At the present time, the exact cause is unknown; however, it is known that PBC is not caused by alcohol. It is believed that PBC results from an abnormal reaction of the body's immune system possibly initiated by an infection. Designed to protect the body from infection, the immune system of PBC patients attacks the liver causing slow, progressive damage to the bile ducts (small tubes through which bile flows out of the liver).
Pruritus is often refractory to medical therapy and significantly impacts patients' quality of life. Antihistamines are first-line agents to relieve pruritus in early stages and are the first line of medication for patients with mild-to-moderate pruritus. Use caution in patients with cirrhosis and signs of encephalopathy because antihistamines can further depress brain function.
About 25% of patients with PBC are diagnosed as a result of blood tests taken for other reasons and are asymptomatic at the time. The diagnosis of PBC should be suspected where chronic cholestasis is found after exclusion of other causes of liver disease. Around 55% report pruritus and in 10% this is severe. It is usually assumed to be due to deposition of bile pigments in skin.