Chilled EDTA plasma
Serum (clotted blood) or heparinised plasma
Arises from multiple tissue sources but primarily muscle and liver. There is a long clearance time so do not be alarmed when values are still high a week or more after an acute myopathy. CK will normalise far more quickly with recovery. Thus, with mild, recovering or intermittent myopathy you are more likely to detect a high AST than a high CK.
See also: