What is primary biliary cirrhosis (PBC)?
Primary biliary cirrhosis (PBC) is a chronic liver disease that causes slow, progressive destruction of bile ducts in the liver. This destruction interferes with the excretion of bile. Continued liver inflammation causes scarring and eventually leads to
cirrhosis. Cirrhosis is present only in the later stage of the disease.
Primary biliary cirrhosis progressively destroys the system that drains bile from the liver into the intestines. Bile is a collection of waste products excreted by the liver. As the disease progresses it also scars the liver, leading to cirrhosis. Bile, a substance that helps digest fat, leaves the liver through these ducts. When the ducts are damaged, bile builds up in the liver and damages liver tissue. Over time, the disease can cause cirrhosis and may make the liver stop working. Bile contains substances required for digestion and absorption of fat called bile acids, as well as other compounds that are waste products, such as the pigment bilirubin. (Bilirubin is a yellow-orange compound produced by the breakdown of hemoglobin from old red blood cells.) Bile is stored in the gallbladder between meals and discharged into the small intestine during digestion of the meals.
Although the cause of this serious condition is not known, it has many features to suggest that it is an autoimmune disease. Autoimmunity describes the process whereby the body's defense mechanisms are turned against itself. The immune system is supposed to recognize and attack only dangerous foreign invaders like germs, but many times it attacks, for no apparent reason, the cells of the body itself. Autoimmune reactions occur in many different tissues of the body, creating a great variety of diseases.
Women are affected 10 times more frequently than men. The disease usually is first diagnosed in people 30 to 60 years old. Many patients have no symptoms of disease and are diagnosed by finding an abnormality on routine liver blood tests. Itching and fatigue are common symptoms. Other signs include jaundice, cholesterol deposits in the skin, fluid accumulation and darkening of the skin. Several other disorders are often associated with PBC. The most common are impaired functioning of the tear and salivary glands, causing dry eyes or mouth. Arthritis and thyroid problems may also be present. Bone softening and fragility leading to fractures can occur in late stages of the disease.