Biomarkers of acute kidney injury in different clinical settings: a time to change the paradigm?

Acute kidney injury (AKI) is diagnosed in 5% of all hospitalized patients and in up to 50% of all ICU patients. In the last years a dramatic rise in the prevalence of AKI has been observed with virtually no change in mortality, reaching up to 50-80% in all dialyzed ICU patients. AKI may progress to end-stage renal disease, and even subclinical episodes of AKI, which are common, may also progress to end-stage renal disease. The early detection of AKI may enable timely intervention and prevention of progression; however, in animal models and in human studies the 'window of therapeutic intervention' is narrow. Different urinary and serum proteins have been intensively investigated as possible biomarkers for the early diagnosis of AKI. There are promising candidate biomarkers with the ability to detect an early and graded increase in tubular epithelial cell injury and distinguish pre-renal disease from acute tubular necrosis. In this review, new emerging biomarkers of AKI are presented and described in some clinical settings, such as cardiac surgery, contrast-induced nephropathy, delayed graft function and ICU/emergency departments, where biomarkers are urgently needed to diagnose, make prognoses and differentiate.