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CREATINE KINASE (CK)

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  • CREATINE KINASE (CK)

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    CREATINE KINASE (CK)

    Creatine kinase (CK) is found in heart muscle, skeletal muscle, and brain. It is elevated at some time in about 90%-93% (literature range, 65%-100%) of patients with acute MI. In acute MI, CK behaves similarly to AST. In addition, elevations have also been reported in myocarditis and also in some patients with tachyarrhythmias (mostly ventricular) for unknown reasons. Acute liver cell damage, which frequently causes an abnormal AST value, has no effect on CK. This is an advantage, since the situation often arises in which an elevated AST (or LDH) level might be due to severe hepatic passive congestion from heart failure rather than from acute MI.
    Use of CK measurements in diagnosing primary diseases of skeletal muscle is discussed elsewhere . A considerable number of conditions associated with acute muscle injury or severe muscle exertion affect CK values. Thus, CK values are usually elevated in muscle trauma, myositis, muscular dystrophy, after surgery, postpartum, after moderately severe exercise (e.g., long-distance running), and in delirium tremens or convulsions. Increased serum values have been reported in about 80% of patients with hypothyroidism (literature range, 20%-100%) and in patients with severe hypokalemia, due to changes induced in skeletal muscle. CK elevation can be due to effects of alcohol on muscle. For example, one study found that CK levels became abnormal after 24-48 hours in the majority of persons following heavy drinking episodes as well as in most patients with delirium tremens. Levels of CK are said to be normal in chronic alcoholics without heavy intake.
    CK levels are frequently elevated after intramuscular injection. Since therapeutic injections are common, this probably constitutes the most frequent cause of CK elevation. Specimens must be drawn before injection or at least within 1 hour after injection. Trauma to muscle makes the CK level unreliable for a few days postoperatively.
    Although CK is present in brain tissue as well as muscle, reports differ to some extent as to the effect of central nervous system (CNS) disease on serum CK levels. According to one report, CK levels may be elevated in a wide variety of conditions that affect the brain, including bacterial meningitis, encephalitis, cerebrovascular accident, hepatic coma, uremic coma, and grand mal epileptic attacks. Elevation is not always present, and when it is present, the degree of elevation varies considerably. Elevations in some patients in acute phases of certain psychiatric diseases, notably schizophrenia have been reported; the cause is not known. According to one report, CK is elevated in 19%-47% of patients with uremia.
    Since the major source for body CK is skeletal muscle, individuals with relatively small muscle mass will tend to have lower normal CK levels than the average person; those with increased muscle mass will tend to have relatively higher normal values. Normal CK values for African-American males are double those for European males; values for African-American and European females are nearly equal in most (but not all) reports.
    The major drawbacks of total CK are (1) the relatively short time period after onset of infarction during which the CK value is elevated and (2) false positive elevations due to skeletal muscle injury (especially intramuscular injections).
    Creatine kinase isoenzyme measurement. Total CK can be separated into 3 major fractions (isoenzymes): CK-BB (CK-1), found predominantly in brain and lung; CK-MM (CK-3), found in skeletal muscle; and the hybrid CK-MB (CK-2), found predominantly in cardiac muscle. CK isoenzyme assays are now available in most hospital laboratories. Isoenzymes offer a way to detect myocardial damage that minimizes skeletal muscle contribution to CK values.
    Creatine kinase MM fraction. CK-MM comprises well over 95% of skeletal muscle CK and about 70%-75% of myocardial CK. Since the total amount of body skeletal muscle is so much greater than myocardium, elevation of the MM fraction is usually due to skeletal muscle injury or hypoxia, including moderately severe or severe exercise, convulsions, inflammation, trauma, intramuscular injection, or muscular dystrophy. Some conditions producing less obvious effects on muscle, such as hypothyroidism and hypokalemia, may also produce CK-MM increase.
    Creatine kinase MB fraction. CK-MB can be reported in two ways: percentage of total CK (MB/total CK) or in mass units (either by multiplying total CK by the percentage of MB value or by assaying the MB fraction directly using immunoassay). The most recommended method is to screen with mass unit values, because a low normal MB value divided by a relatively low total CK value can give a misleading, rather high percentage of MB. Skeletal muscle contains mostly CK-MM isoenzyme, but there is also about 3%-5% MB present (the amount depends on the particular muscle assayed). Therefore, serum MB can be increased over baseline to some degree by sufficient skeletal muscle injury as well as by myocardial muscle injury. When acute skeletal muscle hypoxia or other injury of sufficient degree elevates CK-MB levels above the upper limit of the reference range in terms of CK-MB units, CK-MM levels are usually increased at the same time and to a much greater degree. Because of the concurrent CK-MM increase, the CK-MB level (although it may be increased) usually remains less than a small MB/total CK cutoff value (which ranges in the literature from 2.5%-5% in different laboratories). Therefore, when the CK-MB value is increased, it is very helpful to know the total CK value in order to calculate the percentage of MB relative to total CK (the “relative index”). If the MB value in terms of units is not increased, the percentage of MB is not useful and may be misleading (e.g., if normal CK-MB levels are 0-10 units and normal total CK units are 0-40 units, a CK-MB level of 2 units is 20% of a total CK value of 10 units, even though both values are well within reference range). Each laboratory should determine the MB “relative index” experimentally because of considerable differences in MB and total CK methodology and analysis conditions.
    The CK-MB level begins to rise 3-6 hours after onset of acute MI, reaches a peak in 12-24 hours, and returns to normal in 24-48 hours (sometimes earlier). There is a rough correlation between the size of the infarct and the degree of elevation. Since small infarcts may not elevate the MB fraction dramatically, it is important to time the collection of specimens so as not to miss the peak values. Some recommend five specimens: one immediately, then at 6, 12, 18, and 24 hours afterward. Others use 4 specimens: one immediately, then at 8, 16, and 24 hours or at 6, 12, and 18 hours. Some use 3 specimens: immediately, 12 hours, and 24 hours.
    Some laboratories do not perform CK-MB assay unless the total CK value is elevated. However, reports indicate that about 10% of acute MI patients (literature range 0%-16%) demonstrate elevated CK-MB levels with the total CK value remaining within reference range limits. This is especially common in persons with relatively small muscle mass, whose preinfarct normal total CK value is apt to be in the lower part of the population reference range[/SIZ
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    No difference between CK or CPK may be in isoenzyme


