One of the major problems in the diagnosis and treatment of AKI is the difficulty in identifying it timely. From the moment of AKI occurs, the increase in the creatinine can be up to 72 h. For this reason, there is an intense search for biomarkers that allow the timely diagnosis of AKI. Several biomarkers for the early detection of AKI have been identified. These include: neutrophil gelatinase-associated lipocalin (NGAL), a protein of the lipocalin family, present in neutrophil secondary granules. Upon renal damage this protein is released from the affected epithelium early. Studies that have evaluated its usefulness as a marker of renal damage have been performed mainly in children, and its usefulness in critically ill patients has been debated. Another biomarker that has been used for the detection of renal damage is the transmembrane glycoprotein Kim-1, which releases its extracellular ectodomain by the action of proteases. Under normal conditions, Kim-1 expression is very low and increases significantly when there is tubular damage, such as occurs during AKI. A characteristic feature of this molecule is that it is expressed only in injured renal tissue. Although the induction of Kim-1 after an AKI episode is important, unfortunately this protein has not been shown to be useful as an early biomarker of AKI. Recently, our group identified a new, non-invasive, and reliable biomarker to detect AKI earlier by measuring the concentration of the 72 kilodaltons heat shock protein (HSP72). Similar to Kim-1, this protein is practically not expressed under normal conditions, but is induced in the tubular epithelium after an episode of AKI. In addition to being a highly sensitive and early biomarker, it was able to stratify different degrees of renal injury and to monitor the efficacy of a renoprotective maneuver in animals undergoing ischemia/reperfusion. In addition, we have also observed that in critically ill patients, the detection of HSP72 in urine specimens made it possible to detect AKI 48 h before diagnosis of creatinine elevation or reduction of urinary flow.