Primary biliary cirrhosis, sometimes called PBC, is a disease in which the bile ducts in your liver are slowly destroyed. Bile, a fluid produced in your liver, plays a role in digesting food and helps rid your body of worn-out red blood cells, cholesterol and toxins.
When bile ducts are damaged, as in primary biliary cirrhosis, harmful substances can build up in your liver and sometimes lead to irreversible scarring of liver tissue (cirrhosis).
Primary biliary cirrhosis is considered an autoimmune disease, in which the body turns against its own cells. Researchers think it is triggered by a combination of genetic and environmental factors. Primary biliary cirrhosis usually develops slowly and medication can slow its progression, especially if treatment begins early.
Although some people with primary biliary cirrhosis remain symptom-free for years after they're diagnosed, others experience a number of signs and symptoms.
Common early symptoms include:
- Itchy skin
- Dry eyes and mouth
Later signs and symptoms may include:
- Pain in the upper right portion of the abdomen
- Bone, muscle or joint (musculoskeletal) pain
- Yellowing of the skin and eyes (jaundice)
- Darkening of the skin that's not related to sun exposure (hyperpigmentation)
- Swollen feet and ankles (edema)
- Buildup of fluid in the abdomen due to liver failure (ascites)
- Fatty deposits on the skin around your eyes, your eyelids, or in the creases in your palms, soles, elbows or knees (xanthomas)
- Weak and brittle bones (osteoporosis), which can lead to fractures
- Elevated cholesterol
- Diarrhea that can be greasy (steatorrhea)
- Underactive thyroid (hypothyroidism)
It's not clear what causes primary biliary cirrhosis. Many experts consider primary biliary cirrhosis an autoimmune disease in which the body turns against its own cells.
How primary biliary cirrhosis develops
The inflammation of primary biliary cirrhosis begins when T lymphocytes (T cells) start accumulating in your liver. T cells are white blood cells that are part of your immune system response.
Normally, T cells recognize and help defend against harmful invaders, such as bacteria. But in primary biliary cirrhosis, the T cells invade and destroy the cells lining the small bile ducts in your liver.
Inflammation in the smallest ducts spreads, in time, and destroys nearby liver cells. As these cells are destroyed, they're replaced by scar tissue (fibrosis) that can contribute to cirrhosis. Cirrhosis is scarring of liver tissue that makes it difficult for your liver to carry out essential functions.
The following factors may increase your risk of primary biliary cirrhosis:
- Your sex. The great majority of people with primary biliary cirrhosis are women.
- Your age. Primary biliary cirrhosis is most likely to occur in people 30 to 60 years old.
- Genetic factors. Having a family member with the disease makes it more likely that you will develop it.
Researchers think that genetic factors, when combined with environmental factors, trigger primary biliary cirrhosis. These environmental factors may include:
- Infection. Researchers suspect primary biliary cirrhosis could be triggered by a bacterial, fungal or parasitic infection.
- Smoking. Smoking is associated with increased risk of primary biliary cirrhosis.
- Environmental toxins. Some research suggests that toxic chemicals may play a role in developing primary biliary cirrhosis.
As liver damage progresses, people with primary biliary cirrhosis may develop a number of serious problems, including:
- Cirrhosis. Cirrhosis is liver scarring that makes it difficult for the liver to function normally. Cirrhosis can occur in the later stages of primary biliary cirrhosis. Ongoing cirrhosis can lead to liver failure, which occurs when your liver is no longer able to function properly.
- Increased pressure in the portal vein (portal hypertension). Blood from your intestine, spleen and pancreas enters your liver through a large blood vessel called the portal vein. When scar tissue from cirrhosis blocks normal circulation through your liver, blood backs up, much like water behind a dam, leading to increased pressure within the vein. And because blood doesn't flow normally through your liver, drugs and other toxins aren't filtered properly from your bloodstream.
- Enlarged spleen (splenomegaly). Your spleen can become enlarged with white blood cells and platelets due to portal hypertension.
- Gallstones and bile duct stones. If bile cannot flow through the bile ducts, it may harden into stones, causing pain and infection.
- Enlarged veins (varices). When circulation through the portal vein is slowed or blocked, blood may back up into other veins — mainly those in your stomach and esophagus. The blood vessels are thin walled, and increased pressure in your veins can cause bleeding in your upper stomach or esophagus. This bleeding is a life-threatening emergency that requires immediate medical care.
- Liver cancer. The destruction of healthy liver tissue that occurs in cirrhosis increases your risk of liver cancer.
- Weak bones (osteoporosis). People with primary biliary cirrhosis have an increased risk of weak, brittle bones that may break more easily.
- Vitamin deficiencies. A lack of bile affects your digestive system's ability to absorb fats and the fat-soluble vitamins, A, D, E and K. This sometimes leads to deficiencies of these vitamins in advanced cases of primary biliary cirrhosis.
- Decreased mental function (hepatic encephalopathy). Some people with primary biliary cirrhosis with liver failure have problems with memory, concentration and personality change.
- An increased risk of other disease. In addition to bile duct and liver damage, people with primary biliary cirrhosis are likely to have other metabolic or immune system disorders, including thyroid problems, limited scleroderma (CREST syndrome) and rheumatoid arthritis.