Also known as: CK-2, CK-MB.

An increased 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 muscle. It can also indicate that your muscles have experienced extreme use. If your doctor suspects a heart attack and your CK is high, s/he will usually also order CK-MB to see if your heart is damaged. Normally, test results are reported as numerical values rather than as "high" or "low", "positive" or "negative", or "normal". In these instances, it is necessary to know the reference range for the particular test. However, reference ranges may vary by the patient's age, sex, as well as the instrumentation or kit used to perform the test.