Creatine kinase

Creatine kinase (also known as CK, CPK, creatine phosphokinase or creatine kinase ) is an enzyme, the N- phosphoryl group of phospho- creatine to adenosine diphosphate ( ADP) transmits (phosphorylation is indicative of kinases). This enzymatic reaction is adenosine triphosphate ( ATP), the universal power supply in all cells regenerated. The enzyme is found in all muscle cells and in the brain. There are four isoenzymes: CK -MM (skeletal muscle type), CK- MB ( Myokardtyp ), CK -BB (brain type) and CK- MiMi ( mitochondrial type).

It is also very often encounters the misnomer creatinine kinase. However, creatinine excretion is only the form of creatine.

Physiological significance

ATP has in organisms primarily as an energy source, but also as a signaling molecule, is of outstanding importance. ATP can be obtained both by substrate chain as well as by Elektronentransportphosphorylierung ( respiratory chain ) from ADP. The phosphorylation of phosphocreatine and ADP to creatine and ATP is a very fast method of synthesis and is used in accordance with short-term energy needs.

Creatine kinase in the diagnosis

Total CK is the sum of the four isoenzymes (see above). Because the total CK is usually measured N -acetyl-cysteine ​​-stabilized, is often used to indicate the total CK activity, the abbreviation CK- NAC.

An increase in the CK indicates a heart or skeletal muscle disease, were damaged in the muscle cells. The CK is therefore an important enzyme for the diagnosis of those lesions of the heart and skeletal muscles that are associated with an increase in CK. The level of CK increase and infarct size are correlated. Because you can differentiate between heavy heart and other muscle damage from the activity of CK, troponin is used for diagnosis of heart attack more frequently. Is the value of CK-MB greater than 6 percent of the total CK, one starts from a Myocardschaden. Before the possibility of determining the troponin was, was an CK-MB increase > 10 % together with a characteristic ECG findings or characteristic symptoms as a safe infarct detection.

Laboratory diagnostics

In the laboratory diagnosis, the CK activity is determined from the plasma or serum of suspected cardiac or skeletal muscle diseases. However, measurement of CK activity in the diagnosis of heart attack is no longer necessary because better tests such as troponin T / I or CK- MB mass ( CK- MB = concentration) are available.

Reference range for measurements at 37 ° C according to IFCC

  • Women: < 145 U / l,
  • Men: < 170 U / l

Children:

  • 0d - 1d: < 712 U / l
  • 2d - 5d: < 652 U / l
  • 6d - 6m: < 295 U / l
  • 7m - 11m: < 203 U / l
  • 1a - 3a: < 228 U / l
  • 4a - 6a: < 149 U / l
  • 7a - 12a:

In general, muscle diseases, such as the Progressive muscular dystrophy, post-polio syndrome, or myositis, the CK activity is greatly increased to over 25 000 U / l. In a heart attack, the CK activity is usually under 7500 U / L.

During intense, eccentric (negative, yielding ) strength training and top- endurance sports often values ​​in areas 20000-45000 are measured, usually two or three days after exposure. An increased value can thus be attributed to a previous training.

Just strength training exercises such as deep squats, deadlifts and pull-ups or rowing movements and endurance sports, which stress the large muscles of high intensity increase, CK levels quickly to values ​​beyond 1000 U / L.

After surgery, injections (intramuscular ) and injuries in which muscle cells are affected, the CK activity also increases. Here, the activity is dependent on the size of the injury.

Also medications such as statins and fibrates can affect blood CK concentration.

Digital Object Identifier Protein isoform Isozyme Substrate-level phosphorylation Acetylcysteine Medical diagnosis Arginine Histidine Blood plasma Serum (blood) Intermembrane space Adenylate kinase Biochimica et Biophysica Acta PubMed Central
191705
de