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What is Creatine Kinase (CK) in Blood Test? What is High and Low Creatine Kinase (CK) Level? Causes & Treatment?

Updated: Jun 16, 2024

  • Creatine kinase (CK) in blood test is a test that shows the level of creatine kinase in the blood.

  • Creatine kinase (CK) is an enzyme in protein structure and is also known as creatine phosphokinase (CPK). Basically, it helps muscles produce energy.

  • Creatine kinase (CK) is found in skeletal muscle, cardiac muscle and small amounts in the brain. If damage occurs in these areas, it is released from the damaged cells and is detected at high levels in the blood. Therefore, creatine kinase (CK) is used to help diagnose and monitor injuries and diseases in skeletal muscle, cardiac muscle, and the brain.

  • There are three types of CK enzymes: CK-MM: It is mostly found in skeletal muscles and indicates muscle-related damage. CK-MB: It is mostly found in the heart muscle and indicates damage to the heart muscle. CK-BB: It is mostly found in the brain and indicates brain-related damage. If it is not clear why the CK level is elevated, a more specific test, the CK isoenzyme test, may be performed. With the creatine kinase (CK) isoenzyme test, the location of the damage can be determined.

Creatine kinase (CK) in blood test is a test that shows the level of creatine kinase in the blood.  Creatine kinase (CK) is an enzyme in protein structure and is also known as creatine phosphokinase (CPK). Basically, it helps muscles produce energy.  Creatine kinase (CK) is found in skeletal muscle, cardiac muscle and small amounts in the brain. If damage occurs in these areas, it is released from the damaged cells and is detected at high levels in the blood. Therefore, creatine kinase (CK) is used to help diagnose and monitor injuries and diseases in skeletal muscle, cardiac muscle, and the brain.  There are three types of CK enzymes: CK-MM: It is mostly found in skeletal muscles and indicates muscle-related damage. CK-MB: It is mostly found in the heart muscle and indicates damage to the heart muscle. CK-BB: It is mostly found in the brain and indicates brain-related damage. If it is not clear why the CK level is elevated, a more specific test, the CK isoenzyme test, may be performed. With the creatine kinase (CK) isoenzyme test, the location of the damage can be determined. Normal creatine kinase level should be between 39-308 U/L (units per liter) for males and 26-192 U/L for females mg/dL in a blood test. If the creatine kinase (CK) level is high, it means there may be damage to skeletal muscle, heart muscle or brain. Low creatine kinase (CK) in a blood test is a value below 39 U/L for men and 26 U/L for women. Since the creatine kinase enzyme is mainly associated with muscle mass; A low creatine kinase value indicates that muscle mass is weakened or decreased for various reasons.
What is Creatine Kinase (CK) in Blood Test? What is High and Low Creatine Kinase (CK) Level? Causes & Treatment?

What is A Normal Creatine Kinase (CK) Level in Blood Test ?

Normal creatine kinase level should be between 39-308 U/L (units per liter) for males and 26-192 U/L for females mg/dL in a blood test. Age, gender and race, muscle mass and physical activity intensity cause normal CK values to differ. Additionally, reference values may differ between laboratories. It is important to consider the reference range of the laboratory where the test was performed.


What is High Creatine Kinase (CK) Level in Blood Test?

  • High creatine kinase (CK) in a blood test is a value above 308 U/L in men and 192 U/L in women.

  • If the creatine kinase (CK) level is high, it means there may be damage to skeletal muscle, heart muscle or brain.


What Causes High Creatine Kinase (CK) Level in Blood Test?

Some possible causes of high creatine kinase (CK) include:

Causes related to the nervous system

  • Cerebrovascular diseases such as stroke

  • Epilepsy type seizures

  • Brain tumors

  • Conditions affecting smooth muscles

The form of creatine kinase located in the nervous system is CK-BB. Therefore, high CK-BB in the creatine kinase isoenzyme test indicates nervous system damage.

