Biochemical Investigation of lIver Function

Question 1

what is a functional unit of the liver

Answer 1

liver lobule

Question 2

what is the composition of a lobule

Answer 2

hexagonal shape and composed of:

- hepatocytes arranged in plates and in contact with the bloodstream on one side and bile canaliculi on the other

Question 3

what are between the plates of the lobules

Answer 3

vascular spaces (sinusoids) containing kupffer cells (phagocytic macrophages)

Question 4

what does the liver store

Answer 4

glycogen, vitamins and iron

Question 5

what are the protective functions of the liver

Answer 5

detoxification and elimination of toxic compounds, kupffer cells ingest bacteria and other foreign material from the blood

Question 6

bile production and excretion

Answer 6

• formed in the biliary canaliculi
• emulsifies fat
• provides route for waste removal

Question 7

causes of acute hepatitis

Answer 7

• poisoning
• infection (hep a - c)
• inadequate perfusion

Question 8

what are the outcomes of acute hepatitis

Answer 8

resolution - majority of cases
profession to acute hepatic failure
progression to chronic hepatic damage

Question 9

common causes of chronic liver disease

Answer 9

alcoholic fatty liver disease
chronic active hepatitis
primary biliary cirrhosis

Question 10

unusual causes of chronic liver disease

Answer 10

alpha-1 AT deficiency
haemochromatosis
Wilsons disease

Question 11

cholestasis

Answer 11

consequence of failure to produce or excrete bile.

Question 12

what can cause cholestasis

Answer 12

failure by hepatocytes - intrahepatic cholestasis
obstruction of bile flow - extrahepatic cholesasis

these can can also both go together

Question 13

what is the resulting implications from cholestasis

Answer 13

this results in the accumulation of bilirubin in the blood leading to jaundice

Question 14

what can cause jaundice

Answer 14

may also be due to excessive haemolytic - bilirubin is unconjugated and does not appear in the urine

Question 15

what leads to liver failure

Answer 15

• Inadequate synthesis of albumin leading to oedema & ascites
• Inadequate synthesis of clotting factors resulting in bruising
• Inability to eliminate bilirubin causing jaundice
• Inability to eliminate nitrogenous waste e.g. ammonia, giving rise to hepatic encephalopathy, a poorly defined neuro- psychiatric disorder.

Question 16

advantages of LFTS

Answer 16

• cheap, widely available, interpretable

- direct subsequent investigation (e.g. imaging)

Question 17

disadvantages of LFTS

Answer 17

– Do not assess liver “function”
– Lack of complete organ specificity
– Lack of disease specificity
– May be “over-sensitive”
– >40 years old, many newly discovered diseases for which they have no diagnostic value