Biomarkers of Acute Kidney Injury after Cardiac Surgery: A Narrative Review

Table 1

KDIGO criteria for the classification of AKI.

Stage	Serum creatinine level	Urine output
1	Increase of ≥0.3 mg/dl (≥26.5 μmol/l) within 48 h; or increase of 1.5–1.9-fold over baseline within 7 days	< 0.5 ml/kg/h for 6 to 12 h
2	Increase of 2.0–2.9-fold over baseline	< 0.5 ml/kg/h for 12 h
3	Increase of 3.0-fold over baseline,; increase of ≥4.0 mg/dl (≥353.6 μmol/l),; initiation of renal replacement therapy,; or a GFR decrease < 35 ml/min/1.73 m^2 for patients < 18	< 0.3 ml/kg/h for 24 h or anuria for 12 h

KDIGO: Kidney Disease Improving Global Outcomes; AKI: acute kidney injury; GFR: glomerular filtration rate.