Key points to be noted in coagulation experiments

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First of all, we must realize that most of the errors in thrombosis and hemostasis test results come from before analysis, so it is very important to ensure the quality of hemostasis test specimens for the accuracy of the experimental results. The following points are for reference:

Desheng Laboratory

1. The patient's own preparation and influencing factors

1. Age: It is very important to explain the results of hemostasis test for newborns and infants in the reference range determined by age. Many scholars have reported the influence of age and gender on platelet function and coagulation activity.

2. Physical condition, disease, menstrual period, pregnancy, anemia and polycythemia, etc.

3. Drugs: Foreign scholars have studied the effect of drugs taken by outpatients on clinical test items.

4. Lifestyle: Smoking can increase the levels of plasma fibrinogen, vWF and other coagulation factors, and increase thrombin production and platelet activation; quit smoking!

5. Seasonal changes: platelets are most easily activated in the early morning, and the incidence of myocardial infarction is the highest; in cold seasons, blood coagulation activity increases, which increases the incidence of myocardial infarction and sudden death.

2. Collection of specimens

1. The patient should be resting before blood sampling or have 15-30 minutes of rest before blood sampling. Vigorous activity can activate the platelet and coagulation system.

2. The influence of blood collection technique or blood collection process. Blood collection should be done to the nail on the head. Mix with anticoagulant immediately after collection, while avoiding vigorous shaking.

3. Location of blood collection: It is strictly forbidden to collect blood from the transfusion tube, especially when or near heparin infusion.

4. Influence of blood coagulation tube: The use of blood coagulation tube should be standardized, that is, siliconized glass tube is used to avoid the activation of endogenous contact pathways. Common glass tube has the greatest impact on the activity of factor VIII, which can significantly reduce it.

3. Transport and storage of specimens

1. The specimens need to be transported at room temperature, because low temperature will damage platelets, activate factor VII and factor XI, and shorten the PT and APTT results.

2.For newly collected specimens, it is best to separate the plasma within 2 hours.

3.The specimens that cannot be made at present should be frozen in the refrigerator at -20℃. To

4. Specimens that need to be stored for a long time are frozen and stored in a refrigerator at -80℃.

5. When the frozen plasma is melting, it should not be allowed to stand at room temperature and gradually melt. In this way, fibrin will be precipitated out of cryoprecipitated protein. It should be gently shaken in a 37℃ water bath to make it melt quickly.

4. The influence of temperature and time:

Among the coagulation factors, factors V and VIII will be denatured and inactivated over time after being isolated, and this inactivation can be accelerated with increasing temperature. As a result, the PT and APTT time are prolonged due to the prolonged time from collection to analysis.

The temperature and time of specimen storage can affect the activity of coagulation factors.

The blood begins to change in vitro. Depending on the storage method and time, the coagulation factors are gradually consumed or activated, especially the consumption of factors V, Ⅷ, IX and the activation of factor VII are more obvious.