Creatine kinase

ck level of blood

1. ASSIGNMENT:
TOPIC: CREATINE KINASE (CK)
SUBMITTED BY: MADIHA DURRANI

2. CREATINE KINASE (CK):
CK- was 1st indicated as cardiac biomarker in the year 1979, formerly known as creatine phosphokinase,
is an intracellular enzyme present in greater amount in cardiac muscle, skeletal muscle and brain also
and smaller amount occurs in other visceral tissues.
Disruption of cell membranes due to hypoxia or other injury releases CK- from the cellular cytosol into
the systemic circulation. On this bases, elevated serum level of CK- have been used as a sensitive but
non- specific test for myocardial infarction. The speed of release of a marker from injured myocardial
tissue depends on number of factors:
 The molecular size of putative marker is important and as a generalization, small molecules are
released at a faster rate than the larger molecules
 The intracellular location of a marker also limits its rate of release, molecule located in the
cytoplasm will appear in blood stream sooner than structural proteins. The early appearance of
a marker released into the blood stream soon after an injury may facilitate early diagnosis.
It is an enzyme that catalyzes the reversible phosphorylation of creatine by adenosine triphosphate
(ATP), physiologically when muscle contracts, ATP is converted to ADP and CK- catalyzes the
rephosphorylation of ADP to ATP using creatine phosphate as the phosphorylation reservoir.
CREATINE
ATP ATP
CREATINE KINASE
ADP ADP+ H
+

CREATINE PHOSPHATE
FUNCTIONS OF CK:
 Creatine kinase (CK), has several functions in cellular energy metabolism. It catalyzes the
reversible transfer high energy phosphate from ATP to creatine, facilitating storage of energy in
the form of phosphocreatine. In muscle cells, this extra energy buffer plays a pivotal role in
maintaining ATP haemostasis.
NORMAL VALUES:
MEN 5- 100 IU/L
WOMEN 10- 70 IU/L
IN PREGNANCY 5- 40 IU/L

ISO- ENZYMES OF CK:
CK- is a dimer molecule composed of two subunits designated as M and B, so combination of these sub-
units forms the iso- enzymes CK-MM, CK-MB, and CK-BB:

3. 1. CK- MM:
It is found primarily in skeletal muscles and heart, and rises generally in response to muscle damage in
heart, brain or skeleton after:
 Muscular dystrophy
 Muscle inflammation
 Seizures
 Any other skeletal muscle disorder
2. CK- MB:
It is found primarily in heart, and generally rises in in response to:
 Heart attack
 Inflammation of heart muscle
 Muscular dystrophy
 Cardiac surgery
 Endomyocardial biopsy
 Defibrillation or cardioversion
 Left ventricular hypertrophy
 Coronary artery disease
The CK- MB rises in serum at 4-9 hr. after the onset of chest pain, peaks at 24hr and return to baseline
values at 48- 72 hr. the one advantage of CK- MB over troponin is the early clearance that helps in
detection of reinfarction. Thus, the serum level of troponin along with the level of CK-MB fraction is
assessed for the diagnosis of MI.
3. CK- BB:
It is found in brain, and tends to rise in response to:
 Brain injury
 Meningitis
 Abnormal cell growth
 Severe shock
 Stroke

ISO- ENZYME NAME COMPOSITION PRESENT IN ELEVATED IN
CK- 1 BB brain CNS- disorders
CK- 2 MB Myocardium/ heart Acute MI
CK- 3 MM Skeletal muscle Muscle disorders

WHEN IT IS ORDERED?
A CK- test may be ordered when muscle damage is suspected and at regular intervals to monitor for
continued damage. It may be ordered when a muscle disease (myopathy) such as muscular dystrophy is

4. suspected or when someone has experienced physical trauma such as crushing injuries or extensive
burns, and for diagnosing of an acute MI. This test may be ordered when a person has symptoms
associated with muscle injury as:
 Muscle pain or aches
 Muscle weakness
 Dark urine (the urine may be dark due to the presence of myoglobin)
 Suspected damage to myocardium
If a CK- is elevated and the location of muscle damage in unclear, then a healthcare practitioner may
order CK- isoenzymes to distinguish between three types (isoenzymes) of CK as CK-MB (found primarily
in heart muscle), CK-MM (found in skeletal muscle), and CK-BB (found in brain).
 You may also need this test if you have symptom of coronary artery blockage as:
 Chest pain or pressure that lasts for more than a few minutes
 Pain or discomfort in shoulder, neck, arm or jaw
 Chest pain that gets worse
 Chest pain that doesn’t get better by rest or by taking nitroglycerine
Other symptoms that may happen along with chest pain:
 Sweating
 Shortness of breath
 Nausea or vomiting
 Dizziness or fainting
 Unexplained weakness or fatigue
 Rapid or irregular pulse
HOW IS IT USED?
This test may be used to:
 Diagnose heart attack
 Evaluate cause of chest pain
 To determine if or how badly a muscle is damaged
 To detect rhabdomyolysis, muscular dystrophy and other muscle diseases
 Acute renal failure
WHAT OTHER TESTS SHOULD DONE ALONG WITH THIS TEST?
The healthcare provider may order other tests to measure other factors in blood, these includes:
 Echocardiogram
 Complete blood count
 Electrolytes (sodium, potassium, chloride)
 Blood lipids (cholesterol and triglycerides)
 Blood sugar (glucose)
 Electrocardiogram (ECG)

5.  Echocardiogram
 Cardiac catheterization or coronary angiogram
LOW SERUM CK- VALUES:
Subnormal activity of creatine kinase (CK), in serum has been observed in a variety of clinical conditions.
The subnormal activity may be found because of diminished efflux of muscle enzyme into serum from
reduced physical activity caused by illness or advanced age or may result from reduced muscle mass was
accompanying muscle wasting or cachectic state.
 Low serum ck- values reported in acute viral hepatitis have been explained based on reduced
physical activity because these patients have been confined to bed for therapeutic reasons or
because of the severity of illness
 Low ck- values in alcoholic liver disease has been considered to reflect the reduced muscle mass
 Reduced serum ck- activity has also been observed in patients with connective tissue disease
unassociated with diminished physical activity
 Diminished enzyme efflux from altered muscle membrane permeability may account for the low
serum ck- values reported in cushing’s disease
 Low ck- values have been reported in malignant disease metastatic to liver
FACTORS MIGHT AFFECT THE TEST RESULTS:
 Intense physical exercise will lead to higher ck- level
 Skeletal muscle damage especially burnt trauma to the muscle and cocaine abuse can also
increase the level of CK- MB
 Drinking too much alcohol can increase the CK- level
 Serum ck and LDH level become higher in dehydrated group than in non- dehydrated group
usually among the wrestlers because of food and fluid restriction following excercises.
 CK- level will also become elevated in diabetes, and hypertension etc.