What is the difference between RIFLE and KDIGO staging?

RIFLE (2004) uses three severity grades defined by creatinine ratio or GFR decrease and urine output, plus two outcome categories. KDIGO (2012) uses three stages defined by absolute creatinine rise (≥0.3 mg/dL within 48 h) or ratio, and was validated in larger, more contemporary cohorts. RIFLE Risk ≈ KDIGO Stage 1; RIFLE Injury ≈ KDIGO Stage 2; RIFLE Failure ≈ KDIGO Stage 3. KDIGO added the 48-hour absolute-rise criterion that RIFLE lacked.

How do I choose the baseline creatinine?

Use the lowest serum creatinine from the 7 days before the acute event. If no prior values are available, the original ADQI recommendation is to back-calculate from an assumed eGFR of 75 mL/min/1.73m² using the MDRD formula adjusted for age, sex, and race. Your institution may have a different protocol.

What defines RIFLE Failure?

Failure is a serum creatinine increase ≥3× baseline, OR a GFR decrease ≥75% from baseline, OR a urine output <0.3 mL/kg/hr for ≥24 hours, OR anuria for ≥12 hours.

What are the RIFLE outcome categories (Loss and End-stage)?

Loss is defined as persistent acute renal failure — complete loss of kidney function — for more than 4 weeks requiring renal replacement therapy. End-stage kidney disease is defined as complete loss of kidney function for more than 3 months. These are outcome categories, not severity grades, and cannot be determined from a single creatinine measurement.

Does this tool replace clinical judgment?

No. This calculator is a reference aid for educational and clinical documentation purposes. Volume status, underlying chronic kidney disease, medications, and clinical trajectory must all inform management. Always confirm classification and treatment decisions with the treating clinician or nephrologist.

RIFLE AKI Criteria

Classify acute kidney injury using RIFLE criteria (Risk/Injury/Failure/Loss/End-stage) from serum creatinine change, GFR reduction, or urine output.

For educational and clinical documentation use only. Not a substitute for clinical judgment.

Serum Creatinine

Baseline Creatinine (mg/dL)

Lowest value in prior 7 days; back-calculate from eGFR 75 if unavailable

Current Creatinine (mg/dL)

Worst (highest) value in the acute episode

GFR Reduction (optional)

eGFR decrease from baseline (%)

Enter if your lab provides eGFR; not required when creatinine is entered

Urine Output (optional)

Urine output rate (mL/kg/hr)

Duration of oliguria (hours)

Outcome Categories (optional)

Loss — complete loss of kidney function for >4 weeks requiring RRT End-stage — complete loss of kidney function for >3 months

Enter values and click Classify AKI (RIFLE) to see the result.

RIFLE Classification

—

Criterion Breakdown

Criterion	Value	Class Met

Interpretation Note

The final RIFLE class is the highest class met by any single criterion. Loss and End-stage are outcome categories determined by duration of renal replacement therapy dependency, not by a single creatinine value. This tool does not account for RRT initiation as a Failure criterion — note that separately.

RIFLE Criteria Reference

Class	Creatinine / GFR	Urine Output
Risk	Cr ×1.5 baseline OR GFR decrease >25%	<0.5 mL/kg/hr for >6 h
Injury	Cr ×2 baseline OR GFR decrease >50%	<0.5 mL/kg/hr for >12 h
Failure	Cr ×3 baseline OR GFR decrease >75% OR Cr ≥4 mg/dL (acute rise ≥0.5)	<0.3 mL/kg/hr for >24 h OR anuria >12 h
Loss	Persistent complete loss of kidney function >4 weeks (requires RRT)
End-stage	Complete loss of kidney function >3 months

Source: Bellomo R, et al. Acute renal failure — definition, outcome measures, animal models, fluid therapy and information technology needs. Crit Care. 2004;8(4):R204–R212.

Summary

The RIFLE criteria (Risk, Injury, Failure, Loss, End-stage) were introduced in 2004 by the Acute Dialysis Quality Initiative (ADQI) to provide a standardized classification of acute kidney injury. The system uses three severity grades (Risk, Injury, Failure) based on relative changes in serum creatinine or estimated GFR from baseline and duration of oliguria, plus two outcome categories (Loss and End-stage) based on duration of renal function loss. Classification is assigned at the highest class met by any single criterion. RIFLE preceded and informed the later AKIN and KDIGO systems and remains widely used in older literature and ICU research.

How it works

Enter the baseline serum creatinine (the lowest value in the prior 7 days or, if unavailable, back-calculated from an assumed GFR of 75 mL/min/1.73m²).
Enter the current (worst) serum creatinine measured in the acute setting.
Optionally enter the estimated GFR reduction percentage if your lab provides eGFR values.
Optionally enter the urine output rate (mL/kg/hr) and how many hours it has been maintained.
For Loss or End-stage, indicate duration of complete renal function loss.
Click Classify to see the highest RIFLE class met and the clinical guidance for that class.

Use cases

Classify AKI severity at the bedside in an ICU or emergency setting.
Apply RIFLE terminology when interpreting older nephrology or critical care literature.
Compare RIFLE classification alongside KDIGO staging for academic or quality-improvement work.
Educate medical students and residents on the original ADQI AKI framework.
Document AKI class in clinical notes where RIFLE is the institutional standard.
Assess progression from Risk to Injury to Failure during serial measurements.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu