MDCalc

McMahon Score for Rhabdomyolysis

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

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.

Age, years
Sex
Initial creatinine
Initial calcium <7.5 mg/dL (1.88 mmol/L)
Initial CPK >40,000 U/L
Rhabdo secondary to seizures, syncope, exercise, statins, or myositis
Initial phosphate
Initial bicarbonate <19 mEq/L (19 mmol/L)

Result:

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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.

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