Heart-related causes

  • Heart attack due to cardiovascular diseases

  • Infectious diseases that cause inflammation of the heart muscle, such as myocarditis

  • Physical traumas that cause damage to the heart muscle

  • Blood clot in the lung

  • Heart surgery

  • Congestive heart failure

  • Hypothyroidism

  • Kidney failure

The form of creatine kinase found in heart muscle is CK-MB. Therefore, high CK-MB in the creatine kinase isoenzyme test indicates heart damage.

Causes related to skeletal muscles

  • Severe traumas that cause damage to the muscles

  • Muscle destruction due to long-term inactivity

  • Destruction that begins in muscles after heavy exercise

  • Infections or some chronic diseases affecting the muscles

  • Genetic muscle diseases such as Duchenne Muscular Dystrophy

  • Some rheumatological diseases such as polymyositis or dermatomyositis

  • Malignant hyperthermia

  • Side effects of some medications

  • Epileptic seizures that cause intense contraction of muscle groups

  • Extreme burns and electric shock

The form of creatine kinase found in skeletal muscles is CK-MM. Therefore, high CK-MB in the creatine kinase isoenzyme test indicates muscle-related damage.


High Creatine Kinase (CK) Symptoms

  • Muscle pain and/or cramps

  • Muscle weakness

  • Balance problems and/or falling a lot

  • Numbness or tingling

  • Dark colored urine

  • Swollen legs or feet

How to Treat High Creatine Kinase (CK) Level?

Treatment for high creatine kinase depends on the underlying cause. Patients need to be evaluated with a detailed disease history and detailed physical examination by a specialist. Additional imaging and laboratory tests may be requested when deemed necessary.


What is Low Creatine Kinase (CK) Level in Blood Test?

Low creatine kinase (CK) in a blood test is a value below 39 U/L for men and 26 U/L for women. Since the creatine kinase enzyme is mainly associated with muscle mass; A low creatine kinase value indicates that muscle mass is weakened or decreased for various reasons.


What Causes Low Creatine Kinase (CK) Level in Blood Test?

Possible causes of low creatine kinase can be listed as follows:

  • Muscle weakness: In case of muscle diseases or muscle wasting, muscle tissues are damaged and reduced. In this case, the creatine kinase value in the blood may decrease.

  • Medicines: Some drugs used for muscles suppress the creatine kinase enzyme activity, causing it to decrease. Thus, the level of creatine kinase in the blood may decrease.

  • Liver and kidney disorders: When there is a problem in the liver or its functions are impaired, there may be a decrease in the level of creatine kinase in the blood.

  • Muscle problems: Diseases such as muscle inflammation or muscular dystrophy can affect creatine kinase levels and cause them to decrease.

  • Hormonal problems: Conditions such as imbalances in hormones and malfunction of the thyroid gland may cause the creatine kinase value to decrease.

  • Reasons such as advanced age, sedentary lifestyle, and weight loss can cause muscle loss, which causes low creatine kinase value in the blood.

Low Creatine Kinase (CK) Symptoms

Low creatine kinase levels usually do not cause any symptoms. Therefore, it is usually discovered accidentally with a blood test.

However, in rare cases, low creatine kinase levels can cause certain symptoms, such as:

  • Muscle weakness: Low CK levels can reduce the ability of muscles to produce energy, which can lead to muscle weakness.

  • Fatigue: Muscle weakness can also cause fatigue.

  • Strain when exercising: Low CK levels can cause muscles to fatigue during exercise, making it difficult to exercise.

  • Muscle aches: Some people may experience muscle aches when they have low CK levels.

How to Treat Low Creatine Kinase (CK) Level?

Treatment for low creatine kinase depends on the underlying cause. For this, your doctor may request additional tests. Once the diagnosis is made, the appropriate treatment protocol is applied. If there is no underlying medical condition, your doctor may recommend lifestyle changes, such as exercise and diet changes.

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