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  • Acute kidney injury (AKI) is a clinical syndrome generally defined by an abrupt reduction in kidney functions as evidenced by changes in serum creatinine (Scr), blood urea nitrogen (BUN), and urine output.

  • RIFLE (Risk, Injury, Failure, Loss of Kidney Function, and End-Stage Renal Disease), AKIN (Acute Kidney Injury Network), and the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guidelines are three criteria-based classification systems developed to define and stage AKI in different patient populations (Table 73–1).

  • All three staging systems have been validated across different patient populations and their staging correlates closely with hospital mortality, cost, and length of stay.

  • Scr and urine output are the main diagnostic criteria for each staging system.

TABLE 73–1abcRIFLE, AKIN, and KDIGO Classification Schemes for Acute Kidney Injurya


  • AKI can be categorized as prerenal (resulting from decreased renal perfusion in the setting of undamaged parenchymal tissue), intrinsic (resulting from structural damage to the kidney, most commonly the tubule from an ischemic or ...

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