eGFR Requirement for Stage 3 AKI in KDIGO Criteria
According to the KDIGO criteria, Stage 3 AKI includes a decrease in eGFR to less than 35 mL/min/1.73 m² in patients under 18 years of age. 1
KDIGO Definition of Stage 3 AKI
Stage 3 AKI is defined by any of the following criteria:
- Increase in serum creatinine (SCr) to ≥3.0 times baseline 1
- Increase in SCr to ≥4.0 mg/dL (353.6 μmol/L) 1
- Initiation of renal replacement therapy 1
- In patients <18 years, decrease in eGFR to <35 mL/min/1.73 m² 1
- Urine output <0.3 mL/kg/h for ≥24 hours 1
- Anuria for ≥12 hours 1
Important Considerations for AKI Classification
- The eGFR criterion of <35 mL/min/1.73 m² applies specifically to pediatric patients (under 18 years) 1
- For adult patients, the KDIGO criteria rely on changes in serum creatinine, urine output, or initiation of renal replacement therapy rather than absolute eGFR values 1
- The KDIGO definition combines elements from previous RIFLE and AKIN definitions but includes some modifications that have not been fully validated 1
Clinical Implications and Caveats
- eGFR equations are not accurate during AKI and should not be used to assess kidney function in this setting 2
- Small fluctuations in serum creatinine (such as an increase from 4.0 to 4.3 mg/dL) may be within normal daily variation in patients with pre-existing CKD 1
- The KDIGO AKI definition requires an acute increase in serum creatinine by 0.3 mg/dL within 48 hours for patients with SCr ≥4.0 mg/dL to be classified as stage 3 AKI 1
- This differs from prior AKIN and RIFLE definitions, which required an SCr ≥4.0 mg/dL and increase of 0.5 mg/dL over an unspecified period 1
Long-term Outcomes and Monitoring
- Patients who experience AKI should be evaluated 3 months after the event for resolution, new onset, or worsening of pre-existing CKD 1
- AKI events can cause a progressive decline in kidney function, with each subsequent AKI event potentially accelerating this decline 3
- The risk of developing chronic kidney disease is significantly higher in patients who have experienced AKI 4, 5
Special Populations
- In pediatric patients, the eGFR criterion (<35 mL/min/1.73 m²) is an important component of the KDIGO staging system 1
- Different criteria may yield different AKI incidence rates, as demonstrated in studies comparing KDIGO with other definitions 6
- Patients with baseline CKD require careful interpretation of AKI criteria, as small changes in serum creatinine may have different clinical significance compared to those with normal baseline kidney function 1