## KDIGO Classification of Acute Kidney Injury **Key Point:** KDIGO (Kidney Disease: Improving Global Outcomes) divides AKI into three stages based on serum creatinine change and urine output criteria. Stage 2 represents moderate AKI with 2–2.9× baseline creatinine elevation. ### KDIGO AKI Staging Table | Stage | Serum Creatinine Criteria | Urine Output Criteria | |-------|---|---| | **Stage 1** | 1.5–1.9× baseline | <0.5 mL/kg/hr for 6–12 hours | | **Stage 2** | 2.0–2.9× baseline | <0.5 mL/kg/hr for ≥12 hours | | **Stage 3** | ≥3.0× baseline OR ≥4.0 mg/dL absolute | <0.3 mL/kg/hr for ≥24 hours OR anuria ≥12 hours | **High-Yield:** The KDIGO criteria use **both** serum creatinine AND urine output; if either criterion is met, the patient is classified at that stage. The stage assigned is the **higher** of the two. ### Mnemonic: "KDIGO AKI Stages — 1-2-3" - **Stage 1:** **1.5–1.9×** creatinine; **6–12 hour** oliguria - **Stage 2:** **2.0–2.9×** creatinine; **≥12 hour** oliguria - **Stage 3:** **≥3.0×** creatinine OR **≥4.0 mg/dL** absolute; **≥24 hour** oliguria or anuria **Clinical Pearl:** Stage 2 AKI carries a significantly higher risk of progression to Stage 3 and need for renal replacement therapy compared to Stage 1. Mortality increases substantially at Stage 2 and beyond. **Warning:** Do not confuse KDIGO with older classification systems (RIFLE, AKIN). KDIGO is the current standard and is what NEET PG expects. The creatinine multipliers and oliguria thresholds differ from RIFLE/AKIN. [cite:KDIGO Clinical Practice Guideline for Acute Kidney Injury 2012]
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