Liver Function Tests

Question 1

AST (indicative of …)

Answer 1

hepatocellular damage
in cytosol and mitochondria
in liver, heart muscle, blood

Question 2

ALT (indicative of …)

Answer 2

hepatocellular damage
in CYTOSOL only
in LIVER only

Question 3

AST and ALT Abnormalities

mild elevation

Answer 3

Less than 5x normal value
Think hepatic dz (viral, EtOH, autoimmune etc.)
… and non-hepatic (hemolysis, myopathy, thyroid dz, strenuous exercise)

Question 4

AST and ALT Abnormalities

severe elevation

Answer 4

Greater than 15x normal
Acute viral (A-E, herpes)
Meds/toxins
Ischemic hepatitis
Autoimmune hepatitis
Wilson
Acute Budd-Chiari syndrome (hepatic vein thrombosis)
Hepatic artery ligation of thrombosis

Question 5

AST/ALT ratio

Answer 5

Normal 1 suggestive of cirrhosis

>2 SUGGESTIVE OF EtOH LIVER DZ

Question 6

Bilirubin (Indicative of …)

Answer 6

Cholestasis, impaired conjugation, or biliary obstruction

[Bilirubin is insoluble in H2O so requires conjugation (via UDP-GT) to be excreted into bile]

Question 7

Bilirubin (Elevated Unconjugated)

Answer 7

Gilbert’s: mutation in UDP-GT so decr UDP-GT, common, 5-10% of western population homozygous

Crigler-Najjar: rare AR, UDP-GT defic. Type 1: severe jaundice, NEURO IMPAIRMENT; Type 2: lower serum bilirubin, NO NEURO IMPAIRMENT

Hemolysis: fasting, fever, physical stress, hemolytic anemia

Question 8

Bilirubin (Elevated Direct)

Answer 8

extrahepatic, intrahepatic, hepatitis, cirrhosis

Question 9

Alkaline Phosphatase (ALP)
(indicative of ...)

Answer 9

Cholestasis, infiltrative dz, biliary obstruction

[Present in nearly all tissues, loclaized to microvili of bile canaliculus in liver]

Question 10

Alkaline Phosphatase (ALP)
(Abnormalities)

Answer 10

Cholestasis, infiltrative dz (sarcoidosis, TB, fungal infx etc.), biliary obstruction
PBC (maybe only presents with ALP elev)
Drug rxn
Non-hepatic (bone dz, pregnancy, renal failure, CHF, lymphoma)

Question 11

Alkaline Phosphatase (ALP)
Isozymes that are liver-specific ...

Answer 11

5’-nucleotidaease (significantly elev ONLY in liver dz)

Gamma-Glutamyltransferace (GGT): NOT present in bone, ELEVATED AFTER ETOH AND ALMOST ALL LIVER DZ

Question 12

Albumin (indicative of …/abnormalities due to …)

Answer 12

Indicative of synthetic dysfunction of liver

Can be due to malnutrition, severe ilness with catabolism of proteins, nephrosis, malabsorption

Question 13

Prothrombin time (can assess …)

Answer 13

extrinsic clotting pathway

synthetic dysfunction of liver (along with albumin)

Question 14

Prothrombin time (abnormalities)

Answer 14

Could be Vit K defic –> administer Vit K to distinguish DEFECT vs DEFICIENCY
(could also be drugs (i.e warfarin) or clotting disorder