State of the art: Renal recovery after AKI - from basic science to clinical practice.

PURPOSE Acute kidney injury (AKI) is common in critically ill patients and associated with a high risk of mortality, chronic kidney disease (CKD) and cardiovascular morbidity. The risks are higher in patients with incomplete or no renal recovery. The purpose of this review is to summarize the current understanding of the mechanisms of renal recovery, list some key risk factors for nonrecovery and highlight knowledge gaps. METHODS Narrative review of key data in the literature. RESULTS Recovery from AKI is an active process. When damage to the kidney is mild, full regeneration is possible; with extensive damage, fibrosis sets in. Current strategies to achieve renal recovery focus on identification of the mechanism of injury and minimizing further insults. Nephrotoxic exposures and various forms of dialytrauma impair recovery. The likelihood that repair will be maladaptive increases with age and extent/duration of injury. Return of glomerular filtration rate to pre-injury levels does not exclude nephron loss and development of CKD. Post-discharge follow-up of AKI survivors is important, but there are ongoing uncertainties and clinical practice is variable. Research is ongoing to determine the role of pharmacological interventions. CONCLUSIONS The prognosis of AKI is critically tied to renal recovery, and there is great urgency to identify effective therapies.