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    McMahon Score for Rhabdomyolysis

    Predicts mortality or acute kidney injury (AKI) in rhabdomyolysis patients.
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    INSTRUCTIONS

    Use in patients ≥18 years old with rhabdomyolysis (CPK >5,000 U/L within 72 hours of admission). Do not use in patients with pre-existing end-stage renal disease or with elevated CPK due to MI.

    When to Use
    Pearls/Pitfalls
    Why Use

    • Patients ≥18 years old with rhabdomyolysis (CPK >5,000 U/L within 72 hours of admission).

    • Do not use in patients with pre-existing end-stage renal disease or elevated CPK due to MI.

    • Can be used in both traumatic and atraumatic rhabdomyolysis.

    • Not validated for patients who have had renal replacement therapy (RRT) within 24 hours.

    • Not yet prospectively validated (has been retrospectively validated).

    • Uses readily available clinical demographic and laboratory values.

    • More specific than CPK alone at predicting need for RRT (AUROC 0.775 vs 0.631).

    ≤50
    0
    51-70
    +1.5
    71-80
    +2.5
    >80
    +3
    Male
    0
    Female
    +1
    <1.4 mg/dL (124 µmol/L)
    0
    1.4–2.2 mg/dL (124–195 µmol/L)
    +1.5
    >2.2 mg/dL (195 µmol/L)
    +3
    No
    0
    Yes
    +2
    No
    0
    Yes
    +2
    Yes
    0
    No
    +3
    <4.0 mg/dL (1.0 mmol/L)
    0
    4.0–5.4 mg/dL (1.0-1.4 mmol/L)
    +1.5
    >5.4 mg/dL (1.4 mmol/L)
    +3
    No
    0
    Yes
    +2

    Result:

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    Next Steps
    Evidence
    Creator Insights

    Advice

    • CPK >1,000 U/L provides laboratory confirmation of the clinical diagnosis (CPK >40,000 U/L is used as a risk factor in the score).

    • Delayed increase in CPK is common and therefore serial levels should be obtained.

    Management

    Renal protective therapy should include fluid resuscitation targeting euvolemia and urinary output of at least 1–2 mL/kg/hr.

    Critical Actions

    Renal protective therapies should be considered in all patients deemed to be at high risk (score ≥6) irrespective of admission CPK.

    Content Contributors
    About the Creator
    Dr. Gearoid M. McMahon
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