Serum creatine kinase

Creatine kinase (CK), also known as creatine phosphokinase, reversibly catalyzes the reaction of creatine and adenosine triphosphate to produce phosphocreatine and adenosine diphosphate. Under pH neutral conditions, ATP is mainly produced to ensure the energy supply of tissue cells. The forward reaction facilitates the ATP produced by oxidative phosphorylation in the mitochondria and enters the cell fluid in the form of phosphocreatine to meet the physiological activities of the cell. CK is widely found in skeletal muscle, myocardium, and brain tissue.

Basic Information

Specialist classification: cardiovascular examination classification: biochemical examination

Applicable gender: whether men and women apply fasting: fasting

Tips: After the specimens are collected, the serum should be separated as soon as possible and measured in time. Can not be measured in time, should be protected from light, low temperature preservation. Enzyme inactivation caused by elevated temperatures is irreversible. Normal value

1, creatine color development method 8 ~ 60U / L (0.5 ~ 3.6U).

2, enzyme coupling method male 24 ~ 195U / L, female 24 ~ 170U / L.

Clinical significance

CK measurement is mainly used for the diagnosis of myocardial infarction, and it also has certain significance for the diagnosis and treatment of other system diseases.

1. Acute myocardial infarction begins to increase in the onset of 2 to 4 hours, peaks at 12 to 48 hours, and returns to normal in 2 to 4 days. The degree of elevation is greater than that of AST and LDH, and occurs early, which is basically consistent with the degree of myocardial injury. The CK activity was also increased in subendocardial myocardial infarction and recurrent myocardial infarction, which were difficult to diagnose with electrocardiogram. Dynamic monitoring contributes to the observation of the condition and prognosis of myocardial infarction.

2, polymyositis, progressive muscular dystrophy, severe muscle trauma and other CK also significantly increased.

3, cerebrovascular accident, meningitis, systemic convulsions, shock, tetanus and other CK activity also increased.

4, hypothyroidism, some infectious diseases, malignant hyperthermia, strenuous exercise, all kinds of intubation and surgery, intramuscular injection of chlorpromazine, antibiotics and other CK also increased.

5, hyperthyroidism, systemic lupus erythematosus, chronic arthritis and the use of steroid preparations, birth control pills and chemotherapy can reduce CK activity.

High results may be diseases: Legionella pneumonia, pediatric myocarditis, pediatric idiopathic ventricular tachycardia, pediatric pre-excitation syndrome, congenital myotonia, myotonic myopathy, lipid deposition myopathy, polymyositis Precautions

1, creatine color method:

(1) Creatinine, arginine, indole acetic acid and the like may also react color with α-naphthol and diacetyl. Therefore, patients with renal failure use their own serum as a blank control to eliminate the effects of creatinine.

(2) α-naphthol is white or slightly yellow crystal, the color is too dark, and should be recrystallized in ethanol before use.

(3) Mg2+ is an activator, cysteine ​​provides a sulfhydryl group, cesium hydroxide and zinc sulfate precipitate proteins and neutralize the reaction.

(4) When serum CK activity is >200 U/L, it is re-tested by dilution with serum known to have normal CK activity, and the result is multiplied by the dilution factor.

2. Enzyme coupling method:

(1) It is best to use serum as a specimen or heparin anticoagulated plasma. Because CK activity is unstable, room temperature can only be stabilized for 4 hours, and 4 °C is only stable for 8 to 12 hours. Therefore, serum should be separated as soon as possible after collection. Can not be measured in time, should be protected from light, low temperature preservation. Enzyme inactivation caused by elevated temperatures is irreversible.

(2) erythrocytes do not contain CK, mild hemolysis has no effect, but moderate and severe hemolysis can be falsely increased due to AK, ATP and G6P released in red blood cells.

(3) Mg2+, Ca2+ and Mn2+ have an activation effect on the enzyme, and Cl-, SO42-, PO43-, citric acid and fluoride can inhibit the activity.

Inspection process

Immediately after venous blood collection, the test is sent. Enzyme coupling detection: Each laboratory can be programmed according to the automatic analyzer model and manual of this room. The main parameters are: 340nm wavelength, 37°C, sample to reagent volume ratio is 1:50, delay time 60s, reaction time 60s, Dynamic law.

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