- CK (Creatinine Phosphate Kinase) is ordered in patients who may have had a heart attack. The test will usually be ordered when a patient arrives at the emergency room and again at intervals of 4-6 hours for a total of three tests. If you have muscle pain or weakness, your doctor may also order CK to see if other muscles have been damaged.
- A high CK, or one that goes up from the first to the second or later samples, generally indicates that there has been some damage to the heart or other muscles. It can also indicate that your muscles have experienced heavy use. If your doctor suspects a heart attack and your CK is high, she will usually order a more specific test (troponin or CK-MB) to see if your heart is damaged.
- CK-MB is usually ordered, along with total CK, in persons with chest pain to determine whether the pain is due to a heart attack. It may also be ordered in a person with a high CK to determine whether damage is to the heart or other muscles.
- If the value of CK-MB is elevated and the ratio of CK–MB to total CK (relative index) is more than 2.5–3, it is likely that the heart was damaged. A high CK with a relative index below this value suggests that skeletal muscles were damaged.