McMahon score is the sum of points for each risk factor at admission:

Variable	Criteria (admission)	Points
Age	≤50 years	0
	>50 to ≤70 years	1.5
	>70 to ≤80 years	2.5
	>80 years	3
Sex	Female	1
Creatinine	<1.4 mg/dL (<124 µmol/L)	0
	1.4 to 2.2 mg/dL (124–194 µmol/L)	1.5
	>2.2 mg/dL (>194 µmol/L)	3
Calcium	<7.5 mg/dL (<1.875 mmol/L)	2
Creatine kinase (CK/CPK)	>40,000 U/L	2
Cause of rhabdomyolysis	Not seizures, syncope, exercise, statins, or myositis	3
Phosphate	≤3.9 mg/dL (≤1.29 mmol/L)	0
	4.0 to 5.4 mg/dL (1.30–1.74 mmol/L)	1.5
	>5.4 mg/dL (>1.74 mmol/L)	3
Bicarbonate	<19 mEq/L (<19 mmol/L)	2

Possible score range is 0–19 points. Higher scores indicate higher risk of in-hospital mortality or acute kidney injury requiring renal replacement therapy.

McMahon Score for Rhabdomyolysis