Diagnosis of acute kidney injury using functional and injury biomarkers: workgroup statements from the tenth Acute Dialysis Quality Initiative Consensus Conference.

Acute kidney injury (AKI) commonly occurs in hospitalized patients and is independently and strongly associates with morbidity and mortality. The clinical benefits of a timely and definitive diagnosis of AKI have not been fully realized due to limitations imposed by the use of serum creatinine and urine output to fulfill diagnostic criteria. These restrictions often lead to diagnostic delays, potential misclassification of actual injury status, and provide little information regarding underlying cause. Novel biomarkers of damage have shown ability to reflect ongoing kidney injury and help further refine existing Risk, Injury, Failure, Loss, End-stage kidney disease (RIFLE) and Acute Kidney Injury Network (AKIN) diagnostic criteria. A comprehensive review of the published literature to date was performed using previously published methodology of the Acute Dialysis Quality Initiative (ADQI) working group to establish consensus statements regarding (i) the overall implementation of injury biomarkers in the concept of AKI diagnosis, (ii) their clinical use, and (iii) future research. On the basis of published data on the ability of novel damage biomarkers to provide diagnostic and prognostic information on AKI, we recommend that novel damage biomarkers may, in the appropriate clinical setting and context (situation consistent with AKI), be used to diagnose AKI even in the absence of changes in serum creatinine or the presence of oliguria as described in the existing RIFLE/AKIN criteria for diagnosis of AKI. Adding injury biomarkers as a criterion for AKI will complement the ability of RIFLE/AKIN to define AKI. Promising diagnostic injury markers include neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), interleukin 18 (IL-18) and liver-type fatty acid binding protein (L-FABP). However, there are currently insufficient data on damage biomarkers to support their use for AKI staging. Rigorous validation studies measuring the association between the novel damage biomarker(s) and clinically relevant outcomes are needed.