LFTs - amboss Flashcards
ALT is specific to
specific to the cytoplasm of hepatocytes
AST is specific to
present in the liver, heart muscle, and erythrocytes
elevation of ALT and AST
all types of hepatocyte damage, muscle damage, myocardial infarction
significant elevation of AST and ALT
hepatotoxic drugs
some hepatitis subtypes eg. autoimmune, ishchaemic, or acute viral hepatitis
AST/ALT < 1 is called
inflammatory type hepatocellular damage
AST/ALT < 1 can be caused by
uncomplicated viral hepatitis
minor fatty liver disease
extrahepatic cholestasis
AST/ALT > 1 is called
necrotic type hepatocellular damage
AST/ALT >/= 1 can be caused by
alchoholic hepatitis
fulminant, necrotic hepatitis
decompensated cirrhosis
hepatocellular carcinoma, liver mets
muscle damage
myocardial infarction
AST/ALT in alchoholic hepatitis
> 2
AST usually does not exceed 500
AST/ALT in muscle damage
AST is present in skeletal muscle cells more than ALT, so damage to myocytes causes more increase in AST than ALT
cholestasis leads to an increase in
typically leads to an increase in direct (conjugated) bilirubin and induces the production of ALP and GGT
retention of bile salts can also cause hepatocyte damage
fractionating bilirubin
determining total bilirubin and direct bilirubin
can help to differentiate between cholestasis and other causes of hyperbilirubinaemia
cholestasis leads to high direct bilirubin
ALP is found in
isoenzymes found in numerous tissues, inclduing liver, bones, placenta and kidney
GGT is found in
most sensitive for liver and biliary tract
usually the first enzyme to rise after bile duct obstruction
ALP elevation
cholestasis (obstructive or non obstructive)
infiltrative diseases of the liver (malignancies or amyloidosis)
increased osteoblast activity
seminoma
pregnancy (third trimester)
chronic kidney disease
GGT elevation
cholestasis
alchohol use
not elevated in bone diseae
unconjugated bilirubin is
lipophillic and water soluble
conjugated bilirubin is
water soluble
unconjugated bilirubin elevation
overpoduction (extra-hepatic)
- hemolysis
- large hematomas
- ineffective erythropoiesis
impaired uptake (pre-hepatic)
- congestive heart failure
- portosystemic shunts
- drugs
impaired conjugation (intrahepatic)
- gilbert syndrome
- neonates
- chronic hepatitis
- advanced cirrhosis
- hyperthyroidism
conjugated bilirubin elevation
cholestasis
Dublin-johnson syndrome
rotor syndrome
conjugated bilirubin rise in cholestasis
obstructive (extrahepatic) causes
- choledocholithiasis
- tumours
- primary sclerosing cholangitis
- pancreatitis
- strictures
- parasitic infections
non obstructive (intrahepatic) causes
- hepatitis
- primary biliary cholangitis
- drugs
- sepsis
- infiltrative disease
- pregnancy
parameters of hepatic synthesis
albumin
PT and INR
platelet count
albumin elevation
dehydration
albumin reduction
liver cirrhosis
loss of protein
malnutrition
acute or chronic inflammation
PT and INR elevation
decreased hepatic production of coagulation factors eg. in liver cirrhosis
platelet count reduction
liver cirrhosis
portal hypertension leading to hypersplenism and increased platelet sequestration