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    AKIN Classification for Acute Kidney Injury (AKI)

    Classifies severity of acute kidney injury, similar to RIFLE Criteria.


    Patients on renal replacement therapy (RRT) are considered to be stage 3 regardless of whether they meet formal criteria.

    When to Use

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    Criteria for AKI (must have ≥1 within the past 48 hrs)


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    To be diagnosed with acute kidney injury by the AKIN definition, patient must have at least one of the following within the past 48 hours:

    • Absolute increase in serum creatinine ≥0.3 mg/dL (≥26.4 μmol/L).

    • Increase in serum creatinine ≥1.5x above baseline.

    • Oliguria (urine output <0.5 mL/kg per hour) for >6 hours.

    Then, select the appropriate criterion leading to the highest possible stage, e.g. if serum creatinine is normal but urine output is <0.5 mL/kg/hour for >12 hours, AKIN Stage is 2.

    AKIN Classification

    Serum creatinine

    Urine output

    Not AKI according to AKIN

    Normal creatinine, or <1.5x from baseline

    ≥0.5 mL/kg per hour for >6 hours

    Stage 1

    Absolute increase ≥0.3 mg/dL (≥26.4 μmol/L), or ≥1.5-2x from baseline

    <0.5 mL/kg per hour for >6 hours

    Stage 2

    Increase to >2-3x from baseline

    <0.5 mL/kg per hour for >12 hours

    Stage 3

    Increase to >3x from baseline, or ≥4.0 mg/dL (≥354 μmol/L) with acute increase ≥0.5 mg/dL (≥44 μmol/L)

    <0.3 mL/kg per hour for ≥24 hours, or anuria for 12 hours

    Dr. Ravindra L. Mehta

    About the Creator

    Ravindra L. Mehta, MD, is a nephrology professor and associate chair for clinical affairs in the department of medicine at the University of California, San Diego. He is also the president of the Acute Dialysis Quality Initiative and the Acute Kidney Injury Network (AKIN). Dr. Mehta’s primary research focuses on kidney disease and its underlying causes.

    To view Dr. Ravindra L. Mehta's publications, visit PubMed

    About the Creator
    Dr. Ravindra L. Mehta