Re: Elevated CPK .. dould that be normal in some people?
I have muscular dystrophy. My CPK is always around 500. But...I can hardly walk or get out of a chair. I definitely have a muscle disease.
I remember though, when I first went to a neurologist in 2002 about my weakness. The first thing he asked when he saw my blood work was "Do you have high cholesterol or have you taken any cholesterol medication in the past year or so". These drugs are known to elevate the CPK from what's normal (80-120 I believe)
500 isn't terribly high. Some MDs can result in readings of 15,000 - 20,000. There's something strange at work here. A lot of MD patients complain of increased weakness after they start cholesterol reducing drugs. My cholesterol is 230 but I don't want to start drugs because of this fact. My doctor agrees.
Bottom line: If you are not extremely weak, above and beyond what you'd consider the "weak" end of normal, I'd not worry just yet. But definitely see a neurologist or local MDA clinic if you're symptoms get worse.
(PS - Myositis is just one of many forms of Muscular Dystrophy).
Best of Luck,