Also known as: CK Fractionation ; CK Isoenzymes ; CPK Isoenzymes ; Creatine Phosphokinase Isoenzymes.

CK is most commonly elevated in acute myocardial infarction (AMI) in which it has its greatest usefulness. Collection of specimen at onset of symptoms to establish baseline values is needed. A patient at onset of AMI will have normal results, but some patients reach medical attention at or beyond CK peak. To support the diagnosis of AMI, three CK isoenzyme determinations have classically been recommended, one on admission, a second 12 hours after admission, a third 24 hours after admission. Another at 48 hours may be needed. CK-MB usually peaks between 15 and 20 hours after the onset of a myocardial infarction. Pappas summarizes current literature regarding timing as follows. In non-Q wave, incomplete occlusion, nontransmural MI, CK-MB peaks on the average 15 hours from onset. In Q wave (complete occlusion) (transmural) infarction, CK-MB average peak is 17 to 20 hours after onset of symptoms. He emphasizes the importance of a sample for CK-MB drawn 16 hours after onset.  When increased CK-MB values have returned to normal, CK isoenzyme determinations are usually no longer required.