It is an enzyme (a protein that helps to elicit chemical changes in your body) found in your heart, brain, and skeletal muscles.
A creatine kinase (CK) test may be used to detect inflammation of muscles (myositis) or serious muscle damage and/or to diagnose rhabdomyolysis if a person has signs and symptoms, such as muscle weakness, muscle aches, and dark urine.  The creatine phosphokinase test measures the amount of creatine phosphokinase (CPK) present in the blood. The test is also known as creatine kinase, CPK test, and CK test. Creatine phosphokinase is a specific enzyme found primarily in the heart, skeletal muscle, and brain. The creatine phosphokinase test is performed to assess damage to tissue in the brain, muscle tissue, or heart. When tissue is damaged, creatine phosphokinase leaks from tissue into the blood. The test is used to diagnose and evaluate the following conditions: 1  heart attack. 2  chest pain. 3  muscle damage. 4  early dermatomyositis (a muscle and connective-tissue disease). 5  polymyositis (results in inflammation of the muscles). A. CPK stands for creatine phosphokinase. It’s an enzyme found in high concentrations in muscles, where it facilitates muscle contraction. CPK is also called creatine kinase or CK. Doctors may check CPK when there’s concern for muscle damage or breakdown: 1  In a rare condition called rhabdomyolysis, extreme muscle breakdown floods the blood with CPK and other chemicals in muscle cells. 2  Some of these are toxic to the kidneys, making the condition dangerous Definition: Creatine Phosphokinase (CPK). Creatine phosphokinase (CPK) is an enzyme found mainly in the heart, brain, and skeletal muscle. Creatine kinase (CK), also known as creatine phosphokinase (CPK) or phospho-creatine kinase, is an enzyme (EC 2.7.3.2) expressed by various tissues and cell types. CPK is also referred to as, 'creatine kinase,' or, 'CK.' A doctor might check a person's CPK when they are concerned a person has experienced muscle damage or breakdown. In a rare condition called, 'rhabdomyolysis,' extreme muscle breakdown floods a person's blood with CPK and additional chemicals in their muscle cells. an organ-specific enzyme catalyzing the transfer of a phosphate group from phosphocreatine to ATP. It has three isoenzymes: CK 1, found primarily in the brain; CK 2, found in the myocardium; and CK 3, found in both skeletal muscle and the myocardium.  Creatine kinase (CK) — also known as creatine phosphokinase (CPK) or phospho-creatine kinase — is an enzyme (EC 2.7.3.2) expressed by various tissues and cell types. CK catalyses the conversion of creatine and utilizes adenosine triphosphate (ATP) to create phosphocreatine (PCr) and adenosine diphosphate (ADP).  An elevated CPK result, or one that goes up from the first test to the second one or later samples, usually indicates there has been some recent muscle damage.... Creatine phosphokinase or, 'CPK,' is an enzyme found in high concentrations in a person's muscles where it facilitates a person's muscle contraction. CPK is also referred to as, 'creatine kinase,' or, 'CK.' A doctor might check a person's CPK when they are concerned a person has experienced muscle damage or breakdown. In a rare condition called, 'rhabdomyolysis,' extreme muscle breakdown floods a person's blood with CPK and additional chemicals in their muscle cells. Creatine kinase or creatine phosphokinase is an enzyme chiefly found in the brain, skeletal muscles, and heart. There are three different forms of creatine kinase that can be measured: CK-MM (located in the skeletal muscles and heart), CK-MB (mainly located in the heart), and CK-BB (located in the brain). An elevated level of creatine kinase, specifically CK-MB, occurs within hours of a heart attack as the heart muscle cells die. Creatine kinase, also called CK or creatine phosphokinase or CPK, is a blood enzyme. Tests for CK and the fraction CK-MB are used to confirm the existence of heart muscle damage and are used as rapid detection of a heart attack.  Creatine Phosphokinase (CPK). Creatine phosphokinase (a.k.a., creatine kinase, CPK, or CK) is an enzyme (a protein that helps to elicit chemical changes in your body) found in your heart, brain, and skeletal muscles. When muscle tissue is damaged, CPK leaks into your blood. 
https://labtestsonline.org/understanding/analytes/ck/tab/test http://www.healthline.com/health/creatine-phosphokinase-test http://answers.webmd.com/answers/1198399/what-is-creatine-phosphokinase-cpk http://www.disabled-world.com/health/cpk.php http://medical-dictionary.thefreedictionary.com/creatine+phosphokinase https://en.wikipedia.org/wiki/Creatine_kinase http://www.disabled-world.com/health/cpk.php http://www.healthgrades.com/symptoms/elevated-creatine-kinase https://www.sharecare.com/health/heart-attack/what-is-creatine-kinase-and-creatine-phosphokinase http://www.hopkinslupus.org/lupus-tests/clinical-tests/creatine-phosphokinase-cpk/
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