Creatine kinase (CK; synonyms: creatine kinase; creatine phosphokinase (CPK); creatine phosphokinase (KPK), adenosine 5′-triphosphate-creatinine-phosphotransferase) is an enzyme that is formed in two subunits of type M or B. Thus, the following isoenzymes can be detected in the blood.
- CK-BB – occurs mainly in the brain or in advanced diseases.
- CK-MB – occurs mainly in the heart muscle; accounts for about six percent [see under CK-MB].
- CK-MM – occurs in skeletal muscle.
Furthermore, a macro-CK type 1 and type 2 can be distinguished from the CK. This is a norm variant, which can feign an increased concentration of CK. In addition to the diagnosis of skeletal muscle diseases, creatine kinase is also used in the diagnosis of myocardial infarction. An increase in CK can be expected after 3 (-4) to 12 hours after the onset of infarction.The maximum is between 12 and 24 hours after the onset of infarction.Normalization of CK occurs after approximately 3 to 6 days. CK-MB (see CK-MB for details) usually returns to normal after 2 to 3 days.The half-life of CK-MM is approximately 17 hours.
The procedure
Material needed
- Blood serum
Preparation of the patient
- Not known
Disruptive factors
- Dark-skinned individuals have higher levels (increased up to 1.5 times)
- Avoid hemolysis! Adenylate kinase from erythrocytes (red blood cells) increases enzymatically measured CK and CK-MB.
Normal values
| Normal value in U/l (new reference range) | Normal value in U/l (old reference range) | |
| Women | 10-70 | 0-145 |
| Men | 0-170 | 0-170 |
| Children | ≤ 370 |
Indications
- Suspected skeletal muscle disease
- Suspicion of myocardial infarction (heart attack)
- Suitable for rough estimation of infarct size.
- Reveals reinfarction more reliably than troponin T (TnT) because CK normalizes faster (after about 3 – 6 days) than TnT (after up to 10 days)
Interpretation
Interpretation of increased values
- Skeletal muscle or disease
- Genetic myopathies (muscle diseases) such as muscular dystrophy.
- Dermato-/Polymyositis – diseases from the group of forms of collagenoses (connective tissue diseases).
- Glycogenoses, esp. type V (synonyms: McArdle myopathy, McArdle disease, McArdle syndrome); defect of the isoform of the enzyme glycogen phosphorylase occurring in skeletal muscle, also known as myophosphorylase; autosomal recessive inherited disease.
- Infectious myositis(muscle inflammation).
- Seizure (due tomuscle lesions).
- Muscle necrosis
- Muscle overuse (e.g., long running).
- Rhabdomyolysis (crush syndrome)
- Burns (high-grade)
- Condition after intramuscular injection.
- Cardiac muscle
- Endocarditis (inflammation of the inner lining of the heart)
- Coronary heart disease (CHD)
- Myocardial infarction (heart attack)
- Myocarditis (inflammation of the heart muscle)
- Pericarditis (inflammation of the pericardium)
- Denervation processes/denervation processes (polyneuropathy; motor neuron disease).
- Pregnancy
- Sectio (Caesarean section)
- Delivery
- CK depending on the intensity of labor and muscle damage.
- Values of 2-5 times the upper norm are observed
- Further
- Alcohol intoxication
- Hemolysis (dissolution of red blood cells).
- Hypothyroidism (underactive thyroid gland).
- Heavy muscle work (eg, construction workers, bodybuilders, high-performance athletes).
- Post-operative
False high values: macro-CK may be elevated in severe cerebral disease and advanced tumor disease. Macro-CK refers to CK variants with high molecular mass, which mimic a high CK concentration in the serum. Interpretation of Decreased Values
- Not relevant to disease
Further notes
- If myocardial infarction is suspected, the following laboratory parameters should be determined:
- Myoglobin
- Troponin T (TnT)
- CK-MB (creatine kinase myocardial type).
- CK (creatine kinase)
- Aspartate aminotransferase (AST, GOT)
- LDH (lactate dehydrogenase)
- HBDH (hydroxybutyrate dehydrogenase)