What causes long clotting time

Prolonged clotting time may be caused by genetic coagulation factor deficiency, acquired coagulation dysfunction, drug effects, liver disease, vitamin K deficiency, and other factors.

1. Genetic factors:

Hemophilia A VIII factor deficiency and hemophilia B IX factor deficiency are typical genetic coagulation disorders, and patients may experience spontaneous bleeding in the joint cavity or muscles from a young age. Von Willebrand disease (vWD) is caused by abnormal von Willebrand factor, leading to impaired platelet adhesion and a tendency towards skin and mucosal bleeding. This type of disease needs to be diagnosed through genetic testing and coagulation factor activity assays.

2. Drug interference:

Warfarin exerts anticoagulant effects by inhibiting the synthesis of vitamin K-dependent coagulation factors II, VII, IX, and X. Heparin drugs directly enhance antithrombin activity and rapidly prolong APTT. New oral anticoagulants such as rivaroxaban selectively inhibit factor Xa, and routine coagulation tests may show abnormalities. Although antiplatelet drugs do not affect clotting time, they may synergistically increase the risk of bleeding.

3. Liver lesions:

In cirrhosis, the synthesis function of liver cells decreases, leading to a decrease in the production of coagulation factors such as fibrinogen and prothrombin. Cholestasis affects the absorption of fat soluble vitamin K and further interferes with the gamma carboxylation of coagulation factors. Abnormal liver function can also accelerate fibrinolysis, manifested as synchronous prolongation of PT and APTT accompanied by elevated D-dimer levels.

4. Vitamin deficiency:

Vitamin K is a key cofactor for post-translational modifications of coagulation factors II, VII, IX, and X. Long term use of antibiotics can lead to disruption of gut microbiota, chronic diarrhea affecting absorption, and complete parenteral nutrition without supplementation of vitamin K, all of which can cause deficiencies. Newborns are prone to hemorrhagic diseases due to intestinal sterility and insufficient placental transport, and require routine intramuscular injection of vitamin K for prevention.

5. Acquired diseases:

During disseminated intravascular coagulation (DIC), a large amount of coagulation factors are consumed, and laboratory tests show multiple abnormal indicators accompanied by thrombocytopenia. Primary fibrinolysis is rare, characterized by a significant decrease in fibrinogen and normal D-dimer levels. Some autoimmune diseases can produce coagulation factor inhibitors, such as acquired hemophilia, which can produce factor VIII antibodies.

Avoid vigorous exercise and external injuries in daily life, and use a soft bristled toothbrush to reduce gum bleeding. Diet should ensure protein and vitamin K intake. Foods such as spinach, broccoli, and animal liver are rich in vitamin K. Long term use of anticoagulant drugs requires regular monitoring of INR values to avoid sudden dose adjustments. When there is unexplained bruising, nosebleeds, or joint swelling and pain, it is recommended to seek medical attention at the hematology department as soon as possible for specialized tests such as coagulation tests and factor activity. Patients with abnormal liver function need to have their liver synthesis function evaluated simultaneously, and if necessary, fresh frozen plasma should be supplemented to correct coagulation disorders.