Table 2.

Definitions of Muscle Syndromes

	Myopathy	Myalgia	Myositis	Rhabdomyolysis
Canadian Working Group²³	General term for muscle events	Normal CK Aching or weakness	CK more than the ULN Aching or weakness	Aching or weakness CK >10× ULN ± Renal dysfunction
NLA Muscle Safety Task Force²⁴	Spectrum of muscle events	Muscle soreness, stiffness, cramps, tenderness	Muscle inflammation	CK >3× ULN with myoglobinuria or acute renal failure
ACC/AHA/NHLBI Clinical Advisory²⁵	General term for muscle events	Normal CK Aching or weakness	CK more than the ULN Aching or weakness	Aching or weakness Marked CK elevation + Elevated creatinine + Urine myoglobin

ACC, American College of Cardiology; AHA, American Heart Association; CK, creatine kinase; NHLBI, National Heart Lung and Blood Institute; NLA, National Lipid Association; ULN, upper limit of normal.