Liver failure (45) Flashcards
What is normal plasma bilirubin?
17 micromol/L
- if [BR] > 30 –> yellow sclera and mucous membranes
- if [BR] > 34 –> skin turns yellow
What is cholestasis?
- slow/cessation of bile flow
- normally results in jaundice
What are pre-hepatic causes of jaundice?
- haemolysis
- massive blood transfusion (transfused erythrocytes short-lived)
- large haematoma resorption
- ineffective erythropoiesis–> overproduction of haem
What are intrahepatic causes of jaundice?
- Gilberts syndrome: dec. BR uptake into liver, so raised unconjugated BR
- Crigler-Najar syndrome: dec. conjugation of BR
- Dubin-Johnson + Rotor syndrome: dec. secretion of BR into biliary canaliculi
^^^ autosomal recessive disorders - intrahepatic cholestasis
- liver failure: acute and chronic
When does liver failure occur?
- when rate of hepatocyte death> hepatocyte regeneration
- combination of apoptosis and necrosis (ischaemia–> most affects zone 3, bc furthest away from blood supply)
- can cause catastrophic illness and lead to coma/death
What are the 2 types of acute liver failure?
- fulminant hepatic failure= rapid development of sever acute liver injury < 8weeks–> impaired synthetic function and encephalopathy
- sub-fulminant= < 6months
What are the causes of acute liver failure?
- paracetamol overdoses
- amanita phalloides mushroom
- bacillus cereus
- exacerbations of chronic hep B (Hong Kong)
- hep E (India)
- pregnancy diseases: AFLP, HELLP syndrome, hepatic infarction, HEV, Budd-Chiari
- idiosyncratic drug reactions: single agent or drug combination
- vascular diseases: ischaemic hepatitis, post-OLTx hepatic artery thrombosis, post-arrest, VOD
- Wilson’s disease, Reye’s syndrome
What are the causes of chronic liver failures?
- inflammation: chronic persistent viral hepatitis
- alcohol abuse
- cardiovascular disease: hepatic congestion due to right sided heart failure
- side effects of drugs
- inherited diseases: galactosaemia, alpha1-antitrypsin deficiency, glycogen storage diseases, Wilson’s disease
- non alcoholic steatohepatitis
- autoimmune hepatitis, PBC, PSC
What are the consequences of liver failure?
- X production of clotting factors (except vwf and factor VIIIC)–> coagulopathy and bleeding
- X protein synthesis–> ascites bc inability to produce enough protein to retain fluid in the bloodstream
- X detoxification–> encephalopathy and cerebral oedema
- X glycogen storage–> hypoglycaemia
- inc. susceptibility to infection bc liver has immunological function
- renal failure and circulatory collapse
Which clotting factors are dependent on vitamin K?
prothrombin (II), VII, IX and X
What are the consequences of cholestasis?
bile leaks through tight junctions
- jaundice bc inc. BR
- pruritus/itching bc bile salts
- cholesterol deposition
- malabsorption in small intestine
- cholangitis
What are the consequences of portal hypertension?
- blood cannot enter portal vein, so goes through small vessels/ forms portosystemic shunts–> they enlarge
- splenomegaly bc blood backs up here–> thrombocytopenia bc spleen traps platelets
- oesophageal varices (enlarged oesophageal veins)–> easily ruptured–> bleeding
- exudative enteropathy: bowel exudes protein
What are the causes of portal hypertension?
prehepatic - portal vein thrombosis, causing obstruction intrahepatic - cirrhosis - schistosomiasis - sarcoidosis (inflammatory cells form granulomas) posthepatic - right sided heart failure - constrictive pericarditis
What is encephalopathy and what causes it?
tremor, apathy, memory gaps
- hyperammonaemia
- hypokalaemia
- toxins bypassing liver and not being extracted
- false transmitters being released e.g. serotonin
What parameters can be used to assess the severity of liver failure?
- total bilirubin
- serum albumin
- INR
- ascites
- hepatic encephalopathy
Child-Pugh score system
