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Reaction Sequence
Creatine Kinase (CK)
Creatine kinase is found at high activity only in the cytoplasm of cardiac and skeletal muscle. This
enzyme catalyzes the reversible phosphorylation of creatine by ATP to creatine phosphate and ADP.
Creatine phosphate is the major source of high-energy phosphate used in muscle contraction.
Principal Reason for Performing the Test
To identify injury to skeletal or cardiac muscle.
Most Common Abnormality Indicated by the Test
Skeletal muscle lesions attributable to trauma or vigorous exercise.
Sample Type and Precautions
Samples must be processed and centrifuged immediately after drawing blood. Blood samples
should be taken within 6 hours of a suspect lesion. It is important to determine that the patient
has not been exercised vigorously during the 12 hours prior to sampling. This may cause marked
increases in creatine kinase activity. Remove plasma or serum from the cells or clot. If plasma
is being collected, use only lithium heparinized samples. EDTA and fluoride/oxalate will reduce
creatine kinase results.
Complementary Tests
Creatine kinase determination provides a specific, sensitive indication of muscle cell damage.
Aspartate aminotransferase and lactate dehydrogenase activities may also be measured but are
less specific and show smaller corresponding increases when muscle damage is present.
Reaction Sequence
Appendices
