- It is done on serum (clotted blood 3-5 ml).
- The plasma may also be used.
- The sample is stable 4 to 8 hours at room temperature.
- 1 to 2 days stable at 4 °C. (in another reference the stability at 4 °C for 8 to 12 hours).
- One month stable at -20 °C.
- Avoid excessive physical therapy.
- There is no needed for special preparation of the patient.
- Avoid the hemolyzed sample.
- Citrate and fluoride inhibit the CK activity.
- Protect from light.
- Store in airtight tubes.
Purpose of the test
- To find cardiac muscular injury (myocardial infarction).
- To support the possibility of neurologic or skeletal muscle diseases (Muscular dystrophy).
- This test is specific for the muscular and cardiac muscle injury.
- CPK (creatine phosphate) is the incorrect name and actually, this is Creatine kinase.
- CK gives reversible phosphorylation reaction.
- Creatine Kinase (CK) is found predominantly in the heart muscles and Skeletal muscles.
- Low concentration is seen in the brain.
- Ck level rises within 6 hours after the injury.
- If the injury is transient then peak level is at 18 hours and then return to normal in 2 to 3 days.
- Isoenzymes of CPK are:
- CK-MM = This is found in the Skeletal and cardiac muscle. Skeletal muscle is 99% MM and cardiac is 70%.
- CK-MB =This is found in cardiac and skeletal muscles. Cardiac muscle has 30% and skeletal muscle has 1% MB.
- CK-BB = This is found mainly in the Brain and the lesser amount found in urinary bladder, stomach, and prostate.
- These enzymes are present in the cytosol and myofibrillar structure of the cells.
- CK activity in the serum depends upon various physiologic variants like muscle mass.
- It is lower in the female as a comparison to male.
- Depends on the ethnic group like more in black American female than white males.
- CK-MM is raised in the muscular injury.
- CK-MB is raised in the myocardial infarction.
- CK-BB is raised in the brain injury (also in the lung injury).
- CK-MB level does not rise in angina, pulmonary embolism, or congestive heart failure.
- This greatly elevated in the muscular diseases, especially muscular dystrophy (Duchenne type) where it is 50 times of the upper normal limit.
- This may be raised before the clinical disease is apparent.
- CK activity decreases with the increasing age of the patient.
- Patient with Duchenne disease carriers female, 50 to 80% has 3 to 6 times raised the level of CK in their blood.
- Markedly raised level of CK is seen viral myositis, polymyositis, and muscle diseases.
- The level is normal in the neurogenic muscular diseases like myasthenia gravis, multiple sclerosis, poliomyelitis, and Parkinson disease.
- CK-MM is 7 to 12 times increased than normal value.
- Myocardial infarction
- CK-MB is normal initially in MI and begins to rise:
- After 2 to 4 hours after the infarction.
- The peak between 12 to 24 hours.
- Return to normal within 48 hours.
- 10 to 25 times of the normal value.
- Nowadays more specific test than CK- MB is Troponin-T.
- CK-MB is diagnostic of MI.
- If there is negative CK-MB for > 48 hours, then it is clear that the patient had no MI attack.
- The CK-MB level is helpful to quantify the level of muscle damage in MI.
- Liver diseases
- As the liver has the negligible amount of CK, so there is no marked increase of CK in liver diseases.
- In cirrhosis CK is normal.
- Central nervous system diseases
- There is an increase in the CK level in cerebrovascular diseases and with cerebral ischemia.
- There is a main increase in the CK-3 (CK-MM).
- There is no CK-1 (CK-BB) increase.
- Thyroid diseases
- In hypothyroid 60% of the cases, there is 5 to 50 times elevation than the normal range.
- In hyperthyroidism, the CK activity is low to the lower level of normal.
- The main isoenzyme is CK-3 (CK-MM).
- 0 to 250 U/L
- Adult male = 55 to 170 units /L
- female = 30 to 135 units /L
- Above 90 years
- male = 21 to 203 U/L
- female = 22 to 99 U/L
- Newborn = 68 to 580 U/L (2 to 3 times of adult value).
- CK-MM (CK-3) =94 to 100 %
- CK-MB (CK-2)= 0 to 6 %
- CK-BB (CK-1) = 0 %
|At 37 °C
|20 to 60 years
||52 to 200
||35 to 165
||38 to 174
||26 to 140
||21 to 203
||22 to 99
|AT 30 °C
|20 to 59 years
||25 to 80
||20 to 75
|60 to 69 years
||20 to 110
||61 to 81
|70 to 90
||22 to 90
||19 to 76
||15 to 105
||10 to 80
|At 25 °C
||10 to 65
||7 to 55
- To convert to SI unit x 0.017 = µKat/L
Raised level of total CK:
- Increased CK / CPK seen in :
- Acute myocardial infarction.
- Severe myocarditis.
- After open heart surgery.
- Acute cerebrovascular accidents.
- Progressive muscular dystrophy.
- Dermatomyositis and Polymyositis.
- Electric shock.
- Malignant hyperthermia.
- Reye's syndrome.
- Last week of pregnancy and during childbirth.
- Acute psychosis.
- Neoplasm of the prostate, GI Tract, and Urinary bladder.
CK is increased in:
- The only raised level of CK is seen in the injury of heart muscles, skeletal muscles, and brain.
- CK-MM is raised in muscular injuries.
- CK-MB is raised in myocardial infarction of damage.
- CK-BB is raised in brain injury.
Raised level of CK-MB:
- Acute myocardial infarction.
- Cardiac surgery ( e.g an aneurysm ).
- cardiac defibrillation.
- cardiac ischemia.
- ventricular arrhythmias
Raised level of CK-MM:
- Muscular dystrophy.
- Recent injury.
- Intramuscular injection.
- Trauma and crushing injuries.
Raised level of CK-BB:
- Brain Injury.
- Brain cancers.
- Cerebrovascular accidents.
- Subarachnoid hemorrhage.
- Adenocarcinoma especially lung and breast.
- Pulmonary infarction.
- Normal values are found in myasthenia gravis and multiple sclerosis.
Possible References Used
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