abnormal liver function tests W5

Question 1

liver function tests - what are they useful for?

Answer 1

not sensitive or specific
reflect damage rather than function
but clinically useful
and patterns give clues

Question 2

bilirubin features?

Answer 2

difficult to assay and non-specific
breakdown product of haem
isolated rise in Gilberts syndrome or haemolysis

Question 3

alanine transaminase (ALT)?

Answer 3

enzyme in hepatocyte which is increased when hepatocytes die. has a short half life of hours so tells you how many hepatocytes died in last ~12 hrs

Question 4

aspartate transaminase (AST?)

Answer 4

less liver specific than ALT.
can be useful for NAFLD when used in a ratio with ALT

Question 5

level of ALTs meaning?

Answer 5

all dead = 10,000
10% dead = 1000
1% dead = 100

Question 6

when is AST greater than ALT?

Answer 6

ALD, advancing fibrosis

Question 7

alkaline phosphate features?

Answer 7

from bile ducts
enzyme with different isoforms - bone, intestine, placenta, liver
when elevated in liver shows something wrong in bile ducts. tells you how irritated the ducts are, not the level of obstruction

Question 8

how do you know if alkaline phosphatase is high in the liver or just generally high?

Answer 8

check GGTP as this also comes from bile ducts (doesn’t come in liver function tests in hospital)
if alkaline phosphatase is high and GGTP is low, then problem is not in liver

Question 8

gamma glutamyltranferase features? when is it increased?

Answer 8

increases by induction not damage.
not just in liver
increases with alcohol, obesity, phenytoin, carbamazepine, NAFLD cirrhosis

Question 9

albumin features? when is it high/low?

Answer 9

large amount in blood
important for osmotic effect
high in dehydration
low due to dilution or reduced synthesis
often normal in cirrhosis until liver failing

Question 10

prothrombin time is a good marker of what?

Answer 10

good marker of synthetic function of the liver
very good in acute liver failure
rarely very abnormal in cirrhosis

Question 11

LFT patterns: bilirubin raised only?

Answer 11

Gilberts or haemolysis

Question 12

LFT patterns: ALT mildly increased?

Answer 12

common eg
-NAFLD
-HepC
-ALD
-Alc Hep

Question 13

LFT patterns: ALT high?

Answer 13

hepatitis including drug damage

Question 14

LFT patterns: GGTP only?

Answer 14

induction eg drug, inactive cirrhosis
often high in alcohol excess

Question 15

LFT patterns: ALK phos + GGTP?

Answer 15

biliary disorder eg stones, pancreatic cancer, PBC

Question 16

what does a liver screen consist of

Answer 16

hepatitis viruses
autoantibodies ANA, AMA, AntiSMAb (markers for autoimmune liver disease)
ferritin
caeruloplasmin and alpha-1-antitrypsin
immunoglobulins
and an ultrasound scan and referral