Indications and timing of renal replacement therapy in acute kidney injury.

The optimal timing for initiation of renal replacement therapy in patients with acute kidney injury remains uncertain. Conventionally accepted indications include volume overload, hyperkalemia, metabolic acidosis, overt uremia, and even progressive azotemia in the absence of specific symptoms; however, precise definitions for these indications are lacking. Data from recent observational trials have suggested that early initiation of renal replacement therapy may be associated with decreased mortality; however, the results of these studies are inconclusive. Existing data on timing of initiation of renal replacement therapy in acute kidney injury that guide current clinical practice are summarized and issues that need to be addressed in future clinical trials are discussed.