blood enzyme activity level serum creatine kinase activity level serum creatine phosphokinase activity level jsmith serum CPK activity level The amount of enzymatic activity of creatine kinase (CK) enzyme in a specified sample of serum. CK catalyses the reversible transfer of phosphate between ATP and various phosphogens such as creatine phosphate. Serum CK level is used as an enzymatic marker for myocardial infarction, rhabdomyolysis and acute renal failure. serum CK activity level VT:1000047 clinical_measurement_ontology CMO:0002244 2014-03-11T14:14:26Z