Primary Biliary Cirrhosis

Pathophysiology

Primary biliary cirrhosis is a condition where the immune system attacks the small bile ducts within the liver. The first parts to be affected are the intralobar ducts, also known as the Canals of Hering. This causes obstruction of the outflow of bile, which is called cholestasis. The back-pressure of the bile obstruction and the overall disease process ultimately leads to fibrosis, cirrhosis and liver failure.

Bile acids, bilirubin and cholesterol are usually excreted through the bile ducts into the intestines. When there is obstruction to the outflow of these chemicals they build up in the blood as they are not being excreted. Bile acids cause itching, bilirubin causes jaundice and raised cholesterol causes cholesterol deposits in the skin called xanthelasma (xanthomas are larger nodular deposits in the skin or tendons) and blood vessels causing increased risk of cardiovascular disease.

Bile acids are normally responsible for helping the gut digest fats. Having a lack bile acids in the stool cause gastrointestinal disturbance, malabsorption of fats and greasy stools. Bilirubin normally causes the dark colour of stools, so a lack of bilirubin can cause pale stools.

 

Presentation

  • Fatigue
  • Pruritus
  • GI disturbance and abdominal pain
  • Jaundice
  • Pale stools
  • Xanthoma and xanthelasma
  • Signs of cirrhosis and failure (e.g. ascites, splenomegaly, spider naevi)

 

Associations

  • Middle aged women
  • Other autoimmune diseases (e.g. thyroid, coeliac)
  • Rheumatoid conditions (e.g. systemic sclerosis, Sjogrens and rheumatoid arthritis)

 

Diagnosis

Liver Function Tests

  • Alkaline phososphatase is first liver enzyme to be raised (as with most obstructive pathology)
  • Other liver enzymes and bilirubin are raised in later disease

 

Autoantibodies

  • Anti-mitochondrial antibodies is the most specific to PBC and forms part of the diagnostic criteria
  • Anti-nuclear antibodies are present in about 35% of patients

 

Other blood tests:

  • ESR raised
  • IgM raised

 

Liver biopsy is used in diagnosing and staging the disease

 

Treatment

  • Ursodeoxycholic acid reduces the intestinal absorption of cholesterol
  • Colestyramine is a bile acid sequestrate in that it binds to bile acids to prevent absorption in the gut and can help with pruritus due to raised bile acids
  • Liver transplant in end stage liver disease
  • Immunosuppression (e.g. with steroids) is considered in some patients

 

Disease progression

Disease course and symptoms vary significantly. Some people live decades without symptoms. The most important end results of the disease are advanced liver cirrhosis and portal hypertension.

Some other issues / complications:

  • Symptomatic pruritus
  • Fatigue
  • Steatorrhoea (greasy stools due to lack of bile salts to digest fats)
  • Distal renal tubular acidosis
  • Hypothyroidism
  • Osteoporosis
  • Hepatocellular carcinoma

 

Last updated January 2019
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