Acute kidney injury in intensive care unit patients: a comparison between the RIFLE and the Acute Kidney Injury Network classifications

Table 2 Classification/staging system for acute kidney injury [13] modified from the Risk, Injury, Failure, Loss of Kidney Function, End-stage Kidney Disease criteria [2]

Stage	Serum creatinine criteria	Urine output criteria
1	Increase in serum creatinine ≥0.3 mg/dl (≥26.4 μmol/l) or increase to ≥150% to 200% (1.5-fold to 2-fold) from baseline	< 0.5 ml/kg/hour for > 6 hours
2	Increase in serum creatinine to > 200% to 300% (> 2-fold to 3-fold) from baseline	< 0.5 ml/kg/hour for > 12 hours
3^a	Increase in serum creatinine to > 300% (> 3-fold) from baseline, or serum creatinine ≥4.0 mg/dl (≥354 μmol/l) with an acute increase of at least 0.5 mg/dl (44 μmol/l)	< 0.3 ml/kg/hour for 24 hours, or anuria for 12 hours

Acute kidney injury is defined as an abrupt (within 48 hours) reduction in kidney function, currently defined as an absolute increase in serum creatinine ≥0.3 mg/dl (≥26.4 μmol/l), a percentage increase in serum creatinine ≥50% (1.5-fold from baseline), or a reduction in urine output (documented oliguria < 0.5 ml/kg/hour for > 6 hours). ^aIndividuals who receive renal replacement therapy are considered to have met the criteria of Stage 3 irrespective of the stage they are in at the time of renal replacement therapy.

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