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Creatine Phosphokinase




Creatine kinase (CK), also known as '''phosphocreatine kinase''' or '''creatine phosphokinase''' (CPK) is an Enzyme () expressed by various tissue types. Its function is the catalysis of the conversion of Creatine to Phosphocreatine , consuming Adenosine Triphosphate (ATP) and generating Adenosine Diphosphate (ADP).


TYPES

Every CK enzyme consists of two subunits, which can be either ''B'' (brain type) or ''M'' (muscle type). There are, therefore, three different creatine kinases, the ''ubiquitous'' and ''sarcomeric'' form.

  Symbol CKB
  Chromosome 14
  Locus q323
  AApre 381
  AApro ---
  HGNCid 1991
  Codes , , ,


  Symbol CKM
  Chromosome 19
  Locus q132-q133
  AApre 381
  AApro ---
  HGNCid 1994
  Codes , , ,



Isoenzyme patterns differ in tissues. CK-BB occurs mainly in tissues, and its levels do rarely have any significance in bloodstream. Muscle expresses CK-MM (98%) and CK-MB at low levels (1%) in muscle. The Myocardium (heart muscle), in contrast, expresses CK-MM at 70% and CK-MB at 30%.


USES

CK is often determined routinely in emergency patients. In addition, it is determined specifically in patients with Chest Pain and Acute Renal Failure . Normal values are usually between 25 and 200 U/ L . This test is not specific for the ''type'' of CK that is elevated.

Elevation of CK is an indication of damage to Muscle . It is therefore indicative of Injury , Rhabdomyolysis , Myocardial Infarction , Myositis , Myocarditis , Malignant Hyperthermia and Neuroleptic Malignant Syndrome .

Lowered CK can be an indication of Alcoholic Liver Disease and Rheumatoid Arthritis .

Isoenzyme determination has been used extensively as an indication for myocardial damage in heart attacks. Troponin measurement has largely replaced this in many hospitals, although some centres still rely on CK-MB.


SEE ALSO



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