liver pathophysiology Flashcards
what is jaundice?
Yellow discolouration of sclera and skin – due to hyperbilirubin (>50umol/L)
what is the cause of pre-hepatic jaundice?
excessive RBC breakdown – overwhelming livers ability to conjugate bilirubin and causes unconjugated hyper bilirubin
- can not bind bile and hence remains in blood stream
what conditions can lead to pre-hepatic jaundice?
haemolytic anaemia, gilberts syndrome, criggler- Najjar
how does stool and urine present with pre hepatic jaundice?
normal
what is hepatocellular jaundice?
dysfunction of hepatic cells. liver loses ability to conjugate bilirubin.
- Can come cirrhotic and this compresses intra-hepatic portions of biliary tree and causing obstruction
- Can have both unconjugated and conjugated bilirubin
what conditions can cause hepatocellular jaundice?
alcoholic liver disease, viral hep, iatrogenic, HH, autoimmune hep, primary biliary cirrhosis or PSC, hepatocellular carcinoma
what does the stool and urine present as with hepatocellular jaundice?
- Dark urine + normal stools
what is the aetiology of post hepatic jaundice?
obstruction of biliary drainage. Bilirubin will not be excreted even though it is conjugated by the liver.
what type of bilirubin is seen in post hepatic jaundice?
conjugated hyperbilirubin
what type of hyper bilirubin is seen in hepatocellular jaundice?
mixed - unconjugated and conjugated
what would urine and stools present with post hepatic jaundice?
dark urine and pale stools
what conditions cause post hepatic jaundice?
gallstones, drug induced cholestasis, pancreatic cancer or abdo masses
how is jaundice treated?
- Symptomatic: often needed for itching caused by hyperbilirubin – obstructive may need cholestyramine and others may need anti-histamine
- Monitor for complications: coagulopathy, constipation
what can cause drug induced hepatotoxicity?
can be acute or chronic liver injury secondary to drugs or herbal compounds
what is intrinsic drug induced hepatoxicity?
both predictable and reproducible from drugs known to cause liver injury in dose dependent manner with short latency period eg acetaminophen toxicity
what is idiosyncratic drug induced hepatotoxicity?
unpredictable course and not reproducible, has variable latency periods. Can be further divided into immune mediated (allergic) from hypersensitivity or non immune mediated metabolic – mitochondrial injury
what is ALT?
alanine transaminase
what is alkaline phosphatase?
ALP
where is high ALT found normally?
within hepatocytes - enters following hepatic injury
where is ALP high?
particularly high in liver, bile and bone tissues. Often raised in liver pathology due to increases synthesis of cholestasis
what ALT/ ALP numbers would indicate hepatocellular injury?
- Greater than 10 fold in ALT + less than 3 fold increase in ALP
what ALP/ ALT scores would indicate cholestasis?
- Less than 10 fold increase in ALT + more than 3 fold increase in ALP
what is GGT?
gamma-glutamyl transferase
when would you check GGT?
is rise in ALP
what can GGT indicate?
- Can suggest biliary epithelial damage and bile flow obstruction
- Can also be raised in response to alcohol and drugs such as phenytoin
what does raised GGT and raised ALP indicate?
cholestatsis
what would isolated raise in ALP indicate?
non-hepatobiliary pathology
- Causes of isolated raise in ALP: bony metastases/ primary bone tumour, vitD deficiency, recent bone fracture, renal osteodystrophy
what condition is most likely if raise in bilirubin (NO ALP/ ALT RAISE)
gilberts syndrome
what is gilberts syndrome?
mild liver genetic disease - can not metabolise bilirubin as normal
what investigations can be done to assess liver function?
serum bilirubin, serum albumin, prothrombin time (PT), serum blood glucose
what is the function of albumin?
synthesised in the liver – helps bind water, cations, fatty acids ad bilirubin – plays key role in maintaining oncotic pressure
how can cirrhosis effect albumin?
liver disease resulting in decreased production of albumin (cirrhosis)
how does cirrhosis effect albumin?
- Inflammation triggering acute phase response which temporarily increases livers production of albumin
- Excessive loss of albumin due to protein-losing enteropathies or nephrotic syndrome
what does PT measure?
Prothrombin time (PT): measure of blood coagulation tendency – specifically extrinsic way
what does ALT > AST indicate?
chronic liver disease
what does AST > ALT indicate?
cirrhosis and acute alcoholic hepatitis
does gluconeogenesis become impacted by liver disease?
- Gluconeogenesis tends to be one of last functions to become impaired in context of liver failure
what are common causes of acute hepatocellular injury?
- Poisoning (paracetamol overdose)
- Infection – hepA and B
- Liver ischaemia
what are common causes of chronic hepatocellular injury
- Alcoholic fatty liver disease
- Non-alcoholic fatty liver disease
- Chronic infection – Hep B/ C
- Primary biliary cirrhosis
what are less common causes of chronic hepatocellular injury?
alpha -1-antitrypsin deficiency, wilsons, HH
what would increase in PT/ INR and decrease in platelets indicate?
chronic liver disease
what factors can contribute to decreases platelets?
- Many factors contribute to give low platelet: decreased production – bone marrow suppression which can be caused by alcohol, iron overload, drugs and chronic liver injury, splenic sequestrian – hypersplenism which is a consequence of portal hypertension, increased destruction - liver cirrhosis owing shear stress, fibrinolysis and bacterial translocation, autoimmune dysfunction can also result in platelet destruction.
how does liver disease tend to progress?
Liver disease tends to progress silently with no symptoms until later stages.