The cause can be found in more than 80% of patients. * Primary<unk>  (75%): thrombosis of the hepatic vein * Hepatic vein thrombosis is associated with the following in decreasing order of frequency: # Polycythemia vera # Pregnancy # Postpartum state # Use of oral contraceptives # Paroxysmal nocturnal hemoglobinuria # Hepatocellular carcinoma # Lupus anticoagulants * Secondary<unk>  (25%): compression of the hepatic vein by an outside structure (e.g. a tumor)<unk>  is also seen in tuberculosis, congenital venous webs and occasionally in inferior vena caval stenosis. Often, the patient is known to have a tendency towards thrombosis, although<unk>  can also be the first symptom of such a tendency. Examples of genetic tendencies include protein C deficiency, protein S deficiency, the Factor V Leiden mutation, hereditary anti-thrombin deficiency and prothrombin mutation G20210A. An important non-genetic risk factor is the use of estrogen-containing (combined) forms of hormonal contraception. Other risk factors include the antiphospholipid syndrome, aspergillosis, Behçet's disease, dacarbazine, pregnancy, and trauma. Many patients have<unk>  as a complication of polycythemia vera (myeloproliferative disease of red blood cells). People who have paroxysmal nocturnal hemoglobinuria (PNH) appear to be especially at risk for<unk> , more than other forms of thrombophilia: up to 39% develop venous thromboses, and 12% may acquire<unk><unk> . A related condition is veno-occlusive disease, which occurs in recipients of bone marrow transplants as a complication of their medication. Although its mechanism is similar, it is not considered a form of<unk> . Other toxicologic causes of veno-occlusive disease include plant & herbal sources of pyrrolizidine alkaloids such as Borage, Boneset, Coltsfoot, T'u-san-chi, Comfrey, Heliotrope (sunflower seeds), Gordolobo, Germander, and Chaparral.
Budd–Chiari syndrome
Hepatic veno-occlusive disease
Liver cancer
Nephrotic syndrome
Alcoholic liver disease
Fatty liver disease
Adams–Oliver syndrome
Hepatopulmonary syndrome