Liver, disorders of

The liver is a common site of disease. The most significant liver conditions include alcohol-related disorders (see liver disease, alcoholic), hepatitis, and liver cancer. Disorders can also result from infection. Certain viruses cause hepatitis (see hepatitis, viral). Bacteria may spread up the biliary system to the liver, causing cholangitis or liver abscess. Parasitic diseases affecting the liver include schistosomiasis, liver fluke, and hydatid disease. Certain metabolic disorders, such as haemochromatosis and Wilson’s disease, may involve the liver. Other types of liver disorder include Budd–Chiari syndrome, in which the veins draining the liver become blocked. Occasionally, defects of liver structure are present at birth. Such defects principally affect the bile ducts; one example is biliary atresia, in which the bile ducts are absent. Because the liver breaks down drugs and toxins, damage to liver cells can also be caused through overdose or drug allergy. (See also jaundice; liver failure; portal hypertension.)