The causes of high prothrombin time in children mainly include the following: 1. Symptoms caused by children suffering from vitamin K deficiency, if the vitamin K in children’s bodies is low, it will cause coagulation dysfunction, especially reflected in the prothrombin time is significantly longer, need to give children timely vitamin K supplementation. 2. Caused by children taking anticoagulant drugs, if children are taking drugs such as warfarin can also cause a significantly longer prothrombin time. If a child has bleeding gums or skin bleeding, the child can be given vitamin K to correct the problem.