Lecture 8-9 (Liver) Flashcards
Major functions of the liver
Carbohydrate metabolism Fat metabolism Protein metabolism Hormone metabolism Drugs and foreign compounds Storage Metabolism and excretion of bilirubin
Metabolic pathway of bilirubin
Hemolysis gives unconjugated bilirubin
Unconjugated becomes conjugated in hepatocyte
Small intestine: conjugated bilirubin becomes urobilinogen which is excreted in feces (90%) and urine (10%)
Name abnormalities of bilirubin metabolism
Gilberts
Crigler-Najjar
Rotor
Dublin-Johnson
Conjugated bilirubin is __ soluble
Unconjugated bilirubin is __ soluble
Water
Lipid
Principle of evelyn-malloy procedure
Bilirubin + diazo = azobilirubin which can be measured colormetrically
Unconjugated bilirubin needs addition of alcohol to interact with diazo
Tests to measure bilirubin
Jendrassik-Grof procedure
Evelyn-malloy procedure
Do liver function test indicate there is something wrong with the liver
No.
However normal LFTs don’t mean the liver is normal.
What are the most used markers of hepatocyte injury
Aspartate aminotrans - ferase (AST) Alanine aminotransaminase (ALT)
ALT - cytosolic
AST - cytosolic & mitochondrial
Example where AST & ALT lack sensitivity in detecting chronic liver disease
Hepatitis C
Serum ALT correlates only moderately well
Found in skeletal muscle too so could be increased after muscle injury
What happen enzymes of the liver in necorsis/hepatitis/injury/ischemic
Enzymes leak into circulation
Which enzyme rises more after toxic liver injury ALT or AST
ALT
What is cholestasis
Lack of bile flow
What does cholestasis result from
Blockage of bile ducts or from disease that impairs bile formation in the liver itself
What rises in cases of cholestasis
AP and gamma glutamyltransferase (GGT)
Other than cholestasis why would AP levels rise
In 3rd trimester of pregnancy because of a form of the enzyme produced in the placenta
Do healthy persons have detectable conjugated bilirubin in their blood
No.
Conjugated bilirubin is conjugated with glucuronic acid in hepatocytes to increase water solubility and transported into bile
What factors make albumin concentrations difficult to interpret
Functional capacity of liver
Half life of albumin in serum (3 weeks)
2/3 of total body albumin ECF
Reasons for low serum albumin (nonhepatic)
Proteinuria
Acute/chronic inflammatory state
Indicators of how well the liver functions
Bilirubin
Albumin
Prothrombin time
Causes of acute liver disease
Poisoning
Infection
Inadequate perfusion
Most common poisons affecting liver
Paracetemol
Carbon tetrachloride
What happens in the case of hepatic failure
Severe metabolic acid-base disturbances
Hypoglycaemia
Renal failure due to exposure of toxins usually metabolised by liver
Failure to synthesis clotting factors - leads to haemorrhage
Three forms of liver damage
Alcoholic fatty liver
Chronic active hepatitis
Primary biliary cirrhosis
Definition of cirrhosis
Disease characterised by the replacement of active liver tissue with an inactive fibrosis mass
Most common causes of cirrhosis
Chronic excess alcohol ingestion
Viral hepatitis
Autoimmune disease
Terminal stage signs of cirrhosis
developing jaundice
encephalopathy
ascites
bleeding tendencies terminal liver failure
