To determine if muscles in your body have been damaged. Previously used to determine if you are having a heart attack.
If you have chest pain or muscle pain and weakness
A blood sample drawn from a vein in the arm
Creatine kinase is an enzyme found in the heart, brain and skeletal muscle. Enzymes are proteins that help cells to perform their normal functions. CK occurs in three major forms, called isoenzymes:
CK in the blood comes mainly from your muscles. The CK in your brain almost never gets into the blood.
A blood sample is taken by needle from the arm.
No test preparation is needed.
Blood levels of CK rise when your muscle or heart cells are injured. Your doctor requests measurement of CK (along with tests for other substances, particularly the CK-MB form) if you have chest pain to see if you may have had a heart attack. In the first 4 to 6 hours after a heart attack, CK in blood begins to rise. It reaches its highest level after about 18 to 24 hours, and returns to normal in about 2 to 3 days. The test for CK can also indicate if your other muscles are damaged.
It can be requested if your doctor suspects a heart attack. However, currently the use of CK as a marker of heart attack has been superseded by more specific tests such as cardiac troponin I or T.
If you have muscle pain or weakness, your doctor may order CK to see if skeletal muscles have been damaged.
A high CK, or one that increases usually indicates that there has been some damage to the heart or other muscle. It can also indicate that your muscles have experienced heavy use, for example if you have exercised excessively. If your doctor suspects a heart attack and your CK is high, they will usually also request troponin or CK-MB to see if your heart is damaged.
People who have greater muscle mass have higher CK levels (for example a young fit male will have more muscle mass and hence a higher CK level than an elderly female), and Afro-Caribbeans may have higher CK levels than other ethnic groups. Raised CK levels can also be seen in those with hypothyroidism. Very heavy exercise (such as in weight lifting, contact sports, or long exercise sessions) can also increase CK.
Other forms of muscle damage, such as from a fall, a car accident, surgery or after an injection, can also increase CK. Drinking too much alcohol slightly increases CK. Rarely, some drugs, particularly cholesterol-lowering drugs (statins), can damage muscle and increase CK. If you are taking one of these drugs, let your doctor know if you experience any muscle pain or weakness. Early pregnancy can decrease CK levels.
A heart attack usually occurs because one of the blood vessels (called coronary arteries) that bring blood to your heart muscle is blocked. This happens when a blood clot forms in a blood vessel that is already partially blocked. The partial blockage, which happens gradually over many years, is usually caused by too much fat layered in the wall of the blood vessel (this is often called hardening of the arteries — the medical term for this is atherosclerosis).
Doctors often use more than one test to determine if a person who has chest pain is having a heart attack. Troponin is generally considered as the most accurate test. Myoglobin and creatine kinase rise in patients with a heart attack, but they are less specific. CK-MB may also be used.
CK-MB, myoglobin, troponin
Tests: Troponin, CK-MBConditions: Heart attack, heart disease
RCPA Manual: CKNational Heart FoundationHealthInsite: heart attackBetter Health Channel: Heart attack