    The creatine kinase test measures the blood levels of certain muscle and brain enzyme proteins
    ------------
    Creatine kinase (CK or CPK) is an enzyme (a type of protein) found

    in muscle and brain. Normally, very little CK is found circulating in
    the blood. Elevated levels indicate damage to either muscle or brain;
    possibly from a myocardial infarction (heart attack), muscle disease,
    or strokeThere are three types, or isoforms, of CK-I, or BB, is produced primarily by brain and smooth muscleCK-II, or MB, is produced primarily by heart muscleCK-III, or MM, is produced primarily by skeletal muscle

    Normal resultsIn females, total CK should be 10-79
    units per liter (U/L). In males, total CK should be 17-148 U/L. CK
    levels are reduced in the first half of pregnancy, and increased in the
    second half. CK levels are elevated in newborns
    The distribution of isoenzymes should be
    CK-I: 0%
    CK-II: 0-5%
    CK-III: 95-100%


    Abnormal resultsElevation of CK-I may be seen in stroke, extreme shock, or brain tumor.Elevation
    of CK-II is seen after a myocardial infarction. It begins to rise three
    to six hours after the heart attack, and may peak within 24 hours. It
    should then return to normal. For this reason, it is a useful marker
    for recent myocardial infarction, but not for one which occurred more
    than a day before the test.Elevation of CK-III indicates
    skeletal muscle damage. This may occur from normal exercise, trauma, or
    muscle disease. CK levels may be very high early on in muscular
    dystrophy, but may fall to normal later as muscle tissue is lost.
    Elevated CK is also seen in myositis, myoglobinuria, toxoplasmosis, and
    trichinosis. Hypothyroidism may also cause elevated CK.
    creatine phosphokinase (CPK), an enzyme found mainly in the heart, brain, and skeletal muscle

    CPK isoenzymes are performed when the total CPK level is elevated.
    Isoenzyme testing can help differentiate the source of the damaged
    tissue


    CPK-1 (also called CPK-BB) is concentrated in the brain and lungs


    CPK-2 (also called CPK-MB) is found mostly in the heart


    CPK-3 (also called CPK-MM) is found mostly in skeletal muscle


    Because the CPK-1 isoenzyme is predominately found in the brain and
    lungs, injury to either of these organs (for example, stroke or lung
    injury due to a pulmonary embolism) are associated with elevated levels
    of this isoenzyme.

    CPK-2 levels rise 3 - 6 hours
    If there is no further damage to the heart muscle, the level peaks at
    12 - 24 hours and returns to normal 12 - 48 hours after tissue death.
    CPK-2 levels do not usually rise with chest
    caused by
    (blood clot in the lung), or congestive heart failure
    .

