Aki staging kdigo: Free Evidence-Based nephrology Scoring Tool

How it Works

KDIGO Staging Criteria

Stage 1	Cr ×1.5–1.9 baseline OR ↑ ≥ 0.3 mg/dL; OR UO < 0.5 mL/kg/hr for 6–12h
Stage 2	Cr ×2.0–2.9 baseline; OR UO < 0.5 mL/kg/hr for ≥ 12h
Stage 3	Cr ×3.0 baseline, OR Cr ≥ 4.0 mg/dL, OR initiation of RRT; OR UO < 0.3 mL/kg/hr for ≥ 24h, or anuria for ≥ 12h

Staging Rule

Final AKI Stage = the HIGHER stage determined by either the creatinine criterion OR the urine output criterion. Both are assessed independently and the worst-case staging applies.

RIFLE vs. AKIN vs. KDIGO

RIFLE (2004)	Risk / Injury / Failure / Loss / ESRD — 5 categories
AKIN (2007)	Stages 1–3; introduced 48h window and 0.3 mg/dL criterion
KDIGO (2012)	Unified and current standard — incorporates best of RIFLE and AKIN

Clinical Pearls

Why Baseline Creatinine Matters

If no baseline creatinine is known, back-calculate using the MDRD equation assuming eGFR = 75 mL/min/1.73m2. This can prevent over- or under-staging. In communities without prior labs, historical values from prior admissions or GP records are invaluable.

Clinical Pearls

Do not wait for both creatinine AND urine output criteria — AKI is staged on whichever criterion is met first.

Time-stamps matter: the 48-hour window for the creatinine criterion resets with every new measurement.

Even Stage 1 AKI increases 90-day mortality by 2–3× in hospitalised patients.

Urine Output Pitfall

Urine output requires an indwelling catheter for accurate measurement in ICU patients.

Oliguria from urinary retention or catheter obstruction can mimic AKI — always rule out post-renal cause first.

Next Steps

Management by Stage

Stage 1	Review nephrotoxins. Volume resuscitation if hypovolaemic. Hourly UO monitoring.
Stage 2	Nephrology consult. Avoid contrast. Strict I&O. Optimise cardiac output.
Stage 3	Urgent Nephrology. Assess RRT criteria: refractory acidosis, hyperkalaemia, fluid overload, uraemia.

Diagnose the Cause

01

Prerenal: FEUrea < 35% (FENa < 1% if no diuretics). Treat with volume and vasopressors.

02

Intrinsic (ATN): FEUrea > 50%. Granular casts on UA. Stop nephrotoxins.

03

Post-renal: Bladder scan, renal US. Relieve obstruction urgently.

Complementary Tools

FENa — Fractional Excretion of Sodium

FEUrea — Fractional Excretion of Urea

KFRE — Kidney Failure Risk Equation

The Evidence

KDIGO 2012 Guideline

KDIGO Clinical Practice Guideline for Acute Kidney Injury.

Kidney Disease: Improving Global Outcomes (KDIGO) AKI Work Group. • Kidney Int Suppl.. 2012;2(1):1–138. The unifying guideline that consolidated RIFLE and AKIN into the current 3-stage system.

Origins & History

Evolution of AKI Classification

Prior to 2004, there was no universal definition of Acute Renal Failure. The field used over 35 different definitions in the literature, making comparison of studies virtually impossible. The ADQI (Acute Dialysis Quality Initiative) group proposed RIFLE in 2004, which was refined into AKIN in 2007, and finally unified into the current KDIGO system in 2012. This standardisation has been one of the most impactful developments in modern nephrology.

AKI Staging (KDIGO)

When to Use

When to Use

KDIGO AKI Definition

How it Works

KDIGO Staging Criteria

Staging Rule

RIFLE vs. AKIN vs. KDIGO

Clinical Pearls

Why Baseline Creatinine Matters

Clinical Pearls

Urine Output Pitfall

Next Steps

Management by Stage

Diagnose the Cause

Complementary Tools

The Evidence

KDIGO 2012 Guideline

KDIGO Clinical Practice Guideline for Acute Kidney Injury.

Origins & History

Evolution of AKI Classification

In Recent Clinical News

AKI Staging (KDIGO)

When to Use

When to Use

KDIGO AKI Definition

How it Works

KDIGO Staging Criteria

Staging Rule

RIFLE vs. AKIN vs. KDIGO

Clinical Pearls

Why Baseline Creatinine Matters

Clinical Pearls

Urine Output Pitfall

Next Steps

Management by Stage

Diagnose the Cause

Complementary Tools

The Evidence

KDIGO 2012 Guideline

KDIGO Clinical Practice Guideline for Acute Kidney Injury.

Origins & History

Evolution of AKI Classification

In Recent Clinical News