I had normal blood work done in April, CPK came back 749....has never been higher than 188 back in 2009. Retested 2 weeks ago, now at 313. All other labs come back completely normal. I have not been doing extra hard physical things, no heart conditions, liver and all others are fine. I take Levothroxin for thyroid condition, and 10mg of Simvastatin because of a slight blockage of Carotid artery, but cholesterol levels are the best any doctor has seen. I am 76 and am very active but do not work out .... I still work and am on the go all of the time. Is there a specialist that I should see to find out if this is related to muscle, heart or brain????? Need to know what is causing it to make it right again.