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Source: Dager W, Halilovic J. Acute Kidney Injury. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th edition. Accessed August 12, 2012.


  • Wide continuum of damage to kidneys, ranging from mild renal dysfunction to need for renal replacement therapies (RRTs), such as hemodialysis and peritoneal dialysis.
    • Term acute kidney injury (AKI) replaces acute renal failure (ARF).
      • ARF describes abrupt decrease in glomerular filtration rate (GFR) or creatinine clearance (CLcr).
      • AKI may lead to ARF.
  • Risk, Injury, Failure, Loss of Kidney Function, and End-Stage Renal Disease (RIFLE) and Acute Kidney Injury Network (AKIN) criteria are classification systems based on separate criteria for serum creatinine (Scr) and urine output used to stage severity of AKI (Table 1).
    • Multiple studies validate ability of RIFLE criteria to predict certain patient outcomes, particularly hospital mortality.

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Table 1. RIFLE and AKIN Classification Schemes for Acute Kidney Injury

  • Etiology divided into broad categories based on anatomic location of injury associated with precipitating factor(s).
    • Prerenal: Results from decreased renal perfusion in setting of undamaged parenchymal tissue.
    • Intrinsic: Results from structural damage to kidney, most commonly tubule from ischemic or toxic insult.
    • Postrenal: Results from obstruction of urine flow downstream from kidney (Figure 1).
  • Differentiation of cause of AKI determined by laboratory tests (Table 2 and 3).

Figure 1.

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