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McMahon Rhabdomyolysis Score

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McMahon Rhabdomyolysis Score, McMahon Score

  • See Also
  1. Rhabdomyolysis
  • Indications
  1. Predicts Rhabdomyolysis associated Renal Failure
  • Criteria
  • Assumes Rhabdomyolysis with initial CPK >1000 (or 5 times normal)
  1. Age
    1. Score 0: <=50 years old
    2. Score 1.5: 51-70 years old
    3. Score 2.5: 71-80 years old
    4. Score 3: >80 years old
  2. Gender
    1. Score 0: Male
    2. Score 1: Female
  3. Initial Serum Creatinine
    1. Score 0: <1.4 mg/dl (<125 µmol/L)
    2. Score 1.5: 1.4 to 2.2 (125-195 µmol/L)
    3. Score 3: >2.2 mg/dl (>195 µmol/L)
  4. Initial Serum Calcium <7.5 mg/dL (1.88 mmol/L)
    1. Score 0: No
    2. Score 2: Yes
  5. Initial Creatine Phosphokinase (CK) >40,000
    1. Score 0: No
    2. Score 2: Yes
  6. Caused by Seizure, Syncope, Exercise, Statin or Myositis
    1. Score 0: Yes
    2. Score 3: No
  7. Initial Phosphate
    1. Score 0: <4 mg/dl (<1 mmol/L)
    2. Score 1.5: 4 to 5.4 mg/dl (1-1.4 mmol/L)
    3. Score 3: >5.4 mg/dl (>1.4 mmol/L)
  8. Initial Serum Bicarbonate <19 mEq/L (<19 mmol/L)
    1. Score 0: No
    2. Score 2: Yes
  • Interpretation
  1. Score <6: Low risk of serious adverse outcomes
    1. Risk <3% for death or Acute Kidney Injury requiring renal replacement therapy
  2. Score >=6: Not Low Risk
    1. Increased risk of serious adverse outcomes (Test Sensitivity 83%)
  • Resources
  1. MD Calc
    1. https://www.mdcalc.com/mcmahon-score-rhabdomyolysis
  2. QxMD
    1. https://qxmd.com/calculate/calculator_587/mcmahon-rhabdomyolysis-risk-score
  • References
  1. McMahon (2013) JAMA Intern Med 173(19):1821-8