CPK results of 475 are not a big deal if you are training hard. A very intense heavy workout could raise your CK levels to the 10000 mark. Your doctor sounds like a Family Doc. New terms now are CK and CK-MB (or just MB). These test are done to check for the present of a Heart attack (MI). The CK portion of the test has to do with muscle damage (any muscle in the body not just cardiac). The MB portion is more cardiac related. Other things of importance: Why did your doctor do this test? Where you having chest pain? Make sure that your doctor was reporting the CK portion, If your MB was this high, this would more than likely indicate a HEART ATTACK (normal MB levels 0 - 10). If you were having chest pain your doctor should have pulled a Troponin level (this test is very cardiac specific, a level of >=0.5 = MI). Hope this imformation helps out.