Functions of Liver and LFT Flashcards
What are the functions of the liver (4)
Synthesis
Detoxification
Immune
Storage
What does the liver synthesise
Clotting factors
Bile acids
Carbohydrate metabolism
Proteins - Albumin
Lipids - cholesterol, lipoprotein, triglyceride
Hormones - angiotensin, insulin-like growth factor
What does the liver detoxify / metabolise / breakdown
Ammonia –> Urea
Drugs
Bilirubin
Insulin and hormones
What immune role does the liver have
Clearing blood of bacteria and particles
Neutralising all drugs and toxins
What does the liver store
Glycogen
Vitamin A, D, B12, K
Copper and Iron
What liver function tests can be done
Bilirubin Aminotransferases (AST, ALT) Alkaline Phosphatase (ALP) Gamma GT Albumin Prothrombin Time Creatinine Platelet Count
What is bilirubin, where is it generated and what is it initially bound to
A by product of haem metabolism generated by senescent RBC’s in spleen.
Initially bound to albumin (unconjugated) and solubilised in the liver (conjugated)
When is bilirubin elevated (pre-hep, hep and post-hep)
Pre-hepatic - haemolysis
Hepatic - parenchymal damage
Post-hepatic - obstructive
What are aminotransferases and which is more specific
Enzymes present in hepatocytes
- Alanine (ALT) - specific
- Asparate (AST)
What can the AST/ALT ratio suggest
Alcoholic liver disease
Parenchymal involvement
What is alkaline phosphatase (ALP)
Enzyme present in bile ducts
When is ALP elevated
With obstruction or liver infiltration
Where is ALP also present in
Bone, placenta and intestines
- therefore, elevation is not indicative of liver disease
What is Gamma GT and when is it elevated
A non-specific liver enzyme
Elevated with alcohol use - can be used to measure patient compliance
NSAIDS can raise levels
What can gamma GT confirm
Liver source of ALP
What does albumin test and what do low levels suggest
Synthetic function of liver
Low levels suggest chronic liver disease, kidney disorders and malnutrition
What does prothrombin time indicate
Degree of liver dysfunction
Used to calculate scores to decide the stage of liver disease and who gets a liver transplant
What is creatinine and when is it used
Assesses kidney function
Determines survival from liver disease so used as assessment for need for transplant
Why can platelet count be used to test liver function
Liver sources thrombopoietin which drives the bone marrow to produce platelets
How does cirrhosis affect platelet count
Cirrhosis results in splenomegaly as when the liver is scarred blood can’t flow through the liver
This results in low platelets in cirrhotic patients
Is an indirect marker of portal hypertension
