What are the indicators for the four coagulation tests

The four coagulation tests mainly detect four indicators: plasma prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen.

1. Plasma prothrombin time

Plasma prothrombin time reflects the function of exogenous coagulation pathways, and the coagulation status is evaluated by detecting the activity of coagulation factors II, V, VII, and X. The prolongation of this indicator may indicate vitamin K deficiency, liver disease, or warfarin anticoagulant therapy, while shortening can be seen in hypercoagulable states. During the examination, venous blood should be collected on an empty stomach to avoid hemolysis affecting the accuracy of the results.

2. Activated partial thromboplastin time

Activated partial thromboplastin time evaluates the function of endogenous coagulation pathways, mainly detecting the activity of coagulation factors VIII, IX, XI, and XII. Abnormal results may indicate hemophilia, antiphospholipid antibody syndrome, or effects of heparin treatment. Before the examination, the doctor should be informed of their recent medication history, as certain antibiotics and anticoagulants may interfere with the test results.

3. Thrombin time

Thrombin time measures the process of fibrinogen conversion to fibrin, reflecting the function of the common coagulation pathway. Numerical prolongation is common in cases of low fibrinogen, abnormal fibrinogen, or the presence of heparin like substances. 24 hours before the examination, vigorous exercise and high-fat diet should be avoided to prevent changes in blood composition from affecting the test.

4. Fibrinogen

Fibrinogen detection directly quantifies the protein content in plasma and is a key substrate in the coagulation process. A decrease in levels may be caused by cirrhosis and disseminated intravascular coagulation, while an increase is seen in acute phase reactions such as inflammation and trauma. When collecting blood, it is necessary to ensure smooth venipuncture, as the mixing of tissue fluid can lead to a false decrease in detection values.

Before undergoing the four coagulation tests, one should maintain a normal daily routine and avoid staying up late and drinking alcohol. Wear loose clothing on the day of the examination to facilitate blood collection, and press the puncture point for 5 minutes after blood collection to prevent bruising. If taking anticoagulant drugs such as aspirin and warfarin, it is necessary to inform the doctor in advance, and the pregnancy status should be specifically indicated during the pregnancy test. Regular monitoring of coagulation function is particularly important for patients with thrombotic diseases, and it is recommended to follow medical advice for standardized follow-up examinations.