Acute kidney injury: from clinical to molecular diagnosis

The RIFLE classification was introduced in 2004 to describe the presence of acute kidney injury (AKI) and to define its clinical stage, based upon the serum creatinine level and urine output. The same criteria, although slightly modified, are used in the other scoring systems AKIN and KDIGO. Mortality and morbidity remain high in AKI, suggesting that current diagnostic methods are suboptimal, poorly accurate, and often timely inadequate in detecting the presence of early kidney injury. Conversely, a growing body of evidence indicates that new AKI biomarkers can be used to both rule out AKI and to assess high-risk conditions or the presence of subclinical forms. Neutrophil gelatinase-associated lipocalin or cell cycle arrest biomarkers seem to be sensitive and specific enough to be used in conjunction with existing markers of AKI for better classifying renal injury as well as dysfunction. Improvements in diagnosis, risk identification, stratification, prognosis, and therapeutic monitoring may improve prevention and protection from organ damage and help to identify patients at risk, allowing individualized therapy. In this view, we may say that AKI diagnosis has finally moved from clinical to molecular level with potential benefits for the patients because similar progress has been shown in other disciplines.