staging of acute kidney injury (AKI)
Last edited 04/2019 and last reviewed 10/2022
Staging of AKI
| Stage of AKI | Serum creatinine (SCr) criteria | Urine output criteria |
| 1 |
increase >=26 µmol/L within 48hrs or increase >= 1.5 to 1.9 X reference SCr |
<0.5 mL/kg/hr for > 6 consecutive hrs |
| 2 | increase >= 2 to 2.9 X reference SCr | <0.5 mL/kg/ hr for > 12 hrs |
| 3 |
increase >=3 X reference SCr or increase >=354 µmol/L or commenced on renal replacement therapy (RRT) irrespective of stage |
<0.3 mL/kg/ hr for > 24 hrs or anuria for >= 12 hrs |
Definition of AKI
Acute kidney injury is defined when one of the following criteria is met
- serum creatinine rises by >= 26 µmol/L within 48 hours or
- serum creatinine rises >= 1.5 fold from the reference value, which
is known or presumed to have occurred within one week or
- oliguria (urine output is < 0.5ml/kg/hr for >6 consecutive hours) or
- a 25% or greater fall in eGFR in children and young people within the past 7 days (3)
The reference serum creatinine should be the lowest creatinine value recorded within 3 months of the event
If a reference serum creatinine value is not available within 3 months and AKI is suspected
- repeat serum creatinine within 24 hours
- a reference serum creatinine value can be estimated from the nadir serum creatinine value if patient recovers from AKI
Notes:
- formula-based estimated GFR should be interpreted with caution in AKI - this is because the formulae rely on a stable serum creatinine concentration
-
is a clinical syndrome characterised by a rapid decline in excretory function occurring over a period of hours or day
-
if a patient has suspected AKI the s/he should be referred to a nephrologist
- acute on chronic renal failure
- if there has been a fall in estimated GFR of >25% since the last measurement of kidney function in a patient with CKD should prompt a repeat measurement of kidney function, assessment as for AKI and referral if the deterioration is confirmed
Reference: