Liver lecture notes

Question 1

Key roles of the liver

Answer 1

• glucose and fat metabolism
• detoxification and excretion (bilirubin, ammonia, drugs/hormones/pollutants)
• protein synthesis (albumin, clotting factors)
• defence against infection (reticuloendothelial system)

Question 2

describe the blood flow through the liver

Answer 2

Blood enters via the portal vein (from the gut) and the hepatic artery. These lie with the bile duct to form the portal triad.
Then flows through sinusoids (zones 1 - 2 - 3) between lobules, and leave through central vein. Blood becomes progressively less oxygenated as it flows through the sinusoids, and so as the zones progress the cells become more sensitive to toxicity.

Question 3

What are some examples of factors causing acute liver injury?
What are the 2 possible outcomes for acute liver injury?

Answer 3

Viral hepatitis (A, B, Epstein-Barr)
Drugs, alcohol
Vascular (although this is rare thanks to the liver’s dual blood supply)
Obstruction
Congestion
Damage can result in either recovery or liver failure.

Question 4

What are the possible outcomes of chronic liver injury?

Causes?

Answer 4

Causes: alcohol, viral hepatitis (B, C), autoimmune, metabolic, iron/copper
Outcomes:
Recovery
Cirrhosis –> liver failure
Liver failure: presence of varices/haematoma

Question 5

How do patients present with acute liver injury?

Answer 5

Malaise, nausea, anorexia, jaundice.

sometimes confusion, bleeding, liver pain, hypoglycaemia

Question 6

WHat (basic) is cirrhosis?

Answer 6

Scarring, disorganisation

Question 7

How do individuals with chronic liver injury present?

Answer 7

ascites, haematemesis (blood in sick) due to varices, malaise, anorexia, wasting, easy bruising, intching, hepatomegaly, abnormal LFTs
rarer: jaundice(unlike acute), confusion

Question 8

How much of the liver is reserve?

Answer 8

2/3

Question 9

Liver function tests:
Serum levels of which molecules can indicate liver function?
Serum levels of which molecules indicate how inflamed the liver is, but do not give an index of function?

Answer 9

Serum bilirubin, albumin and prothrombin time give an index of function as they are all produced by protein synthesis in the liver/as a result of liver detoxification.
Serum liver enzymes: cholestatic/hepatocellular - indicate how inflamed the liver is, but do not indicate function.

Question 10

Why does jaundice give individuals characteristic yellow colouring?

Answer 10

Raised serum bilirubin

Question 11

In what type(s) of jaundice is serum bilirubin unconjugated and why?

Answer 11

Unconjugated = pre-hepatic. Excessive haemolysis means too much bilirubin delivered to liver.
In intra-hepatic jaundice bilirubin may also be unconjugated, as the problem may be in the conjugation process, but it may also be conjugated.

Question 12

Jaundice:

Which types of jaundice lead to a raised serum bilirubin that is conjugated and why?

Answer 12

Cholestatic
Post-hepatic: Mechanical obstruction of bile flow causing impaired excretion
Intrahepatic: eg due to liver disease(however if the defect is in the conjugation process, it will be unconjugated)

Question 13

Describe prehepatic jaundice in terms of presentation:

• urine
• stools
• itching
• liver tests

Answer 13

• urine: normal
• stools: normal
• itching: none
• liver tests: normal

Question 14

Describe cholestatic jaundice in terms of presentation:

• urine
• stools
• itching
• liver tests

Answer 14

• urine: dark
• stools: pale
• itching: maybe
• liver tests: abnormal

Question 15

If a patient with jaundice describes rigors (episodes of uncontrollable shivering), what must be suspected?

Answer 15

Acute cholangitis: inflammation of the bile duct usually caused by bacteria ascending from its junction with the duodenum. It tends to occur if the bile duct is already partially obstructed by gallstones.

Question 16

What does the ALT/AST blood test look for?

Answer 16

Measure enzymes that your liver releases in response to damage or disease. Therefore elevated results indivate liver disease.

Question 17

what is cholangitis?

Answer 17

Inflammation of the bile duct.

Usually due to bacteria from stones obstructing the tract.

Question 18

What are spider naevi and what can they be a sign of?

Answer 18

Visible central vein with branching vessels that blanch when pressed then fill in to out. Sign of liver disease.

Question 19

what is ascites? Common causes?

Answer 19

Accumulation of protein-containing (ascitic) fluid within the abdomen.
Causes:
Chronic liver disease (with/without portal vein thrombosis, TB, hepatoma) causing portal hypertension
Neoplasm
Pancreatitis
Cardiac causes

Question 20

What factors are thought to cause ascities?

Answer 20

Portal hypertension is caused both by systemic vasodilation and increased intrahepatic resistance.
Systemic vasodilation triggers the RA system as well as noradrenaline and ADH release, all of which lead to fluid retention.
Portal hypertension leads to ascites.
Low serum albumin leads to ascites.

Question 21

how is ascites managed?

Answer 21

fluid and salt restriction

Question 22

how can alcohol lead to fatty liver and cirrhosis?

Answer 22

Alcohol changes fat metabolism leading to deposits in hepatocytes.
If these fatty cells are damaged, the fat acts as an inducer of fibrosis.
Long term, collagen deposits are found in sinusoids and around the central vein: cirrhosis.

Question 23

Portal hypertension
Causes
Pathology
Consequences

Answer 23

Causes: cirrhosis, fibrosis, portal vein thrombosis
Pathology: increased hepatic resistance, increased splanchnic blood flow
Consequences: varices, splenomegaly

Question 24

what is a high white cell count of neutrophils suggestive of? lymphocytes?

Answer 24

neutrophils - bacterial

lymphocytes - viral

Question 25

what are some complications of chronic liver disease?

Answer 25

• infection due to impairment of reticulo-endothelial system(Kupffer cells): often spontaneous bacterial peritonitis
• GI bleeding
• renal failure
• coma: hepatic encephalopathy(brain is poisoned by the toxic elements from the liver), hyponatraemia/hypoglycaemia, intracranial event
  have to be careful about which drugs you prescribe due to altered excretion metabolism.

Question 26

what are the 5 most common types of liver disease and what are they caused by?

Answer 26

Alcohol-related liver disease:
regularly drinking too much alcohol
Non-alcoholic fatty liver disease:
being very overweight (obese) – this may cause fat to build up in the liver
Hepatitis:
catching a viral infection, regularly drinking too much alcohol
Haemochromatosis:
a gene that runs in families and may be passed from parents to children
Primary biliary cirrhosis:
may be caused by a problem with the immune system