The normal range for the creatine phosphokinase or CPK level during a blood test is 10 to 120 micrograms per liter, according to MedlinePlus. However, the range may differ from one lab to another because the samples tested and measurements applied may vary with labs.
The CPK is an enzyme that mainly occurs in the brain, heart and skeletal muscle, explains MedlinePlus. Typically, an elevated CPK level indicates stressed or injured brain, heart or skeletal muscle. Doctors determine the level of CPK in the body through a blood test, which helps diagnose conditions such as heart attack, dermatomyositis and polymyositis. However, the test may be risky because some patients may faint or bleed excessively in the process. It may also cause a hematoma, which is an accumulation of blood beneath the skin.