Table 2.

Staging of AKI for adults

	Serum	Creatinine	Criteria	Urine volume criteria
AKI stage	KDIGO	AKIN	RIFLE	KDIGO/AKIN/ RIFLE
1 (R)	1.5–1.9 times baseline or ≥0.3 mg/dl (≥26 µmol/l) increase within 48h	Increase≥0.3 mg/dl (26.5 µmol/l) or≥1.5- to 2-fold from baseline	Increase×1.5 baseline or GFR decrease >25%	<0.5ml/kg/h for 6–12 h
2 (I)	2.0–2.9 times baseline	Increase >2- to 3-fold from baseline	Increase×2 from baseline or GFR decreased >50%	<0.5ml/kg/h for 12 h
3 (F)	3.0 times baseline or increase in serum creatinine to≥4.0 mg/dl (354 µmol/l) or initiation of renal replacement therapy or, in patients <18 years, decrease in eGFR to <35ml/min per 1.73 m2	Increased >300% (>3-fold) from baseline, or ≥4.0 mg/dl (354mmol/l) with an acute increase of ≥0.5 mg/dl (44 µmol/l) or on renal replacement therapy	Increase × 3 from baseline, or serum creatinine >4mg/dl (>354 µmol/l) with an acute rise >0.5mg/dl (>44 µmol/l) or GFR decreased >75%	<0.3ml/kg/h for 24 h or anuria for 12 h

Abbreviations: AKI, acute kidney injury; AKIN, Acute Kidney Injury Network; eGFR, estimated glomerular filtration rate; KDIGO, Kidney Disease: Improving Global Outcomes.

RIFLE, Risk, Injury, Failure, Loss and End stage kidney failure.

For AKIN, the increase in serum creatinine must occur in <48h. For RIFLE, AKI should be both abrupt (within 1–7 days) and sustained (>24 h).