity 87.5%, specificity 62.07%, cutoff level 47.9 mg/l). Urine α1m 24-hours before SAAKI, serum creatinine on sepsis onset and Acute Physiology and Chronic Health Evaluation II (APACHE II) score on sepsis onset emerged as the most powerful independent predictors of SAAKI. The combination of these three parameters improved the AUC for SAAKI prediction to 0.944.
  
  
  CONCLUSIONS
  Urine α1m levels might help in the early prediction of SAAKI development and may prove useful biomarker. The pathogenetic implications of α1m in sepsis and SAAKI need further investigation. Hippokratia 2014; 18 (3): 262-268.
authors.affiliation: Second Department of Internal Medicine, General University Hospital of Alexandroupolis, Greece.
authors.forename: I
authors.initials: I
authors.lastname: Terzi
authors.affiliation: Intensive Care Unit, General University Hospital of Alexandroupolis, Greece.
authors.forename: V
authors.initials: V
authors.lastname: Papaioannou
authors.affiliation: Second Department of Internal Medicine, General University Hospital of Alexandroupolis, Greece.
authors.forename: N
authors.initials: N
authors.lastname: Papanas
authors.affiliation: Intensive Care Unit, General University Hospital of Alexandroupolis, Greece.
authors.forename: C
authors.initials: C
authors.lastname: Dragoumanis
authors.affiliation: Intensive Care Unit, General University Hospital of Alexandroupolis, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Petala
authors.affiliation: Intensive Care Unit, General University Hospital of Alexandroupolis, Greece.
authors.forename: V
authors.initials: V
authors.lastname: Theodorou
authors.affiliation: Department of Biopathology, General University Hospital of Alexandroupolis, Greece.
authors.forename: T
authors.initials: T
authors.lastname: Gioka
authors.affiliation: Department of Nephrology, General University Hospital of Alexandroupolis, Greece.
authors.forename: V
authors.initials: V
authors.lastname: Vargemezis
authors.affiliation: Second Department of Internal Medicine, General University Hospital of Alexandroupolis, Greece.
authors.forename: E
authors.initials: E
authors.lastname: Maltezos
authors.affiliation: Intensive Care Unit, General University Hospital of Alexandroupolis, Greece.
authors.forename: I
authors.initials: I
authors.lastname: Pneumatikos
keywords: Acute kidney injury; Critically ill patients; Sepsis; Urinary biomarkers; alpha1-microglobulin