Aim: An ideal biomarker for early diagnosis of septic acute kidney injury (AKI) should reflect renal stress or damage at initiation point, at cellular level. The aim of this study was to assess the role of a urinary cell cycle arrest marker, insulin-like growth factor-binding protein 7 (IGFBP7) in early diagnosis of septic AKI in adult critical care patients.
Methods: This was a single-center prospective cohort study. Patients without AKI, admitted to a medical intensive care unit (ICU) between January 2010 and March 2013, were included. According to 'sepsis' and 'AKI' development during their ICU stay, they were grouped as 'sepsis-non AKI', 'sepsis-AKI' and 'non-sepsis-non AKI (control)'. Among these groups, urine IGFBP7 was studied and compared with Human ELISA Kit/96 Test/USCNK(®) first on admission and then on daily collected serial urine samples.
Results: A total of 118 patients formed the cohort; 52 in sepsis-non AKI, 43 in sepsis-AKI, 23 in control group. Admission urine IGFBP7 predicted septic AKI development with 72% sensitivity and 70% specificity for a threshold level of 2.5 ng/mL with an area under the receiver operating characteristics curve (AUC) of 0.79 (95% CI: 0.70-0.88). No impact of sepsis was observed on urine IGFBP7 levels in the absence of AKI. In the septic AKI group urine IGFBP7 levels continuously increased up to the day of AKI development and high levels were suspended for 10 days further.
Conclusion: Admission urine IGFBP7 levels and following its course in ICUs can be used as a promising new biomarker for the early diagnosis of septic AKI development without being affected by sepsis itself.
Keywords: Acute kidney injury; IGFBP7 protein; biomarker; cell cycle arrest; intensive care units; predictive value of tests; sepsis.