Chempath: LFTs + Cases Flashcards
What are the different LFTs?
AST (aspartate aminotransferase)
ALT (alanine transaminase)
ALP (alkaline phosphatase)
GGT (gamma glutamyltransferase)
Bilirubin
Albumin
What is the best measure of liver function?
prothrombin time (PT)
or albumin
What do these do the following LFT results mean?
AST and ALT are high
AST > ALT
ALT > AST
AST and ALT are high: Hepatocyte damage (e.g. hepatitis)
AST > ALT: Alcoholic hepatitis (S for Smirnoff)
ALT > AST: Viral hepatitis (L for ViraL)
What extra ix can be performed in people w/ raised AST and ALT?
Bloods
- Clotting
- Antibodies (e.g. anti-SMA)
Hepatitis serology
Abdo U/S
Liver biopsy
What do these do the following LFT results mean?
ALP and GGT are high
ALP > GGT
GGT > ALP
ALP and GGT are high Biliary obstruction (gallstones, Pancreatic cancer)
ALP > GGT
Bone problem? (osteomalacia, Paget’s)
Pregnancy?
GGT > ALP
Recent alcohol intake
What extra ix are required in these pts?
Bloods
- Clotting
- CA19-9 (pancreatic cancer)
- Calcium + phosphate
- Blood alcohol level
Abdo U/S
- Dilated bile ducts (obs cause): gallstones, pancreatic cancer
- Non-dilated bile ducts: PBC, PSC, pregnancy, co-amoxiclav
Liver biopsy
What causes are there of high bilirubin levels?
Pre-hepatic
- Haemolytic anaemia
Hepatic
- Hepatitis
- PBC/PSC
- Gilbert syndrome
Post-hepatic
- Biliary obstruction (gallstones, pancreatic cancer)
Describe how bilirubin is excreted normally
Unconjugated bilirubin is converted to conjugated bilirubin by UDP-glycoronyl-transferase (affected in Gilberts)
This unconjugated bilirubin is converted by colonic bacteria to urobilinogen (makes urine yellow - some is reabsorbed via enterohepatic circulation) and stercobilinogen (makes poo brown)
How is normal bilirubin excretion affected in obstructive jaundice?
Here conjugated bilirubin can’t get converted to urobilinogen by the colonic bacteria as a result:
- No stercobilinogen in stool -> Pale stools
- Urobilinogen in urine is replaced by conjugated BR -> Dark urine
- No urobilinogen is found in enterohepatic circulation
Which of the following is found in obstructive jaundice?
There is increased bilirubin in urine The stools are dark GGT is usually normal AST is usually normal ALP is usually normal
There is increased bilirubin in urine
The stools are dark
GGT is usually normal - very high
AST is usually normal - may be slightly raised
ALP is usually normal - very high
Which of the following is found in haemolytic jaundice?
Bilirubin is normal AST is raised CK is raised The stools are pale There is increased urobilinogen in urine
There is increased urobilinogen in urine - increased bilirubin causes raised everything:
- Unconjugated BR
- Conjugated BR
- Urobilinogen
- Stercobilinogen
What do blood tests reveal in haemolytic anaemia?
= ↑ unconjugated BR
= ↑ urobilinogen (in urine)
= ↑ LDH
= ↓ haptoglobin
(protein that binds to free Hb)
What can be found in Gilbert syndrome blood tests?
↑ unconjugated BR
↔ AST, ALT, ALP, GGT
What do blood tests reveal in a obstructive jaundice?
= ↑ conjugated BR
= ↓ urobilinogen (in urine)
What is the difference between the two best measures of liver function?
Low albumin - this has a long 1/2 life hence this is a marker of chronic liver damage
High Prothrombin time (poor clotting factor production) - this has a shorter 1/2 life hence indicates acute damage
