[Idiopathic thrombosis].

Idiopathic thrombosis involves a group of inherited thrombophilia predisposed to severe thrombosis of early onset and associated with an adverse outcome due to recurrence, and therefore, requires long-term anticoagulation therapy. The causative factors of a predisposition to thrombosis include immobility, dehydration, infection, surgery, injury, cancer, pregnancy, and estrogen use. The inherited deficiencies of antithrombin (AT), protein C (PC), and protein S (PS) are specified as "Specific Pediatric Chronic Diseases." However, medical expense assistance for patients terminates when they reach the age of 20 years. On April 1st 2017, "Idiopathic Thrombosis due to Inherited Thrombophilia," consisting of inherited AT, PC, and PS deficiencies, was specified as an "Intractable Disease," and aid for medical expenses became available. Accordingly, progress in the research and practice of idiopathic thrombosis is expected in future to improve the medical care system and to construct a database via clinical surveys.