Chem path 11 - LFTs Flashcards
What are some consequences of liver failure?
Hypoglycaemia
Lactic acidosis
Hyperammonaemia
Outline the process of xenobiotic metabolism
- Chemical modification: P450 enzyme system, acetylation/de-acetylation, oxidation/reduction
- Conjugation: glucuronation/sulphation
- Excretion
Outline the process of bilirubin metabolism and transporit
RBCs are broken down in to heme, iron and globin
The heme then goes on to form bilirubin –> bound to albumin in the plasma
The uBr goes to the liver to be glucuronidated i.e. conjugated
The cBr is released in to the bile
What are the two reticulo-endothelial functions of the liver?
Kuppfer cells (clearance of infection and LPS, antigen presentation, immune modulation) Erythropoietin
What are the markers of liver cell damage?
ALT
AST
ALP
GGT
What are the synthetic markers of liver function?
Albumin and PT
What does the portal triad consist of?
Portal vein
Portal artery
Bile duct
Where are zones 1 and 3 of the liver?
Zone 1 = periportal
Zone 3 = centrilobular
What does an AST:ALT >2 indicate?
Alcoholic liver disease
In the absence of alcohol, what does an AST:ALT >0.8 suggest?
Advanced fibrosis or cirrhosis
Where is GGT found in the liver?
in the hepatocytes and in the epithelial cells lining the bile duct
When does GGT rise?
Chronic alcohol use, Bile duct obstruction and hepatic metastases
Where is ALP found?
Bone Liver Intestine Placenta BLIP High in bone disease and pregnancy
What is the major protein synthesised by the liver?
Albumin
What is the half life of albumin and why is this significant?
long half-life of 20 days therefore it only really goes down in chronic liver disease
What are some causes of low albumin?
Low production states (chronic liver disease, malnutrition)
Losses(nephrotic syndrome, gutlosing enteropathy)
Sepsis - 3rd spacing (commonest cause in hospitals)
What are PT and INR markers of?
aCUTE liver function as their half lives are a matter of hours
Is aPTT or PT extrinsic or intrinsic pathway?
aPTT - Intrinsic
PT - extrinsic
What is the serum marker for HCC?
AFP (also rasied in testicular cancer, pregnancy)
Where is AFP produced in the foetus?
Yolk sac, GI epithelium, liver
If a patient has jaundice and a raised bilirubin, a cholestatic picutre (i.e. raised ALP), what would the differentials be if there were dilated or undilated bile ducts
Dilated: gallstones, cancer
Undilated: PBC/PSC, pregnancy
On urine dipstick, should there ever be any bilirubin?
No
Can uBr or cBr be found in the urine?
Only conjugated –> dark urine
What is urobilinogen?
A breakdown product of bilirubin in the intestines by bacteria. It is soluble so some of it will enter enterohepatic circulation and be found in small amounts in urine.
