"Acute kidney injury (AKI), previously known as acute renal failure, refers to a sudden reduction in kidney function. This chapter reviews the consensus definitions for AKI, along with recent work to develop consensus regarding acute kidney disease that does not meet the technical definition of AKI and recovery from AKI. It also reviews common settings in which AKI may occur and the epidemiology of the disease and potential role of novel biomarkers in disease recognition and classification. Careful history-taking, chart review, and physical examination remain the fundamental tenets of the workup. AKI can be subdivided into prerenal, intrarenal, and postrenal etiologies. While there have been numerous publications on the role of novel biomarkers in the risk stratification, diagnosis, prognosis, and long-term outcomes of AKI, to date there has not been the formal inclusion of these novel tests into diagnostic criteria and none have gained wide clinical acceptance". -- Provided by publisher.