TABLE 2.

Definitions of AKI: 3 common staging systems to define and stage AKI

System	Stage I	Stage II	Stage III
AKIN17	SCr increase by 1.5- to 1.9-fold from baseline; SCr increase of ≥0.3 mg/dL; or urine output of <0.5 mL/kg/h >6 h	SCr increase 2.0–2.9 times baseline or urine output of <0. 5 mL/kg/h for >12 h	SCr increase 3.0 times baseline; SCr increase of ≥4.0 mg/dL with an acute increase of at least 0.5 mg/dL; or urine output of <0. 3 mL/kg/h >24 h or anuric for >12 h
KDIGO18	SCr increase 1.5–1.9 times baseline; or Cr increase of ≥0.3 mg/dL or urine output of <0.5 mL/kg/h for 6–12 h	SCr increase 2.0–2.9 times baseline; or urine output of <0.5 mL/kg/h for >12 h	SCr increase 3.0 times baseline; SCr increase of ≥4.0 mg/dL; initiation of renal replacement therapy; or urine output of <0.3 mL/kg/h for 24 h or anuric for >12 h
IAC19	SCr increase (0.3 mg/dL) or increase in SCr of ≥1.5–2.0 times from baseline	SCr increase >2.0–3.0 times from baseline	SCr increase >3.0 times from baseline; SCr of ≥4.0 mg/dL with an acute rise of 0.3 mg/dL; or initiation of renal replacement therapy

AKIN, Acute Kidney Injury Network; IAC, International Ascites Club; KDIGO, Kidney Disease Improving Global Outcomes; SCr, serum creatinine.