- Last Update On : 2013-02-22
Creatine kinase is an enzyme that catalyzes the reversible phosphorylation of creatine by ATP. The end product, phosphocreatine, is a readily available energy source for cells. CK is present in many tissues but skeletal and heart muscles contain the highest concentrations. CK released from skeletal muscle accounts for almost all of the CK activity detected in the plasma of healthy individuals. Circulating CK is cleared by degradation in the liver and reticuloendothelial system and has a circulating half-life of 12 hours.
Historically, CK has been used most often measured to diagnose acute myocardial infarction. Serum CK increases 4 to 6 hours after myocardial necrosis and remains elevated 24 to 48 hours post infarction. Serial measurement of CK activity at 0, 6, and 12 hours after the onset of chest pain yields the greatest sensitivity and specificity (See Cardiac Marker History). In May 2001, the American College of Cardiologists recommmended that total CK no longer be incl