    The CPK-3 isoenzyme is normally responsible for almost all CPK enzyme
    activity in healthy people. When this particular isoenzyme is elevated,
    it usually indicates injury or stress to skeletal muscle.-------------------------------------------------




    Creatine kinase (CK), also known as phosphocreatine
    kinase or creatine phosphokinase (CPK) is an enzyme
    (EC2.7.3.2) expressed by various tissue types. It catalyses the conversion of creatine to phosphocreatine, consuming adenosine
    triphosphate (ATP) and generating adenosine diphosphate (ADP).

    In tissues that consume ATP rapidly, especially skeletal muscle, but also brain
    and smooth muscle,

    phosphocreatine serves as an energy reservoir for the rapid

    regeneration of ATP. Thus Creatine Kinase is an important enzyme in

    such tissues.

    Clinically, creatine kinase is assayed in blood tests as a marker of myocardial
    infarction (heart attack), rhabdomyolysis (severe muscle breakdown) and in acute
    renal failure.



    In most of the cell, the CK enzyme consists of two subunits, which can be
    either B (brain type) or M (muscle type). There are, therefore,
    three different isoenzymes: CK-MM, CK-BB and CK-MB. The genes for these
    subunits are located on different chromosomes: B on 14q32 and M
    on 19q13. In addition to those, there are two mitochondrial creatine kinases,
    the ubiquitous and sarcomeric form.



    Isoenzyme patterns differ in tissues.
    CK-BB occurs mainly in

    tissues, and its levels do rarely have any significance in bloodstream.

    Skeletal muscle expresses CK-MM (98%) and
    low levels of CK-MB (1%).
    The

    myocardium

    (heart muscle), in contrast, expresses CK-MM
    at 70% and CK-MB at

    25-30%. CK-BB is expressed in all tissues at
    low levels and has little

    clinical relevance.

    The mitochondrial creatine kinase (CKm),
    which produces

    ATP from ADP by converting creatine phosphate to creatine, is present

    between the two membranes of the mitochondrion. Apart from the

    mitochondrial form, there are three forms present in the cytosol—CKa
    (in times of acute need, produces ATP in the cytosol at the cost
    of creatine phosphate), CKc

    (maintains critical concentration of creatine and creatine phosphate in

    the cytosol by coupling their phosphorylation and dephosphorylation

    respectively with ATP and ADP) and CKg
    (which couples direct phosphorylation of creatine to the glycolytic pathway



    CK is often determined routinely in emergency patients. In addition, it is
    determined specifically in patients with chest pain and acute renal failure is
    suspected. Normal values are usually between 25 and 200 This test is not specific
    for the type of CK that is elevated.

    Elevation of CK is an indication of damage to muscle. It is therefore
    indicative of injury, rhabdomyolysis, myocardial infarction, muscular dystrophy,
    myositis, myocarditis, malignant hyperthermia and neuroleptic malignant
    syndrome. It is also seen in McLeod syndrome and hypothyroidism. The use of statin

    medications, which are commonly used to decrease serum cholesterol

    levels, may be associated with elevation of the CPK level in about 1%

    of the patients taking these medications, and with actual muscle damage

    in a much smaller proportion.

    Lowered CK can be an indication of alcoholic liver disease and rheumatoid
    arthritis.

    Isoenzyme determination has been used extensively as an indication for
    myocardial damage in heart attacks. Troponin measurement has largely replaced
    this in many hospitals, although some centres still rely on CK-MB
    التعديل الأخير تم بواسطة labspe; الساعة 04-02-2008, 09:35 PM.
    http://www.arb-up.com/files/arb-up-2008-1/btx24479.gif

  • #2
    Excellent daloo i write before in the same subjest but you are very good in details i think its better next time to write it as attachement as writting all of this in here is alittle difficult to read , in general very good i said before the place you are working on it are lucky to have you ...good luck
    :extra77:

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    • #3
      مجهود راااااااااااااااااااائع
      http://cdn-users1.imagechef.com/ic/s...b4abede7f5.jpg

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      • #4
        In fact the objective very very very good

        thanks for you
        - من جن بالحب فهو عاقل ومن جن بغيره فهو مجنون

        -إذا أحبك مليون فأنا معهم.. وإذا أحبك واحد فهو أنا ..وإذا لم يحبك أحد فاعلم أنني مت.:sm184:.

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