(1) Department of Internal Medicine IV, University Hospital Munich, University of Munich, Munich, Germany
(2) Medizinische Klinik, SRH Wald-Klinikum Gera, Gera, Germany
*Corresponding author Email: firstname.lastname@example.org
Current assessments of renal function by serum creatinine or blood urea nitrogen display poor sensitivity and specificity for indicating early changes in kidney function and do not differentiate between causes of acute kidney injury (AKI). The discovery, characterization and validation of novel biomarkers specific for structural kidney damage, such as neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, interleukin-18 and liver fatty acid binding protein enable a timely diagnosis of AKI through better reflection of real-time damage of AKI, promise discrimination of the underlying aetiology and may enable incremental risk identification for worsening AKI, need of renal replacement and death. However, case-mix, comorbidities, aetiology of the renal insult, timing of measurements and selected thresholds for diagnosis influence the performance of these novel biomarkers. Additional studies are necessary before novel biomarkers can be used in routine clinical practice. To answer the question of how to optimally utilize novel biomarkers (the right test, at the right time, on the right patient, for the right clinical setting of AKI) all promising AKI biomarkers should undergo systematic evaluation in various clinical setting of AKI in order to validate the temporal expression patterns of these biomarkers for early detection of AKI, to determine how to combine multiple biomarkers for earlier diagnosis and to discover how the temporal course relates to onset, severity and outcome of AKI. There is a vital need that large future investigations demonstrate the association between biomarkers and hard clinical outcomes independent of serum creatinine concentrations. It needs to be shown that early renoprotective treatment for AKI based on high biomarker levels actually results in an improved outcome. The aim of this review is to discuss early diagnosis of acute kidney injury in critically ill patients by novel biomarkers.
Until effective renoprotective therapies are available, there is little benefit from early diagnosis of AKI during critical illness.