Table 50-1.

International Renal Interest Society Grading Scheme for Acute Kidney Injury

Grade†	Creatinine	Clinical Description
Stage I	<1.6 mg/dL (<140 µmol/L)	Nonazotemic AKI Documented AKI: Historical, clinical, laboratory, or imaging evidence of AKI; clinical oliguria/anuria; volume responsiveness* and/or Progressive nonazotemic increase in serum creatinine ≥0.3 mg/dL (≥26.4 µmol/L) within 48 hours Measured oliguria (<1 mL/kg/hr) or anuria over 6 hours
Stage II	1.7-2.5 mg/dL (141-220 µmol/L)	Mild AKI Documented AKI and static or progressive azotemia Progressive azotemic increase in serum creatinine ≥0.3 mg/dL (≥26.4 µmol/L) within 48 hours, or volume responsiveness* Measured oliguria (<1 mL/kg/hr) or anuria over 6 hours
Stage III	2.6-5.0 mg/dL (221-439 µmol/L)	Moderate to severe AKI Documented AKI and increasing severities of azotemia and functional failure
Stage IV	5.1-10.0 mg/dL (440-880 µmol/L)
Stage V	>10.0 mg/dL (>880 µmol/L)

AKI, Acute kidney injury.

^*Volume responsive is an increase in urine production to >1 mL/kg/hr over 6 hours and/or decrease in serum creatinine to baseline over 48 hours.

^†Each stage of AKI is further substaged on the basis of current urine production as oliguric or nonoliguric and on the requirement for renal replacement therapy.