Differential diagnosis of AKI in clinical practice by functional and damage biomarkers: workgroup statements from the tenth Acute Dialysis Quality Initiative Consensus Conference.

Acute kidney injury (AKI) is a common but complex clinical syndrome with multiple etiologies. These etiologies target different sites and pathways within the kidney. Novel biomarkers of 'kidney damage' (which can be tubular or glomerular) can be used to diagnose AKI, even in the absence of an increase in serum creatinine or oliguria. These biomarkers of kidney damage can be combined with biomarkers of kidney function to facilitate classification of AKI. A comprehensive review of the literature was performed using the published methodology of the Acute Dialysis Quality Initiative (ADQI) working group and used to establish consensus statements regarding the use of biomarkers in the differential diagnosis of AKI. We recommend that the pathophysiological terms 'functional change' and 'kidney damage' be used in preference to the anatomical classification using the terms pre-renal, renal and post-renal AKI. We further recommend the use of both renal and non-renal biomarkers in establishing the specific cause of AKI as soon as possible after diagnosis. The presence of underlying CKD or of sepsis poses additional challenges in differential diagnosis, since these conditions alter both baseline biomarker excretion and biomarker performance. We recommend that biomarkers be validated within the clinical context in which they are to be used. Within that context, combinations of biomarkers may, in the future, allow differentiation of the site, mechanism and phase of injury.