Table 2

Definition and classification of neonatal acute kidney injury

AKIN			RIFLE			KDIGO
Stage	sCr	UO	Stage	eGFR	UO	Stage	sCr	UO
1	Rise of ≥0.3 mg/dL or 1.5–1.9 times the baseline.	<0.5 mL/kg/hour for 6 hours.	Risk	25% decrease in eGFR.	<1.5 mL/kg/hour for 24 hours.	0	No change or rise of <0.3 mg/dL.	≥0.5 mL/kg/hour.
2	2–3 times the baseline.	<0.5 mL/kg/hour for >12 hours.	Injury	50% decrease in eGFR.	<1.0 mL/kg/hour for 24 hours.	1	Rise of ≥0.3 mg/dL or 1.5–1.9 times the baseline.	<0.5 mL/kg/hour for 6–12 hours.
3	3 times the baseline or rise of ≥4.0 mg/dL with acute rise of at least 0.5 mg/dL.	<0.3 mL/kg/hour for 24 hours or anuria for 12 hours.	Failure	75% decrease in eGFR.	<0.7 mL/kg/hour for 24 hours or anuria for 12 hours.	2	2–2.9 times the baseline.	<0.5 mL/kg/hour for ≥12 hours.
			Loss	Persistent failure of >4 weeks.		3	3 times the baseline or rise of ≥2.5 mg/dL or initiation of RRT.	<0.5 mL/kg/hour for ≥24 hours or anuria for ≥12 hours.
			End stage	Persistent failure of >3 months.

Baseline refers to the lowest previous level of sCr.
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 Disease; RRT, renal replacement treatment; sCr, serum creatinine; UO, urine output.