| Class | Serum Creatinine/ GFR | Urine Output |
| Risk | in Serum Creatinine x 1.5 or GFR ¯ >25% | <0.5 ml/kg/hr – more than 6 hours |
| Injury | in Serum Creatinine x 2 or GFR ¯ >50% | <0.5 ml/kg/hr – more than 12 hours |
| Failure | in Serum Creatinine x 3 or creatinine > 354mmol/l with an acute rise >44mmol/l GFR ¯ >75% | <0.3 ml/kg/hr – more than 24 hours or anuric for 12 hours |
| Loss | Persistent acute renal failure with loss of kidney function >4 weeks | – |
| End-stage kidney disease | ESRD > 3 months | – |
