When taking medication, there are three types of labels in the drug instructions, which should generally be noted: the first is prohibited, which means absolutely prohibited from use. The second method is to use with caution, which means that the medication can be used, but close attention should be paid to the patient's condition after oral administration. Once adverse reactions occur, the use should be stopped immediately. The third type is contraindication, which indicates that the medication has clear adverse reactions in this population and should be recommended by a doctor based on the condition. If this medication is necessary, it can be taken in combination with other drugs that can alleviate adverse reactions. In the future, when taking medication, pay more attention to the instructions and precautions to avoid adverse reactions. Why is the instruction manual written like this? It's to prevent certain components of the drug from affecting the clotting factors in the body. Let's learn about it together!
1. What is coagulation factor?
Coagulation time refers to the time required for blood to flow out of blood vessels and produce fibrin filaments. Measuring coagulation time mainly reflects the presence or absence of coagulation factor deficiency or reduction. Coagulation factors are various protein components involved in the process of blood clotting. Its physiological function is to be activated during vascular bleeding, adhere to platelets, and fill the gaps in blood vessels. This process is called coagulation. They are partially generated by the liver and can be inhibited by coumarin. For the purpose of unified naming, the World Health Organization assigns Roman numerals in the order of their discovery, including coagulation factors I, ll, III, IV, V, VLI, VIII, etc. The coagulation process is a series of enzymatic reactions, in which each coagulation factor is activated by its preceding related factor, ultimately producing thrombin and fibrin.
2. Blood coagulation can be divided into three pathways
Endogenous coagulation pathway: refers to the process in which all factors involved in coagulation come from the blood, from factor XIl activation to factor X activation, including the interactions between factors XIl, Xl, IX, VIII, Ca2+, PK, and HMWK.
Exogenous coagulation pathway: refers to the process in which the factors involved in coagulation are not entirely derived from the blood, from the release of factor III (TF) to the activation of factor X, including the interactions between factors II, VII, and Ca2+.
Co coagulation pathway: refers to the process from the activation of factor X to the formation of fibrin, including the interactions between factor X, V, II, XII1, and Ca2+.
The measurement methods of fully automatic coagulation analyzer include coagulation method (PT, APTT, Fbg, TT) and immunoturbidimetric method (D-Dimer).
2. Clinical significance of prothrombin time (PT)
Prothrombin time mainly reflects whether exogenous coagulation is normal, simulates all conditions of exogenous coagulation in vitro, and measures the time required for plasma coagulation. Normal range: 11-13 seconds. Prolonged prothrombin time: a. Congenital coagulation factor deficiency, such as prothrombin, factor II, factor V, factor V, factor X, and fibrinogen deficiency. b. Acquired coagulation factor deficiency: such as secondary/primary hyperfunction of fibrinolysis, severe liver disease, etc. C. The use of heparin can cause prolonged prothrombin time due to the presence of antibodies against prothrombin, factor V, factor VII, factor X, and fibrinogen in the bloodstream.
Shortened prothrombin time is seen in women taking oral contraceptives, thromboembolic diseases, and hypercoagulable states.
3. Clinical significance of activated partial thromboplastin time (APTT)
APTT simulates all the conditions for endogenous coagulation in vitro and measures the time required for plasma coagulation. Normal time of 21-40 seconds, exceeding 3 seconds has clinical significance. APTT is one of the commonly used and sensitive screening indicators for the endogenous coagulation system, which reflects whether endogenous coagulation factors, common pathways are abnormal, and whether anticoagulant substances are present in the blood. Extended clinical significance: (1) Hemophilia A and B with reduced FVIII and FIX levels, FXI deficiency, and some cases of vascular hemophilia. (2) Severe deficiencies in FI, FII, FV, FX, such as severe liver disease/vitamin K deficiency. (3) Primary or secondary fibrinolysis. (4) Oral anticoagulants, application of heparin, etc. (5) There are pathological anticoagulant substances in the blood circulation, such as anti FVIII or anti FIX antibodies, lupus anticoagulant substances, etc. Shortening: hypercoagulable state and thrombotic diseases, such as DIC hypercoagulable phase, myocardial infarction, deep vein thrombosis, etc.
4. Clinical significance of thrombin time (TT)
TT is a simple test for detecting the function of coagulation, anticoagulation, and fibrinolysis systems. The normal range is 16-18 seconds; exceeding the normal control for more than 3 seconds is considered abnormal.
Prolonged thrombin time: seen in decreased plasma fibrinogen or structural abnormalities, clinical use of heparin or increased heparin like anticoagulant substances in liver disease, kidney disease, and systemic lupus erythematosus, hyperfunction of fibrinolytic system
Shortened thrombin time: seen in the presence of calcium ions in the blood or acidic blood.
In summary, coagulation tests are required for surgical patients, liver or kidney puncture surgery, laparoscopic examination, and induced abortion surgery, with the aim of screening and eliminating certain coagulation issues.