Intervals are Mayo-derived, unless otherwise designated. The rate of NADH formation, measured at 340 nm, is, therefore, directly proportional to creatine kinase activity. Suggests clinical disorders or settings where the test may be helpfulDiscusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory testDescribes reference intervals and additional information for interpretation of test results. Additionally, standard reference ranges can vary from lab to lab. This elevation occurs as the cells that make up the heart muscle die. Physiologically, when muscle contracts, ATP is converted to adenosine diphosphate (ADP), and CK catalyzes the rephosphorylation of ADP to ATP using creatine phosphate as the phosphorylation reservoir. This CK enzyme reaction is reversible and thus ATP can be generated from PCr and ADP. St. Louis, Saunders Elsevier, 2006;306-3072. CK may be measured to evaluate myopathy and to monitor patients with rhabdomyolysis for acute kidney injury.Reference values have not been established for patients that are less than 3 months of age.Serum creatine kinase (CK) activity may increase in patients with acute cerebrovascular disease or neurosurgical intervention and with cerebral ischemia as well as in nearly all patients when injury, inflammation, or necrosis of skeletal or heart muscle occurs, including:-All types of muscular dystrophy particularly in progressive muscular dystrophy (particularly Duchenne sex-linked muscular dystrophy).-Viral myositis, polymyositis, and similar muscle diseases-Malignant hyperthermia, an inherited life-threatening condition characterized by high fever and brought on by administration of inhalation anesthesia-Muscle trauma, which causes CK elevations within 12 hours of onset, peaking within 1 to 3 days, and declining 3 to 5 days after cessation of muscle injury---Serum CK activities exceeding 200 times the upper reference limit may be found in acute rhabdomyolysis, putting the patient at great risk for developing acute renal failure.-When given at pharmacologic doses, some drugs including statins, fibrates, antiretrovirals, and angiotensin II receptor antagonists -Endocrine myopathy, for which hpothyroidism is a common cause, about 60% of hypothyroid subjects show an average elevation of CK activity 5-fold greater than the upper reference limit-Normal childbirth causes a 6-fold elevation in maternal serumFor detection of myocardial infarction, changes in serum CK and its heart tissue (MB) isoenzyme have been largely replaced by the more cardiac-specific nonenzymatic markers, cardiac troponin I or T.Exercise, muscle trauma (contact sports, traffic accidents, intramuscular injections, surgery, convulsions, wasp or bee stings, and burns), and drugs such as cholesterol-lowering statins can damage muscle and increase serum creatine kinase (CK) concentrations.CK concentrations have been found to be relatively higher in black race populations.1. Edited by Wu AHB. This happens at intracellular sites where ATP is used in the cell, with CK acting as an Isoenzyme patterns differ in tissues. Serum CK concentrations are reflective of muscle mass causing males to have higher concentrations than females. If an interpretive report is provided, the reference value field will state this.Provides information to assist in interpretation of the test resultsDiscusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substancesRecommendations for in-depth reading of a clinical nature CK : Creatine kinase (CK) is an enzyme that catalyzes the reversible phosphorylation of creatine (Cr) by adenosine triphosphate (ATP). An elevated level of creatine kinase, specifically CK-MB, occurs within hours of a heart attack as the heart muscle cells die. Diagnosing and monitoring myopathies or other trauma, toxin, or drug-induced muscle injuryCreatine kinase (CK) is an enzyme that catalyzes the reversible phosphorylation of creatine (Cr) by adenosine triphosphate (ATP).