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DIAGNOSIS IMPORTANCE OF CREATINE KINASE
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DIAGNOSIS IMPORTANCE OF CREATINE KINASE
• Introduction• Isomers of creatine kinase• Location of Enzyme• Normal value • When CK level is high in blood• When CK level is low in blood• Diagnostic importance of Creatine
phosphokinase
Introduction
• Enzyme catalysing Creatine and ATP to Phosphocreatine (PCr) and ADP
• Action – This enzyme is associated with the regeneration and storage of high energy phosphate (ATP).
• It catalyzes the following reversible reaction in the body.
Enzyme unstable in serumActivity lost due to sulfhydryl group oxidation at active site.Its molecular weight is approximately 82,000Dimer (each of 41000 Da) B (brain) – chromosome 14 M (muscle) –chromosome 19
Creatine Kinase
skeletal muscleheart musclebrain tissue.
Highest activities are found in
Smaller quantities are found in
kidneythe bladderprostategastrointestinal tractliverpancreasspleenuterusplacentathyroidlung
Indicators of Cardiac Injury
Creatine kinase (CK)
• creatine phosphokinase (CPK)
• catalyze transfer of a PO4 group between creatine PO4 & ADP to form creatine + ATP
• requires magnesium as cofactor
• dimeric with pair of two different monomers M & B
• 3 isozymes: CK1 (BB), CK2 (MB), CK3 (MM)
• M and B subunits antigenically distinct proteins encoded by different genes
• primary tissue sources:
1. Brain, smooth muscle, prostate, thyroid, gut, lung CK-BB
2. Cardiac muscle – MB (20-30%) & MM (70-80%)
3. Skeletal muscle – MB (1-2%) & MM (98-99%)
• relatively small molecular size allows leakage out of ischemic muscle or brain cells
Creatine kinase (CK)
• reference ranges in serum affected by:
1. Amount of lean muscle mass
Thin, sedentary = 30 – 50 U/L
Muscular, exercising regularly = 500 – 1000 U/L
2. Age – in neonates, CK-MB 5-10% of total CK
3. Gender
4. Race – Africans 30% higher than Europeans
5. Muscle activity – direct relationship between intensity of exercise and CK level
Creatine kinase (CK)
• persons exercising periodically & at usual intensity levels with lower CK than those who do not exercise at all
• decrease with severe inactivity
• short-term strenuous exercise 10-100 fold increase
• marathon runners up to 2000 U/L as resting value
Creatine kinase (CK)
CK-MM, which is found in your skeletal muscle and heart.
CK-MB, which is found in the heart and rises when heart muscle is damaged.
CK-BB, which is found mostly in your brain
The three types of CK are called isoenzymes.
• released from damaged muscles: CK, AST, LD, myoglobin
Myoglobin >> CK >> AST and LD
• released during ischemia, injury or inflammation
• also increased in:
1. Chronic myopathies
2. Chronic renal failure
3. Acute respiratory exertion – respiratory muscles with more CK than other muscles
Diagnostic Applications
CM-MM
• Brain trauma or brain surgery
1. Injury to smooth muscles (e.g. intestinal ischemia)
2. Transient increase after cardiac arrest reflect cerebral ischemia
CK-BB
Diagnostic Applications
• primary clinical use: detection of acute MI
Following MI:
Total CK – 98% sensitive but 68-85% specific; peak value 18-30 hrs; duration 2-5 days; level 5-10x normal
CK-MB – rise proportional to extent of infarction; appears in serum within 6 hrs after AMI; peak value 12-24 hrs; duration 1.5-3 days persistence indicates extension or infarction or re-infarctionPost AMI CK-MB
CK-MB increases 4 – 8 hours post AMI
Peaks at 12 - 24 hours post AMI
Returns to normal 48 - 72 hours
CK-MB
Diagnostic Applications
Normal: 24 – 170 U/L (women) 24 – 195 U/L (men)
• Marked elevation (> 5x normal)
1. After trauma from electrocution, crush injury, convulsion, tetany, surgical incision or IM injection
2. Athletic individuals – inc. muscle mass & inc. release during strenuous activity
3. Muscular dystrophies
4. Chronic inflammation of muscle (dermatomyositis or polymyositis)
Total Serum CK
Diagnostic Applications
55 to 170 units/L for men
30 to 135 units/L for women
68 to 580 units/L for newborns
Generally the normal range is:
CK-MM generally rises in response to muscle damage in your heart, brain, or skeleton after a crush injury, seizures, muscular dystrophy, muscle inflammation, or another skeletal muscle disorder.
CK-MB generally rises in response to a heart attack, inflammation of the heart muscle, muscular dystrophy, and other problems related to the heart.
CK-BB tends to rise in response to a brain injury, meningitis, abnormal cell growth, severe shock, stroke, hypothermia, or restricted blood flow to the bowel.
This test may be used to
Diagnose heart attack Evaluate cause of chest pain Determine if or how badly a muscle is
damaged Detect rhabdomyolysis dermatomyositis,
Muscular dystrophy polymyositis, and other muscle diseases
Tell the difference between malignant hyperthermia and postoperative infection.
Acute Renal Failure
LOW LEVEL OF CK IN BLOOD
Having lower-than-normal CK levels in your blood is rare.
Low than normal Level is not abnormality.
Muscle diseases - or renal failure could fall under this genetic abnormality
Brain injury or strokeConvulsionsDelirium tremensDermatomyositis or polymyositisElectric shockHeart attackInflammation of the heart muscle (myocarditis)Lung tissue death (pulmonary infarction)Muscular dystrophiesMyopathyPolymyositis vitamin E-selenium deficiency snake bite poisoningAdditional conditions may give positive test results:HypothyroidismHyperthyroidismPericarditis following a heart attackRhabdomyolysis
High CPK levels may be seen in patients who have:
Cardiac catheterization Intramuscular injections Trauma to muscles Recent surgery Heavy exercise.Drinking too much alcohol
Factors that may affect test results include
Amphotericin B Certain anestheticsStatins FibratesDexamethasone Alcohol Cocaine
Drugs that can increase CPK measurements include
If you have had a heart attack, your doctor may look for high levels of myoglobins or troponins, other proteins that are also found in your heart.
Troponin blood testElectrocardiogram, or ECG, to measure the electrical activity of your heart
What other tests might I have along with this test?
These other tests include:
DO YOU HAVE ANY
QUESTION?