Statin muscle damage missed

A recent study has called into question whether normal or mildly elevated levels of serum creatine phosphokinase can be used to exclude underlying and possibly ongoing muscle injury in those taking statins. Published online in the Canadian Medical Association Journal, the Swiss researchers obtained biopsy samples from the vastus lateralis muscle of 83 patients. Overall, 44 subjects had clinically diagnosed statin-associated myopathy, and of these, 29 were currently taking a statin, while 15 had discontinued statin therapy for at least three weeks. Among the 83 patients, 19 were currently taking a statin but had no myopathy and 20 patients served as healthy controls. The researchers classified the muscles as injured if 2% or more of the muscle fibres in a biopsy sample showed damage. Among the 44 individuals with myopathy, 57% had muscle injury, as did one patient without clinically diagnosed myopathy. Just one patient with structural muscle injury had circulating creatine phosphokinase levels that exceeded 10 times the upper limit of normal, or >1950 U/L. In current clinical practice, patients who present with muscle symptoms while receiving statin therapy have their creatine phosphokinase levels measured. If the level is within normal limits or is modestly elevated, patients are frequently advised to continue their current statin therapy. “This is based on the assumption that a lack of increased creatine phosphokinase levels supports a lack of underlying muscle damage,” the researchers explained. “Our findings suggest that normal or moderately elevated levels of creatine phosphokinase do not exclude statin-associated muscle injury,” they concluded....