PSC and PBC Flashcards
PBC summary of pathophysiology, presentation, diagnosis and management.
Practice recall
Explain the pathophysiology of PBC:
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.
Autoimmune inflammation of the small bile ducts.
How does cholestasis effect the patient?
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.
How does primary biliary cirrhosis present?
Fatigue Pruritus GI disturbance and abdominal pain Jaundice Pale stools Xanthoma and xanthelasma Signs of cirrhosis and failure (e.g. ascites, splenomegaly, spider naevi)
PBC is associated with what other conditions?
Middle aged women Other autoimmune diseases (e.g. thyroid, coeliac) Rheumatoid conditions (e.g. systemic sclerosis, Sjogrens and rheumatoid arthritis)
How is PBC diagnosed?
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.
How is PBC treated?
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.
Complications of 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
PSC summary of pathophysiology, presentation, diagnosis and management.
Recall - Strictures and inflammation of the intra and extra hepatic ducts.
What is PSC?
Primary sclerosing cholangitis is a condition where the intrahepatic or extrahepatic ducts become strictured and fibrotic. This causes an obstruction to the flow of bile out of the liver and into the intestines. Sclerosis refers to the stiffening and hardening of the bile ducts, and cholangitis is inflammation of the bile ducts. Chronic bile obstruction eventually leads to liver inflammation (hepatitis), fibrosis and cirrhosis.
What causes PSC?
The cause is mostly unclear although there is likely to be a combination of genetic, autoimmune, intestinal microbiome and environmental factors. There is an established association with ulcerative colitis.
How does PSC present?
Jaundice Chronic right upper quadrant pain Pruritus Fatigue Hepatomegaly
What do liver function tests show in PSC?
Liver function tests show a “cholestatic” picture. This means alkaline phosphatase is the most deranged LFT and may be the only abnormality at first.
There may be a rise in bilirubin as the strictures become more severe and prevents bilirubin from being excreted through the bile duct. Other LFTs (i.e. transaminases: ALT and AST) can also be deranged, particularly as the disease progresses to hepatitis.
What is the gold standard test for diagnosing PSC?
The gold standard investigation for diagnosis is an MRCP, which is short for magnetic resonance cholangiopancreatography. This involves an MRI scan of the liver, bile ducts and pancreas. In primary sclerosis cholangitis it may show bile duct lesions or strictures.
What are the complications of PSC?
Acute bacterial cholangitis Cholangiocarcinoma develops in 10-20% of cases Colorectal cancer Cirrhosis and liver failure Biliary strictures Fat soluble vitamin deficiencies
