Creatine kinase
and Martina Feichter, medical editor and biologistDr. med. Andrea Reiter is a freelance writer for the medical editorial team.
More about the expertsMartina Feichter studied biology with an elective subject pharmacy in Innsbruck and also immersed herself in the world of medicinal plants. From there it was not far to other medical topics that still captivate her to this day. She trained as a journalist at the Axel Springer Academy in Hamburg and has been working for since 2007 - first as an editor and since 2012 as a freelance writer.
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The enzyme creatine kinase (creatine kinase or CK, CPK) is important for the energy metabolism of the muscle cells. If the cells are damaged, for example by a heart attack or a fall, there is increased creatine kinase in the blood. Read everything you need to know about creatine kinase and causes of elevated levels.
What is Creatine Kinase?
Creatine kinase (CK) is an enzyme found in all muscle cells in the body and in the brain. It ensures that certain energy stores in the muscle cells, the adenosine triphosphates (ATP), are sufficiently available:
If a phosphate atom is split off from the ATP, energy is released for muscle contraction. What remains is the low-energy adenosine biphosphate, i.e. a molecule with only two phosphate atoms. The creatine kinase "regenerates" the energy molecule by building a new phosphate onto the molecule. In this way, “kinases” ensure a sustained supply of energy in the body.
If muscle cells are damaged by overload, lack of oxygen or, for example, a fall, larger amounts of creatine kinase are released from the affected cells. The enzyme is then increasingly detectable in the blood. Muscle cells in the heart also perish in the event of a heart attack. Since the creatine kinase in the brain, in the heart and in the rest of the muscles has slight differences in its structure, one can draw conclusions about the respective damage in the body if the values are increased, depending on the type of enzyme. The following types of creatine kinase occur in the body:
- CK-MB (in heart muscle cells)
- CK-MM (in the muscle cells of the musculoskeletal system)
- CK-BB (in the nerve cells of the brain)
When is creatine kinase determined?
The creatine kinase concentration is used to diagnose many diseases, for example:
- Heart attack
- Coronary heart disease (CHD)
- Myocarditis
- Muscle wasting of the trunk and extremities (muscular dystrophies)
- Muscle breakdown (rhabdomyolysis, triggered by seizures, medication, or other causes)
Furthermore, the creatine kinase can be increased by burns, electrical accidents, Parkinson's disease, poisoning, drug use and infections.
After intensive sport, especially after strength training or extreme endurance exertion, as well as after childbirth, after operations, vaccinations or a fall, the creatine kinase is often detectable in the blood without it being a disease.
Creatine Kinase Reference Levels
The creatine kinase concentration in the blood is usually not measured in its absolute concentration, but in its activity. The activity of an enzyme is determined by the substrate it converts per minute. The information is given in units (U) per liter of substrate (L). Normal values for creatine kinase (all forms) in the blood serum are (measurement at 37 ° C):
|
age |
CK normal value |
|
2 to 4 days |
<652 U / l |
|
5 days to 5 months |
<295 U / l |
|
6 months to 2 years |
<229 U / l |
|
3 to 5 years |
<150 U / l |
|
6 to 11 years |
male: <248 U / l female: <157 U / l |
|
12 to 17 years |
male: <269 U / l female: <124 U / l |
|
adult |
male: <171 U / l female: <145 U / l |
For the creatine kinase subform CK-MB, a normal range of <25 U / l applies to all ages and genders.
When is the CK value increased?
A blood test usually first determines the total creatine kinase concentration. If there is a suspicion of a certain disease, or if the total CK value in the blood is increased, the different CK sub-forms are also differentiated.
CK-MB
For example, the CK-MB value plays a major role in diagnosing a heart attack. The severity of the heart muscle damage can also be assessed using the CK-MB.
CK-MM
If the muscle cells of the musculoskeletal system break down, the CK-MM increases. This often happens with muscle wasting. It can occur with malnutrition, in old age or with persistent physical inactivity. Sometimes muscle wasting is also congenital, for example in amyotrophic lateral sclerosis or Duchenne muscular dystrophy.
What to do if creatine kinase is increased
If the creatine kinase is increasingly detectable in the blood, the cause must first be clarified. If the creatine kinase is increased due to pregnancy, after childbirth or during growth, it is checked again at intervals. People whose CK value is greatly increased after endurance or muscle strength training should reduce the training intensity.
If a drug is the cause, it usually has to be discontinued immediately. If a heart attack is possible, a cardiac catheter examination is performed. If the concentration of creatine kinase is increased due to a muscle disease, this must be treated by a specialist.
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