Also known as: Total CK, Creatine phosphokinase, CPK
Name: Creatine kinase
Related tests: Cardiac biomarkers, CK-MB, Myoglobin, Troponin
Why is the test done?
To find out whether you have had a heart attack or whether there is muscle damage.
When is it done?
If there are signs or symptoms of a heart attack (e.g. tightness in the chest); if there is muscle pain or loss of strength.
What samples are required?
A blood sample taken from a vein in the arm
What is being tested?
Creatine kinase is an enzyme found in the heart, brain, skeletal muscle and other tissues. Enzymes are proteins needed for normal cell function. In skeletal muscle and the heart, much of this energy is used during contraction. There are three different forms of CK, called isoenzymes:
CK-MM (skeletal and heart muscle)
CK-MB (mainly in the heart)
CK-BB (mainly in the brain)
The main source of CK in the blood is muscle. CK from the brain never enters the bloodstream
How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?
How is it used?
Blood CK levels rise when the muscles or heart are injured. The doctor requests the test when there is chest tightness or other signs and symptoms of a heart attack. In the first 4-6 hours after a heart attack, the concentration of CK in the blood begins to rise. It peaks within 18-24 hours and returns to normal within 2-3 days. CK levels also rise when skeletal muscle is damaged.
When is it requested?
CK is requested in patients who may have had a heart attack. The test is usually requested when the patient arrives in the emergency department and then at 4-6 hour intervals, three times in all. It can also be requested when there is muscle pain or weakness, to check for muscle damage.
What does the test result mean?
A high CK, or one that rises between the first and second and between the second and third samples, generally indicates some damage to the heart or muscles. It may also indicate intense muscular exertion. If the doctor suspects a heart attack and CK is raised, more specific tests (troponin or CK-MB) are usually requested to assess heart damage.
Is there anything else I should know?
People with a large muscle mass have higher CK levels than those with little muscle mass, and African Americans have higher levels than other ethnic groups. Intense exercise (such as weightlifting, contact sports or long exercise sessions) can raise CK.
Other forms of muscle damage, such as falls, road accidents, surgery or gunshot wounds, can raise CK levels. Several medicines can raise CK. Alcohol abuse can raise CK. Rarely, some medicines, specifically cholesterol-lowering medicines (statins), can damage muscle and raise CK levels. If you are taking these medicines, tell your doctor if you have muscle pain or weakness. Early pregnancy lowers CK levels.
1. What is a heart attack?
2. If I have chest pain, does it mean I am having a heart attack?
3. What other specific tests are there for a heart attack?
4. What should I do if I am not sure whether I am having a heart attack?
1. What is a heart attack?
A heart attack means that part of the heart muscle has died. The medical term for this condition is myocardial infarction. A heart attack often begins with a feeling of heaviness or pain in the chest, which then spreads to the left shoulder and arm. There may be difficulty breathing, weakness and a cold sweat.
A heart attack is usually caused by the blockage of some of the vessels (called coronary arteries) that carry blood to the heart muscle. This usually happens when a blood clot blocks a vessel that is already partly narrowed. The partial narrowing develops gradually over the years and is due to excessive build-up of fat in the vessel wall (known as hardening of the arteries; the medical term is atherosclerosis).
2. If I have chest pain, does it mean I am having a heart attack?
Many problems can cause chest pain, and it is not always possible to tell from the type of pain alone whether it is a heart attack. Many people can have this symptom with strained chest muscles or with lung problems. This symptom can be a warning sign of hardening of the heart arteries (coronary artery disease). Pain that comes on during physical exertion, hard work or stress, lasts a few minutes and then goes away is called angina. If this symptom lasts longer, especially at rest, it needs medical attention.
3. What other specific tests are there for a heart attack?
Doctors usually use several tests to check for a heart attack. Troponin is generally considered the most accurate test; CK-MB (the cardiac isoenzyme of CK) is also accurate in detecting heart damage even in the absence of other evidence. Myoglobin and CK rise during a heart attack, but they are less specific: other conditions can cause these values to rise.
4. What should I do if I am not sure whether I am having a heart attack?
If you have chest pain, especially if it does not go away with rest, or if you have been diagnosed with angina and the prescribed medicines do not relieve the pain, you need immediate medical attention. Many people with a heart attack die without trying to call an ambulance or seek medical help.