liver function test

Question 1

abnormalities in LFT

Answer 1

1) hepatocellular injury: disproportional elevation of AST/ALT as compared to ALP
2) cholestatic injury: disproportional elevation of ALP compared to AST/ALT
3) isolated bilirubinemia: elevation of serum bilirubin with normal ALP, AST/ALT

Question 2

R ratio formula

Answer 2

R = (ALT/ALT upper limit normal) / (ALP/ALP upper limit normal)

Question 3

what is R ratio used for

Answer 3

. to determine what type of injury when AST/ALT and ALP both elevated
. R > 5: hepatocellular injury
. R < 2: cholestatic injury
2 < R < 5: mix of both

Question 4

when to use GGT

Answer 4

confirm rise in ALP of hepatic origin
but not very specific for liver disease

Question 5

cholestatic liver injury (extra vs intra)

Answer 5

. extra hepatic: biliary obstruction
. intra hepatic: functional impairment of hepatocytes to form bile

Question 6

causes of increase in direct and indirect bilirubin

Answer 6

indirect (unconjugated): overproduction of bilirubin (increase haemolysis), decreased hepatic uptake/conjugation

direct (conjugated): presence of parenchymal liver disease, biliary obstruction

Question 7

what is serum albumin and prothrombin time used for

Answer 7

to measure synthetic function of liver

Question 8

AST/ALT

Answer 8

. usually ALT > AST
. alcoholic liver disease: AST > ALT