The creatine kinase


Creatine kinase is an enzyme that uses a biochemical reaction to ensure that sufficient energy is available to the cells.

It is found in the muscle cells and in the brain and is always released by the body when it comes due to disease or stress caused damage to the muscle tissue. This can be the case without physical illness during exercise or childbirth.

However, creatine kinase is also an important indicator of life-threatening diseases such as heart attack.

What is creatine kinase?

Creatine kinase or Creaktine kinase (CK) is an important enzyme in the human body that is needed for energy metabolism. Most of the time, creatine kinase is found inside the muscle cells - but the enzyme can also be found in the brain and in other organs, such as the heart.

Depending on the organ, the creatine kinase has a different chemical structure, so that four subforms can be distinguished:

  • CK-MM occurs in muscle cells of the musculoskeletal system
  • CK-MB in the heart muscle cells
  • CK-BB in the nerve cells of the brain and
  • CK-Mini in the sheaths of the mitochondria.

What is the function of creatine kinase?

Creatine kinase belongs to the group of kinases. This group of enzymes has the task of providing the cells with sufficient energy for movement and metabolism. For every muscle contraction the cell needs energy in the form of adenosine triphosphate (ATP). This molecule consists of carbon, hydrogen, oxygen and three phosphate atoms.

For energy to be released, the connection must be broken and a phosphate atom split off. What remains is a low-energy adenosine diphosphate (= compound with two phosphates). Since the storage of ATP in cells with 5 micromoles per gram of muscle is very low, ATP is rapidly consumed.

In order to continue to have energy available, the ATP must be restored. This succeeds as fast as possible with the aid of creatine kinase.

As soon as it comes to a lack of energy and concomitant loss of muscle cell tissue due to illness or stress, creatine kinase is released. It enters the blood and attaches a new phosphorus group to the adenosine phosphate without oxygen consumption, so that it is converted back into the activated state ATP.

Values ​​for creatine kinase

The creatine kinase values ​​indicate how high the concentration of the enzyme in the blood serum is . However, not the absolute concentration is measured, but the activity of the enzyme. This is calculated by the amount of converted substrate per minute. The result is given in units (U) per liter of substrate (L). The reference values ​​may vary from laboratory to laboratory as there are different methods of measurement.

Often the following reference values ​​are used for measurements at 37 °: For men, the creatine kinase value is in the normal range if it is below 190 U / L; for women, creatine kinase should be below 170 U / L. Since there are some strong daytime and seasonal variations and various factors (such as exercise, medications) can affect creatine kinase levels, the values ​​must always be interpreted by a physician.

In addition, creatine kinase levels must be analyzed in conjunction with other blood values ​​and over time. This means that elevated levels of creatine kinase do not necessarily have to be a disease.

Typical examples of elevated creatine kinase values ​​without pathological value include muscle soreness, postoperative or postpartum conditions. However, creatine kinase levels are often used for diagnosis.

First, the general creatine kinase value is considered. If this is too high, one determines and analyzes the different subforms. Depending on which of these values ​​is too high, then a conclusion can be drawn on the respective damage location.

  • If this is, for example, the CK-MB value, this indicates a heart disease such as myocardial infarction, myocarditis or coronary heart disease . You might also be interested in this: diagnosis of a heart attack
  • Other diseases in which the determination of CK levels is elemental are Parkinson's disease, epilepsy, hereditary muscle diseases or congenital amyotrophic lateral sclerosis.
  • But even with acute injuries, electrical accidents or injections in the muscles creatine kinase value is higher.

On the other hand, low creatine levels have no pathological value.

Creatine kinase in sports

The enzyme creatine kinase is always released by the body when the muscle tissue is damaged. This is the case with oxygen deficiency, overload or injury. Consequently, the creatine kinase level may also increase due to exercise. This process is purely physiological and has no pathological value - even if the values ​​even rise to two thousand times the normal values. This happens rarely with regular and constant mechanical stress but rather with unfamiliar and strong changes of the extent of load and the intensity.

Above all, this occurs in athletes who start training again after a long break in training. The body is then unable to cope with the new strain and thus releases creatine kinase. Especially with eccentric muscle contractions, strength and strength training, the creatine kinase values ​​increase significantly. The same happens at unusually long load, such as in marathon races or triathlon. Competitive athletes therefore generally have an elevated creatine kinase concentration in their blood. Normally, the values ​​should have returned to normal after two weeks of physical protection. This long period of time is explained by the fact that creatine kinase leaves many waste products. These must all be reduced by the kidney. If creatine kinase levels in the blood are too high, this can in extreme cases damage the kidneys.


Creatine kinase is an enzyme that occurs mainly in muscles, but also in organs. Depending on the functional location, four sub-forms are distinguished, which differ in their chemical structure. It is not only elementary for the energy supply in the cells, but is an important marker in the diagnosis. Thus, the creatine kinase value can be a clear indication of a heart attack, Parkinson's or hereditary muscle diseases.

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