Liver Function Tests

Question 1

what are transaminases?

Answer 1

hepatic enzymes that are usually intracellular, but are released from hepatocytes in context of hepatocellular injury

Question 2

where is alanine aminotransferase (ALT) located?

Answer 2

cytosol-located in the liver

Question 3

where is aspartate aminotransferase (AST) located?

Answer 3

in cytosol and mitochondria, present in liver, heart, pancreas, skeletal muscle, brain. lungs, RBCs and WBCs

Question 4

what is the half life of ALT?

Answer 4

47hours

Question 5

what is the half life of AST?

Answer 5

17hours

Question 6

when might aminotransferases be increased?

Answer 6

in hepatocellular pathologies

Question 7

what are alkaline phosphatase?

Answer 7

enzymes that catalyse the hydrolysis of a number of organic phosphate esters

Question 8

what is the half life of alkaline phosphatase?

Answer 8

1 week

Question 9

what is the origin of alkaline phosphatase?

Answer 9

biliary cholestasis enhances synthesis and release of ALP
bone 
placenta
intestine
kidney

Question 10

what is bilirubin?

Answer 10

a breakdown product of heme, transported to liver bound to albumin, uptake into the hepatocytes, undergoes conjuction, exctered via urine/feaces

Question 11

what does prothrombin time (PT) measure?

Answer 11

conversion time from PT > thrombin and thus reflects a vital component of the liver

Question 12

what may elevated PT reflect?

Answer 12

reduced synthetic functionality

Question 13

what are other causes of PT prolongation?

Answer 13

drugs
bile malabsorption causing vit K deficiency
consumptive coagulopathies
congenital coagulopathy