creatine kinase (CK, Creatine phosphokinase [CPK])
المؤلف:
Kathleen Deska Pagana, Timothy J. Pagana, Theresa Noel Pagana.
المصدر:
Mosbys diagnostic and laboratory test reference
الجزء والصفحة:
15th edition , p304-306
2025-11-29
8
Type of test Blood
Normal findings
(Varies according to lab and patient statistics)
Total CK: 20-200 U/L
Test explanation and related physiology
Creatine kinase (CK) is an enzyme most commonly used to diagnose and follow muscle disease or injury. CK is located on the inner mitochondrial membrane, on myofibrils, and in the muscle cytoplasm. Age, gender, race, and physical activity can affect CK. It occurs in three isoenzyme forms (CK-MM, CK-MB, and CK-BB). Skeletal muscle has the highest concentration of CK (> 99% is CK-MM form) of any tissue. Cardiac tissue has the highest concentration of CK-MB, and brain tissue has the highest concentration of CK-BB.
Rhabdomyolysis is a syndrome characterized by muscle necrosis and the release of CK into circulation (mainly CK-MM). CK levels are typically over five times the normal value range, and muscle pain and myoglobinuria may be present. The severity of illness ranges from asymptomatic elevations in serum muscle enzymes to life-threatening disease associated with extreme enzyme elevations, electrolyte imbalances, and acute kidney injury.
CK-MB for the assessment of acute myocardial infarction (AMI) has largely been replaced by troponins. When cardiac troponin is available, the CK-MB should not be used for the diagnosis because it is far less sensitive and specific than troponins. The clinical application of CK-BB is limited. Levels are elevated with injury or disease to either the brain or lungs.
Interfering factors
• IM injections may cause elevated CPK levels.
• Strenuous exercise and recent surgery may cause increased levels.
• Early pregnancy may cause decreased levels.
* Drugs that may cause increased levels include alcohol, amphotericin B, ampicillin, some anesthetics, anticoagulants, aspirin, captopril, colchicine, dexamethasone, fibrates, furosemide, lidocaine, lithium, morphine, propranolol, statins, and succinylcholine.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
• Fasting: no
• Blood tube commonly used: red or green
* Discuss with the patient the need and reason for frequent venipuncture in diagnosing myocardial infarction.
• Avoid IM injections, which may falsely elevate the total CK level.
• Record the exact time and date of venipuncture - especially when testing for myocardial infarction.
Abnormal findings
Increased levels of total CK
- Disease or injury affecting the heart, skeletal muscle, or brain
Increased levels of CK-BB
- Disease affecting the central nervous system
- Adenocarcinoma (especially breast and lung)
- Pulmonary infarction
Increased levels of CK-MB
- Acute myocardial infarction and cardiac ischemia
- Cardiac surgery
- Cardiac arrhythmias, defibrillation or cardioversion
- Inflammatory myopathy
- Muscular dystrophy
- Extreme exercise
Increased levels of CK-MM
- Rhabdomyolysis
- Muscular dystrophy
- Myositis
- Drug-induced myopathies
- Hypothyroidism
- Neuroleptic malignant syndrome
- Malignant hyperthermia
- Exercise
- Trauma and crush injuries
- Recent surgery
- Electromyography
- Seizures and electroconvulsive therapy
- IM injections
- Hypokalemia and hyponatremia
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