Liver Function And LFTs

Question 1

What are Kupffer cells?

Answer 1

Phagocytic macrophages which ingest bacteria and other foreign material.

Question 2

What are the functions of the liver?

Answer 2

• stores glycogen, vitamins and iron.
• metabolises carbohydrates, hormones, lipids, drugs, and proteins.
• detoxifies and eliminates toxic compounds, bacteria and other foreign material from blood.
• produces and excretes bileto emulsify fat and provide route for waste removal.

Question 3

What is cholestasis?

Answer 3

Consequence of failure to produce or excrete bile. Leads to bilirubin accumulating in the blood. Causes jaundice.

Question 4

What causes cholestasis?

Answer 4

• failure by hepatocytes (intrahepatic cholestasis)
• obstruction of bile flow (extrahepatic cholestasis)
• mixed.

Question 5

 what does liver failure cause?

Answer 5

• inadequate synthesis of albumin leading tp oedema and ascites.
• inadequate synthesis of clotting factors e.g. thrombin results in bruising.
• inability to eliminate Bilirubin causing jaundice.
• inability to eliminate nitrogenous waste, e.g. Ammonia, giving rise to hepatic encephalopathy, a poorly defined neuropsychiatric disorder.

Question 6

What questions should you attempt to answer when investigating liver disease?

Answer 6

Is liver disease present? What is the aetiology? What is the severity?

Question 7

What is low albumin found in?

Answer 7

Nephrotic syndrome, significant malnutrition, and post surgical/ITU patients due to redistribution.

Question 8

What are Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST)?

Answer 8

Cytoplasmic enzymes which are sensitive markers of acute damage to hepatocytes.

Question 9

What are alkaline phosphatases indicators of?

Answer 9

• biliary epithelial damage and obstruction
• liver disease as it becomes increased as a response to cholestasis.
• also raised in pregnancy, childhood, bony diseases or when a bone is broken and can be induced by some drugs.

Question 10

What are the pros and cons of gamma-glutamyl transferase?

Answer 10

• pros - used to look for biliary epithelial damage and obstruction and it is super sensitive.
• cons - also present in bone, biliary tract, pancreas and kidney. Affected by ingestion of alcohol and drugs such as phenytoin. May be oversensitive?

Question 11

What causes the rise of bilirubin?

Answer 11

• cholestasis
• haemolysis
• hereditary hyperbilirubinaemia e.g. Gilbert’s syndrome.

Question 12

Advantages of current LFTs?

Answer 12

• cheap, widely available, interpretable.

- Direct subsequent investigation (E.G.imaging).

Question 13

What are the disadvantages of current LFTs?

Answer 13

• does not assess liver “ function“.
• lack of complete organ specificity
• lack of disease specificity
• may be “over-sensitive”
• old